FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/ac3.c
Date: 2021-09-16 08:47:15
Exec Total Coverage
Lines: 69 82 84.1%
Branches: 43 58 74.1%

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1 /*
2 * Common code between the AC-3 encoder and decoder
3 * Copyright (c) 2000 Fabrice Bellard
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 /**
23 * @file
24 * Common code between the AC-3 encoder and decoder.
25 */
26
27 #include "libavutil/common.h"
28
29 #include "ac3.h"
30
31 /**
32 * Starting frequency coefficient bin for each critical band.
33 */
34 const uint8_t ff_ac3_band_start_tab[AC3_CRITICAL_BANDS+1] = {
35 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
36 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
37 20, 21, 22, 23, 24, 25, 26, 27, 28, 31,
38 34, 37, 40, 43, 46, 49, 55, 61, 67, 73,
39 79, 85, 97, 109, 121, 133, 157, 181, 205, 229, 253
40 };
41
42 /**
43 * Map each frequency coefficient bin to the critical band that contains it.
44 */
45 const uint8_t ff_ac3_bin_to_band_tab[253] = {
46 0,
47 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
48 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
49 25, 26, 27, 28, 28, 28, 29, 29, 29, 30, 30, 30,
50 31, 31, 31, 32, 32, 32, 33, 33, 33, 34, 34, 34,
51 35, 35, 35, 35, 35, 35, 36, 36, 36, 36, 36, 36,
52 37, 37, 37, 37, 37, 37, 38, 38, 38, 38, 38, 38,
53 39, 39, 39, 39, 39, 39, 40, 40, 40, 40, 40, 40,
54 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41,
55 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42,
56 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43,
57 44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44,
58 45, 45, 45, 45, 45, 45, 45, 45, 45, 45, 45, 45,
59 45, 45, 45, 45, 45, 45, 45, 45, 45, 45, 45, 45,
60 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46,
61 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46,
62 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47,
63 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47,
64 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48,
65 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48,
66 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49,
67 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49
68 };
69
70 251084 static inline int calc_lowcomp1(int a, int b0, int b1, int c)
71 {
72
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251084 if ((b0 + 256) == b1) {
73 10723 a = c;
74
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240361 } else if (b0 > b1) {
75 78713 a = FFMAX(a - 64, 0);
76 }
77 251084 return a;
78 }
79
80 223395 static inline int calc_lowcomp(int a, int b0, int b1, int bin)
81 {
82
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223395 if (bin < 7) {
83 37935 return calc_lowcomp1(a, b0, b1, 384);
84
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185460 } else if (bin < 20) {
85 160732 return calc_lowcomp1(a, b0, b1, 320);
86 } else {
87 24728 return FFMAX(a - 128, 0);
88 }
89 }
90
91 16707 void ff_ac3_bit_alloc_calc_psd(int8_t *exp, int start, int end, int16_t *psd,
92 int16_t *band_psd)
93 {
94 int bin, band;
95
96 /* exponent mapping to PSD */
97
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2206574 for (bin = start; bin < end; bin++) {
98 2189867 psd[bin]=(3072 - (exp[bin] << 7));
99 }
100
101 /* PSD integration */
102 16707 bin = start;
103 16707 band = ff_ac3_bin_to_band_tab[start];
104 do {
105 580937 int v = psd[bin++];
106 580937 int band_end = FFMIN(ff_ac3_band_start_tab[band+1], end);
107
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2189867 for (; bin < band_end; bin++) {
108 1608930 int max = FFMAX(v, psd[bin]);
109 /* logadd */
110 1608930 int adr = FFMIN(max - ((v + psd[bin] + 1) >> 1), 255);
111 1608930 v = max + ff_ac3_log_add_tab[adr];
112 }
113 580937 band_psd[band++] = v;
114
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580937 } while (end > ff_ac3_band_start_tab[band]);
115 16707 }
116
