File: howtos.tex

package info (click to toggle)
dvdisaster 0.79.5-10
  • links: PTS, VCS
  • area: main
  • in suites: bullseye, sid
  • size: 42,960 kB
  • sloc: ansic: 33,411; sh: 4,898; makefile: 138
file content (4264 lines) | stat: -rw-r--r-- 145,530 bytes parent folder | download | duplicates (3)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
3732
3733
3734
3735
3736
3737
3738
3739
3740
3741
3742
3743
3744
3745
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
3761
3762
3763
3764
3765
3766
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
3797
3798
3799
3800
3801
3802
3803
3804
3805
3806
3807
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
3825
3826
3827
3828
3829
3830
3831
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
3869
3870
3871
3872
3873
3874
3875
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976
3977
3978
3979
3980
3981
3982
3983
3984
3985
3986
3987
3988
3989
3990
3991
3992
3993
3994
3995
3996
3997
3998
3999
4000
4001
4002
4003
4004
4005
4006
4007
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
4023
4024
4025
4026
4027
4028
4029
4030
4031
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
4052
4053
4054
4055
4056
4057
4058
4059
4060
4061
4062
4063
4064
4065
4066
4067
4068
4069
4070
4071
4072
4073
4074
4075
4076
4077
4078
4079
4080
4081
4082
4083
4084
4085
4086
4087
4088
4089
4090
4091
4092
4093
4094
4095
4096
4097
4098
4099
4100
4101
4102
4103
4104
4105
4106
4107
4108
4109
4110
4111
4112
4113
4114
4115
4116
4117
4118
4119
4120
4121
4122
4123
4124
4125
4126
4127
4128
4129
4130
4131
4132
4133
4134
4135
4136
4137
4138
4139
4140
4141
4142
4143
4144
4145
4146
4147
4148
4149
4150
4151
4152
4153
4154
4155
4156
4157
4158
4159
4160
4161
4162
4163
4164
4165
4166
4167
4168
4169
4170
4171
4172
4173
4174
4175
4176
4177
4178
4179
4180
4181
4182
4183
4184
4185
4186
4187
4188
4189
4190
4191
4192
4193
4194
4195
4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
4206
4207
4208
4209
4210
4211
4212
4213
4214
4215
4216
4217
4218
4219
4220
4221
4222
4223
4224
4225
4226
4227
4228
4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
4263
4264
\newcommand{\goodcd}{\includegraphics[width=15mm]{icons/good-cd.png}}
\newcommand{\badcd}{\includegraphics[width=16mm]{icons/bad-cd.png}}
\newcommand{\badcdone}{\includegraphics[width=19mm]{icons/bad-cd1.png}}
\newcommand{\goodimage}{\includegraphics[width=13mm]{icons/good-image.png}}
\newcommand{\goodimagetwo}{\includegraphics[width=13mm]{icons/good-image2.png}}
\newcommand{\badimage}{\includegraphics[width=15mm]{icons/bad-image.png}}
\newcommand{\oldcd}{\includegraphics[width=15mm]{icons/old-cd.png}}
\newcommand{\oldimage}{\includegraphics[width=15mm]{icons/old-image.png}}
\newcommand{\augmentedcd}{\includegraphics[width=15mm]{icons/augmented-cd.png}}
\newcommand{\eccfile}{\includegraphics[width=13mm]{icons/ecc-file.png}}
\newcommand{\backupone}{\includegraphics[width=18mm]{icons/backup1.png}}
\newcommand{\backuptwo}{\includegraphics[width=19mm]{icons/backup2.png}}
\newcommand{\rightarr}{\includegraphics[width=11mm]{icons/right-arrow.png}}
\newcommand{\downarr}{\includegraphics[height=11mm]{icons/down-arrow.png}}
\newcommand{\downforkarr}{\includegraphics[height=11mm]{icons/down-fork-arrow.png}}
\newcommand{\rdiagarr}{\includegraphics[height=9mm]{icons/rdiag-arrow.png}}
\newcommand{\ldiagarr}{\includegraphics[height=9mm]{icons/ldiag-arrow.png}}
\newcommand{\joinarr}{\includegraphics[height=11mm]{icons/join-arrow.png}}

\newcommand{\slotin}{\includegraphics[height=17mm]{icons/slot-in.png}}
\newcommand{\filemanager}{\includegraphics[height=20mm]{icons/filemanager.png}}
\newcommand{\selectdrive}{\includegraphics[height=10mm]{icons/select-drive.png}}
\newcommand{\selectimage}{\includegraphics[height=8.5mm]{icons/select-image.png}}
\newcommand{\selectecc}{\includegraphics[height=8.5mm]{icons/select-ecc.png}}
\newcommand{\scanicon}{\includegraphics[height=13mm]{icons/scan-icon.png}}
\newcommand{\readicon}{\includegraphics[height=13mm]{icons/read-icon.png}}
\newcommand{\createicon}{\includegraphics[height=13mm]{icons/create-icon.png}}
\newcommand{\fixicon}{\includegraphics[height=13mm]{icons/fix-icon.png}}
\newcommand{\verifyicon}{\includegraphics[height=13mm]{icons/verify-icon.png}}
\newcommand{\stopicon}{\includegraphics[height=13mm]{icons/stop-icon.png}}
\newcommand{\logicon}{\includegraphics[height=6mm]{icons/log-icon.png}}

\section{Typical applications - HowTos}
\label{howtos}

dvdisaster is a complex tool which would require a book of a few hundred pages
to cover all of its features. Since we are currently lacking the resources for
doing such a book (and you might be short on reading time also) we will take
a different approach in this section. First we demonstrate how the different functions
of dvdisaster work together. Then we describe common tasks and provide
step by step instructions for solving them. In most cases following these steps
will be all you need to do. At the end of each instruction set a discussion
of further configuration options is included for advanced users.

\subsection{Symbols used in this document}

Working with dvdisaster requires certain combinations of optical media,
media images and error correction data. Check out the following symbols to
find out what you will need for the respective tasks:

\paragraph{Medium} (a CD for example):

\bigskip

\begin{tabular}{ccl}
  \begin{minipage}{20mm}
  \centerline{\goodcd}
  \end{minipage}
  &
  \begin{minipage}{20mm}
  \centerline{\badcd}
  \end{minipage}
  &
  \begin{minipage}{93mm}
  These symbols indicate whether processing a medium is part of the
  respective task, and if the medium needs to be completely error free or may already be damaged. 
  \end{minipage}\\
  & & \\

  good medium & bad medium & \\
  ({\bf no} read errors) & ({\bf with} read errors) & \\
\end{tabular}

\paragraph{Medium image} (ISO image of a medium stored on the hard disk):

\bigskip

\begin{tabular}{ccl}
  \begin{minipage}{20mm}
  \centerline{\goodimage}
  \end{minipage}
  &
  \begin{minipage}{20mm}
  \centerline{\badimage}
  \end{minipage}
  &
  \begin{minipage}{93mm}
    Some functions do not work directly with the medium, but with an ISO image
    on hard disk instead. Depending on the condition of the respective medium the
    image may be complete or incomplete.
  \end{minipage}\\
  & & \\

  complete image & incomplete image & \\
  (made from  & (made from & \\
  good medium) & bad medium) & \\
\end{tabular}

\paragraph{Error correction data}\quad

\bigskip

\begin{tabular}{ccl}
  \begin{minipage}{20mm}
  \centerline{\augmentedcd}
  \end{minipage}
  &
  \begin{minipage}{20mm}
  \centerline{\eccfile}
  \end{minipage}
  &
  \begin{minipage}{93mm}
    Recovering media images by using error correction data is the
    key feature of dvdisaster. These symbols show whether error
    correction data is required.
  \end{minipage}\\
  & & \\

  Medium containing & Separate error& \\
  error correction data   & correction file & \\
\end{tabular}


\subsection{The big picture - understanding dvdisaster}

In this sub section we are getting a basic understanding
of dvdisaster:

\begin{itemize}
\item It is important to understand that dvdisaster works similar
  to a \tlnk{bigpicture-backup}{conventional backup} in some
  regards, but that there are also important differences.
\item The general
  \tlnk{bigpicture-ecc}{idea of the error correction} is explained.
\item Jane demonstrates the
  \tlnk{bigpicture-goodusage}{proper usage of dvdisaster}.
  She will create error correction data in advance and is
  therefore able to recover all data when her media become defective.
\item However you should \tlnk{bigpicture-badusage}{not follow the way}
  of Joe. He does not use error correction data and finds out that
  his defective media are not recoverable even after multiple
  reading passes. As a consequence he loses data from a defective medium.
\end{itemize}

Of course these stories are purely fictional and any similarities with existing persons or situations are purely conincidental. 

\subsubsection{A comparison of dvdisaster with conventional backup}
\label{bigpicture-backup}

dvdisaster stores data on optical discs in a way that the data
is fully recoverable even after the medium has developed some read errors.
The method employed in dvdisaster uses less storage space (or additional media)
than a full backup would do. Before using dvdisaster it is important to
understand the similarities and differences between dvdisaster and a
conventional (full) backup.

\bigskip

Let's first consider how a conventional backup scheme works:

\bigskip

\begin{tabular}{cccl}
  \begin{minipage}{20mm}
  \centerline{\backupone}
  \end{minipage}
  &
  \begin{minipage}{12mm}
  \centerline{Copy}\par
  \centerline{\rightarr}
  \end{minipage}
  &
  \begin{minipage}{20mm}
  \centerline{\backuptwo}
  \end{minipage}
  &
  \begin{minipage}{92mm}
    An existing medium (1) is copied onto a backup medium (2).
  \end{minipage}\\

  \begin{minipage}{20mm}
  \centerline{\downarr}
  \end{minipage}
  &
  &
  \begin{minipage}{20mm}
  \centerline{\downarr}
  \end{minipage}
  & \\[4mm]

  \begin{minipage}{20mm}
  \centerline{\badcdone}
  \end{minipage}
  &
  &
  \begin{minipage}{20mm}
  \centerline{\backuptwo}
  \end{minipage}
  &
  \begin{minipage}{92mm}
    If any one of the two media is damaged afterwards,
    we still have an intact medium left.
  \end{minipage}\\
\end{tabular}

\bigskip

There are actually some cases where it is important to keep a
second copy of an optical disc: One medium might get lost,
burst while spinning in the drive, or it may be destroyed due
to mishandling. However such cases of complete data loss are
rare as long as optical media are handled properly.

\smallskip

It is more likely that the medium starts to gradually lose data
after a few years - a nearly unavoidable aging process.
When the medium is regularly used (or scanned for defects)
the data loss will typically be noticed after 5\% to 10\% of
the medium have already become unreadable. At this point
the medium is unusable as a whole, but maybe 90\% of
it is still readable. {\em On the other hand a full backup copy
of the medium is not required; we simply need a method for
recovering the missing 10\% of data.}

\smallskip

This is where dvdisaster comes into play. Consider this:

\bigskip

\begin{tabular}{cccl}
  \begin{minipage}{20mm}
  \centerline{\goodcd}
  \end{minipage}
  &
  \begin{minipage}{12mm}
    \centerline{Create}\par
    \centerline{\rightarr}\par
    \centerline{ECC}
  \end{minipage}
  &
  \begin{minipage}{20mm}
  \centerline{\eccfile}
  \end{minipage}
  &
  \begin{minipage}{92mm}
    This time we do not make a full backup. dvdisaster is used
    to create error correction data (``ECC'') which can recover
    up to 20\% of a degraded medium. The value of 20\% was
    chosen to have a safety margin over the expected data loss
    of 5-10\%. 
  \end{minipage}\\

  \begin{minipage}{20mm}
  \centerline{\downarr}
  \end{minipage}
  &
  &
  \begin{minipage}{20mm}
  \centerline{\downarr}
  \end{minipage}
  & \\[4mm]

  \begin{minipage}{20mm}
  \centerline{\badcd}
  \end{minipage}
  &
  &
  \begin{minipage}{20mm}
  \centerline{\eccfile}
  \end{minipage}
  &
  \begin{minipage}{92mm}
    Wenn the medium fails at a later time, its contents are
    recovered from its still readable parts and from the
    error correction data.
  \end{minipage}\\[8mm]

  \begin{minipage}{20mm}
  \mbox{80\%\rdiagarr}
  \end{minipage}
  &
  &
  \begin{minipage}{20mm}
  \mbox{\ldiagarr20\%}
  \end{minipage}
  &
  \begin{minipage}{92mm}
    For a successful recovery at least 80\% of the data must
    still be readable from the medium, and the remaining 20\% are
    recalculated from the error correction data.
  \end{minipage}\\[7mm]

  \multicolumn{3}{c}{\begin{minipage}{20mm}\centerline{\goodimage}\end{minipage}}
  &
  \begin{minipage}{92mm}
  The completely recovered data is now available as an ISO image
  on the hard drive (the medium remains defective as physical
  data loss is irrevocable).
  \end{minipage}\\[8mm]

  \multicolumn{3}{c}{\begin{minipage}{20mm}\centerline{\downarr}\end{minipage}}
  &
  \begin{minipage}{92mm}
    Write the image to a blank medium using your favourite
    optical disc authoring software.
  \end{minipage}\\[6mm]

  \multicolumn{3}{c}{\begin{minipage}{20mm}\centerline{\goodcd}\end{minipage}}
  &
  \begin{minipage}{92mm}
  You now have a new error-free medium.
  \end{minipage}\\
\end{tabular}

\bigskip

As you have seen the data recovery took more steps then
doing a conventional backup and restore. So let's summarize the pros
and cons of dvdisaster compared with conventional backup:

\bigskip

\paragraph{Advantages}\quad 	

\begin{itemize}
\item dvdisaster uses less storage. When using error correction
  data with a 20\% recovery capability, protecting 5 media
  requires only one additional medium for the ECC data.
\item  Since all media will eventually age and start losing data in
  similar places (typically in the outermost region),
  doing a 1:1 copy might not help at all. Both copies may turn
  out defective in the same places after a few years.
\end{itemize}

\paragraph{Similarities}\quad

\begin{itemize}
\item Both backup copies and error correction data must
  be created before the master disc fails. You can't create
  them from an already defective medium.
\end{itemize}

\paragraph{Disadvantages}

\begin{itemize}
\item If the recovery capability of the error correction
  data is exceeded (or the medium gets lost), no data
  can be recovered! Especially take note that error
  correction data with a repair rate of 20\% together
  with a 75\% readable medium does not result
  in 95\% recovery. In that case, nothing beyond the 75\% readable
  data from the medium can be recovered.
\end{itemize}

Some of these points are also discussed in
\tlnk{overview-backup}{Error correction data vs. full backup} in the
``Overview'' section, from a slightly different view point.

\subsubsection{The idea behind the error correction}
\label{bigpicture-ecc}

\bigskip

\begin{tabular}{cccl}
    \begin{minipage}{20mm}
  \centerline{\badcd}
  \end{minipage}
  &
  &
  \begin{minipage}{20mm}
  \centerline{\eccfile}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    The example from the previous page told us how dvdisaster
    reconstructs data by using the still readable parts
    of the medium together with the error correction data.
  \end{minipage}\\[8mm]

  \begin{minipage}{20mm}
  \mbox{80\%\rdiagarr}
  \end{minipage}
  &
  &
  \begin{minipage}{20mm}
  \mbox{\ldiagarr20\%}
  \end{minipage}
  & \\[-3mm]

  \multicolumn{3}{c}{\begin{minipage}{20mm}\centerline{\goodimage}\end{minipage}}
  &
  \begin{minipage}{104mm}
    In order to get the most out of dvdisaster a basic
    understanding of the error correction method is helpful.
    And while we are at it we can refute a misunderstanding we
    sometimes hear - the error correction data is not simply a
    copy of the last 20\% data sectors. That'd really be a cheap shot ;-)
  \end{minipage}\\[8mm]
\end{tabular}

\paragraph{Example: Anna's desk drawer PIN}\quad

Anna has got a desk whose drawers can only be opened after entering
the numbers "8 6 2 3" into a code lock. Since the drawers
do not contain any sensitive information she decides
to note down the numbers directly on the desktop:

\bigskip

\includegraphics[height=11mm]{figures/pin.pdf}

Anna is cautious and expects one of the numbers to become
unreadable by accidentally pouring ink over it.
Therefore she also notes down the sum of the four
numbers (the ``+'' and ``='' signs have only be added
for clarity):

\bigskip

\includegraphics[height=12mm]{figures/pin-sum.pdf}

After a while one of the numbers indeed gets covered by an ink spot:

\bigskip

\includegraphics[height=13mm]{figures/pin-ink.pdf}

But this is not a problem as Anna can re-calculate the missing number x by rearranging the still readable parts of the equation:

\medskip

\verb|8 + x + 2 + 3 = 19|, \quad hence

\smallskip

\verb|x = 19 - 8 - 2 - 3|, \quad and therefore \verb|x = 6|.

