FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavcodec/ac3enc_template.c
Date: 2026-08-11 17:55:23
Exec Total Coverage
Lines: 178 192 92.7%
Functions: 5 5 100.0%
Branches: 115 132 87.1%
Line Branch Exec Source
1 /*
2 * AC-3 encoder float/fixed template
3 * Copyright (c) 2000 Fabrice Bellard
4 * Copyright (c) 2006-2011 Justin Ruggles <justin.ruggles@gmail.com>
5 * Copyright (c) 2006-2010 Prakash Punnoor <prakash@punnoor.de>
6 *
7 * This file is part of FFmpeg.
8 *
9 * FFmpeg is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation; either
12 * version 2.1 of the License, or (at your option) any later version.
13 *
14 * FFmpeg is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with FFmpeg; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 */
23
24 /**
25 * @file
26 * AC-3 encoder float/fixed template
27 */
28
29 #include "config_components.h"
30
31 #include <stdint.h>
32
33 #include "libavutil/attributes.h"
34 #include "libavutil/avassert.h"
35 #include "libavutil/mem_internal.h"
36
37 #include "audiodsp.h"
38 #include "ac3enc.h"
39 #include "eac3enc.h"
40
41 #if AC3ENC_FLOAT
42 #define RENAME(element) element ## _float
43 #else
44 #define RENAME(element) element ## _fixed
45 #endif
46
47 /*
48 * Apply the MDCT to input samples to generate frequency coefficients.
49 * This applies the KBD window and normalizes the input to reduce precision
50 * loss due to fixed-point calculations.
51 */
52 1320 static void apply_mdct(AC3EncodeContext *s, uint8_t * const *samples)
53 {
54 av_assert1(s->num_blocks > 0);
55
56
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 3622 for (int ch = 0; ch < s->channels; ch++) {
57 2302 const SampleType *input_samples0 = (const SampleType*)s->planar_samples[ch];
58 /* Reorder channels from native order to AC-3 order. */
59 2302 const SampleType *input_samples1 = (const SampleType*)samples[s->channel_map[ch]];
60 2302 int blk = 0;
61
62 do {
63 13812 AC3Block *block = &s->blocks[blk];
64 13812 SampleType *windowed_samples = s->RENAME(windowed_samples);
65
66 13812 s->fdsp->vector_fmul(windowed_samples, input_samples0,
67 13812 s->RENAME(mdct_window), AC3_BLOCK_SIZE);
68 13812 s->fdsp->vector_fmul_reverse(windowed_samples + AC3_BLOCK_SIZE,
69 input_samples1,
70 13812 s->RENAME(mdct_window), AC3_BLOCK_SIZE);
71
72 13812 s->tx_fn(s->tx, block->mdct_coef[ch+1],
73 windowed_samples, sizeof(*windowed_samples));
74 13812 input_samples0 = input_samples1;
75 13812 input_samples1 += AC3_BLOCK_SIZE;
76
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 13812 } while (++blk < s->num_blocks);
77
78 /* Store last 256 samples of current frame */
79 2302 memcpy(s->planar_samples[ch], input_samples0,
80 AC3_BLOCK_SIZE * sizeof(*input_samples0));
81 }
82 1320 }
83
84
85 /*
86 * Calculate coupling channel and coupling coordinates.
87 */
88 737 static void apply_channel_coupling(AC3EncodeContext *s)
89 {
90 737 LOCAL_ALIGNED_32(CoefType, cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
91 #if AC3ENC_FLOAT
92 546 LOCAL_ALIGNED_32(int32_t, fixed_cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
93 #else
94 191 int32_t (*fixed_cpl_coords)[AC3_MAX_CHANNELS][16] = cpl_coords;
95 #endif
96 737 int av_uninit(blk), ch, bnd, i, j;
97 737 CoefSumType energy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}};
98 int cpl_start, num_cpl_coefs;
99
100 737 memset(cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
101 #if AC3ENC_FLOAT
102 546 memset(fixed_cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
103 #endif
104
105 /* align start to 16-byte boundary. align length to multiple of 32.
