FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavcodec/aac/aacdec_ac.c
Date: 2026-01-23 19:11:46
Exec Total Coverage
Lines: 94 120 78.3%
Functions: 7 7 100.0%
Branches: 39 63 61.9%
Line Branch Exec Source
1 /*
2 * AAC definitions and structures
3 * Copyright (c) 2024 Lynne
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 #include "libavcodec/aactab.h"
23 #include "aacdec_ac.h"
24
25 7768 uint32_t ff_aac_ac_map_process(AACArithState *state, int reset, int N)
26 {
27 float ratio;
28
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 7768 if (reset) {
29 467 memset(state->last, 0, sizeof(state->last));
30 467 state->last_len = N;
31
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 7301 } else if (state->last_len != N) {
32 int i;
33 uint8_t last[512 /* 2048 / 4 */];
34 ✗ memcpy(last, state->last, sizeof(last));
35
36 ✗ ratio = state->last_len / (float)N;
37 ✗ for (i = 0; i < N/2; i++) {
38 ✗ int k = (int)(i * ratio);
39 ✗ state->last[i] = last[k];
40 }
41
42 ✗ for (; i < FF_ARRAY_ELEMS(state->last); i++)
43 ✗ state->last[i] = 0;
44
45 ✗ state->last_len = N;
46 }
47
48 7768 state->cur[3] = 0;
49 7768 state->cur[2] = 0;
50 7768 state->cur[1] = 0;
51 7768 state->cur[0] = 1;
52
53 7768 state->state_pre = state->last[0] << 12;
54 7768 return state->last[0] << 12;
55 }
56
57 1881867 uint32_t ff_aac_ac_get_context(AACArithState *state, uint32_t c, int i, int N)
58 {
59 1881867 c = state->state_pre >> 8;
60 1881867 c = c + (state->last[i + 1] << 8);
61 1881867 c = (c << 4);
62 1881867 c += state->cur[1];
63
64 1881867 state->state_pre = c;
65
66
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 1881867 if (i > 3 &&
67
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 1850843 ((state->cur[3] + state->cur[2] + state->cur[1]) < 5))
68 1065119 return c + 0x10000;
69
70 816748 return c;
71 }
72
73 1928594 uint32_t ff_aac_ac_get_pk(uint32_t c)
74 {
75 1928594 int i_min = -1;
76 int i, j;
77 1928594 int i_max = FF_ARRAY_ELEMS(ff_aac_ac_lookup_m) - 1;
78
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 18296171 while ((i_max - i_min) > 1) {
79 17565347 i = i_min + ((i_max - i_min) / 2);
80 17565347 j = ff_aac_ac_hash_m[i];
81
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 17565347 if (c < (j >> 8))
82 8903763 i_max = i;
83
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 8661584 else if (c > (j >> 8))
84 7463814 i_min = i;
85 else
86 1197770 return (j & 0xFF);
87 }
88 730824 return ff_aac_ac_lookup_m[i_max];
89 }
90
91 1874099 void ff_aac_ac_update_context(AACArithState *state, int idx,
92 uint16_t a, uint16_t b)
93 {
94 1874099 state->cur[0] = FFMIN(a + b + 1, 0xF);
95 1874099 state->cur[3] = state->cur[2];
96 1874099 state->cur[2] = state->cur[1];
97 1874099 state->cur[1] = state->cur[0];
98
99 1874099 state->last[idx] = state->cur[0];
100 1874099 }
101
102 /* Initialize AC */
103 7768 void ff_aac_ac_init(AACArith *ac, GetBitContext *gb)
104 {
105 7768 ac->low = 0;
106 7768 ac->high = UINT16_MAX;
107 7768 ac->val = get_bits(gb, 16);
108 7768 }
109
110 1967553 uint16_t ff_aac_ac_decode(AACArith *ac, GetBitContext *gb,
111 const uint16_t *cdf, uint16_t cdf_len)
112 {
113 1967553 int val = ac->val;
114 1967553 int low = ac->low;
115 1967553 int high = ac->high;
116
117 int sym;
118 1967553 int rng = high - low + 1;
119 1967553 int c = ((((int)(val - low + 1)) << 14) - ((int)1));
120
121 1967553 const uint16_t *p = cdf - 1;
122
123 /* One for each possible CDF length in the spec */
124
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 1967553 switch (cdf_len) {
125 ✗ case 2:
126 ✗ if ((p[1] * rng) > c)
127 ✗ p += 1;
128 ✗ break;
129 38959 case 4:
130
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 38959 if ((p[2] * rng) > c)
131 17073 p += 2;
132
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 38959 if ((p[1] * rng) > c)
133 17078 p += 1;
134 38959 break;
135 1928594 case 17:
136 /* First check if the current probability is even met at all */
137
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 1928594 if ((p[1] * rng) <= c)
138 1097206 break;
139 831388 p += 1;
140
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 4156940 for (int i = 8; i >= 1; i >>= 1)
141
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 3325552 if ((p[i] * rng) > c)
142 1076155 p += i;
143 831388 break;
144 ✗ case 27:
145 ✗ if ((p[16] * rng) > c)
146 ✗ p += 16;
147 ✗ if ((p[8] * rng) > c)
148 ✗ p += 8;
149 ✗ if (p != (cdf - 1 + 24))
150 ✗ if ((p[4] * rng) > c)
151 ✗ p += 4;
152 ✗ if ((p[2] * rng) > c)
153 ✗ p += 2;
154
155 ✗ if (p != (cdf - 1 + 24 + 2))
156 ✗ if ((p[1] * rng) > c)
157 ✗ p += 1;
158 ✗ break;
159 1967553 default:
160 /* This should never happen */
161 av_assert2(0);
162 }
163
164 1967553 sym = (int)((ptrdiff_t)(p - cdf)) + 1;
165
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 1967553 if (sym)
166 858337 high = low + ((rng * cdf[sym - 1]) >> 14) - 1;
167 1967553 low += (rng * cdf[sym]) >> 14;
168
169 /* This loop could be done faster */
170 while (1) {
171
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 5429757 if (high < 32768) {
172 ;
173
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 4206020 } else if (low >= 32768) {
174 1168857 val -= 32768;
175 1168857 low -= 32768;
176 1168857 high -= 32768;
177
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 3037163 } else if (low >= 16384 && high < 49152) {
178 1069610 val -= 16384;
179 1069610 low -= 16384;
180 1069610 high -= 16384;
181 } else {
182 break;
183 }
184 3462204 low += low;
185 3462204 high += high + 1;
186 3462204 val = (val << 1) | get_bits1(gb);
187 };
188
189 1967553 ac->low = low;
190 1967553 ac->high = high;
191 1967553 ac->val = val;
192
193 1967553 return sym;
194 }
195
196 7768 void ff_aac_ac_finish(AACArithState *state, int offset, int N)
197 {
198 int i;
199
200
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 2110885 for (i = offset; i < N/2; i++)
201 2103117 state->last[i] = 1;
202
203
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 15536 for (; i < FF_ARRAY_ELEMS(state->last); i++)
204 7768 state->last[i] = 0;
205 7768 }
206