\bigskip

It is easily seen that any one of the original five numbers
can be recovered from the remaining four.
The example also demonstrates some important properties
of the error correction: 

\bigskip

\begin{tabular}{cl}
\begin{minipage}{0.40\textwidth}
  \includegraphics[height=28mm]{icons/ecc-example.png}
\end{minipage}
  &
\begin{minipage}{0.56\textwidth}
  For a given set of data (e.g. the numbers ``8 6 2 3'') additional
  error correction data (e.g. the sum ``19'') can be created so
  that a lost datum can be re-calculated from the remaining data.

  \smallskip
  
  The same principle is used in dvdisaster; the protected sequence
  of numbers is nothing else than the ISO image of an optical disc.
\end{minipage}
\end{tabular}

\bigskip

The concept of {\bf redundancy} can be explained as follows:

\begin{itemize}
\item  One ``error correction number'' is calculated for four input
  numbers. 1 of 4 (or 1/4) relates to a redundancy of 25\%.
\item  From one error correction number we can re-calculate exactly
  one missing number, or at most 25\% of data. The redundancy
  is equivalent to the maximum capacity of the error correction.
\item  Additional storage required for the error correction data is
  also determined by the redundancy (again, 25\% in the example).
\end{itemize}

dvdisaster uses the term of redundancy accordingly.
In addition please observe that

\begin{itemize}
\item  no data can be recovered when the data loss exceeds the
  redundancy (the equation in the example can not be solved for
  two or more unknowns).
\item the error correction data must be calculated at a
  point in time where all data is still present / readable.
\end{itemize}
  
The above shown example does not generalize into an error correction
scheme for recovering more than one missing data value. To do so a
more powerful equation system is needed which can be solved for more
than one missing value. dvdisaster uses a Reed-Solomon code which
does have such properties; however the required math is usually
not taught in school. Interested readers are therefore referred
to the respective books in coding theory. 

\newpage
\subsubsection{Using dvdisaster the right way}
\label{bigpicture-goodusage}

Let's demonstrate how Jane uses dvdisaster.

\bigskip

\begin{tabular}{rccl}
  10. Feb. 2009 &
  \begin{minipage}{16mm}\centerline{\goodcd}\end{minipage} &
  &
  \begin{minipage}{88mm}
    Jane creates a new CD with important data.
  \end{minipage}\\[8mm]

  &
  \begin{minipage}{16mm}\centerline{\goodcd}\end{minipage} &
  \begin{minipage}{16mm}\centerline{\eccfile}\end{minipage}  &
  \begin{minipage}{88mm}
    To protect the CD from data loss she creates
    \tlnk{howto-eccfile}{error correction data} with dvdisaster.
    She keeps both kinds of data for later usage.
  \end{minipage}\\[8mm]
  \hline

14. May 2010 &
  \begin{minipage}{16mm}\centerline{\goodcd}\end{minipage} &
  \begin{minipage}{16mm}\centerline{\eccfile}\end{minipage}  &
  \begin{minipage}{88mm}
    \vspace*{3mm}
    Jane knows that during daily use not all data of
    her CD might be accessed. So after a year has passed
    she \tlnk{howto-scan}{scans the CD for read errors} to make sure that
    it has not developed any defects in seldom used data regions.
    However after one year the CD is still perfectly readable.
    \vspace*{3mm}
  \end{minipage}\\[8mm]
  \hline

19. Aug 2012 &
  \begin{minipage}{16mm}\centerline{\badcd}\end{minipage} &
  \begin{minipage}{16mm}\centerline{\eccfile}\end{minipage}  &
  \begin{minipage}{88mm}
    \vspace*{3mm}
    Two more years have passed and Jane notices that
    some data on the CD is no longer readable.
    A \tlnk{howto-scan}{scan for read errors} confirms
    that the CD has become defective due to aging.
  \end{minipage}\\[8mm]

  \tlnk{howto-recover-read}{read} &
  \begin{minipage}{16mm}\centerline{\downarr}\end{minipage} &
  &
  \\[8mm]

  &
  \begin{minipage}{16mm}\centerline{\badimage}\end{minipage} &
  \begin{minipage}{16mm}\centerline{\eccfile}\end{minipage}  &
  \begin{minipage}{88mm}
    \vspace*{3mm}
    Jane uses dvdisaster
    to \tlnk{howto-recover-read}{read as much sectors as possible} from
      the defective CD into an ISO image.
  \end{minipage}\\[8mm]

  \tlnk{howto-recover-fix}{reconstruct} &
  \multicolumn{2}{c}{\begin{minipage}{32mm}\hspace*{5mm}\joinarr\end{minipage}} &
  \\[8mm]

  &
  \begin{minipage}{16mm}\centerline{\goodimage}\end{minipage} &
  \begin{minipage}{16mm}\centerline{\eccfile}\end{minipage}  &
  \begin{minipage}{88mm}
    By using the error correction data
    Jane \tlnk{howto-recover-fix}{recovers the missing parts} in
    the ISO image. 
  \end{minipage}\\[8mm]

  Write new CD&
  \begin{minipage}{16mm}\centerline{\downarr}\end{minipage} &
  &
  \\[8mm]

  &
  \begin{minipage}{16mm}\centerline{\goodcd}\end{minipage} &
  \begin{minipage}{16mm}\centerline{\eccfile}\end{minipage}  &
  \begin{minipage}{88mm}
    Jane writes a new CD from the recovered ISO image.
    She keeps the error correction data for the new CD
    as it may also become defective in the future.
  \end{minipage}\\[8mm]
\end{tabular}

\newpage
\subsubsection{Using dvdisaster the wrong way}
\label{bigpicture-badusage}

Joe bets on his media keeping their content without additional protection.

\bigskip

\begin{tabular}{rccl}
  10. Feb. 2009 &
  \begin{minipage}{16mm}\centerline{\goodcd}\end{minipage} &
  \begin{minipage}{16mm}\centerline{\goodcd}\end{minipage} &
  \begin{minipage}{88mm}
    Joe creates two CDs containing important data.
    But he does not make any provisions against data loss on those media.
  \end{minipage}\\[8mm]

  \hline
  
  \vspace*{3mm}
  14. May. 2010 &
  \begin{minipage}{16mm}
    \vspace*{3mm}
    \centerline{\goodcd}\end{minipage} &
  \begin{minipage}{16mm}
    \vspace*{3mm}
    \centerline{\goodcd}\end{minipage} &
  \begin{minipage}{88mm}
    Joe uses his CDs regularly. After one year they are
    still perfectly readable.
  \end{minipage}\\[4mm]

  \hline

  \vspace*{3mm}
  19. Aug. 2012 &
  \begin{minipage}{16mm}
    \vspace*{3mm}
    \centerline{\badcd}\end{minipage} &
  \begin{minipage}{16mm}
    \vspace*{3mm}
    \centerline{\goodcd}\end{minipage} &
  \begin{minipage}{88mm}
    After two more years Joe notices that some data
    on one CD is no longer readable.
  \end{minipage}\\[-1mm]

  \tlnk{howto-scan}{scan} &
  \begin{minipage}{16mm}\centerline{\downarr}\end{minipage} &
  \begin{minipage}{16mm}\centerline{\downarr}\end{minipage} &
  \\[-1mm]

  20. Aug. 2012 &
  \begin{minipage}{16mm}
    \centerline{\badcd}\end{minipage} &
  \begin{minipage}{16mm}
    \centerline{\badcd}\end{minipage} &
  \begin{minipage}{88mm}
    Joe downloads dvdisaster and performs
    a \tlnk{howto-scan}{read error scan}.
    He finds out that the CD contains 25000 unreadable sectors.
    A scan of the second CD reveals that it has developed 1500
    unreadable sectors gone unnoticed so far. 
  \end{minipage}\\[-2mm]

  \tlnk{howto-recover}{reading} &
  \begin{minipage}{16mm}\centerline{\downarr}\end{minipage} &
  \begin{minipage}{16mm}\centerline{\downarr}\end{minipage} &
  \\[5mm]

  21. Aug. 2012 &
  \begin{minipage}{16mm}
    \centerline{\badimage}\end{minipage} &
  \begin{minipage}{16mm}
    \centerline{\badimage}\end{minipage} &
  \begin{minipage}{88mm}
    Joe uses dvdisaster to read as much sectors as
    possible from the defective media. But since he
    does not have error correction data there is no way
    of recalculating the unreadable sectors.
  \end{minipage}\\[6mm]

  \begin{minipage}{20mm}
    many reading attempts
  \end{minipage}
    &
  \begin{minipage}{16mm}\centerline{\downarr}\end{minipage} &
  \begin{minipage}{16mm}\centerline{\downarr}\end{minipage} &
  \\[-10mm]

  05. Sep. 2012 &
  \begin{minipage}{16mm}
    \centerline{\badimage}\end{minipage} &
  \begin{minipage}{16mm}
    \centerline{\goodimage}\end{minipage} &
  \begin{minipage}{88mm}
    Joe takes advantage of dvdisaster's feature to complete images
    through multiple reading passes. He moves the defective images
    to several computers to perform reading attempts with
    different drives. After two weeks of trying at least all
    missing sectors from the second CD have been read. However
    on the first CD still 21000 sectors remain unreadable by any
    drive he tried.
  \end{minipage}\\[-4mm]

  \begin{minipage}{25mm}
    only one CD recovered
  \end{minipage}
    &
  \begin{minipage}{16mm}\centerline{\downarr}\end{minipage} &
  \begin{minipage}{16mm}\centerline{\downarr}\end{minipage} &
  \\[-2mm]

  06. Sep. 2012 &
  \begin{minipage}{16mm}
    \centerline{\badcd}\end{minipage} &
  \begin{minipage}{16mm}
    \centerline{\goodcd}\end{minipage} &
  \begin{minipage}{88mm}
    Joe dismisses the first CD as unrecoverable and
    considers himself lucky to have a complete image
    from the second CD again. However if he had created
    error correction data in time, he'd probably\footnotemark
    saved two weeks of reading attempts and recovered
    the contents from both CDs.
  \end{minipage}\\[8mm]
\end{tabular}

\footnotetext{The
  error correction assumes a typical aging process. If the CD
  gets severely damaged it becomes unrecoverable even with
  error correction data. Do not rely on dvdisaster alone
  for protecting important data; instead employ additional
  measures like creating additional copies on different types of media.}

\newpage

\subsection{Scanning media for errors}
\label{howto-scan}

\begin{tabular}{lll}
  \multicolumn{2}{l}{\bf Task} &
  The medium is scanned for unreadable sectors. \\[10mm]

  \multicolumn{2}{l}{\bf Required:} & \\[3mm]

  \begin{minipage}{15mm}
    \goodcd
  \end{minipage} &

  \begin{minipage}{15mm}
    \badcd
  \end{minipage} &

  A medium in any state (good or containing read errors) \\[10mm]

  \begin{minipage}{15mm}
    \eccfile
  \end{minipage} &
  &
  \begin{minipage}{110mm}
  If error correction data is available additional tests are
  carried out. However scanning will also work without error correction
  data.
  \end{minipage}
  \\[13mm]

  \multicolumn{2}{l}{\bf What to do:} &
  \tlnk{howto-scan-basic-settings}{1. Configure basic settings} \\[2mm]

  & &
  \tlnk{howto-scan-walkthrough}{2. Scan the medium} \\[2mm]

  & &
  \tlnk{howto-scan-interpret}{3. Interpret the results} \\[10mm]


  \multicolumn{2}{l}{\bf Related functions:} &
  \tlnk{howto-recover-read}{Reading of damaged media} and \\[2mm]

  & &
  \tlnk{howto-recover-fix}{recovering images} \\[2mm]
\end{tabular}

\vspace{10mm}

\subsubsection{Basic settings}
\label{howto-scan-basic-settings}

\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/global-prefs-invoke.png}}
\caption{Opening the configuration dialog.}  
\label{howto-scan-open-preferences}
\end{figure}

The relevant tabs are described on the next pages. They are
found in the configuration dialog.
Open the dialog by selecting the symbol marked green in the
screen shot ( \begin{minipage}{8mm}\includegraphics{icons/prefs-icon.png}\end{minipage}, see figure \ref{howto-scan-open-preferences}).
The symbol may look different due to the symbol theme you are using.

\newpage

\begin{figure}[h]
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/scan-prefs-image.png}}
\caption{The ``Image'' tab.}  
\label{howto-scan-prefs-image}
\end{figure}

\paragraph{Error correction data recognization.} If you
are sure that your medium contains embedded RS02 or RS03 error
correction data, activate the respective items (marked yellow).
Using the error correction (ecc) data will improve scanning results,
but searching for non existing ecc data will cost several minutes.

\paragraph{Image properties.} Selecting the proper
method for determining the image size is important.
Make sure that ``Ignore image size recorded in ISO/UDF file system''
(marked red) is switched off.
This option should only be used
in \tlnk{howto-eccfile-advanced-settings-image}{special cases during image recovery}.

\smallskip

Adjust the remaining settings as shown in the screen shot.

\newpage

\begin{figure}[h]
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/scan-prefs-drive.png}}
\caption{The ``Drive'' tab.}  
\label{howto-scan-prefs-drive}
\end{figure}

\paragraph{Drive initialization.} Reading data
from the drive while it is spinning up can generate spurious error
reports. Adjust the spin up time for your drive (typically 5-10 seconds)
in the field marked green to make dvdisaster wait for the appropriate time.

\smallskip

Leave the other settings at the values shown; you
can \tlnk{howto-scan-advanced-settings}{optimize} them later.

\newpage

\begin{figure}[h]
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/scan-prefs-read-attempts.png}}
\caption{The ``Read attempts'' tab.}  
\label{howto-scan-prefs-read-attempts}
\end{figure}

\paragraph{Sector read errors.} The option ``Read and analyse raw sectors''
(first green marking) uses C2 analysis and possibly more raw data
reported by the drive for a better assessment of CD media quality.
This setting does nothing for DVD and BD media, but it is safe to
remain activated unless it causes problems with your drive reading CDs.

Adjust the reading attempts settings as shown here. Using larger
values causes unnecessary reading activity but will not improve the scan.
After a read error no less than 16 sectors should be skipped (second
green marking); when scanning badly damaged media this setting can
be \tlnk{howto-scan-advanced-settings-read-attempts}{optimized using larger values}.

\paragraph{Media read attempts.} Performing multiple read attempts
is not recommended during a scan; set the number of retries to 1
in the three places marked in orange. Collecting raw sectors should
also be off during the scan.

\newpage

\begin{figure}[h]
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/general-prefs-misc.png}}
\caption{The ``Misc'' tab.}  
\label{howto-scan-prefs-misc}
\end{figure}

\paragraph{The ``Misc Tab''.} Currently
this tab only has functions for creating log files.
This is helpful for \tlnk{reporting-defects}{reporting defects} but
should be left off during normal operation.

\paragraph{Not used tabs.} The ``Error correction'' and ``Files'' tabs
have no influence on scanning media. The ``Appearance'' tab
allows you to adapt the output colors to your taste, but these have
no further effects on the scanning process. 

\newpage
\subsubsection{Scanning for errors - Walkthrough}
\label{howto-scan-walkthrough}

Please make sure that dvdisaster has been configured as
described in the \tlnk{howto-scan-basic-settings}{basic settings} section
as some settings might negatively affect the scanning results.
Then perform the following steps: 

\bigskip

\begin{tabular}{cl}
  \begin{minipage}{50mm}
    \centerline{\slotin}
  \end{minipage}
  &
  \begin{minipage}{104mm}
  {\bf Insert the medium you want to scan into a drive} which
  is directly connected to your computer. You can not use network
  drives, software drives and drives inside virtual machines.
  \end{minipage}\\

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\

  \begin{minipage}{50mm}
    \centerline{\filemanager}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Close any windows} which may be opened by your
    operating system for viewing or performing the medium contents.
    Wait until the drive has recognized the medium and the medium
    has spun down. 
  \end{minipage}\\

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[6mm]

  \begin{minipage}{50mm}
    \centerline{\selectdrive}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Select the drive containing the medium} in dvdisasters
    drop down menu. 
  \end{minipage}\\[4mm]

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\

  \begin{minipage}{50mm}
    \centerline{\selectecc}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Select the error correction file for this medium} if you
    have one available. Ecc data from RS02 or RS03 augmented media
    is used automatically.
  \end{minipage}\\

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[6mm]

  \begin{minipage}{50mm}
    \centerline{\scanicon}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    Start the scan by {\bf clicking the "Scan" button.}
  \end{minipage}\\[6mm]

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[6mm]

  \begin{minipage}{50mm}
    \centerline{\includegraphics[width=40mm]{screenshots/good-cd-scan.png}}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Watch the scanning progress.} Do not perform any other
    actions on your computer while the scan is running.
    Opening or working with other programs as well as moving
    other windows around might affect the scanning results. 
  \end{minipage}\\
\end{tabular}

\newpage
\subsubsection{Interpreting the results}
\label{howto-scan-interpret}

\begin{figure}[h]
\centerline{\includegraphics[width=0.97\textwidth]{screenshots/defective-cd-scan.png}}
\caption{Scanning the medium.}  
\label{howto-scan-general-results}
\end{figure}

\vspace*{-5mm}

\paragraph{Overview.} dvdisaster provides several information
about the scanning results (see fig. \ref{howto-scan-general-results}): 

\begin{itemize}
  \item The spiral under {\bf ``Medium State''} (to the right).

