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
|
/*
* Copyright (c) 2016, Alliance for Open Media. All rights reserved.
*
* This source code is subject to the terms of the BSD 2 Clause License and
* the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
* was not distributed with this source code in the LICENSE file, you can
* obtain it at www.aomedia.org/license/software. If the Alliance for Open
* Media Patent License 1.0 was not distributed with this source code in the
* PATENTS file, you can obtain it at www.aomedia.org/license/patent.
*/
#include <math.h>
#include <stdlib.h>
#include <string.h>
#include "gtest/gtest.h"
#include "test/acm_random.h"
#include "aom/aom_integer.h"
#include "aom_dsp/bitreader.h"
#include "aom_dsp/bitwriter.h"
using libaom_test::ACMRandom;
namespace {
const int num_tests = 10;
} // namespace
TEST(AV1, TestBitIO) {
ACMRandom rnd(ACMRandom::DeterministicSeed());
for (int n = 0; n < num_tests; ++n) {
for (int method = 0; method <= 7; ++method) { // we generate various proba
const int kBitsToTest = 1000;
uint8_t probas[kBitsToTest];
for (int i = 0; i < kBitsToTest; ++i) {
const int parity = i & 1;
/* clang-format off */
probas[i] =
(method == 0) ? 0 : (method == 1) ? 255 :
(method == 2) ? 128 :
(method == 3) ? rnd.Rand8() :
(method == 4) ? (parity ? 0 : 255) :
// alternate between low and high proba:
(method == 5) ? (parity ? rnd(128) : 255 - rnd(128)) :
(method == 6) ?
(parity ? rnd(64) : 255 - rnd(64)) :
(parity ? rnd(32) : 255 - rnd(32));
/* clang-format on */
}
for (int bit_method = 0; bit_method <= 3; ++bit_method) {
const int random_seed = 6432;
const int kBufferSize = 10000;
ACMRandom bit_rnd(random_seed);
aom_writer bw;
uint8_t bw_buffer[kBufferSize];
aom_start_encode(&bw, bw_buffer);
int bit = (bit_method == 0) ? 0 : (bit_method == 1) ? 1 : 0;
for (int i = 0; i < kBitsToTest; ++i) {
if (bit_method == 2) {
bit = (i & 1);
} else if (bit_method == 3) {
bit = bit_rnd(2);
}
aom_write(&bw, bit, static_cast<int>(probas[i]));
}
GTEST_ASSERT_GE(aom_stop_encode(&bw), 0);
aom_reader br;
aom_reader_init(&br, bw_buffer, bw.pos);
bit_rnd.Reset(random_seed);
for (int i = 0; i < kBitsToTest; ++i) {
if (bit_method == 2) {
bit = (i & 1);
} else if (bit_method == 3) {
bit = bit_rnd(2);
}
GTEST_ASSERT_EQ(aom_read(&br, probas[i], nullptr), bit)
<< "pos: " << i << " / " << kBitsToTest
<< " bit_method: " << bit_method << " method: " << method;
}
}
}
}
}
#define FRAC_DIFF_TOTAL_ERROR 0.18
TEST(AV1, TestTell) {
const int kBufferSize = 10000;
aom_writer bw;
uint8_t bw_buffer[kBufferSize];
const int kSymbols = 1024;
// Coders are noisier at low probabilities, so we start at p = 4.
for (int p = 4; p < 256; p++) {
double probability = p / 256.;
aom_start_encode(&bw, bw_buffer);
for (int i = 0; i < kSymbols; i++) {
aom_write(&bw, 0, p);
}
GTEST_ASSERT_GE(aom_stop_encode(&bw), 0);
aom_reader br;
aom_reader_init(&br, bw_buffer, bw.pos);
uint32_t last_tell = aom_reader_tell(&br);
uint32_t last_tell_frac = aom_reader_tell_frac(&br);
double frac_diff_total = 0;
GTEST_ASSERT_GE(aom_reader_tell(&br), 0u);
GTEST_ASSERT_LE(aom_reader_tell(&br), 1u);
ASSERT_FALSE(aom_reader_has_overflowed(&br));
for (int i = 0; i < kSymbols; i++) {
aom_read(&br, p, nullptr);
uint32_t tell = aom_reader_tell(&br);
uint32_t tell_frac = aom_reader_tell_frac(&br);
GTEST_ASSERT_GE(tell, last_tell)
<< "tell: " << tell << ", last_tell: " << last_tell;
GTEST_ASSERT_GE(tell_frac, last_tell_frac)
<< "tell_frac: " << tell_frac
<< ", last_tell_frac: " << last_tell_frac;
// Frac tell should round up to tell.
GTEST_ASSERT_EQ(tell, (tell_frac + 7) >> 3);
last_tell = tell;
frac_diff_total +=
fabs(((tell_frac - last_tell_frac) / 8.0) + log2(probability));
last_tell_frac = tell_frac;
}
const uint32_t expected = (uint32_t)(-kSymbols * log2(probability));
// Last tell should be close to the expected value.
GTEST_ASSERT_LE(last_tell, expected + 20) << " last_tell: " << last_tell;
// The average frac_diff error should be pretty small.
GTEST_ASSERT_LE(frac_diff_total / kSymbols, FRAC_DIFF_TOTAL_ERROR)
<< " frac_diff_total: " << frac_diff_total;
ASSERT_FALSE(aom_reader_has_overflowed(&br));
}
}
TEST(AV1, TestHasOverflowed) {
const int kBufferSize = 10000;
aom_writer bw;
uint8_t bw_buffer[kBufferSize];
const int kSymbols = 1024;
// Coders are noisier at low probabilities, so we start at p = 4.
for (int p = 4; p < 256; p++) {
aom_start_encode(&bw, bw_buffer);
for (int i = 0; i < kSymbols; i++) {
aom_write(&bw, 1, p);
}
GTEST_ASSERT_GE(aom_stop_encode(&bw), 0);
aom_reader br;
aom_reader_init(&br, bw_buffer, bw.pos);
ASSERT_FALSE(aom_reader_has_overflowed(&br));
for (int i = 0; i < kSymbols; i++) {
GTEST_ASSERT_EQ(aom_read(&br, p, nullptr), 1);
ASSERT_FALSE(aom_reader_has_overflowed(&br));
}
// In the worst case, the encoder uses just a tiny fraction of the last
// byte in the buffer. So to guarantee that aom_reader_has_overflowed()
// returns true, we have to consume very nearly 8 additional bits of data.
// In the worse case, one of the bits in that byte will be 1, and the rest
// will be zero. Once we are past that 1 bit, when the probability of
// reading zero symbol from aom_read() is high, each additional symbol read
// will consume very little additional data (in the case that p == 255,
// approximately -log_2(255/256) ~= 0.0056 bits). In that case it would
// take around 178 calls to consume more than 8 bits. That is only an upper
// bound. In practice we are not guaranteed to hit the worse case and can
// get away with 174 calls.
for (int i = 0; i < 174; i++) {
aom_read(&br, p, nullptr);
}
ASSERT_TRUE(aom_reader_has_overflowed(&br));
}
}
|
