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
|
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN//3.0">
<HTML>
<HEAD>
<TITLE>
libsndfile : API Changes in Version 1.0.
</TITLE>
<META NAME="Author" CONTENT="Erik de Castro Lopo (erikd AT zip DOT com DOT au)">
<META NAME="Version" CONTENT="Version 1.0">
<META NAME="Description" CONTENT="libsndfile API changes in version 1.0">
</HEAD>
<BODY TEXT="#FFFFFF" BGCOLOR="#000000" LINK="#5050FF" VLINK="#5050FF" ALINK="#FF00FF">
<FONT SIZE=3>
<CENTER>
<TABLE BORDER="0" WIDTH="94%"><TR><TD>
<FONT SIZE=+20 COLOR="#5050FF"><BR><B>libsndfile : API Changes in Version 1.0.</B></FONT>
<BR><BR>
Document Version 1.0 (2001/11/14)
<BR>
Document Version 1.1 (2001/11/14)
<BR>
Document Version 1.2 (2001/11/15)
<BR>
<FONT COLOR="#20F020">Document Version 1.3 (2002/01/15) (Changes in green)</FONT>
<BR>
<FONT COLOR="#20F0F0">Document Version 1.4 (2002/04/16) (Changes in cyan)</FONT>
<BR>
<FONT COLOR="#D0D000">Document Version 1.5 (2002/04/21) (Changes in yellow)</FONT>
<BR>
<FONT COLOR="#D000D0">Document Version 1.6 (2002/04/30) (Changes in magenta)</FONT>
<BR>
<FONT COLOR="#F02020">Document Version 1.7 (2002/06/24) (Changes in red)</FONT>
<BR><BR>
<B>
This document is now (Aug, 2002) out of date.
It does however document the majority of the changes between version 0 and version 1.
</B>
Some minor changes to the libsndfile API have been made and the changes are listed below.
The full version 1 API can be found <A HREF="api.html">here</A>.
<BR><BR>
<UL>
<LI> <A HREF="#D0000">File Open Functions</A>
<LI> <A HREF="#D0001">64 Bit File Offsets</A>
<LI> <A HREF="#D0002">Command Interface (sf_command)</A>
<LI> <A HREF="#D0003">File Open Functions</A>
<LI> <A HREF="#D0004">Read and Write Functions</A>
<LI> <A HREF="#D0005">Read/Write double Functions</A>
<LI> <A HREF="#D0006">PCM -> PCM Sample Scaling</A>
<LI> <A HREF="#D0007">Faster float to int Conversions</A>
<LI> <A HREF="#D0008">Simple Format Enumeration Interface</A>
<!-- <LI> <A HREF="#D0007">PCM -> float normalisation</A> -->
<LI> <A HREF="#D0009">Format Enumeration Interface</A>
<LI> <A HREF="#D0010">Obsoleted Functions</A>
</UL>
<HR>
<A NAME="D0000">
<FONT SIZE=+2 COLOR="#5050FF"><BR><B>File Open Functions</B></FONT>
<BR><BR>
<FONT COLOR="#D0D000">
Version 0 of libsndfile supplied two functions for opening files; one for
opening a file for read and one for write.
Since it would also be desirable to allow opening a file for modification
(ie read and write) it was decided to merge the two existing open functions
and add the new read/write mode functionality to that.
The new file open function which replaces sf_open_read and sf_open_write looks
like this:
<PRE>
SNDFILE* sf_open (const char *path, int mode, SF_INFO *sfinfo) ;
</PRE>
where the mode parameter can be one of SFM_READ, SFM_WRITE and SFM_RDWR, for
read, write and modification.
<BR><BR>
It is also desirable to allow completely independent read and write operations
ie if the application programmer reads N frames followed by a write
and then does a read of M frames, the application will retrieve the
M frames immediately following the N read earlier.
<BR><BR>
Internally, libsndfile keeps track of the read and write locations using separate
read and write pointers.
In order to allow seeking to be specified on either the read pointer, the write
pointer or both, the usage of the <B>sf_seek</B> function has been modified
slightly.
<BR><BR>
The <B>sf_seek</B> function is defined as follows:
<PRE>
sf_count_t sf_seek (SNDFILE *sndfile, sf_count_t offset, int whence) ;
</PRE>
where the whence parameter is SEEK_SET, SEEK_CUR or SEEK_END.