    The spiral provides information about the medium readability.
    The medium is fully readable when all segments of the spiral
    are colored green. Yellow or red blocks mark places where data
    could not be correctly read from the medium. The total number
    of unreadable sectors is printed in the ``Scanning finished:''
    message at the window bottom.

  \item {\bf ``Speed''} - The reading speed curve (upper left).

    The reading speed is not an absolute gauge of the medium
    health, but it is usable as a rule of thumb: The more
    regular the curve, the better the medium. You will
    find examples of good and bad reading speed curves on the following pages.

  \item {\bf ``C2 errors''} - A medium state gauge provided by the drive (down left).

    This kind of analysis is \tlnk{qa-quality-scans}{currently only available for CD media}.
    CD drives have a built-in error correction
    which can eliminate small data losses caused by minor
    defects on the medium. The number of C2 errors is a
    measurement of how often the drive needed to employ its
    internal error correction during the read - this value
    should be zero on good media.
\end{itemize}

\newpage
\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/good-cd-scan.png}}
\caption{Good CD.}  
\label{howto-scan-good-cd}
\end{figure}

{\bf Example of a good medium:} This screen shot shows
a perfect CD: All blocks under ``Medium state'' are green, no C2
errors have been reported and the reading curve runs smoothly.
A rising reading speed is normal for most media (see the next screen
shot for a counter example). The small spikes at the beginning and
at the end of the curve are normal; minor glitches like the one shown
at 250M are also harmless.

\newpage
\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/good-dvd9-scan.png}}
\caption{Good two-layered DVD.}  
\label{howto-scan-good-two-layered-dvd}
\end{figure}

{\bf Sometimes the reading curve won't rise steadily:} Multi-layered
media might yield reading curves which are rising and dropping
in a symmetric pattern. Not shown but also possible are flat
curves without any change in reading speed (most typically seen
with DVD-RAM).

\newpage
\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/weak-cd-scan.png}}
\caption{Weak CD.}  
\label{howto-scan-weak-cd}
\end{figure}

{\bf An example of a weak medium.} This medium is still
readable as indicated by the green spiral shown under ``Medium state''.
However there are clear signs of serious trouble ahead: The drive must
slow down significantly towards the end of the medium in order to read
from it. Note the steep fall of reading speed after the 600M mark.
This comes along with C2 error rates rising to the 100 mark; this is
another warning that the medium is decaying in the outer region.
If you have not created \tlnk{howto-ecc}{error correction data} this is probably the
last opportunity to do so as the medium will develop the first
read errors soon.

\newpage
\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/defective-cd-scan.png}}
\caption{Defective CD.}  
\label{howto-scan-defective-cd}
\end{figure}

{\bf Example of a defective CD.} \label{howto-interpret-defective-cd}
The red sectors in the spiral
visualize large unreadable sections in the outer region of the medium.
At the bottom of the window you will find the information that the
medium contains 28752 unreadable sectors. This sums up to about
8.2\% defective sectors (of 352486 sectors total) and is well within
the \tlnk{howto-recover}{recovery} bounds
by \tlnk{howto-ecc}{error correction (ecc) data} made with default
settings - if you have made the ecc data in time! Otherwise the
contents of the red sectors are lost since ecc data cannot be
created from already defective media.

\newpage
\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/crc-cd-scan.png}}
\caption{Checksum errors.}  
\label{howto-scan-checksum-errors}
\end{figure}

{\bf Checksum errors.} Yellow spots in the spiral depict places
where the medium was fully readable, but the data read did not
match checksums in the error correction data. There are two main causes:

\begin{itemize}
\item The image has been manipulated after the creation of
  error correction data and before writing it to the medium.
  This can happen when the image is mounted with
  write access after ecc data has been created. Typical signs are
  CRC errors in sector 64 and in sectors 200 to 400 as the system
  updates the file access times there. Performing a data recovery
  using dvdisaster is typically harmless in this situation.

  \medskip

  However if you have modified files in the image after
  creating the ecc data, the error correction data will be both
  worthless and dangerous. Applying a recovery to the medium will
  restore the image state at the time the ecc data has been created,
  and this will obviously not represent the most recent contents of
  the medium.

\item There are technical problems with the computer system,
  especially in mass storage communication. Perform the scan again
  and observe the CRC error locations. If CRC errors disappear
  or surface at different locations your system might have
  defective RAM, bad drive cabling/controllers or incorrect clock speeds.
\end{itemize}

\newpage
\subsubsection{Advanced settings}
\label{howto-scan-advanced-settings}

\begin{figure}[h]
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/scan-prefs-drive-adv.png}}
\caption{Advanced settings in the ``Drive'' tab.}  
\label{howto-scan-prefs-drive-adv}
\end{figure}

{\bf Fatal error handling.} dvdisaster will normally abort the scan
when the drive reports a fatal internal error like mechanical problems.
The intention is to avoid damaging the drive. However some drives
will erroneously report such problems when they get confused by
damaged media. If you have such a drive you can use this option
to force the scan to continue.

\bigskip

{\bf Media ejection.} dvdisaster tries to eject the medium after
a successful scan if this option is activated. However ejecting
the medium might be prohibited by the operating system so this
is not guaranteed to work. For example if upon media insertion
a window is opened for performing the contents it may not be
possible to automatically eject the medium.

\newpage
\begin{figure}[h]
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/scan-prefs-read-attempts-adv.png}}
\caption{Advanced settings in the ``Read attempts'' tab.}  
\label{howto-scan-prefs-read-attempts-adv}
\end{figure}

{\bf Sector read errors.} \label{howto-scan-advanced-settings-read-attempts} Attempts
for reading defective sectors
cost a lot of time. Since it is likely to encounter another defective
sector after hitting a read error, skipping a few sectors after a
read error saves time and reduces wear on the drive. If you only want
a quick overview of a damaged medium setting this value to 1024 might help.
But keep in mind that all skipped sectors are counted as being defective
so the number of reported errors becomes higher and less accurate.

\newpage
\subsection{Selecting the right type of ecc data}
\label{howto-ecc}

Error correction data can either be created in form of
a separate error correction file or it can be placed directly
onto the medium.

\smallskip

Answering the following questions can quickly guide you to the right
ecc data format:

\begin{itemize}
\item {\em Do you need error correction data for a medium which has already been written?}

  In that case, you need to \tlnk{howto-eccfile}{create an error
    correction file} because an already existing medium can not be
  augmented with error correction data. 

\item {\em Are you planning to write the medium right now?}

  If the medium is full or nearly full (less than 20\% free),
  not enough space might be available for storing the error
  correction data. It is strongly recommended to \tlnk{howto-eccfile}{create an
  error correction file} in that case. Otherwise, you can put
  the \tlnk{howto-augment}{error correction data directly onto the medium}.
  To do so you must create an ISO image first and then augment it with
  error correction data before you write it to the medium. 
\end{itemize}

\paragraph{More information on keeping error correction data.}\quad

dvdisaster helps protecting your media from data loss by
forehanded\footnote{ Let's repeat again for clarity: Error correction data
  must be created before the medium becomes defective. It is not possible
  to create error correction data from defective media; in that case
  unreadable sectors can not be recovered.} creation of error correction
data. Error correction data must be treated like normal backup data,
e.g. you need to keep it available during the whole lifetime of the
respective medium.

\smallskip

The easiest way is storing the error correction data on the medium
you want to protect. But this is only possible if the medium has not
yet been written: To employ this method you need to create an ISO image
first, then augment this image with error correction data, and finally
write the augmented image to the medium.

\smallskip

If the medium has already been written, or insufficient space is left
for augmenting the image, you still can create error correction data
in form of a free-standing error correction file. This file must then
be stored somewhere else, e.g. you need to take additional provisions
to \tlnk{howto-eccfile-archival}{archive your error correction files}.

\smallskip

More information about the pro and con of these methods can be found
in the \tlnk{background-methods}{background information} section. 

\newpage

\subsection{Creating ecc data as a separate file}
\label{howto-eccfile}

\begin{tabular}{ll}
  {\bf Task} & An error correction file is created for an optical medium. \\

  &
  \begin{minipage}{132mm}

    \bigskip

    Note: This page describes how error correction data is created
    and placed into a separate file. There is also a method for
    placing the error correction data \tlnk{howto-augment}{directly onto the medium}.

    \smallskip
    
    \tlnk{howto-ecc}{Would you like help on deciding between these two methods?}
    \end{minipage}\\[15mm]
    
  {\bf Required:} & \\[3mm]

  \begin{minipage}{15mm}
    \goodcd
  \end{minipage} &
  \begin{minipage}{132mm}
    A good, error free\footnotemark medium,
  \end{minipage} \\

  & or \\

  \begin{minipage}{15mm}
    \goodimage
  \end{minipage} &
  \begin{minipage}{132mm}
    \addtocounter{footnote}{-1}
    an already existing and complete\footnotemark ISO
    image of the medium (e.g. the image used for
    writing the medium). 
  \end{minipage} \\[10mm]

  {\bf What to do:} &
  \tlnk{howto-eccfile-basic-settings}{1. Configure basic settings} \\[2mm]

  &
  \tlnk{howto-eccfile-create}{2. Create the error correction file} \\[2mm]

  &
  \tlnk{howto-eccfile-archival}{3. Archive the error correction file}
\end{tabular}

\footnotetext{Error correction data must be
      created before any data loss occurs: It is not possible
      to create error correction files from an already defective
      medium.}

\vspace{10mm}

\subsubsection{Basic settings for reading the image from the medium}
\label{howto-eccfile-basic-settings}
\label{howto-eccfile-basic-settings-reading}

\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/global-prefs-invoke.png}}
\caption{Opening the configuration dialog.}  
\label{howto-eccfile-open-preferences-eccfile}
\end{figure}

The relevant tabs are described on the next pages. They are
found in the configuration dialog.
Open the dialog by selecting the symbol marked green in the
screen shot ( \begin{minipage}{8mm}\includegraphics{icons/prefs-icon.png}\end{minipage}, see figure \ref{howto-eccfile-open-preferences-eccfile}).
The symbol may look different due to the symbol theme you are using.

\bigskip

\begin{tabular}{cl}
  \begin{minipage}{20mm}
    \centerline{\goodimage}
  \end{minipage} &
  \begin{minipage}{133mm}
      If you already have an ISO image available you can skip the next
      three tabs and proceed with
      the \tlnk{howto-eccfile-basic-settings-ecc}{error correction settings}.
      But make sure that you really have an ISO type image; other formats
      like ``.nrg'' do not produce usable error correction data.
    \end{minipage}\\
 \end{tabular}
    
\newpage

\begin{figure}[h]
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/eccfile-prefs-image.png}}
\caption{The ``Image'' tab.}  
\label{howto-eccfile-prefs-image}
\end{figure}

\paragraph{Reading strategy.} Make sure that the linear reading strategy is selected
(marked green).

\bigskip

All other options should be turned off; especially those marked green as they
might have adverse effects on the image reading process. 

\newpage

\begin{figure}[h]
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/eccfile-prefs-drive.png}}
\caption{The ``Drive'' tab.}  
\label{howto-eccfile-prefs-drive}
\end{figure}

\paragraph{Drive initialization.} Reading data from the drive while it is spinning
up can generate spurious error reports. Adjust the spin up time for your
drive (typically 5-10 seconds) in the field marked green to make dvdisaster
wait for the appropriate time.

\bigskip

Leave the other settings at the shown values.

\newpage

\begin{figure}[h]
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/eccfile-prefs-read-attempts.png}}
\caption{The ``Read attempts'' tab.}  
\label{howto-eccfile-prefs-read-attempts}
\end{figure}

\paragraph{Sector read errors.} The option ``Read and analyze raw sectors'' (marked green)
uses additional information provided by the drive to check the integrity of read data.
This is recommended as we are interested in creating error correction data
from a properly read image.

\medskip

On the other hand since error correction data can only be created from fully
readable media we do not need multiple reading attempts and caching of
raw sectors as shown in the screen shot. 

\newpage
\subsubsection{Basic settings for the error correction data}
\label{howto-eccfile-basic-settings-ecc}

\begin{figure}[h]
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/eccfile-prefs-ecc-file3.png}}
\caption{The ``Error correction'' tab for the RS03 codec.}  
\label{howto-eccfile-prefs-ecc-file3}
\end{figure}

Error correction files can be created using either the RS03 or the RS01 method
(see this \tlnk{background-methods}{comparison} for details).
It is recommended to use RS03 as it contains all features present in RS01,
but encodes much faster due to certain optimizations.

\paragraph{Settings for encoding with the RS03 method.} First select the entry
``Multithreaded RS codec (RS03)'' in the drop down menu (marked green).
After this selection the contents of the tab will display the choices given
for the RS03 method. 

\paragraph{Error correction storage.} Select ``File'' (also marked green).
This option causes error correction data to be stored in a separate file
and will also make the redundancy choice available which is located below.

\paragraph{Redundancy for new error correction files.} Select the redundancy
which suits your needs. The redundancy will determine the maximum error
correction capability: An error correction file with x\% redundancy can
correct up to x\% of read errors under optimal circumstances.
Since the best case is usually not encountered you should add some safety
margin to the redundancy by picking one of the following choices (see yellow markings):

\begin{itemize}
\item The ``normal'' and ``high'' presets provide a redundancy of 14.3\% and 33.5\%
  respectively.
\item You can freely choose the redundancy by activating the ``other'' item
  and dragging the slider.
\item By activating the ``Use at most'' button you can specify the error
  correction file size in MiB. dvdisaster will choose a suitable redundancy
  so that the error correction file will be close to but not larger than the
  specified size.
\end{itemize}
  
The redundancy will also determine the size of the error correction file;
using x\% redundancy will create an error correction file of about x\% the
size of the image. Using redundancies lower than the ``normal'' setting (14.3\%)
is not recommended as the error correction might be overloaded too quickly.

\paragraph{Multithreading.} The RS03 encoder can distribute its workload
onto multiple processor cores by using multithreading. On machines with
up to four cores, set the number of threads equal to the number of
cores (e.g. use 4 threads on a 4 core machine). On machines with more
than 4 cores, use one thread less than the number of available cores;
e.g. use 7 threads on an 8 core machine - this leaves one core free
for housekeeping tasks).

\smallskip

Leave the other settings as shown in the screenshot; you can
\tlnk{howto-eccfile-advanced-settings-ecc}{optimize} them later.

\newpage

\begin{figure}[h]
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/eccfile-prefs-ecc-file1.png}}
\caption{The ``Error correction'' tab for the old RS01 codec.}  
\label{howto-eccfile-prefs-ecc-file1}
\end{figure}

\paragraph{Settings for encoding with the RS01 method.} If you want to
use the old RS01 method, choose ``Error correction file (RS01)'' in
the ``Storage method'' drop down menu (green marking; see
fig. \ref{howto-eccfile-prefs-ecc-file1}).

\smallskip

Then select a redundancy setting which suits your needs; see the
explanations on redundancy for the RS03 method above for more information.
For RS01, the ``normal'' and ``high'' settings are somehow optimized for
speed, but still much slower than their RS03 counterparts. 

\newpage

\begin{figure}
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/create-prefs-file.png}}
\caption{The ``Files'' tab.}  
\label{howto-eccfile-prefs-file}
\end{figure}

\paragraph{The ``Files'' tab.} In this tab, only
activate the option for confirming file overwriting.
Leave the other options off for the moment; suggestions for
further \tlnk{howto-eccfile-advanced-settings}{optimization} follow later. 

\bigskip

\paragraph{Not used tabs.} The ``Misc'' tab currently has only functions
for creating log files. This is helpful
for \tlnk{reporting-defects}{reporting defects} but
should be left off during normal operation. The ``Appearance'' tab allows
you to adapt the output colors to your taste, but these have no further
effects on the error correction data creation.