106 note: coupling start bin % 4 will always be 1 */
107 737 cpl_start = s->start_freq[CPL_CH] - 1;
108 737 num_cpl_coefs = FFALIGN(s->num_cpl_subbands * 12 + 1, 32);
109 737 cpl_start = FFMIN(256, cpl_start + num_cpl_coefs) - num_cpl_coefs;
110
111 /* calculate coupling channel from fbw channels */
112
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 5159 for (blk = 0; blk < s->num_blocks; blk++) {
113 4422 AC3Block *block = &s->blocks[blk];
114 4422 CoefType *cpl_coef = &block->mdct_coef[CPL_CH][cpl_start];
115
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 4422 if (!block->cpl_in_use)
116 ✗ continue;
117 4422 memset(cpl_coef, 0, num_cpl_coefs * sizeof(*cpl_coef));
118
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 13590 for (ch = 1; ch <= s->fbw_channels; ch++) {
119 9168 CoefType *ch_coef = &block->mdct_coef[ch][cpl_start];
120
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 9168 if (!block->channel_in_cpl[ch])
121 ✗ continue;
122
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 595920 for (i = 0; i < num_cpl_coefs; i++)
123 586752 cpl_coef[i] += ch_coef[i];
124 }
125
126 /* coefficients must be clipped in order to be encoded */
127 4422 clip_coefficients(&s->adsp, cpl_coef, num_cpl_coefs);
128 }
129
130 /* calculate energy in each band in coupling channel and each fbw channel */
131 /* TODO: possibly use SIMD to speed up energy calculation */
132 737 bnd = 0;
133 737 i = s->start_freq[CPL_CH];
134
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 3649 while (i < s->cpl_end_freq) {
135 2912 int band_size = s->cpl_band_sizes[bnd];
136
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 11756 for (ch = CPL_CH; ch <= s->fbw_channels; ch++) {
137
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 61908 for (blk = 0; blk < s->num_blocks; blk++) {
138 53064 AC3Block *block = &s->blocks[blk];
139
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 53064 if (!block->cpl_in_use || (ch > CPL_CH && !block->channel_in_cpl[ch]))
140 ✗ continue;
141
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 852912 for (j = 0; j < band_size; j++) {
142 799848 CoefType v = block->mdct_coef[ch][i+j];
143 799848 MAC_COEF(energy[blk][ch][bnd], v, v);
144 }
145 }
146 }
147 2912 i += band_size;
148 2912 bnd++;
149 }
150
151 /* calculate coupling coordinates for all blocks for all channels */
152
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 5159 for (blk = 0; blk < s->num_blocks; blk++) {
153 4422 AC3Block *block = &s->blocks[blk];
154
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 4422 if (!block->cpl_in_use)
155 ✗ continue;
156
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 13590 for (ch = 1; ch <= s->fbw_channels; ch++) {
157
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 9168 if (!block->channel_in_cpl[ch])
158 ✗ continue;
159
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 44760 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
160 35592 cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy[blk][ch][bnd],
161 energy[blk][CPL_CH][bnd]);
162 }
163 }
164 }
165
166 /* determine which blocks to send new coupling coordinates for */
167
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 5159 for (blk = 0; blk < s->num_blocks; blk++) {
168 4422 AC3Block *block = &s->blocks[blk];
169
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 4422 AC3Block *block0 = blk ? &s->blocks[blk-1] : NULL;
170
171 4422 memset(block->new_cpl_coords, 0, sizeof(block->new_cpl_coords));
172
173
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 4422 if (block->cpl_in_use) {
174 /* send new coordinates if this is the first block, if previous
175 * block did not use coupling but this block does, the channels
176 * using coupling has changed from the previous block, or the
177 * coordinate difference from the last block for any channel is
178 * greater than a threshold value. */
179
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 4422 if (blk == 0 || !block0->cpl_in_use) {
180
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 2265 for (ch = 1; ch <= s->fbw_channels; ch++)
181 1528 block->new_cpl_coords[ch] = 1;
182 } else {
183
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 11325 for (ch = 1; ch <= s->fbw_channels; ch++) {
184
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 7640 if (!block->channel_in_cpl[ch])
185 ✗ continue;
186
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 7640 if (!block0->channel_in_cpl[ch]) {