On files opened for read only or write only, this operation is unchanged.
On files opened for modification, the standard seek operation will change both the
read and the write location.
To limit this the only read, the whence parameter should be logical ORed with
SFM_READ, while to change only the write pointer, the whence parameter should
be ORed with SFM_WRITE.
<BR><BR>
</FONT>
<BR><BR>
<A NAME="D0001">
<FONT SIZE=+2 COLOR="#5050FF"><BR><B>64 Bit File Offsets</B></FONT>
<BR><BR>
Sonic Foundry's 64 bit riff/WAV is one of the new file formats which will be
supported in version 1 of the library.
This format allows for audio files with 64 bit file offsets.
The AU file format, since it is simply a header followed by data should also
support 64 bit file offsets.
<FONT COLOR="#20F0F0">
In addition, WAV and AIFF files use unsigned file offsets so they too can be
larger than 2 gigabytes (although limited to 4 gigabytes) and it would be nice
to support these as well.
<BR><BR>
After a bit of hacking and experimenting libsndfile now reads, writes and
seeks files larger than 2 gigabytes :
<UL>
<LI> Wherever the library is compiled as a 64 bit library on a 64 bit processor.
<LI> Linux (2.4 and later kernels).
<LI> Win32.
<LI> MacOSX (not sure about earlier MacOS).
</UL>
This was achieved by dumping the ISO Standard C fopen/fread/fwrite/fseek/fclose
functions and replacing them with wrapper functions around the POSIX open/read/
write/lseek/close functions.
The big win here is that the POSIX definition of lseek() is :
<PRE>
off_t lseek(int fildes, off_t offset, int whence);
</PRE>
and on most BSD based systems (including MacOSX) <B>off_t</B> is a 64 bit value.
On 32 bit Linux and Solaris, <B>off_t</B> is a 32 bit value but this can be
overridden with some compiler flags resulting in a 64 bit <B>off_t</B> type.
<BR><BR>
To get around the problem of Win32 having a 32 bit <B>off_t</B> type and defining
its 64 bit lseek function like this:
<PRE>
__int64 _lseeki64 (int handle, __int64 offset, int origin);
</PRE>
the sndfile header defines a type <B>sf_count_t</B> which will be set as needed.
<BR><BR>
Some systems like AmigaOS will still be limited to 2 gigabyte maximum file sizes.
<BR><BR>
As part of this shake out, the sf_seek () function call will now be defined as
<PRE>
sf_count_t sf_seek (SNDFILE *sndfile, sf_count_t offset, int whence) ;
</PRE>
Other changes in this area will be covered later in this document.
</FONT>
<BR><BR>
<A NAME="D0002">
<FONT SIZE=+2 COLOR="#5050FF"><BR><B>Command Interface (sf_command)</B></FONT>
<BR><BR>
The sf_command () interface was previewed in version 0 of the library as the
only way to turn normalisation on and off for the functions which read
and wrote float data. This interface was modeled after the ioctl () system
call in Unix.
<BR><BR>
<FONT COLOR="#20F020">
In version 0 of the library, the prototype looked like this:
<PRE>
int sf_command (SNDFILE *sndfile, const char *cmd, void *data, size_t datasize) ;
</PRE>
For version 1 of the library, the command will not longer be encoded as a string
but rather as an integer as follows:
<PRE>
int sf_command (SNDFILE *sndfile, int command, void *data, int datasize) ;
</PRE>
The valid values for command will have symbolic names beginning with <B>SFC_</B>
and will be listed in the header file <sndfile.h>.
<BR><BR>
Most of the commands (other than things like retrieving the library version) will work
on a per file basis, allowing float normalisation to be turned on for some files and
off for others.
<BR><BR>
When an integer values needs to be passed to the library via the sf_command interface,
the data parameter should be a NULL pointer and the value passed in the datasize
argument (see example below).