\newpage
\subsubsection{Creating the error correction file}
\label{howto-eccfile-create}

\begin{tabular}{cccl}
  \begin{minipage}{15mm}
    \goodcd
  \end{minipage}
  &
  \begin{minipage}{10mm}
    \rightarr
  \end{minipage}
  &
  \begin{minipage}{15mm}
    \goodimage
  \end{minipage}
  &
  \begin{minipage}{105mm}
    The error correction file can only be created from an ISO image
    on hard disk, not directly from the medium. If you have the
    ISO image already/still available from making the medium,
    turn over to the next page. Otherwise, follow these instructions
    for extracting the ISO image from the medium.
  \end{minipage}
  \\
\end{tabular}

\bigskip

\hrulefill

\bigskip

\begin{tabular}{cl}
  \begin{minipage}{50mm}
    \centerline{\slotin}
  \end{minipage}
  &
  \begin{minipage}{104mm}
  {\bf Insert the medium you want to read into a drive} which
  is directly connected to your computer. You can not use network
  drives, software drives and drives inside virtual machines.
  \end{minipage}\\

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\

  \begin{minipage}{50mm}
    \centerline{\filemanager}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Close any windows} which may be opened by your
    operating system for viewing or performing the medium contents.
    Wait until the drive has recognized the medium and the medium
    has spun down. 
  \end{minipage}\\

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[6mm]

  \begin{minipage}{50mm}
    \centerline{\selectdrive}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Select the drive containing the medium} in dvdisasters
    drop down menu. 
  \end{minipage}\\[4mm]

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\

  \begin{minipage}{50mm}
    \centerline{\selectimage}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Select a directory and file name} for
    storing the ISO image.
  \end{minipage}\\[4mm]

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\

  \begin{minipage}{50mm}
    \centerline{\readicon}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Create the ISO image} by clicking the "Read" button.
  \end{minipage}\\[6mm]

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[6mm]

  \begin{minipage}{50mm}
    \centerline{\includegraphics[width=40mm]{screenshots/good-cd-scan.png}}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Watch the reading progress.}
    Wait until the medium has been completely read.
    If the medium turns out to contain defective sectors
    it will not be possible to create error correction data. 
  \end{minipage}\\
\end{tabular}

\bigskip
  
Now continue with the next page to create an error correction file
from the ISO image.

\newpage
\label{howto-eccfile-create-ecc}

\begin{tabular}{cccl}
  \begin{minipage}{15mm}
    \goodimage
  \end{minipage}
  &
  \begin{minipage}{10mm}
    \rightarr
  \end{minipage}
  &
  \begin{minipage}{15mm}
    \eccfile
  \end{minipage}
  &
  \begin{minipage}{105mm}
    Now that we have an ISO image of the medium, we can create the
    error correction file from it. It you do not have the ISO image yet,
    please follow the instructions on the previous page for
    extracting it from the medium.
  \end{minipage}
  \\
\end{tabular}

\bigskip

\hrulefill

\bigskip

\begin{tabular}{cl}
  \begin{minipage}{50mm}
    \centerline{\selectimage}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Select the directory and name of the ISO image} for which you want 
    to create the error correction data. It is assumed that the ISO image 
    has been created by some other means, e.g. by using your optical disc 
    authoring software. If you extracted the ISO image from a medium using
    dvdisaster as described one page before, this field is already filled in
    correctly.
  \end{minipage}\\[-8mm]

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[5mm]

  \begin{minipage}{50mm}
    \centerline{\selectecc}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Select a directory and name} for storing the error correction file.
  \end{minipage}\\[4mm]

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[6mm]

  \begin{minipage}{50mm}
    \centerline{\createicon}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Create the error correction file} by clicking the "Create" button.
  \end{minipage}\\[6mm]

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[6mm]

  \begin{minipage}{50mm}
    \centerline{\includegraphics[width=40mm]{screenshots/watch-create.png}}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Wait until the creation process finishes.} This 
    may take a while depending on the image size, selected redundancy 
    and used encoding method.
  \end{minipage}\\[14mm]

  \begin{minipage}{50mm}
    \centerline{\downforkarr}
  \end{minipage}
  & \\[6mm]

  \begin{minipage}{24mm}
    \centerline{\oldimage}
  \end{minipage}
  \begin{minipage}{24mm}
    \centerline{\eccfile}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Wrapping up.} You can delete the image file now. However 
    you must keep the error correction file and, even more important, 
    protect it from being damaged. Refer to the next page for some 
    suggestions about \tlnk{howto-eccfile-archival}{error correction file archival}. 
  \end{minipage}\\
\end{tabular}

\newpage
\subsubsection{Tips for archival of error correction files}
\label{howto-eccfile-archival}

Optical discs are currently among the most cost-effective exchangeable
mass storage media. Therefore you are probably considering them for
storing error correction files.

\medskip

Nothing is wrong with doing so, but be aware that your data and protective
error correction files are kept on media with equal reliability.
When you encounter read errors on a data medium it is likely that
the medium containing the respective error correction files has also
gone defective. After all both media have been written at the same time,
and they have the same aging characteristics.

\medskip

This might come at a surprise, but it can not be
guaranteed that an error correction file remains usable
when it is stored on a defective medium - here
is a \tlnk{background-image-level}{explanation of the technical background}.\marginpar{\hfill\rule{1mm}{13mm}} 

\medskip

Therefore it is important to protect error correction files just as
if they were normal data. To be more specific, the medium containing
error correction files must be protected with error correction data as well.
Here are two ways of doing this:

\begin{enumerate}
\item Storing error correction files on separate media:

Use additional media just for keeping the error correction files.
If you use no more than 80\% per medium for error correction files
it can be \tlnk{howto-augment}{augmented with error correction data}.
This allows you to recover the medium if you run into problems reading
the error correction files at a later time.

\item Storing error correction files on the next medium in sequence:

Maybe you are using media for an incremental backup strategy.
In that case you could collect files until the first medium can be filled.
Write that medium as usual and create an error correction file for it.
Include that error correction file into the backup set which will go onto
the second medium. When the second medium has been written, write the error
correction file for it onto the third medium and so on. This way all media
in the chain are protected with error correction files (with the ecc file
for the last medium residing on hard disk until another medium is written).
\end{enumerate}

Of course Murphys Law may strike and result in all media of the chain
becoming defective. In that case you need to recover all media, starting
with the most recent one ;-)

\newpage
\subsubsection{Advanced settings for the error correction data}
\label{howto-eccfile-advanced-settings}
\label{howto-eccfile-advanced-settings-image}

\vspace{-4mm}
\begin{figure}[h]
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/eccfile-prefs-image-adv.png}}
\caption{The ``Image'' tab.}  
\label{howto-eccfile-prefs-image-adv}
\end{figure}
\vspace{-6mm}

\paragraph{Error correction data recognization.} Since
we are reading the image for the purpose of creating error correction data, it
makes no sense to look for error correction data in the image itself and the options
marked green should remain turned off.

\paragraph{Image properties.} In some cases it might be necessary to change to way
dvdisaster determines the size of the ISO image. The normal strategy is to
query the ISO image from the ISO/UDF file system, and only if this fails,
to query the information directly from the optical drive. Using this order makes
sense as image sizes reported by most drives are unreliable in many cases while
ISO/UDF file system information is usually correct. However in some rare cases the
image size recorded in the ISO/UDF filesystem is wrong. Some GNU/Linux live CDs may have
this problem. If you read back the ISO image from such CDs and its md5sum does not
match the advertised one from the download site, try re-reading the image with
the ``Ignore image size recorded in ISO/UDF file system'' option (marked red)
turned on. But do not blindly turn this option on as it could
create sub optimal or corrupted ISO images, especially if you plan to use the
image for error correction data generation. 

\newpage

\begin{figure}[h]
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/eccfile-prefs-drive-adv.png}}
\caption{The ``Drive'' tab.}  
\label{howto-eccfile-prefs-drive-adv}
\end{figure}

\paragraph{Media ejection.} This feature is helpful
when you are processing a batch of media. Use it together with the
options shown in the ``Files tab'' at the next page.

\smallskip

dvdisaster will try to eject the medium after the image has
been read. However ejecting the medium might be prohibited by
the operating system so this is not guaranteed to work. For example if upon
media insertion a window is opened for performing the contents it may not be possible to
automatically eject the medium.

\newpage

\begin{figure}[h]
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/eccfile-prefs-file-adv.png}}
\caption{The ``Files'' tab.}  
\label{howto-eccfile-prefs-file-adv}
\end{figure}

\paragraph{Local files (on hard disk).} To ease entering new file names,
activate the option marked yellow.
This will append the ``.iso'' and ``.ecc'' file name extensions automatically.

\paragraph{Automatic file creation and deletion.} You can automate the
process of creating error correction files using these options. The
first option marked green lets dvdisaster create the error correction
file immediately after the medium has been (completely) read.
The second option marked green deletes the image when the error correction
file has been successfully created.

\bigskip

\paragraph{Please note:} Remember to choose a different name for the error
correction file after inserting a new medium. Otherwise the
previous error correction file will be overwritten. 

\newpage

\begin{figure}[h]
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/eccfile-prefs-ecc3-adv.png}}
\caption{The ``Error correction'' tab for the RS03 codec.}  
\label{howto-eccfile-prefs-ecc3-image-adv}
\end{figure}

\paragraph{Optimizing the error correction data creation.}\quad
\label{howto-eccfile-advanced-settings-ecc}

Creating error correction data requires both huge processing power
and high random access disk I/O capabilities. When encoding on conventional
hard disks with spinning platters, disk I/O will be the limiting
factor over all other hardware. Therefore it is recommended to encode on
fast storage media like SSDs, or even better, on RAM-based filesystems such
as /dev/shm on GNU/Linux.

\paragraph{I/O parameters.} dvdisaster optimizes access to the
image and error correction data by preloading and caching parts of them.
The optimal preload value (marked red) depends on the storage system
used for the image and error correction files. Use small preload values
for systems with low latency and seek time, e.g. SSDs and the RAM file system.
For magnetic hard disks performance may be better using larger preload values.
Make sure that you do not use more than half of your physical RAM for preloading.
A preload value of $n$ will use approx. $n$ MiB of RAM.

\medskip

The I/O strategy option (marked green) controls how dvdisaster performs
its disk I/O while creating error correction data. Try both options and
see which performs best on your hardware.

The read/write option activates dvdisaster's own I/O scheduler which
reads and writes image data using normal file I/O. The advantage of this
scheme is that dvdisaster knows exactly which data needs to be cached and preloaded;
the disadvantage is that all data needs to be copied between the kernel and
dvdisaster's own buffers. Usually, this I/O scheme works best on slow
storage with high latency and seek times; e.g. on all storage involving spinning platters.

The memory mapped option uses the kernel's memory mapping scheme for direct access
to the image file. This has the advantage of minimal overhead, but may be
adversely affected by poor caching and preloading decisions made by the kernel
(since the kernel does not know what dvdisaster is going to do with the data).
This scheme performs well when encoding in a RAM-based file system
(such as /dev/shm on GNU/Linux) and on very fast media with low latency such as SSDs.

\paragraph{Multithreading.} RS03 can use multiple threads - and
therefore CPU cores - for encoding (yellow slider). For systems with 4 cores
or less, start with setting the number of threads to the number of cores.
If you have more cores, leave one core for doing I/O and graphics updates,
e.g. use 7 threads on an 8 core system. On systems with hyper-threading
capabilities, increasing the number of threads until double the number
of physical cores might improve performance.

\smallskip

Do not expect performance to scale linearly with the number of used
CPU cores (although it should do so for at least the first four to
eight cores). Hard disk performance is more limiting than raw CPU power.
When using more than 8 cores, memory bandwidth may eventually limit performance.

\paragraph{Encoding algorithm.} This option affects the speed of
generating RS03 error correction data per CPU core (buttons marked blue).
dvdisaster can either use a generic encoding algorithm using 32bit or 64bit
wide operations running on the integer unit of the processor,
or use processor specific extensions.
Available extensions are SSE2 for x86 based processors and AltiVec on
PowerPC processors. These extensions encode with 128bit wide operations
and will usually provide the fastest encoding variant.
If ``auto'' is specified, the SSE2/AltiVec algorithms will be selected
if the processor supports them. 

\newpage

\subsection{Putting error correction data directly onto the medium}
\label{howto-augment}

\begin{tabular}{ll}
  {\bf Task} & Error correction data is stored along with the user data on the same medium. \\

  &
  \begin{minipage}{132mm}

    \bigskip

    Note: This page describes how an ISO image is augmented with error
    correction data prior to writing it onto a medium.
    There is also a method for creating and placing error correction data
    \tlnk{howto-eccfile}{into a separate file}. 

    \smallskip
    
    \tlnk{howto-ecc}{Would you like help on deciding between these two methods?}
    \end{minipage}\\[15mm]
    
  {\bf Required:} & \\[-5mm]

  \begin{minipage}{15mm}
\vspace*{8mm}
    \goodimage
  \end{minipage} &
  \begin{minipage}{132mm}
    \begin{itemize}
      \item an authoring (``burning'') software capable of creating ISO images
      \item the medium which is to be augmented with error correction data has not yet
        been written (already written media can not be augmented)
      \item at least 20\% of free space on the medium which is to be created
    \end{itemize}
  \end{minipage} \\[15mm]


  {\bf What to do:} &
  \tlnk{howto-augment-basic-settings}{1. Configure basic settings} \\[2mm]

  &
  \tlnk{howto-augment-make-iso}{2a. Create an ISO image,} \\[2mm]

  &
  \tlnk{howto-augment-overview-ecc}{2b. augment it with error correction data,} \\[2mm]

  &
  \tlnk{howto-augment-write-iso}{2c. and write it to a medium.} \\[2mm]

\end{tabular}

%\footnotetext{An already written medium can not be augmented with error correction data.}

%\vspace{10mm}

\subsubsection{Basic settings for augmenting images with ecc data}
\label{howto-augment-basic-settings}

\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/global-prefs-invoke.png}}
\caption{Opening the configuration dialog.}  
\label{howto-eccfile-open-preferences-augment}
\end{figure}

The relevant tabs are described on the next pages. They are
found in the configuration dialog.
Open the dialog by selecting the symbol marked green in the
screen shot ( \begin{minipage}{8mm}\includegraphics{icons/prefs-icon.png}\end{minipage}, see figure \ref{howto-eccfile-open-preferences-augment}).
The symbol may look different due to the symbol theme you are using.

\medskip

The image can be augmented with error correction data using either
the RS03 or RS02 methods. RS03 is a further development of RS02
and should be preferred for most applications. Especially, RS03
can use multiple threads and will encode much faster on multicore systems
than RS02. RS02 is a bit more space efficient than RS03, so it can
squeeze out slightly more redundancy of the remaining space than
RS03 (typically one additional root for the error correction code). This
effect is most pronounced on small media such as CD. RS03 will always fill
the medium to the maximum possible redundancy while RS02 allows for user
selected redundancies. For media filled with less than 30\% of data,
RS03 will create a three-fold redundancy using 170 roots which
is quite compute intensive. With RS02, a lower redundancy can be
selected which is faster to compute. However due to RS03s multithreading
capabilities it might keep its performance advantage over RS02 even
when encoding with full redundancy. 

\newpage

\begin{figure}[h]
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/augment-prefs-rs03.png}}
\caption{The ``Error correction'' tab for the RS03 codec.}  
\label{howto-augment-prefs-rs03}
\end{figure}

\paragraph{Settings for encoding with the RS03 method.}\quad

Select the entry ``Multithreaded RS codec (RS03)'' in the drop down menu (marked green).
After this selection the contents of the tab will display the choices given
with the RS03 method.

\paragraph{Error correction data storage.} Select ``Image'' (also marked green)
so that error correction data will be appended to a given image. The image will
always be filled to the maximum possible redundancy so there will be no choices
in the ``Redundancy'' field.

\paragraph{Multithreading.} The RS03 encoder can distribute its workload
onto multiple processor cores by using multithreading. On machines with
up to four cores, set the number of threads (marked yellow) equal to the
number of cores (e.g. use 4 threads on a 4 core machine). On machines with
more than 4 cores, use one thread less than the number of available cores;
e.g. use 7 threads on an 8 core machine - this leaves one core free for
housekeeping tasks.

\smallskip

Leave the other settings as shown in the screenshot; you
can \tlnk{howto-augment-advanced-settings}{optimize} them later. 