187 ✗ block->new_cpl_coords[ch] = 1;
188 } else {
189 7640 CoefSumType coord_diff = 0;
190
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 37300 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
191
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 29660 coord_diff += FFABS(cpl_coords[blk-1][ch][bnd] -
192 cpl_coords[blk ][ch][bnd]);
193 }
194 7640 coord_diff /= s->num_cpl_bands;
195
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 7640 if (coord_diff > NEW_CPL_COORD_THRESHOLD)
196 48 block->new_cpl_coords[ch] = 1;
197 }
198 }
199 }
200 }
201 }
202
203 av_assert1(s->fbw_channels > 0);
204
205 /* calculate final coupling coordinates, taking into account reusing of
206 coordinates in successive blocks */
207
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 3649 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
208 2912 blk = 0;
209
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 5916 while (blk < s->num_blocks) {
210 3004 int av_uninit(blk1);
211 3004 AC3Block *block = &s->blocks[blk];
212
213
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 3004 if (!block->cpl_in_use) {
214 ✗ blk++;
215 ✗ continue;
216 }
217
218
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 9132 for (ch = 1; ch <= s->fbw_channels; ch++) {
219 CoefSumType energy_ch, energy_cpl;
220
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 6128 if (!block->channel_in_cpl[ch])
221 ✗ continue;
222 6128 energy_cpl = energy[blk][CPL_CH][bnd];
223 6128 energy_ch = energy[blk][ch][bnd];
224 6128 blk1 = blk+1;
225
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 35716 while (blk1 < s->num_blocks && !s->blocks[blk1].new_cpl_coords[ch]) {
226
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 29588 if (s->blocks[blk1].cpl_in_use) {
227 29588 energy_cpl += energy[blk1][CPL_CH][bnd];
228 29588 energy_ch += energy[blk1][ch][bnd];
229 }
230 29588 blk1++;
231 }
232 6128 cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy_ch, energy_cpl);
233 }
234 3004 blk = blk1;
235 }
236 }
237
238 /* calculate exponents/mantissas for coupling coordinates */
239
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 5159 for (blk = 0; blk < s->num_blocks; blk++) {
240 4422 AC3Block *block = &s->blocks[blk];
241
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 4422 if (!block->cpl_in_use)
242 ✗ continue;
243
244 #if AC3ENC_FLOAT
245 3276 s->ac3dsp.float_to_fixed24(fixed_cpl_coords[blk][1],
246 3276 cpl_coords[blk][1],
247 3276 s->fbw_channels * 16);
248 #endif
249 4422 s->ac3dsp.extract_exponents(block->cpl_coord_exp[1],
250 4422 fixed_cpl_coords[blk][1],
251 4422 s->fbw_channels * 16);
252
253
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 13590 for (ch = 1; ch <= s->fbw_channels; ch++) {
254 int bnd, min_exp, max_exp, master_exp;
255
256
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 9168 if (!block->new_cpl_coords[ch])
257 7592 continue;
258
259 /* determine master exponent */
260 1576 min_exp = max_exp = block->cpl_coord_exp[ch][0];
261
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 6092 for (bnd = 1; bnd < s->num_cpl_bands; bnd++) {
262 4516 int exp = block->cpl_coord_exp[ch][bnd];
263 4516 min_exp = FFMIN(exp, min_exp);
264 4516 max_exp = FFMAX(exp, max_exp);
265 }
266 1576 master_exp = ((max_exp - 15) + 2) / 3;
267 1576 master_exp = FFMAX(master_exp, 0);
268
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 1576 while (min_exp < master_exp * 3)
269 ✗ master_exp--;
270
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 7668 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
271 6092 block->cpl_coord_exp[ch][bnd] = av_clip(block->cpl_coord_exp[ch][bnd] -
272 6092 master_exp * 3, 0, 15);
273 }
274 1576 block->cpl_master_exp[ch] = master_exp;
275
276 /* quantize mantissas */
277
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 7668 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
278 6092 int cpl_exp = block->cpl_coord_exp[ch][bnd];
279 6092 int cpl_mant = (fixed_cpl_coords[blk][ch][bnd] << (5 + cpl_exp + master_exp * 3)) >> 24;
280
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 6092 if (cpl_exp == 15)
281 ✗ cpl_mant >>= 1;
282 else
283 6092 cpl_mant -= 16;
284
285 6092 block->cpl_coord_mant[ch][bnd] = cpl_mant;
286 }
287 }
288 }
289
290
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 546 if (AC3ENC_FLOAT && CONFIG_EAC3_ENCODER && s->eac3)
291 273 ff_eac3_set_cpl_states(s);
292 737 }
293
294
295 /*
296 * Determine rematrixing flags for each block and band.