<BR><BR>
Here are some examples of its uses:
<PRE>
char buffer [1024] ;
int value ;
/* Retrieve a string containing the library version. No SNDFILE*
** pointer needed
*/
sf_command (NULL, SFC_GET_LIB_VERSION, buffer, sizeof (buffer)) ;
/* Retrieve the log generated by the file header parser. */
sf_command (file, SFC_GET_LOG_INFO, buffer, sizeof (buffer)) ;
/* Turn on normalisation of data read/written as float. */
sf_command (file, SFC_SET_NORM_FLOAT, NULL, SF_TRUE) ;
/* Turn off normalisation of data read/written as float. */
sf_command (file, SFC_SET_NORM_FLOAT, NULL, SF_FALSE) ;
/* Turn on normalisation of data read/written as double. */
sf_command (file, SFC_SET_NORM_DOUBLE, NULL, SF_TRUE) ;
/* Retrieve current normalisation settings for doubles. */
sf_command (file, SFC_GET_NORM_DOUBLE, &value, sizeof (value)) ;
</FONT>
</PRE>
This function returns zero on success.
<BR><BR>
This interface will be put to other uses in the future.
<BR><BR>
<A NAME="D0003">
<FONT SIZE=+2 COLOR="#5050FF"><BR><B>File Open Functions</B></FONT>
<BR><BR>
There are a number of minor changes here.
Firstly the pcmbitwith field of the SF_INFO struct has been dropped,
<PRE>
typedef struct
{ <FONT COLOR="#20F0F0">sf_count_t</FONT> frames ;
int samplerate ;
int channels ;
int format ;
int sections ;
int seekable ;
} SF_INFO ;
</PRE>
and the types of these fields have been changed to signed types.
The sample count is now an <FONT COLOR="#20F0F0">sf_count_t</FONT> so that on
machines <FONT COLOR="#20F0F0">where this is a 64 bit type, </FONT> the sample
count can contain a frame count of more than 2 giga samples.
<BR><BR>
The major format types will remain pretty much as they are.
<PRE>
SF_FORMAT_WAV /* Microsoft WAV format (little endian). */
SF_FORMAT_AIFF /* Apple/SGI AIFF format (big endian). */
SF_FORMAT_AU /* Sun/NeXT AU format (big endian). */
SF_FORMAT_RAW /* RAW PCM data. */
SF_FORMAT_PAF /* Ensoniq PARIS file format. */
SF_FORMAT_SVX /* Amiga IFF / SVX8 / SV16 format. */
SF_FORMAT_NIST /* Sphere NIST format. */
SF_FORMAT_SMPLTD /* Sekd Samplitude. */
SF_FORMAT_VOC /* VOC files. */
SF_FORMAT_SD2 /* Sound Designer 2 */
SF_FORMAT_IRCAM /* Berkeley/IRCAM/CARL */
SF_FORMAT_W64 /* Sonic Foundry's 64 bit RIFF/WAV */
</PRE>
The really astute reader may notice that SF_FORMAT_AULE has disappeared.
The reason for this will be dealt with below.
<BR><BR>
The following minor format types will be provided. Note that the bit width of
PCM data is now encoded in the minor format.
<PRE>
SF_FORMAT_PCM_U8 /* Unsigned 8 bit data (WAV and RAW only) */
SF_FORMAT_PCM_S8 /* Signed 8 bit data */
SF_FORMAT_PCM_16 /* Signed 16 bit data */
SF_FORMAT_PCM_24 /* Signed 24 bit data */
SF_FORMAT_PCM_32 /* Signed 32 bit data */
SF_FORMAT_FLOAT /* 32 bit float data */
SF_FORMAT_DOUBLE /* 64 bit float data */
SF_FORMAT_ULAW /* U-Law encoded. */
SF_FORMAT_ALAW /* A-Law encoded. */
SF_FORMAT_IMA_ADPCM /* IMA ADPCM. */
SF_FORMAT_MS_ADPCM /* Microsoft ADPCM. */
SF_FORMAT_GSM610 /* GSM 6.10 encoding. */
SF_FORMAT_G721_32 /* 32kbs G721 ADPCM encoding. */
SF_FORMAT_G723_24 /* 24kbs G723 ADPCM encoding. */
</PRE>
<BR>
As with version 0 of the library, the major and minor format types are combined using
the binary or operator.
For instance, a 16 bit WAV file has a format obtained using
(SF_FORMAT_WAV | SF_FORMAT_PCM_16).
The constants SF_FORMAT_SUBMASK and SF_FORMAT_TYPEMASK behave as they do in
version 0 of the library to mask out the major and minor types of the file
format.