\newpage

\begin{figure}[h]
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/augment-prefs-rs02.png}}
\caption{The ``Error correction'' tab for the RS02 codec.}  
\label{howto-augment-prefs-rs02}
\end{figure}

\vspace*{-3mm}
\paragraph{Settings for encoding with the RS02 method.}\quad

Select the entry ``Augmented Image (RS02)'' in the drop down
menu (marked green). After this selection the contents of the tab
will display the choices given with the RS02 method.

\paragraph{Maximum image size.} Select
``Use smallest possible size from following table'' if you are working
with standard media sizes. dvdisaster will then choose the
smallest possible medium type which can be used for
storing the image. The remaining free space on the medium
will be used for error correction data and the image will
be prepared accordingly.

See the \tlnk{howto-augment-advanced-settings-rs02}{optimization} section
for working with non standard media and the remaining settings. 

\paragraph{Not used tabs.} The ``Misc'' tab currently has only
functions for creating log files. This is helpful for
\tlnk{reporting-defects}{reporting defects}
but should be left off during normal operation.
The ``Appearance'' tab allows you to adapt the output colors
to your taste, but these have no further effects on the error correction data creation.
All other tabs are not relevant for augmenting the image.
 
\subsubsection{Overview: Creating the augmented image and writing it to a medium}
\label{howto-augment-overview}

dvdisaster is specialized in working with error correction data and reading
of defective media. Creating ISO or UDF images and writing them to a medium
is a totally different business, and also bears high complexity. We do not
want to re-invent medium writing in dvdisaster, as a lot of useful programs
have already been written for this task. You should however pick a writing
application which supports SAO/DAO (session at once / disc at once) writing
on CD media and does not modify ISO images supplied by third-party software
(like dvdisaster). Some common free burning programs for GNU/Linux have been
\tlnk{burning-compatibility}{evaluated in the burning software compatibility section}.
For a start try using the K3B burning program.

\bigskip

The following overview shows the steps for creating, augmenting and writing the
ISO image. More detailed information on these steps is given in the next pages.

\medskip

\begin{tabular}{cl}
  \begin{minipage}{50mm}
    \centerline{\includegraphics[width=40mm]{screenshots/make-iso1.png}}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf First create an ISO image} using your optical disc writing software.
    Select the files you want to write to the medium, but do not start the writing
    process yet. Instead, create an ISO image on your hard disk. See the
    \tlnk{howto-augment-make-iso}{walkthrough for creating an ISO image with K3B}
    for more information.
  \end{minipage}\\[14mm]

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[4mm]

  \begin{minipage}{50mm}
    \centerline{\goodimage}
  \end{minipage}
  &
  \begin{minipage}{104mm}
\label{howto-augment-overview-ecc}
    When you have prepared the image {\bf switch over to dvdisaster}.
    Make sure that it has been configured as described in
    the \tlnk{howto-augment-basic-settings}{basic settings}. 
  \end{minipage}\\[6mm]

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[-4mm]

  \begin{minipage}{50mm}
    \centerline{\selectimage}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Select the directory and name of the ISO image} which
    you have just created. You can either enter the image file name directly
    into the text field or bring up a file dialog by selecting the icon to
    the left of the text field.
  \end{minipage}\\[-4mm]

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[4mm]

  \begin{minipage}{50mm}
    \centerline{\createicon}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Augment the image with error correction data} by clicking on
    the ``Create'' button.
  \end{minipage}\\[5mm]

    \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[4mm]

  \begin{minipage}{50mm}
    \centerline{\includegraphics[width=40mm]{screenshots/make-ecc3.png}}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Please wait while the error correction data is being created.} This
    may take a while depending on the image size and the available free
    space on the medium. Processing a DVD image with about 20-30\% free
    space should take a few seconds on recent hardware. 
  \end{minipage}\\[14mm]

  \begin{minipage}{50mm}
    \centerline{\downarr}

    \centerline{(continued: next page)}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Please note:} dvdisaster does not create a new image,
    but will rather augment the existing one. If you look at the image
    in the file manager before and after processing it with dvdisaster
    you will note how the image size increases.
  \end{minipage}\\
\end{tabular}

\newpage
\begin{tabular}{cl}
  \multicolumn{2}{l}{(continued from previous page)} \\

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[4mm]

  \begin{minipage}{50mm}
    \centerline{\includegraphics[width=40mm]{screenshots/write-iso1.png}}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Write the augmented ISO image on the medium.} Select the
    augmented image in your writing software and start the writing
    process. See the \tlnk{howto-augment-write-iso}{walkthrough for writing an ISO image with K3B}
    for more information.
  \end{minipage}\\[14mm]

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[5mm]

  \begin{minipage}{50mm}
    \centerline{\augmentedcd}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Finished!} You have now created an optical disc which
    is protected by error correction code.
  \end{minipage}\\
\end{tabular}

\bigskip

\paragraph{Related information}\quad

\medskip

\begin{itemize}
  \item \tlnk{howto-compat-augment}{Check whether the writing process has affected the error correction data.}

    
    It is recommended to perform this test once every time you change
    to a new version (or vendor) of your media writing software to make
    sure that it interoperates well with dvdisaster.
\end{itemize}

\newpage
\subsubsection{Detailed example: Creating an ISO image on hard disk.}
\label{howto-augment-make-iso}

Since there are many different media writing programs available we are
demonstrating the required steps by using the free optical disc writing
application {\bf K3B} as an example. If you are using a different software
you should be able to figure out the required actions from the descriptions below.

\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/make-iso1.png}}
\caption{Starting a new project.}  
\label{howto-augment-make-iso-new-project}
\end{figure}

\paragraph{Begin a new project.} First open your media
writing application. Many programs expect you to start a new project.
Within the project you will then make the selections for the new medium.

\bigskip

Using K3B: {\em Begin a new project by clicking the ``New Data Project''
  button located in the lower left area of the main window.} 

\newpage
\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/make-iso2.png}}
\caption{File selection.}  
\label{howto-augment-make-iso-file-selection}
\end{figure}

\paragraph{Select the files to be written on the medium.} Typically there
is a file selection dialog from which you can select files or drag them into the project.

\medskip

Using K3B: {\em Use the upper half of the window to navigate your
  filesystem. Drag the files and folders you want to write to the
  medium into the ``Current projects'' area in the bottom half of the
  window. In the example the folder {\tt papers} and the file {\tt archive.tar.gz}
  have been selected for writing onto CD.}

\medskip

\paragraph{Important:} Do not completely fill the medium.
Make sure to keep at least 20\% of the medium space for the error correction data.

\medskip

Using K3B: {\em The currently used medium space is shown in the
  scale bar at the bottom of the window (486,8 MiB).} 

\newpage
\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/make-iso3.png}}
\caption{Configuring the writing software.}  
\label{howto-augment-make-iso-configure}
\end{figure}

\paragraph{Configure the writing software.} The software will let you
choose the writing target before the actual writing process is invoked.
Do {\bf not} select the optical drive or medium here, but configure the creation
of an ISO/UDF image on hard disk as described below. If your program seems
to be missing an image writing option you might have to select
an ``image recorder'' instead of the actual optical drive.

\smallskip

{\bf Hint:} Remove all media from the drives before proceeding
to make sure that you do not inadvertently start the writing process.

\bigskip

Using K3B: {\em Click the ``Burn'' button in the ``Current projects''
  window (see previous screen shot) to open the medium burning dialog.
  Select ``Only create image'' from the choices listed under ``Settings''.} 

\newpage
\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/make-iso4.png}}
\caption{Select image file and type.}  
\label{howto-augment-make-iso-filename}
\end{figure}

\paragraph{Select the image file and type.} Select the target directory,
name and type for the image file. Use image files of type ``.iso'' or ``.udf'' only!
Other image formats like ``.nrg'' are not supported by dvdisaster;
processing such image files with dvdisaster will render them unusable
without further notice or error messages.

\bigskip

Using K3B: {\em Switch to the ``Image'' tab in the dialog you opened
  in the previous step. Pick the destination directory and file name
  in the text field below ``Write image file to:'', or click the
  button right to the text field to bring up the file chooser.
  In the example, the image file will be named ``medium.iso'' and placed
  in the ``backup'' directory in the user cg's home folder. K3B only
  allows you to create ``.iso'' type images, so there is nothing to
  do with respect to the image file type. }

\newpage
\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/make-iso5.png}}
\caption{Select the medium name/label.}  
\label{howto-augment-make-iso-label}
\end{figure}

\paragraph{Select the medium name.} Optionally, provide the disc
with a descriptive volume name.

\bigskip

Using K3B: {\em Switch to the ``Filesystem'' tab in the dialog.
  Enter the desired name under ``Volume Name''. In the example, the volume
  is named ``My backup disc''.}

\bigskip

Finally, click the ``Start'' button to create the ISO image. 

\newpage
\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/make-iso6.png}}
\caption{Wait for the image creation to finish.}  
\label{howto-augment-make-iso-create}
\end{figure}

\paragraph{Wait for the image creation to finish.} It
might take a while to produce the image.

\bigskip

When the ISO image has been created, please return to
the \tlnk{howto-augment-overview}{overview of creating augmented images}
and continue with the second step (``switch over to dvdisaster'').

\newpage
\subsubsection{Detailed example: Writing the augmented ISO image on a medium.}
\label{howto-augment-write-iso}

As we have mentioned in the overview section, writing the augmented image
onto the medium is not dvdisaster's task. Use your favourite optical disk
writing software for performing this step; in the following example
we are using {\bf K3B} again.

\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/write-iso1.png}}
\caption{Switching the application to image writing.}  
\label{howto-augment-write-iso-prepare}
\end{figure}

\paragraph{Select writing of the image.} Open your media writing
software again. Invoke the mode for writing pre-existing ISO images
on the medium.

\bigskip

Using K3B: {\em From the ``Tools'' menu, select the ``Burn image'' entry.} 

\newpage
\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/write-iso2.png}}
\caption{Image selection.}  
\label{howto-augment-write-iso-select}
\end{figure}

\paragraph{Image selection.} Select the image you have
just created and augmented with dvdisaster.

\bigskip

Using K3B: {\em Fill in the path to the image file in the text
  field under ``Image to burn'', or invoke the file chooser
  by pushing the button to the right of the text field.
  Select the image file you have just created with dvdisaster. }

\newpage
\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/write-iso3.png}}
\caption{More settings.}  
\label{howto-augment-write-iso-settings}
\end{figure}

\paragraph{More settings.} Select the drive which contains the
blank medium you are going to write. When writing CD media,
select the ``SAO'' (``session at once'') writing mode if
supported by your drive. Sometimes this mode is also
called ``DAO'' (``disc at once''). This improves the compatibility
between the medium and the error correction. In addition this
prevents you from accidentally adding more sessions to the disc
which would destroy the error correction data.

\bigskip

Using K3B: {\em Select the medium you wish to write in the drop
  down menu under ``Burn Medium'' (marked yellow). If you have
  more than one optical drive, it is recommended to leave all
  drives empty except for the one you wish to use for burning.
  Choose ``DAO'' in the drop down menu under ``Writing mode''
  (marked green) when writing CD media. }

\newpage
\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/write-iso4.png}}
\caption{Writing the medium.}  
\label{howto-augment-write-iso-medium}
\end{figure}

\paragraph{Writing the medium.} Now start the writing process
and wait until it finishes.

\bigskip

Using K3B: {\em Click on the ``Start'' button in the window
  from the previous screen shot. }

\bigskip

After this step, you have finished creating an optical disc
which is protected by error correction code.

\newpage
\subsubsection{Advanced settings for augmenting images with ecc data}
\label{howto-augment-advanced-settings}

\begin{figure}[h]
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/augment-prefs-rs03-adv.png}}
\caption{Settings for the RS03 codec.}  
\label{howto-augmented-settings-rs03-adv}
\end{figure}

\paragraph{Settings for encoding with the RS03 method.}\quad

\paragraph{I/O parameters.} dvdisaster optimizes access to the image
and error correction data by preloading and caching parts of them.
The optimal preload value (see options marked yellow) depends on the
storage system used for the image and error correction files. Use
small preload values for systems with low latency and seek time,
e.g. SSDs. For magnetic hard disks performance may be better using
larger preload values. A preload value of $n$ will used approx. $n$ MiB
of RAM. Do not preload more data than you have physical RAM available.

The {\em I/O strategy} setting controls how dvdisaster performs its
disk I/O while creating error correction data. Try both options and
see which performs best on your hardware setting. The read/write
option (marked green) activates dvdisaster's own I/O scheduler
which reads and writes image data using normal file I/O. The
advantage of this scheme is that dvdisaster knows exactly which
data needs to be cached and preloaded; the disadvantage is that
all data needs to be copied between the kernel and dvdisaster's
own buffers. Usually, this I/O scheme works best on slow storage
with high latency and seek times; e.g. on all storage involving
spinning platters. It may also be helpful when the system is under
high load; e.g. when a lot of I/O intensive processes are competing
for the global I/O buffers (but it is not recommended to use dvdisaster
concurrently with other I/O intensive processes anyways). The memory
mapped option uses the kernel's memory mapping scheme for direct access
to the image file. This has the advantage of minimal overhead, but may
be adversely affected by poor caching and preloading decisions made by
the kernel (since the kernel does not know what dvdisaster is going to
do with the data). This scheme usually performs well when encoding in
a RAM-based file system (such as /dev/shm on GNU/Linux) and on very fast
media with low latency such as SSDs.

\paragraph{Encoding algorithm.} This option (marked blue) affects
the speed of generating RS03 error correction data. dvdisaster can
either use a generic encoding algorithm using 32bit or 64bit wide
operations running on the integer unit of the processor, or use
processor specific extensions. Available extensions are SSE2 for
x86 based processors and AltiVec on PowerPC processors. These
extensions encode with 128bit wide operations and will usually
provide the fastest encoding variant. If ``auto'' is selected,
the SSE2/AltiVec algorithms will be selected if the processor
supports them; otherwise the 64bit algorithm will be used. Therefore,
the ``auto'' setting is a good choice unless you are running very
uncommon or legacy hardware.

\newpage
\begin{figure}[h]
\vspace*{-5mm}
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/augment-prefs-rs02-adv.png}}
\caption{Settings for the RS02 codec.}  
\label{howto-augmented-settings-rs02-adv}
\end{figure}

\vspace*{-8mm}

\paragraph{Settings for encoding with the RS02 method.}\quad
\label{howto-augment-advanced-settings-rs02}

Please note that this section is only relevant to RS02.
RS03 does not have the respective features.

\paragraph{Choosing the image size.} dvdisaster has a table of
standard sizes for CD, DVD and BD media. Any media should meet
these size requirements. Some vendors produce slightly higher
capacity media. If you have such media, insert a blank one into
the currently selected drive and click the ``query medium'' button
(marked green) to the right of the proper medium type. dvdisaster
will determine the medium size and update the table accordingly.
Alternatively, you can also enter the medium size directly into the
respective numerical fields.

Note: The medium size can only be determined in drives which are
capable of writing the respective media type.

\paragraph{Arbitrary image sizes.} You can set a specific image
size which will not be exceeded after augmenting it with RS02
error correction data. To do so activate the button beneath
``Use at most ... sectors'' and enter the maximum image size
in units of sectors (1 sector = 2KiB).

\newpage

\subsection{Recovering media images}
\label{howto-recover}

\begin{tabular}{lll}
  \multicolumn{2}{l}{\bf Task} &
Recover the contents of a defective medium. \\[10mm]

  \multicolumn{2}{l}{\bf Required:} & \\[3mm]

  \begin{minipage}{15mm}
    \quad
  \end{minipage} &

  \begin{minipage}{15mm}
    \augmentedcd
  \end{minipage} &
  A defective medium containing \tlnk{howto-augment}{error correction data}, \\

  & & or \\
  
  \begin{minipage}{15mm}
    \badcd
  \end{minipage} &

  \begin{minipage}{15mm}
    \eccfile
  \end{minipage} &

  a defective medium with an
  appropriate \tlnk{howto-eccfile}{error correction file}\footnotemark. \\[10mm]

  \multicolumn{2}{l}{\bf What to do:} &
  \tlnk{howto-recover-basic-settings}{1. Configure basic settings for reading,} \\[2mm]

  & &
  \tlnk{howto-recover-read}{2a. create an ISO image from the defective medium,} \\[2mm]

  & &
  \tlnk{howto-recover-fix}{2b. recover the image and write it to a new medium.} \\[10mm]

\end{tabular}

\footnotetext{The error correction file must have been created
  at a time the medium was still intact: It is not possible to
  create error correction data from an already defective medium. }

\vspace{10mm}

\subsubsection{Basic settings for recovering media images}
\label{howto-recover-basic-settings}

\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/global-prefs-invoke.png}}
\caption{Opening the configuration dialog.}  
\label{howto-recover-open-preferences}
\end{figure}

The relevant tabs are described on the next pages. They are
found in the configuration dialog.
Open the dialog by selecting the symbol marked green in the
screen shot ( \begin{minipage}{8mm}\includegraphics{icons/prefs-icon.png}\end{minipage}, see figure \ref{howto-recover-open-preferences}).
The symbol may look different due to the symbol theme you are using.