297 */
298 1320 static void compute_rematrixing_strategy(AC3EncodeContext *s)
299 {
300 int nb_coefs;
301 int blk, bnd;
302 1320 AC3Block *block, *block0 = NULL;
303
304
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 1320 if (s->channel_mode != AC3_CHMODE_STEREO)
305 428 return;
306
307
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 6244 for (blk = 0; blk < s->num_blocks; blk++) {
308 5352 block = &s->blocks[blk];
309 5352 block->new_rematrixing_strategy = !blk;
310
311 5352 block->num_rematrixing_bands = 4;
312
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 5352 if (block->cpl_in_use) {
313 4314 block->num_rematrixing_bands -= (s->start_freq[CPL_CH] <= 61);
314 4314 block->num_rematrixing_bands -= (s->start_freq[CPL_CH] == 37);
315
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 4314 if (blk && block->num_rematrixing_bands != block0->num_rematrixing_bands)
316 ✗ block->new_rematrixing_strategy = 1;
317 }
318 5352 nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]);
319
320
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 5352 if (!s->rematrixing_enabled) {
321 1038 block0 = block;
322 1038 continue;
323 }
324
325
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 21570 for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) {
326 /* calculate sum of squared coeffs for one band in one block */
327 17256 int start = ff_ac3_rematrix_band_tab[bnd];
328 17256 int end = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
329 CoefSumType sum[4];
330 17256 sum_square_butterfly(s, sum, block->mdct_coef[1] + start,
331 17256 block->mdct_coef[2] + start, end - start);
332
333 /* compare sums to determine if rematrixing will be used for this band */
334
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 17256 if (FFMIN(sum[2], sum[3]) < FFMIN(sum[0], sum[1]))
335 9547 block->rematrixing_flags[bnd] = 1;
336 else
337 7709 block->rematrixing_flags[bnd] = 0;
338
339 /* determine if new rematrixing flags will be sent */
340
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 17256 if (blk &&
341
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 14380 block->rematrixing_flags[bnd] != block0->rematrixing_flags[bnd]) {
342 1886 block->new_rematrixing_strategy = 1;
343 }
344 }
345 4314 block0 = block;
346 }
347 }
348
349 12 static void copy_input_samples(AC3EncodeContext *s, const AVFrame *frame)
350 {
351
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 12 int end = frame ? frame->nb_samples : 0;
352
353 /* copy new samples and zero any remaining samples */
354
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 12 if (frame) {
355 9 av_samples_copy(s->input_samples, frame->extended_data, 0, 0,
356 9 frame->nb_samples, s->channels,
357 9 s->avctx->sample_fmt);
358 }
359 12 av_samples_set_silence(s->input_samples, end,
360 12 s->avctx->frame_size - end,
361 12 s->channels, s->avctx->sample_fmt);
362 12 }
363
364 1320 static void encode_frame(AC3EncodeContext *s, const AVFrame *frame)
365 {
366 uint8_t **samples;
367
368
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 1320 if (!frame || frame->nb_samples < s->avctx->frame_size) {
369 12 copy_input_samples(s, frame);
370 12 samples = s->input_samples;
371 } else
372 1308 samples = frame->extended_data;
373
374 1320 apply_mdct(s, samples);
375
376 1320 s->cpl_on = s->cpl_enabled;
377 1320 ff_ac3_compute_coupling_strategy(s);
378
379
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 1320 if (s->cpl_on)
380 737 apply_channel_coupling(s);
381
382 1320 compute_rematrixing_strategy(s);
383
384 #if AC3ENC_FLOAT
385 546 scale_coefficients(s);
386 #endif
387 1320 }
388