<BR><BR>
A number of file formats such as AU, PAF and IRCAM have both a big and
a little endian version.
For these files there are four new constants:
<PRE>
SF_ENDIAN_FILE = 0x00000000, /* file native */
SF_ENDIAN_LITTLE = 0x10000000, /* forced little endian */
SF_ENDIAN_BIG = 0x20000000, /* forced big endian */
SF_ENDIAN_CPU = 0x30000000, /* forced CPU endian */
SF_ENDIAN_MASK = 0x30000000, /* mask out the endian portion of format */
</PRE>
which are binary or-ed with the rest of the format.
A format of (SF_FORMAT_AU | SF_FORMAT_FLOAT) would therefore create a big
endian AU (AU is big endian by default) file, with 32 bit float data.
By using the other three SF_ENDIAN_xxx constants, the default can be
overridden.
Of these three overrides, SF_FORMAT_CPU is the most interesting as data
is stored in the native CPU endian-ness which is the endian-ness which
will allow the fastest reads and writes of that data type regardless of
the host processor type.
<BR><BR>
<A NAME="D0004">
<FONT SIZE=+2 COLOR="#5050FF"><BR><B>Read and Write Functions</B></FONT>
<BR><BR>
To tie in with with 64 bit file offsets, sample and frame counts used with the
read and write functions have been changed from type size_t to type
<FONT COLOR="#20F0F0">sf_count_t</FONT>.
Wherever a function was defined in version 0 as :
<PRE>
size_t sf_read_type (SNDFILE *sndfile, type *ptr, size_t items) ;
size_t sf_readf_type (SNDFILE *sndfile, type *ptr, size_t frames) ;
</PRE>
this will now be defined as :
<PRE>
<FONT COLOR="#20F0F0">sf_count_t</FONT> sf_read_type (SNDFILE *sndfile, type *ptr, <FONT COLOR="#20F0F0">sf_count_t</FONT> items) ;
<FONT COLOR="#20F0F0">sf_count_t</FONT> sf_readf_type (SNDFILE *sndfile, type *ptr, <FONT COLOR="#20F0F0">sf_count_t</FONT> frames) ;
</PRE>
These function will continue to return the number of items read or written.
On error or end of file, a value of zero will be returned.
A call to sf_error () will allow differentiation between error and end of file.
<BR><BR>
<A NAME="D0005">
<FONT SIZE=+2 COLOR="#5050FF"><BR><B>Read/Write double Functions</B></FONT>
<BR><BR>
In version 0, the prototypes looked like this:
<PRE>
size_t sf_read_double (SNDFILE *sndfile, double *ptr, size_t items, int normalize) ;
size_t sf_readf_double (SNDFILE *sndfile, double *ptr, size_t frames, int normalize) ;
size_t sf_write_double (SNDFILE *sndfile, double *ptr, size_t items, int normalize) ;
size_t sf_writef_double (SNDFILE *sndfile, double *ptr, size_t frames, int normalize) ;
</PRE>
while in version 1 it will looks like this:
<BR><BR>
<PRE>
<FONT COLOR="#20F0F0">sf_count_t</FONT> sf_read_double (SNDFILE *sndfile, double *ptr, <FONT COLOR="#20F0F0">sf_count_t</FONT> items) ;
<FONT COLOR="#20F0F0">sf_count_t</FONT> sf_readf_double (SNDFILE *sndfile, double *ptr, <FONT COLOR="#20F0F0">sf_count_t</FONT> frames) ;
<FONT COLOR="#20F0F0">sf_count_t</FONT> sf_write_double (SNDFILE *sndfile, double *ptr, <FONT COLOR="#20F0F0">sf_count_t</FONT> items) ;
<FONT COLOR="#20F0F0">sf_count_t</FONT> sf_writef_double (SNDFILE *sndfile, double *ptr, <FONT COLOR="#20F0F0">sf_count_t</FONT> frames) ;
</PRE>
These have been changed to match the prototypes for sf_read/write_float () functions
which do not have a normalize flag.
Switching normalisation on and off can still be done using the sf_command () interface
as is currently done for floats.
Normalisation will be on by default.