\bigskip

The settings shown here configure dvdisaster for reading the defective
medium. There are no dedicated settings for reconstructing the image
from the error correction data. 

\newpage

\begin{figure}[h]
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/recover-prefs-image.png}}
\caption{The ``Image'' tab.}  
\label{howto-recover-prefs-image}
\end{figure}

First switch the reading strategy to ``Adaptive'' (marked green)
so that dvdisaster uses information from the error correction data
to make the reading process as efficient as possible.

\medskip

When the defective medium has been augmented with RS02 or RS03
error correction data, activate the respective options for error
correction data recognization (marked yellow). Do not activate
these options when working with error correction files. Otherwise
dvdisaster will search the image for error correction data, which
takes a lot of time.

\medskip

Leave the remaining settings at the values shown in the screen shot. 

\newpage

\begin{figure}[h]
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/recover-prefs-drive.png}}
\caption{The ``Drive'' tab.}  
\label{howto-recover-prefs-drive}
\end{figure}

Leave this tab at the shown default settings for the moment.
Some drives might read CD media better using the raw reading
mode ``21h'' (this mode is ignored for DVD and BD media).
See the \tlnk{howto-recover-settings-adv}{advanced settings} for more information.

\newpage

\begin{figure}[h]
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/recover-prefs-read-attempts.png}}
\caption{The ``Reading attempts'' tab.}  
\label{howto-recover-prefs-read-attempts}
\end{figure}

The strength of the adaptive reading strategy lies in finding the
still readable sectors and avoiding the lengthy process of trying
to read defective sectors. Therefore select ``raw'' reading
(marked green) as it will not cost additional processing time,
but reduce the number of reading attempts to the minimum values
(marked yellow). Use a moderate termination criterium of 128 unreadable
sectors (marked blue) for the first reading attempt. Do not activate
raw sector caching yet. If it turns out that these settings do not
provide enough data for a successful recovery they can
be \tlnk{howto-recover-settings-adv}{optimized} later. 

\paragraph{Not used tabs.} The ``Error correction'' and ``Files'' tabs
have no influence on the reading process. The ``Misc'' tab currently
has only functions for creating log files. This is helpful for
\tlnk{reporting-defects}{reporting defects} but should be left
off during normal operation. The ``Appearance'' tab allows you
to adapt the output colors to your taste, but these have no
further effects on the reading process. 

\newpage
\subsubsection{Recovering media images - Walkthrough}
\label{howto-recover-read}

Please make sure that dvdisaster has been configured as
described in the \tlnk{howto-recover-basic-settings}{basic settings} section.
Then perform the following steps: 

\bigskip

\begin{tabular}{cl}
  \begin{minipage}{50mm}
    \centerline{\slotin}
  \end{minipage}
  &
  \begin{minipage}{104mm}
  {\bf Insert the defective medium into a drive} which
  is directly connected to your computer. You can not use network
  drives, software drives and drives inside virtual machines.
  \end{minipage}\\

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\

  \begin{minipage}{50mm}
    \centerline{\filemanager}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Close any windows} which may be opened by your
    operating system for viewing or performing the medium contents.
    Wait until the drive has recognized the medium and the medium
    has spun down. 
  \end{minipage}\\

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[6mm]

  \begin{minipage}{50mm}
    \centerline{\selectdrive}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Select the drive containing the defective medium} in dvdisasters
    drop down menu. 
  \end{minipage}\\[4mm]

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\

  \begin{minipage}{50mm}
    \centerline{\selectecc}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    \label{howto-recover-enter-eccfile}
    If you are using \tlnk{howto-eccfile}{error correction files} enter the file name
    in the shown field. Leave this entry blank when the medium
    has been \tlnk{howto-augment}{augmented with error correction data}.
  \end{minipage}\\

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[6mm]

  \begin{minipage}{50mm}
    \centerline{\readicon}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Click the "Read" button} to start the reading process.
  \end{minipage}\\[6mm]

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[6mm]

  \begin{minipage}{50mm}
    \centerline{\includegraphics[width=40mm]{screenshots/adaptive-progress.png}}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    \paragraph{Watch the reading process progress.} The adaptive reading strategy
    performs a systematic search for readable sectors. You will observe temporary
    gaps which will be closed in later stages. Usually this effect is less
    pronounced as shown in the screen shot. If all defective sectors are
    located at the end of the medium the reading process may even stop
    before touching the first defective sector. 
  \end{minipage}\\

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[6mm]

  \multicolumn{2}{l}{(continued at the next page)} \\
\end{tabular}

\newpage
\paragraph{The next actions depend on the outcome of the reading process.} The
reading process terminates automatically when enough data for a successful
recovery has been gathered (compare the output marked in green). In that
case continue the recovery by clicking on the ``Fix'' button as
\tlnk{howto-recover-fix}{described two pages later}. 
\label{howto-recover-read-success}

\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/adaptive-success.png}}
\caption{A successful reading attempt.}  
\label{howto-recover-reading-success}
\end{figure}

\newpage

The reading process will also abort if it could not find enough readable
sectors (see the output marked in red). The image is not yet recoverable
in this incomplete state. Please try to gather additional data following
the tips shown in \tlnk{howto-recover-settings-adv}{advanced settings}.

\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/adaptive-failure.png}}
\caption{An incomplete reading attempt.}  
\label{howto-recover-reading-failure}
\end{figure}

\newpage

\paragraph{Recovering the image of the defective medium}\quad
\label{howto-recover-fix}

\bigskip

\begin{tabular}{cl}
  \multicolumn{2}{l}{(continued from previous pages)} \\

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[6mm]

  \begin{minipage}{50mm}
    \centerline{\fixicon}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    Click the "Fix" button to begin the {\bf image recovery}. The recovery
    will succeed only if the \tlnk{howto-recover-read-success}{reading process stated success}!
  \end{minipage}\\[6mm]

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[6mm]

    \begin{minipage}{50mm}
    \centerline{\includegraphics[width=40mm]{screenshots/fix-success.png}}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Watch the progress of the recovery.} The adaptive reading
    will stop as soon as enough data has been collected for a
    successful recovery; therefore the error correction will
    always be loaded to the max. This causes the display of the
    massive red area in the ``Errors/Ecc block'' graph and is no
    cause for worry. Depending on the medium size and your system
    speed the recovery may take several minutes to hours.
  \end{minipage}\\[16mm]

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[6mm]

  \begin{minipage}{50mm}
    \centerline{\goodimage}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    When the recovery finishes all data in the ISO image will be complete again.
  \end{minipage}\\[6mm]

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[6mm]

  \begin{minipage}{50mm}
    \centerline{\includegraphics[width=40mm]{screenshots/write-iso1.png}}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Write the recovered ISO image} to a new medium using your
    favourite media writing software. This step is the same as
    \tlnk{howto-augment-write-iso}{writing a newly created augmented image to a medium}.
  \end{minipage}\\[16mm]

 \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[6mm]

 \begin{minipage}{50mm}
  \oldcd\oldimage\goodcd
  \end{minipage}
  &
  \begin{minipage}{104mm}
    Now you have created a new medium containing the fully recovered data.
    Make sure to \tlnk{howto-scan}{check it for read errors}. Then you
    can discard the defective medium and delete the ISO image.
    However if you have created an error correction file for the old
    medium then you can keep it to protect the newly created medium. 
  \end{minipage}\\[6mm]
\end{tabular}

\newpage
\subsubsection{Advanced settings for recovering media images}
\label{howto-recover-settings-adv}

The first attempt of \tlnk{howto-recover-read}{reading the defective medium} will
usually provide enough data for the error correction. If it did not, try the following.

\vspace*{-2mm}

\paragraph{Estimating the chance of recovery}\quad

\bigskip

\centerline{\includegraphics[width=\textwidth]{screenshots/adaptive-failure.png}}

\smallskip

Examine the output of the reading process. Under the
``Sectors processed'' section you will find the actual
percentage of readable sectors and how many percent will
be needed for a full recovery. Using the difference between
the two values (85.6\% - 81.3\% = 4.3\% in the example) you
can estimate the likelyhood of being able to collect enough
sectors for a successful recovery. The following table
relates the missing percentages to the likelyhood of a
successful recovery.

\bigskip

\colorbox{ltgreen}{
  \begin{tabular}{p{30mm}p{118mm}}
    $<$ 5\% &
    Chances are good that you will get enough data using more reading attempts. \\
\end{tabular}}

\vspace*{-1mm}

\colorbox{ltyellow}{
  \begin{tabular}{p{30mm}p{118mm}}
    5\% - 10\% &
    If you have several drives with different reading characteristics
    you may get the required data by being persistent and patient. \\
\end{tabular}}

\vspace*{-1mm}

\colorbox{ltorange}{
  \begin{tabular}{p{30mm}p{118mm}}
    10\% - 20\% &
    You are in trouble. If the missing sectors do not drop significantly
    below 10\% during the next 2-3 reading attempts the medium is probably
    unrecoverable. \\
\end{tabular}}

\vspace*{-1mm}

\colorbox{ltred}{
  \begin{tabular}{p{30mm}p{118mm}}
    10\% - 20\% &
    Too much data loss; you can write this medium off as unrecoverable.
    To prevent this from happening again, use error correction data
    with higher redundancies and shorten the intervals for defect scanning.  \\
\end{tabular}}

Try the following settings one by one in further read attempts. Please
perform a complete reading pass for each setting so that you learn how
it affects the outcome (sometimes the results also differ depending on
the drive used for reading). When you have gone through the list you may
combine them into more powerful configurations. 

\begin{figure}[h]
\centerline{\includegraphics[width=0.87\textwidth]{screenshots/fix-prefs-read-attempts-adv1.png}}
\caption{Another reading pass with finer granularity.}  
\label{howto-recover-read-attempts-finer}
\end{figure}

\vspace*{-10mm}
\paragraph{Perform another reading pass with a finer granularity}\quad

Do not alter any values except for setting a smaller value for terminating
the reading process. Recommended values are: 32 for BD, 16 for DVD and 0
for CD (use the slider marked green). Perform another reading attempt
using this setting. You can repeatedly read the medium as long as any
pass provides a significant number of new sectors.

\smallskip

{\bf Hint:} Let the drive cool down between the reading passes.
Eject and load the medium before each pass; sometimes the medium
comes to rest in a better position and the number of readable sectors improves. 

\vspace*{-3mm}
\paragraph{Complete the image using different drives}\quad

Perform additional reading attempts using different drives.
Transfer the image to other computers to see if their drives
can contribute more readable sectors.

\newpage

\begin{figure}[h]
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/fix-prefs-read-attempts-adv2.png}}
\caption{Increasing the number of reading attempts per sector.}  
\label{howto-recover-read-attempts-per-sector}
\end{figure}

\paragraph{Increase the number of reading attempts per defective sector.}\quad

\bigskip

{\em For all media types (CD, DVD, BD):}

\medskip

Set the number of reading attempts per sector to a minimum of 5 and
a maximum of 9 (green markings).

\bigskip

{\em Only for CD media:}

\medskip

Some drives are capable of partially reading defective sectors on
CD media. Activate the ``Raw sector caching'' option and specify
a directory where fragments of defective sectors should be stored
(yellow markings). If enough fragments of a defective sector have
been collected it may be possible to fully reconstruct it from
that information. 

\medskip

See the hints on the next page to check that these settings
really have an effect.

\paragraph{Making sure that the new settings work:}\quad

\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/fix-reread-dvd.png}}
\caption{Multiple reading attempts.}
\label{howto-recover-multiple-read-attempts}
\end{figure}

{\em Examining results of multiple reading attempts (CD, DVD, BD):}

Not all drives show an improvement after increasing the number of
reading attempts. Watch for messages of the
form "Sector ..., try x: success" (highlighted in yellow). These
indicate that the drive could read a sector after several reading
attempts. If you never see such messages, increasing the number of
reading attempts does not pay off for the respective drive. 

\bigskip

{\em Examining partial reading of defective CD sectors:}

When the whole medium has been processed, look into the directory you
entered above (/var/tmp/raw in the example). If no raw files have
been created the drive may not support the required reading mode.
However if you have several drives which do create raw files, then
let them all work in the same raw file directory. Collecting raw sector
fragments from different drives hightens the chance of reconstructing
the defective sectors. 

\newpage

\begin{figure}[h]
\centerline{\includegraphics[width=0.9\textwidth]{screenshots/fix-prefs-read-drive-adv.png}}
\caption{Use a different raw reading mode.}
\label{howto-recover-different-raw-reading-mode}
\end{figure}

{\em Use a different raw reading mode for CD media:}

Using the preset "20h" raw reading mode might not work on
some drives. Perform another reading attempt using raw reading
mode "21h" (see the screenshot). Check again whether some raw
files have been created. 

\newpage
\subsection{Getting information on images and error correction data}
\label{howto-info}

\bigskip

\begin{tabular}{lll}
  \multicolumn{2}{l}{\bf Task} &
  \begin{minipage}{119mm}
  Shows information on types and states of images and error correction files.
  \end{minipage}
  \\[10mm]

  \multicolumn{2}{l}{\bf Required:} & \\[3mm]

  \begin{minipage}{15mm}
    \goodimage
  \end{minipage} &

  \begin{minipage}{15mm}
    \eccfile
  \end{minipage} &
  \begin{minipage}{119mm}
  An image file (either fully working or defective) and optionally
  the \tlnk{howto-eccfile}{error correction file} for it.
  \end{minipage}\\[10mm]

  \multicolumn{2}{l}{\bf What to do:} &
  \tlnk{howto-info-show}{1. Show the information} \\[2mm]

  & &
  2. Interpret the results for \tlnk{howto-info-rs01}{RS01},
 \tlnk{howto-info-rs02}{RS02}, or \tlnk{howto-info-rs03}{RS03}.
  \\[2mm]
\end{tabular}

\subsubsection{Showing the information}
\label{howto-info-show}

The are no settings for this function; however you need an
image file and optionally the \tlnk{howto-eccfile}{error correction file}
belonging to it. 

\vspace{10mm}

\begin{tabular}{cl}
  \begin{minipage}{50mm}
    \centerline{\selectimage}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Enter the file name of the ISO image} for which you want
    to get information. The image must already be present on hard disk;
    otherwise use the "Read" function to get it from a medium. 
  \end{minipage}\\

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\

    \begin{minipage}{50mm}
    \centerline{\selectecc}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Enter the name of the error correction file} which belongs
    to this medium. Leave this entry blank when the image has
    been \tlnk{howto-augment}{augmented with error correction data}. 
  \end{minipage}\\

  \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[6mm]

  \begin{minipage}{50mm}
    \centerline{\verifyicon}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Start the evaluation} by clicking on the "Verify" button.
  \end{minipage}\\[6mm]

 \begin{minipage}{50mm}
    \centerline{\downarr}
  \end{minipage}
  & \\[6mm]

 \begin{minipage}{50mm}
    \centerline{\includegraphics[width=40mm]{screenshots/info-okay-rs02.png}}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Watch the verification progress.} In order to display
    all information the image and error correction files must be fully read. 
  \end{minipage}\\
\end{tabular}

\newpage

The verification process produces slightly different output
depending on the the type of error correction data used:

\begin{itemize}
\item whether \tlnk{howto-eccfile}{error correction files} or
  \tlnk{howto-augment}{augmented images} have been used; and
\item which \tlnk{background-methods}{error correction method}
  (e.g. RS01, RS02 or RS03) has been used.
\end{itemize}

See the following subsections for interpreting the specific outputs for:

\begin{itemize}
\item \tlnk{howto-info-rs01}{error correction files created by the RS01 method}; or
\item \tlnk{howto-info-rs02}{images augmented with error correction data by the RS02 method}; or
\item \tlnk{howto-info-rs03}{any error correction data created by the RS03 method.}
\end{itemize}

\subsubsection{Results for images with RS01 error correction files}
\label{howto-info-rs01}

\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/info-okay-rs01.png}}
\caption{Info for an image with RS01 error correction file.}
\label{howto-info-good-rs01}
\end{figure}

\newpage

Output field {\bf ``Image file summary''}:

\medskip

\begin{tabular}{lp{125mm}}
  Medium sectors  & 
  The number of sectors in the ISO image (one sector = 2KiB). \\
  Checksum errors &
  The error correction file contains CRC32 checksums for each image sector. 
  If this value is greater than zero some sectors were readable but their 
  contents do not match the checksum. The error correction will try to 
  recalculate the contents of these sectors.  \\
  Missing sectors & 
  This is the number of sectors which could not be read from 
  the medium. The error correction will try to recover the contents of these sectors. \\
  Image checksum &
  A MD5 checksum is calculated for the complete ISO image. You can reproduce 
  this value using the command line of GNU/Linux: \par
  {\tt md5sum medium2.iso}
\end{tabular}

\medskip

If all values in this output field are okay the 
message "\textcolor{dkgreen}{Good image.}" appears. 
Otherwise the most important error will be explained there. 