117 16849 int ff_ac3_bit_alloc_calc_mask(AC3BitAllocParameters *s, int16_t *band_psd,
118 int start, int end, int fast_gain, int is_lfe,
119 int dba_mode, int dba_nsegs, uint8_t *dba_offsets,
120 uint8_t *dba_lengths, uint8_t *dba_values,
121 int16_t *mask)
122 {
123 int16_t excite[AC3_CRITICAL_BANDS]; /* excitation */
124 int band;
125 int band_start, band_end, begin, end1;
126 int lowcomp, fastleak, slowleak;
127
128
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16849 if (end <= 0)
129 return AVERROR_INVALIDDATA;
130
131 /* excitation function */
132 16849 band_start = ff_ac3_bin_to_band_tab[start];
133 16849 band_end = ff_ac3_bin_to_band_tab[end-1] + 1;
134
135
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16849 if (band_start == 0) {
136 12998 lowcomp = 0;
137 12998 lowcomp = calc_lowcomp1(lowcomp, band_psd[0], band_psd[1], 384);
138 12998 excite[0] = band_psd[0] - fast_gain - lowcomp;
139 12998 lowcomp = calc_lowcomp1(lowcomp, band_psd[1], band_psd[2], 384);
140 12998 excite[1] = band_psd[1] - fast_gain - lowcomp;
141 12998 begin = 7;
142
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26900 for (band = 2; band < 7; band++) {
143
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26627 if (!(is_lfe && band == 6))
144 26421 lowcomp = calc_lowcomp1(lowcomp, band_psd[band], band_psd[band+1], 384);
145 26627 fastleak = band_psd[band] - fast_gain;
146 26627 slowleak = band_psd[band] - s->slow_gain;
147 26627 excite[band] = fastleak - lowcomp;
148
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26627 if (!(is_lfe && band == 6)) {
149
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26421 if (band_psd[band] <= band_psd[band+1]) {
150 12725 begin = band + 1;
151 12725 break;
152 }
153 }
154 }
155
156 12998 end1 = FFMIN(band_end, 22);
157
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236821 for (band = begin; band < end1; band++) {
158
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223823 if (!(is_lfe && band == 6))
159 223395 lowcomp = calc_lowcomp(lowcomp, band_psd[band], band_psd[band+1], band);
160 223823 fastleak = FFMAX(fastleak - s->fast_decay, band_psd[band] - fast_gain);
161 223823 slowleak = FFMAX(slowleak - s->slow_decay, band_psd[band] - s->slow_gain);
162 223823 excite[band] = FFMAX(fastleak - lowcomp, slowleak);
163 }
164 12998 begin = 22;
165 } else {
166 /* coupling channel */
167 3851 begin = band_start;
168 3851 fastleak = (s->cpl_fast_leak << 8) + 768;
169 3851 slowleak = (s->cpl_slow_leak << 8) + 768;
170 }
171
172
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326495 for (band = begin; band < band_end; band++) {
173 309646 fastleak = FFMAX(fastleak - s->fast_decay, band_psd[band] - fast_gain);
174 309646 slowleak = FFMAX(slowleak - s->slow_decay, band_psd[band] - s->slow_gain);
175 309646 excite[band] = FFMAX(fastleak, slowleak);
176 }
177
178 /* compute masking curve */
179
180
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602941 for (band = band_start; band < band_end; band++) {
181 586092 int tmp = s->db_per_bit - band_psd[band];
182
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586092 if (tmp > 0) {
183 412309 excite[band] += tmp >> 2;
184 }
185 586092 mask[band] = FFMAX(ff_ac3_hearing_threshold_tab[band >> s->sr_shift][s->sr_code], excite[band]);
186 }
187
188 /* delta bit allocation */
189
190
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16849 if (dba_mode == DBA_REUSE || dba_mode == DBA_NEW) {
191 int i, seg, delta;
192 if (dba_nsegs > 8)
193 return -1;
194 band = band_start;
195 for (seg = 0; seg < dba_nsegs; seg++) {
196 band += dba_offsets[seg];
197 if (band >= AC3_CRITICAL_BANDS || dba_lengths[seg] > AC3_CRITICAL_BANDS-band)
198 return -1;
199 if (dba_values[seg] >= 4) {
200 delta = (dba_values[seg] - 3) * 128;
201 } else {
202 delta = (dba_values[seg] - 4) * 128;
203 }
204 for (i = 0; i < dba_lengths[seg]; i++) {
205 mask[band++] += delta;
206 }
207 }
208 }
209 16849 return 0;
210 }
211