<BR><BR>
<A NAME="D0006">
<FONT SIZE=+2 COLOR="#5050FF"><BR><B>PCM -> PCM Sample Scaling</B></FONT>
<BR><BR>
There is currently an inconsistency in the way version 0 if the library handles
conversion of PCM data from one sized container to another sized container.
<BR><BR>
Version 1 of the library will obey the following rule : whenever integer data
is moved from one sized container to another sized container, the most significant
bit in the source container will become the most significant bit in the
destination container.
<BR><BR>
<A NAME="D0007">
<FONT SIZE=+2 COLOR="#5050FF"><BR><B>Faster float to int Conversions</B></FONT>
<BR><BR>
Version 1 of the library uses the fast float to integer conversion techniques
detailed
<A HREF="http://www.mega-nerd.com/FPcast/">here</A>.
This should work for Linux on all CPUs, Win3232 and MacOS (old and new).
<BR><BR>
<A NAME="D0008">
<FONT SIZE=+2 COLOR="#5050FF"><BR><B>Simple Format Enumeration Interface</B></FONT>
<BR><BR>
During a discussion with Dominic Mazzoni it was decided that libsndfile needed an easy
way for an application to present a choice of a small set of standard file formats to
the user.
This will be done using the sf_command () interface and a new typedef in <sndfile.h>:
<PRE>
typedef struct
{ int format;
const char *name;
const char *extension;
} SF_FORMAT_INFO ;
</PRE>
There are two new commands which are used as follows:
<PRE>
SF_FORMAT_INFO format_info ;
int format_count ;
/* Retrieve the simple format count */
sf_command (NULL, SFC_GET_SIMPLE_FORMAT_COUNT, &format_count, sizeof (format_count)) ;
/* Retrieve format count 3 */
format_info.format = 3 ;
sf_command (NULL, SFC_GET_SIMPLE_FORMAT, &format_info, sizeof (format_info)) ;
</PRE>
The SF_FORMAT_INFO struct would then be filled with information like:
<PRE>
{ SF_FORMAT_AIFF | SF_FORMAT_PCM_S8,
"AIFF (Apple/SGI 8 bit)",
"aiff"
},
</PRE>
or
<PRE>
{ SF_FORMAT_WAV | SF_FORMAT_IMA_ADPCM,
"WAV (Microsoft 4 bit IMA ADPCM)",
"wav"
},
</PRE>
The SF_FORMAT_INFO structs retrieved from number 0 through the value obtained with
SFC_GET_SIMPLE_FORMAT_COUNT, will be alphabetically sorted
on the name field.
<BR><BR>
<A NAME="D0009">
<FONT SIZE=+2 COLOR="#5050FF"><BR><B>Format Enumeration Interface</B></FONT>
<BR><BR>
<FONT COLOR="#20F020">
After the above Simple Format Enumeration Interface was developed the need for a more
extensive interface became apparent.
Discussion with Dominic Mazzoni resulted in four new commands for the sf_command()
interface; SFC_GET_FORMAT_MAJOR_COUNT, SFC_GET_FORMAT_MAJOR, SFC_GET_FORMAT_SUBTYPE_COUNT
and SFC_GET_FORMAT_SUBTYPE.
<BR><BR>
These commands work very much like the Simple Format Enumeration Interface and use the
same SF_FORMAT_INFO typedef.
When combined with the sf_format_check () function, these new commands will allow an
application program to build up a complete list of formats supported by the current
version of libsndfile even if new formats have been added after the application was
compiled.
<BR><BR>
The examples/ directory of the libsndfile-1.0.X source code distribution contains an
example program <B>list_formats.c</B> which prints out a list of all the supported
subtypes for all of the supported major formats.
</FONT>
<BR><BR>
<A NAME="D0010">
<FONT SIZE=+2 COLOR="#5050FF"><BR><B>Obsoleted Functions</B></FONT>
<BR><BR>
The functions
<PRE>
size_t sf_get_header_info (SNDFILE *sndfile, char* buffer, size_t bufferlen, size_t offset) ;
size_t sf_get_lib_version (char* buffer, size_t bufferlen) ;
<FONT COLOR="#F02020">double sf_signal_max (SNDFILE *sndfile) ;</FONT>
</PRE>
will be dropped and replaced with calls to sf_command which is documented
<A HREF="command.html">here</A>.
<BR><BR>
</TD></TR>
</TABLE>
</CENTER>
|