\bigskip

Output field {\bf ``Error correction file summary''}:

\medskip

\begin{tabular}{lp{124mm}}
  Created by: &
  Prints the dvdisaster version which was used for creating the 
  error correction data. Alpha/developer versions are highlighted in red. \\
  Method: &
  The method and redundancy used for creating the error correction file. \\
  Requires: &
  Processing the error correction data may require at least the shown version of dvdisaster. \\
  Medium sectors: &
  The expected number of sectors in the image file (as recorded in the ecc data). \\
  Image checksum: &
  The expected MD5 sum of the image file. \\
  Fingerprint: &
  dvdisaster uses the checksum of a special sector to determine 
  whether the error correction file was made for a given image. \\
  Ecc blocks: &
  The error correction divides the image into small blocks which can 
  be processed independently. This information is not of interest as long 
  as the number of ecc blocks is correct ;-) \\ 
  Ecc checksum: &
  A MD5 checkum is calculated over the error correction file, not taking 
  into account the first 4KiB. You can reproduce this value using 
  the command line of GNU/Linux: \par
  {\tt tail -c +4097 medium.ecc | md5sum} \\
\end{tabular}

\medskip

If all values in this output field are okay the 
message "\textcolor{dkgreen}{Good error correction file.}" appears. Otherwise 
the most important error will be explained there. 

\newpage
 	
\subsubsection{Results for images augmented with RS02 error correction data}
\label{howto-info-rs02}

\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/info-okay-rs02.png}}
\caption{Info for an image augmented with RS02 error correction data.}
\label{howto-info-good-rs02}
\end{figure}

When verifying an image against its embedded error correction data the 
information will be given with respect to:

\begin{itemize}
\item the whole (augmented) image (``Image file summary''), and
\item the error correction data part (``Error correction data'').
\end{itemize}

\bigskip

Output field {\bf ``Image file summary''}:

\medskip

\begin{tabular}{p{28mm}p{125mm}}
  Medium sectors  & 
  The number of sectors in the augmented image (including the sectors added by dvdisaster; 
  one sector = 2KiB). \\
  Data checksum: &
  The MD5 checksum of the original image (prior to augmenting it with error correction data). \\
  Ecc headers, \par
  Data section,\par
  Crc section, \par
  Ecc section  & 
  The augmented image consists of three sections plus some ecc header sectors 
  embedded into them. These values describe how many sectors are unreadable 
  in the respective sections. \\
\end{tabular}

\medskip

If all values in this output field are okay the 
message "\textcolor{dkgreen}{Good image.}" appears. 
Otherwise the most important error will be explained there. 
\newpage

Output field {\bf ``Error correction file summary''}:

\medskip

\begin{tabular}{lp{125mm}}
Created by: &
Prints the dvdisaster version which was used for creating the error 
correction data. Alpha/developer versions are highlighted in red. \\
Method: &
The method and redundancy used for creating the error correction data. \\
Requires: &
Processing the error correction data may require at least the shown version of dvdisaster. \\
Medium sectors: &
The first value is the number of sectors in the augmented image; 
the second one describes the number of sectors the image had before 
it was processed with dvdisaster. Since the error correction data is 
placed behind the user data, the checksum of the original image can be 
obtained as follows (using the command line of GNU/Linux):

\smallskip

{\tt head -c \$((2048*121353)) medium.iso | md5sum}

\smallskip

The first parameter for head is the sector size (2048) multiplied 
with the original image length (121353). This property of augmented images 
can also be used to cut off the error correction data:

\smallskip

{\tt head -c \$((2048*121353)) medium.iso $>$stripped\_image.iso}\\
Data checksum: &
The MD5 checksum of the original image (see previous explanations). \\
CRC checksum: & MD5 checksums of the CRC and ECC sections of the augmented image. \\
ECC checksum: & These two can not be easily reproduced outside of dvdisaster. \\
\end{tabular}

\bigskip

If all values in this output field are okay the
message "\textcolor{dkgreen}{Good error correction data.}" appears.
Otherwise the most important error will be explained there.

\subsubsection{Results for RS03 error correction data (ecc files and augmented images)}
\label{howto-info-rs03}

The RS03 error correction method can produce both error correction files
and augmented images. The information screen is very similar for both ways
of storing the error correction data (see fig. \ref{howto-info-good-rs03-file}
and  \ref{howto-info-good-rs03-augmented}).

\bigskip

Output field {\bf ``Error correction properties''}:

\medskip

\begin{tabular}{lp{126mm}}
  Type: &
  Indicates whether the error correction data is stored
  in a separate file (``Error correction file'') or contained
  within the image (``Augmented image''). \\
 	
  Method: &
  The method and redundancy used for creating the error correction data. \\
 	
  Created by: &
  Prints the dvdisaster version which was used for creating the error correction data. \\
 	
  Requires: &
  Processing the error correction data may require at least the shown version
  of dvdisaster. \\
 	
  Data checksum: &
  The MD5 checksum of the original image used for creating
  the error correction data, if available. Calculating this
  checksum requires reading the image twice, so it is turned off by default
  for performance reasons. Future versions of dvdisaster will provide a switch
  in the preferences dialogue (currently it is not possible to switch this feature on).\\

  Fingerprint: &
  dvdisaster uses the checksum of a special sector to determine 
  whether the error correction file was made for a given image.
  Not used for augmented images.\\

\end{tabular}

\newpage
\begin{figure}[h]
\vspace*{-5mm}
\centerline{\includegraphics[width=\textwidth]{screenshots/info-okay-rs03-file.png}}
\caption{Info for an image with RS03 error correction file.}
\label{howto-info-good-rs03-file}
\end{figure}
\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/info-okay-rs03-augmented.png}}
\caption{Info for an image augmented with RS03 error correction data.}
\vspace*{-50mm}
\label{howto-info-good-rs03-augmented}
\end{figure}
\newpage

If no problems are identified with the error correction data,
the message ``\textcolor{dkgreen}{Good error correction data.}'' appears.
Otherwise the most important error will be explained there. 

\bigskip

Output field {\bf ``Data integrity''}:

\medskip

\begin{tabular}{p{29mm}p{125mm}}
  Medium sectors: &
  For error correction files, the first value is the number of
  sectors in the image, and the second value is the size of
  the error correction file measured in 2048 KiByte sectors.
  For augmented images, the first value is the total number of
  sectors in the augmented image, and the second one describes
  the number of sectors the image had before it was processed with dvdisaster.

  \smallskip
  
  Please note that given the same image and redundancy, the size of
  the error correction file will not match the size of the ecc data
  in the augmented image. This is normal behaviour due to padding
  in the augmented image.\\[2mm]
 	
  Data checksum: &
  The MD5 checksum of the image, calculated during the verification process.

  \smallskip
  
  For RS03 augmented images, the checksum can be calculated using
  GNU/Linux tools just as for RS02. The checksum of the original image
  can be obtained as follows (using the command line of GNU/Linux):

  \smallskip
  
  {\tt head -c \$((2048*121353)) medium.iso | md5sum}

  \smallskip
    
  The first parameter for head is the sector size (2048) multiplied
  with the original image length (121353). This property of augmented
  images can also be used to cut off the error correction data:

  \smallskip

  {\tt head -c \$((2048*121353)) medium.iso $>$stripped\_image.iso}\\[2mm]

    Data section,\par
    CRC section,\par
    ECC section &
  If any inconsistencies or missing sectors are found in the
  image (data section) or the error correction data (CRC and ECC section),
  they are reported here.\\[2mm]
 	
  ECC block test: &
  In addition to testing the internal checksums, the RS03
  verify process uses the error correction data to prove
  that all data in the image (and optionally the ecc file)
  is correct. This process may take several minutes depending
  on the image size and can be interrupted using the ``Stop'' button. \\
\end{tabular}

\bigskip

If all values in this output field are okay the
message ``\textcolor{dkgreen}{Good image.}'' appears.
Otherwise the most important error will be explained there. 

\newpage

\subsubsection{Examples}

You have already seen examples
of \tlnk{howto-info-rs01}{good images and error correction files}
and \tlnk{howto-info-rs02}{good images augmented with error correction data} on
the previous pages. In the following some typical examples
of error situations are presented:

\bigskip

\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/info-bad-rs01.png}}
\caption{Image with unreadable sectors, RS01.}
\label{howto-info-bad-rs01}
\end{figure}

{\bf Image with unreadable sectors and error correction file.} This is a typical
case of an image from a defective medium, before the error correction has been
applied. The image shown here
contains 6245 unreadable sectors; error correction data is present
by means of an error correction file. 

\newpage

\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/info-bad-rs02.png}}
\caption{Image with unreadable sectors, RS02.}
\label{howto-info-bad-rs02}
\end{figure}

\paragraph{Image augmented with error correction data, containing unreadable sectors.} This
is another example of an image from a defective medium before recovery.
This image contains unreadable sectors towards its end. Especially
the ECC section is affected since the error correction data is located
at the end of the image. Please note that this does not weaken the error
correction since its corrective power is independent from the error
location: 10000 errors at the beginning of the medium are just as easy
to correct as 10000 errors towards its end. See also the 
\tlnk{bigpicture-ecc}{introduction into the error correction}
and \tlnk{qa-ecc-distribution}{QA item 1.4} on this topic.

\bigskip

The RS02 encoder which was used for creating the error correction data is
capable of predicting the odds of a successful image recovery. These are
shown at the end of the error correction data output area. 

\newpage

\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/info-truncated.png}}
\caption{Truncated image due to an aborted read, RS01.}
\label{howto-info-truncated}
\end{figure}

\paragraph{\bf Image from aborted reading process.} This image is shorter
than expected; this usually happens when the reading process is stopped prematurely. 

\newpage

\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/info-padding.png}}
\caption{Image too large because of padding sectors, RS01.}
\label{howto-info-padding}
\end{figure}

\paragraph{Image is larger than expected.} This image is larger than
expected; possible causes are discussed in the section
about \tlnk{howto-compat-overview}{image compatibility}. It may
be possible to recover from this problem; see hints
related to \tlnk{howto-compat-file}{using error correction files} and
\tlnk{howto-compat-augment}{using augmented images}. 

\newpage

\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/info-mismatch.png}}
\caption{Wrong error correction file, RS01.}
\label{howto-info-mismatch}
\end{figure}


\paragraph{Wrong error correction file.} The error correction
file was created for a different image.
This causes lots of CRC errors since the data sectors have different
contents. However the most important hint is:

\medskip

Fingerprint: \textcolor{dkred}{mismatch}

\medskip

This tells you that the error correction file does not belong to the image. 

\newpage
\subsection{Testing image compatibility}
\label{howto-compat-overview}

Since dvdisaster depends on your favourite media writing software for writing media and creating
ISO images, it is important to make sure that both softwares
agree on how to create a proper ISO image.

\paragraph{Why dvdisaster uses ISO images.} Some dvdisaster functions work on 
image files stored on hard disk. Optical drives are too slow for carrying out 
the required access patterns, and they would wear out quickly during this process. 
However hard disks are designed for this type of access, and they do them quickly and without wear.

\paragraph{Testing image compatibility is important.} During the work with dvdisaster you 
can (and sometimes must) use ISO images which have been created by third-party software. 
Most products create usable images when advised to use the “.iso” file format, but some
alter the image while writing it to the medium. This renders ecc data unusable. Also,
processing non-iso images with dvdisaster will result in unusable error correction data. 
Especially, {\bf formats like .nrg are not suitable} for processing with dvdisaster.

\paragraph{Possible scenarios.} The following situations require 
exchanging ISO images between dvdisaster and a third party software:

\begin{itemize}
\item[a)] Creating error correction files from ISO images made by a CD authoring software

\smallskip

An optical disc authoring software is used to create an ISO image. This 
image is used for writing the medium and for creating the error correction file. 
When using the authoring software for the first time with dvdisaster, make sure 
that the \tlnk{howto-compat-file}{image was written to the medium without modifications}.

\item[b)] Augmenting ISO images with error correction data

\smallskip

dvdisaster adds ``invisible'' error correction data to the ISO image
in  order to minimize interference with other applications reading from the medium.
But this invisibility might prevent some optical disc writing software from properly
writing the error correction data to the medium. Make sure that your 
writing software does \tlnk{howto-compat-augment}{correctly transfer the error correction data}
when using it with augmented images for the first time.
\end{itemize}
 
\smallskip

Please see also the \tlnk{burning-compatibility}{burning software compatibility list}. From time 
to time the dvdisaster project evaluates some of the most popular burning 
software for the GNU/Linux platform and summarizes the results there. 

%\newpage

\subsubsection{Testing compatibility with CD/DVD/BD writing software for error correction files}
\label{howto-compat-file}

\paragraph{Motivation:} You want to write data to a medium and create an error correction file for it.
In order to save time you do the following:

\begin{enumerate}
\item You create an ISO image using your optical disc writing software.
\item You write the image to a medium.
\item You create the error correction file from the same image.
\end{enumerate}

\paragraph{Possible incompatibility:} The writing software creates a medium which
does not exactly match the image. This might prevent the error correction from recovering
the medium contents when it becomes defective. 

\paragraph{How to test compatibility:} Please note that some steps are only sketched out here; follow
the links to the respective sections to find detailed instructions and examples.

\bigskip

\begin{tabular}{ccl}
  \multicolumn{2}{c}{\begin{minipage}{25mm}\goodimage\end{minipage}}
  &
  \begin{minipage}{100mm}
    {\bf Create an ISO image of the data} you want to write on the medium.
    If you need help on creating ISO images please refer to
    the \tlnk{howto-augment-make-iso}{example of creating ISO images}. 
  \end{minipage} \\[6mm]

  \multicolumn{2}{c}{\begin{minipage}{37mm}\downforkarr\end{minipage}}
  &
  \\[-3mm]
  
  \begin{minipage}{25mm}\goodcd\end{minipage}
    &
  \begin{minipage}{25mm}\eccfile\end{minipage}
    &
  \begin{minipage}{100mm}
    {\bf Write the medium and create the error correction file.} Use the just
    created image to \tlnk{howto-augment-write-iso}{write the medium}. Then
    perform these \tlnk{howto-eccfile-basic-settings-ecc}{basic settings}
    and \tlnk{howto-eccfile-create-ecc}{create an error correction file} from
    the image you still have on your hard disk (e.g. do not yet read it back
    from the medium you have just created).
  \end{minipage}
  \\[-3mm]

  \begin{minipage}{15mm}\downarr\end{minipage}
    &
    &
    \\[-2mm]

  \begin{minipage}{20mm}\goodimagetwo\end{minipage}
    &
    &
     \begin{minipage}{100mm}
       {\bf Create a {\em second} image from the {\em written} medium.} Use
       these  \tlnk{howto-eccfile-basic-settings}{settings} and read the medium
       as described in \tlnk{howto-eccfile-create}{creating an image} for
       making an error correction file. However you can stop the walk-through
       when the reading is finished as we do not need to create the error correction file again. 
     \end{minipage}
  \\[-3mm]

  \begin{minipage}{15mm}\downarr\end{minipage}
    &
    &
    \\[-3mm]
  
  \multicolumn{2}{c}{
  \begin{minipage}{50mm}
    \centerline{\selectimage}
  \end{minipage}}
  &
  \begin{minipage}{100mm}
    {\bf Enter the file name of the {\em second} ISO image} which you have just
    read from the medium. Please note that the following test is useless when
    working with the image which was initially created using the optical disc
    authoring software. 
  \end{minipage}\\[-5mm]

  \multicolumn{2}{c}{
  \begin{minipage}{5mm}\downarr\end{minipage}}
    &
    \\
  
  \multicolumn{2}{c}{
  \begin{minipage}{50mm}
    \centerline{\selectecc}
  \end{minipage}}
  &
  \begin{minipage}{100mm}
    {\bf Enter the name of the error correction file} in case it is not
    already present from the previous actions. 
  \end{minipage}\\

  \multicolumn{2}{c}{
  \begin{minipage}{5mm}\downarr\end{minipage}}
    &
    \\[4mm]
  
  \multicolumn{2}{c}{
  \begin{minipage}{50mm}
    \centerline{\verifyicon}
  \end{minipage}}
  &
  \begin{minipage}{100mm}
    {\bf Start the evaluation} by clicking on the ``Verify'' button.
  \end{minipage}\\[5mm]

  \multicolumn{2}{c}{
  \begin{minipage}{5mm}\downarr\end{minipage}}
    &
    \\[4mm]
  
  \multicolumn{2}{c}{
  \begin{minipage}{50mm}
    \centerline{\includegraphics[width=40mm]{screenshots/info-okay-rs01.png}}
  \end{minipage}}
  &
  \begin{minipage}{100mm}
    {\bf Look at the verification results.} If you get the green messages ``Good image.'' 
    and ``Good error correction file.'' your authoring software and dvdisaster 
    are compatible. You can continue creating the error correction files directly 
    from the ISO images produced by the authoring software. 
  \end{minipage}\\
\end{tabular}
\newpage

{\bf Possible error causes and remedy:}

\bigskip

\begin{tabular}{cl}
  \begin{minipage}{50mm}
    \centerline{\includegraphics[width=40mm]{screenshots/verify-fail1.png}}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Typical problem: wrong image size.} The verification process may find out 
    that the image is larger than expected. Typically the difference is 150 or 300 sectors 
    for CD media and 1-15 sectors for DVD/BD media. These might simply be zero padding
    sectors appended to the image by the writing software. To find out if this really 
    is the case do the following: 
  \end{minipage}\\[14mm]

  \begin{minipage}{50mm}\centerline{\downarr}\end{minipage}
    &
    \\[4mm]

  \begin{minipage}{50mm}\centerline{\fixicon}\end{minipage}
    &
    \begin{minipage}{104mm}
      {\bf Start a recovery process.}
    \end{minipage}
    \\[5mm]

  \begin{minipage}{50mm}\centerline{\downarr}\end{minipage}
    &
    \\[4mm]

  \begin{minipage}{50mm}
    \centerline{\includegraphics[width=40mm]{screenshots/compat-dialog-rs01.png}}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Confirm the dialog.} A dialog will appear asking you if it 
    is okay to remove the superflous sectors from the image. Answer ``OK''.
  \end{minipage} \\[8mm]

  \begin{minipage}{50mm}\centerline{\downarr}\end{minipage}
    &
    \\[4mm]

  \begin{minipage}{50mm}\centerline{\stopicon}\end{minipage}
    &
    \begin{minipage}{104mm}
      {\bf Stop the recovery process,} as after truncating the image there is nothing more to do. 
    \end{minipage}
    \\[5mm]

  \begin{minipage}{50mm}\centerline{\downarr}\end{minipage}
    &
    \\[4mm]

  \begin{minipage}{50mm}\centerline{\verifyicon}\end{minipage}
    &
    \begin{minipage}{104mm}
      {\bf Start the verification again} by clicking on the ``Verify'' button.
    \end{minipage}
    \\[5mm]

  \begin{minipage}{50mm}\centerline{\downarr}\end{minipage}
    &
    \\[4mm]

  \begin{minipage}{50mm}
    \centerline{\includegraphics[width=40mm]{screenshots/info-okay-rs01.png}}
  \end{minipage}
    &
  \begin{minipage}{104mm}
    {\bf Consider the new results.} If you now get the green 
    messages ``Good image.'' and ``Good error correction file.'' your problem 
    is purely cosmetic: The writing software has indeed added zero padding 
    sectors while writing the medium which can always be removed by the process
    described here.
  \end{minipage}
  \\
\end{tabular}

\bigskip

\textcolor{dkred}{If the problem persists after carrying out the above steps do not
 assume that dvdisaster and the writing software are compatible. The created error 
correction files will probably be unusable.}

\bigskip

Use the following method for creating the error correction files instead: 

\newpage

{\bf Alternative method avoiding incompatibilities:}

\begin{enumerate}
\item First write the data to the medium.
\item Use dvdisaster to read an ISO image from the written medium.

Do {\em not use} the original ISO image.
\item Use the  image read by dvdisaster to create the error correction file.
\end{enumerate}

This method takes more time due to the additional reading process, but 
it also has the advantage of testing the newly created medium for readability. 

\newpage
\subsubsection{Testing compatibility with CD/DVD/BD writing software for images augmented with error correction data}
\label{howto-compat-augment}

\paragraph{Motivation:} dvdisaster can put error correction 
data \tlnk{howto-augment}{together with the user data on the medium}. The error 
correction data is appended to the ISO image in a way invisible to most applications 
in order to not interfere with them.

\paragraph{Possible incompatibility:} The optical media writing software 
may also be unable to see the error correction data. While being unlikely 
it is possible that the writing software will truncate or damage the error 
correction data while creating the medium. In this case the error correction will not work.

\paragraph{How to test compatibility:} Please note that some steps are only sketched out here; follow
the links to the respective sections to find detailed instructions and examples.

\bigskip

\begin{tabular}{cl}
  \begin{minipage}{50mm}\centerline{\augmentedcd}\end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf First create a medium which was augmented with error correction data.} Do not
    forget to use the proper \tlnk{howto-augment-basic-settings}{settings} and
    follow the \tlnk{howto-augment-overview}{step by step} instructions.
    Do not use rewriteable DVD or BD media as they may influence the test under
    some circumstances (see \tlnk{qa-rw}{item 3.4} in the questions and answers). 
  \end{minipage} \\[-3mm]

  \begin{minipage}{50mm}\centerline{\downarr}\end{minipage}
  &
  \\

  \begin{minipage}{50mm}\centerline{\goodimagetwo}\end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Create a second image from the written medium.} Use the same
    \tlnk{howto-eccfile-basic-settings}{settings} and steps as in \tlnk{howto-eccfile-create}{reading a medium} for
    creating an error correction file; however you can stop after the reading
    has finished as we do not need the error correction file. 
  \end{minipage}
  \\[3mm]

  \begin{minipage}{50mm}\centerline{\downarr}\end{minipage}
  &
  \\[-5mm]

  \begin{minipage}{50mm}
    \centerline{\selectimage}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Enter the name of the {\em second} ISO image} which you have just read from the
    medium. Please note that the following test is useless when working with
    the image which was initially created using the optical disc authoring software
    and augmented with dvdisaster.
  \end{minipage} \\[-5mm]

  \begin{minipage}{50mm}\centerline{\downarr}\end{minipage}
  &
  \\[5mm]

  \begin{minipage}{50mm}\centerline{\verifyicon}\end{minipage}
    &
  \begin{minipage}{104mm}
    {\bf Start the verification again} by clicking on the ``Verify'' button.
  \end{minipage}
  \\[6mm]

  \begin{minipage}{50mm}\centerline{\downarr}\end{minipage}
  &
  \\[5mm]

  \begin{minipage}{50mm}
    \centerline{\includegraphics[width=40mm]{screenshots/info-okay-rs02.png}}
  \end{minipage}
    &
  \begin{minipage}{104mm}
    {\bf Look at the verification results.} If you get the green
    messages ``Good image.'' and ``Good error correction data.'' your
    authoring software and dvdisaster are compatible with respect to the augmented images. 
  \end{minipage}
  \\
\end{tabular}

\newpage
\paragraph{Possible error causes and remedy:}\quad

\bigskip

\begin{tabular}{cl}
  \begin{minipage}{50mm}
    \centerline{\includegraphics[width=40mm]{screenshots/verify-fail2.png}}
  \end{minipage}
    &
  \begin{minipage}{104mm}
    {\bf Typical problem: wrong image size.} The verification may find out
    that the image is larger as expected. Typically the difference is 150 or 300 sectors
    for CD media and 1-15 sectors for DVD/BD media. These might simply be zero padding
    sectors appended by the writing software. To find out if this really is the case do the following:
  \end{minipage}
  \\[14mm]

  \begin{minipage}{50mm}\centerline{\downarr}\end{minipage}
  &
  \\[4mm]

  \begin{minipage}{50mm}\centerline{\fixicon}\end{minipage}
    &
  \begin{minipage}{104mm}
    {\bf Start a recovery process.}
  \end{minipage}
  \\[5mm]

  \begin{minipage}{50mm}\centerline{\downarr}\end{minipage}
  &
  \\[4mm]

  \begin{minipage}{50mm}
    \centerline{\includegraphics[width=40mm]{screenshots/compat-dialog-rs01.png}}
  \end{minipage}
  &
  \begin{minipage}{104mm}
    {\bf Confirm the dialog.} A dialog will appear asking you if it 
    is okay to remove the superflous sectors from the image. Answer ``OK''.
  \end{minipage} \\[8mm]

  \begin{minipage}{50mm}\centerline{\downarr}\end{minipage}
    &
    \\[4mm]

  \begin{minipage}{50mm}\centerline{\stopicon}\end{minipage}
    &
    \begin{minipage}{104mm}
      {\bf Stop the recovery process,} as after truncating the image there is nothing more to do. 
    \end{minipage}
    \\[5mm]

  \begin{minipage}{50mm}\centerline{\downarr}\end{minipage}
    &
    \\[4mm]

  \begin{minipage}{50mm}\centerline{\verifyicon}\end{minipage}
    &
    \begin{minipage}{104mm}
      {\bf Start the verification again} by clicking on the ``Verify'' button.
    \end{minipage}
    \\[5mm]

  \begin{minipage}{50mm}\centerline{\downarr}\end{minipage}
    &
    \\[4mm]

  \begin{minipage}{50mm}
    \centerline{\includegraphics[width=40mm]{screenshots/info-okay-rs02.png}}
  \end{minipage}
    &
  \begin{minipage}{104mm}
    {\bf Consider the new results.} If you now get the green 
    messages ``Good image.'' and ``Good error correction file.'' your problem 
    is purely cosmetic: The writing software has indeed added zero padding 
    sectors while writing the medium which can always be removed by the process
    described here.
  \end{minipage}
  \\
\end{tabular}

\bigskip

\textcolor{dkred}{If the problem persists after carrying out the above steps
  you can not use the optical disc writing software for creating media from augmented images.
  Perform the test again using a software from a different vendor.}

\newpage
\subsection{Dialogs and buttons}

This section explains commonly used dialogs and buttons
in the dvdisaster user interface:

\bigskip

\begin{tabular}{cp{10cm}}
  \begin{minipage}{20mm}\goodcd\end{minipage} & The \tlnk{howto-dialogs-drive}{drive selection menu.} \\[10mm]
  \begin{minipage}{20mm}\ \goodimage\end{minipage} & The \tlnk{howto-dialogs-image}{image file chooser window}. \\[8mm]
  \begin{minipage}{20mm}\ \eccfile\end{minipage} & The \tlnk{howto-dialogs-eccfile}{error correction file chooser window}. \\[10mm]

  \begin{minipage}{30mm}\readicon\ \createicon\end{minipage} & \\[5mm]
    \begin{minipage}{30mm}\scanicon\ \fixicon\end{minipage} & The \tlnk{howto-dialogs-buttons}{buttons for starting actions}. \\[5mm]
   \begin{minipage}{30mm}\verifyicon\ \stopicon\end{minipage} & \\
\end{tabular}

\subsubsection{Drive selection}
\label{howto-dialogs-drive}

\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/dialog-drive-full.png}}
\caption{Location of the drive selection in the main window.}
\label{howto-dialog-drive-full}
\end{figure}

The drive selection menu is located in the upper left corner of
the tool bar (see green marking). Click into the field to the right
of the CD symbol to drop down the drive selection. Then select the
drive which contains the medium you want to process with dvdisaster.

\medskip

To simplify identification of the drives the following information
is given in the menu entries:

\begin{itemize}
\item The device identification which is typically comprised
  of the vendor name and the drive model number. These values
  have been programmed into the drive by the vendor. Since dvdisaster
  is displaying them without further processing you will see here whatever
  the drive vendor deemed appropriate. Sometimes this identification
  is not very meaningful.
\item The handle under which the drive is managed by the operating
  system (e.g. /dev/sr0 using GNU/Linux)
\end{itemize}

\bigskip

{\bf Example} (for GNU/Linux):

\bigskip

\begin{figure}[h]
\centerline{\includegraphics[width=0.5\textwidth]{screenshots/dialog-drive-linux.png}}
\caption{Unfolded drive selection.}
\label{howto-dialog-drive-linux}
\end{figure}

\subsubsection{Image file selection}
\label{howto-dialogs-image}

\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/dialog-image-full.png}}
\caption{Location of the image file selection in the main window.}
\label{howto-dialog-image-full}
\end{figure}

The image file contains the data from all medium sectors,
including the information whether a sector was readable.
dvdisaster works on image files because they are stored on
hard disk which makes certain random access patterns much faster.
Applying this kind of random access to CD/DVD/BD drives would slow
them down significantly and eventually wear them out (the image
files are read/created using sequential access which unlike random
access is handled efficiently by the drives). The default file
suffix for images is ".iso".

\bigskip

There are two ways of choosing the image file:

\begin{itemize}
\item using a file chooser dialog (button marked green), or
\item by directly entering the file location (text entry field marked blue).
\end{itemize}

The direct entry is helpful when you are processing
several files in the same directory. In that case simply
change the file name in the text field. 

\newpage

\subsubsection{Error correction file selection}
\label{howto-dialogs-eccfile}

\begin{figure}[h]
\centerline{\includegraphics[width=\textwidth]{screenshots/dialog-eccfile-full.png}}
\caption{Location of the error correction file selection in the main window.}
\label{howto-dialog-eccfile-full}
\end{figure}


The error correction file contains information for reconstructing unreadable 
sectors from a defective medium. It can also be used to check a medium for 
damaged or altered sectors. The default file extension is ``.ecc''.

\bigskip

There are two ways of choosing the error correction file:

\begin{itemize}
\item using a file chooser dialog (button marked green), or
\item by directly entering the error correction file location (text entry field marked blue).
\end{itemize}

The direct entry is helpful when you are going to create several 
error correction files in the same directory. In that case simply change the 
file name in the text field. 

\medskip

If you are processing images which are augmented with error correction data
it is recommended to leave this field blank; e.g. to delete any text within it.

\newpage

\subsubsection{Starting actions}
\label{howto-dialogs-buttons}

\begin{tabular}{ll}
\begin{minipage}{108mm}
To start an action in dvdisaster, click on one of the buttons marked green in the thumbnail
image to the right.
\end{minipage}
&
\begin{minipage}{50mm}
    \centerline{\includegraphics[width=40mm]{screenshots/action-buttons.png}}
\end{minipage}
\end{tabular}

\bigskip

\begin{tabular}{ll}
\begin{minipage}{20mm}
\centerline{\readicon}
\end{minipage} 
&
\begin{minipage}{138mm}
Reading medium contents into an image file to:
\begin{itemize}
\item read in a \tlnk{howto-recover-read}{defective medium} for a subsequent recovery.
\item read in an \tlnk{howto-eccfile-create}{error-free medium} for creating an error correction file.
\end{itemize}
\end{minipage} \\[10mm]

\begin{minipage}{20mm}
\centerline{\createicon}
\end{minipage} 
&
\begin{minipage}{138mm}
\tlnk{howto-ecc}{Creating error correction data} \par
(only possible from defect-free media!)
\end{minipage} \\[6mm]

\begin{minipage}{20mm}
\centerline{\scanicon}
\end{minipage} 
&
\begin{minipage}{138mm}
\tlnk{howto-scan}{Scanning a medium for read errors}
\end{minipage} \\[6mm]

\begin{minipage}{20mm}
\centerline{\fixicon}
\end{minipage} 
&
\begin{minipage}{138mm}
\tlnk{howto-recover-fix}{Recover the image of a defective medium}\par
provided that \tlnk{howto-ecc}{error correction data} is available.
\end{minipage} \\[6mm]

\begin{minipage}{20mm}
\centerline{\verifyicon}
\end{minipage} 
&
\begin{minipage}{138mm}
Display  \tlnk{howto-info}{information on images and error correction data.}
\end{minipage} \\
\end{tabular}

\vspace*{10mm}

{\bf Other buttons related to the above actions:}

\bigskip

\begin{tabular}{ll}
\begin{minipage}{30mm}
\centerline{\logicon}
\end{minipage} 
&
\begin{minipage}{138mm}
{\bf View log file of running action} (marked yellow). \par
See also: \tlnk{reporting-defects-log}{Log file creation}. 
\end{minipage}\\[10mm]

\begin{minipage}{30mm}
\centerline{\stopicon}
\end{minipage} 
&
\begin{minipage}{118mm}
{\bf Aborting the running action} (marked red). \par
Some actions may take some time to abort; especially when this button is hit while 
reading a defective sector. 
\end{minipage}\\
\end{tabular}