Libav
ac3enc_template.c
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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 Libav.
8  *
9  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22  */
23 
29 #include <stdint.h>
30 
31 #include "libavutil/internal.h"
32 
33 /* prototypes for static functions in ac3enc_fixed.c and ac3enc_float.c */
34 
35 static void scale_coefficients(AC3EncodeContext *s);
36 
37 static int normalize_samples(AC3EncodeContext *s);
38 
39 static void clip_coefficients(DSPContext *dsp, CoefType *coef, unsigned int len);
40 
41 static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl);
42 
43 
45 {
46  int ch;
47 
48  FF_ALLOC_OR_GOTO(s->avctx, s->windowed_samples, AC3_WINDOW_SIZE *
49  sizeof(*s->windowed_samples), alloc_fail);
50  FF_ALLOC_OR_GOTO(s->avctx, s->planar_samples, s->channels * sizeof(*s->planar_samples),
51  alloc_fail);
52  for (ch = 0; ch < s->channels; ch++) {
53  FF_ALLOCZ_OR_GOTO(s->avctx, s->planar_samples[ch],
54  (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),
55  alloc_fail);
56  }
57 
58  return 0;
59 alloc_fail:
60  return AVERROR(ENOMEM);
61 }
62 
63 
64 /*
65  * Copy input samples.
66  * Channels are reordered from Libav's default order to AC-3 order.
67  */
69 {
70  int ch;
71 
72  /* copy and remap input samples */
73  for (ch = 0; ch < s->channels; ch++) {
74  /* copy last 256 samples of previous frame to the start of the current frame */
75  memcpy(&s->planar_samples[ch][0], &s->planar_samples[ch][AC3_BLOCK_SIZE * s->num_blocks],
76  AC3_BLOCK_SIZE * sizeof(s->planar_samples[0][0]));
77 
78  /* copy new samples for current frame */
79  memcpy(&s->planar_samples[ch][AC3_BLOCK_SIZE],
80  samples[s->channel_map[ch]],
81  AC3_BLOCK_SIZE * s->num_blocks * sizeof(s->planar_samples[0][0]));
82  }
83 }
84 
85 
86 /*
87  * Apply the MDCT to input samples to generate frequency coefficients.
88  * This applies the KBD window and normalizes the input to reduce precision
89  * loss due to fixed-point calculations.
90  */
92 {
93  int blk, ch;
94 
95  for (ch = 0; ch < s->channels; ch++) {
96  for (blk = 0; blk < s->num_blocks; blk++) {
97  AC3Block *block = &s->blocks[blk];
98  const SampleType *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE];
99 
100 #if CONFIG_AC3ENC_FLOAT
101  s->fdsp.vector_fmul(s->windowed_samples, input_samples,
103 #else
104  s->ac3dsp.apply_window_int16(s->windowed_samples, input_samples,
106 #endif
107 
108  if (s->fixed_point)
109  block->coeff_shift[ch+1] = normalize_samples(s);
110 
111  s->mdct.mdct_calcw(&s->mdct, block->mdct_coef[ch+1],
112  s->windowed_samples);
113  }
114  }
115 }
116 
117 
118 /*
119  * Calculate coupling channel and coupling coordinates.
120  */
122 {
124 #if CONFIG_AC3ENC_FLOAT
125  LOCAL_ALIGNED_16(int32_t, fixed_cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
126 #else
127  int32_t (*fixed_cpl_coords)[AC3_MAX_CHANNELS][16] = cpl_coords;
128 #endif
129  int blk, ch, bnd, i, j;
130  CoefSumType energy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}};
131  int cpl_start, num_cpl_coefs;
132 
133  memset(cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
134 #if CONFIG_AC3ENC_FLOAT
135  memset(fixed_cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
136 #endif
137 
138  /* align start to 16-byte boundary. align length to multiple of 32.
139  note: coupling start bin % 4 will always be 1 */
140  cpl_start = s->start_freq[CPL_CH] - 1;
141  num_cpl_coefs = FFALIGN(s->num_cpl_subbands * 12 + 1, 32);
142  cpl_start = FFMIN(256, cpl_start + num_cpl_coefs) - num_cpl_coefs;
143 
144  /* calculate coupling channel from fbw channels */
145  for (blk = 0; blk < s->num_blocks; blk++) {
146  AC3Block *block = &s->blocks[blk];
147  CoefType *cpl_coef = &block->mdct_coef[CPL_CH][cpl_start];
148  if (!block->cpl_in_use)
149  continue;
150  memset(cpl_coef, 0, num_cpl_coefs * sizeof(*cpl_coef));
151  for (ch = 1; ch <= s->fbw_channels; ch++) {
152  CoefType *ch_coef = &block->mdct_coef[ch][cpl_start];
153  if (!block->channel_in_cpl[ch])
154  continue;
155  for (i = 0; i < num_cpl_coefs; i++)
156  cpl_coef[i] += ch_coef[i];
157  }
158 
159  /* coefficients must be clipped in order to be encoded */
160  clip_coefficients(&s->dsp, cpl_coef, num_cpl_coefs);
161  }
162 
163  /* calculate energy in each band in coupling channel and each fbw channel */
164  /* TODO: possibly use SIMD to speed up energy calculation */
165  bnd = 0;
166  i = s->start_freq[CPL_CH];
167  while (i < s->cpl_end_freq) {
168  int band_size = s->cpl_band_sizes[bnd];
169  for (ch = CPL_CH; ch <= s->fbw_channels; ch++) {
170  for (blk = 0; blk < s->num_blocks; blk++) {
171  AC3Block *block = &s->blocks[blk];
172  if (!block->cpl_in_use || (ch > CPL_CH && !block->channel_in_cpl[ch]))
173  continue;
174  for (j = 0; j < band_size; j++) {
175  CoefType v = block->mdct_coef[ch][i+j];
176  MAC_COEF(energy[blk][ch][bnd], v, v);
177  }
178  }
179  }
180  i += band_size;
181  bnd++;
182  }
183 
184  /* calculate coupling coordinates for all blocks for all channels */
185  for (blk = 0; blk < s->num_blocks; blk++) {
186  AC3Block *block = &s->blocks[blk];
187  if (!block->cpl_in_use)
188  continue;
189  for (ch = 1; ch <= s->fbw_channels; ch++) {
190  if (!block->channel_in_cpl[ch])
191  continue;
192  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
193  cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy[blk][ch][bnd],
194  energy[blk][CPL_CH][bnd]);
195  }
196  }
197  }
198 
199  /* determine which blocks to send new coupling coordinates for */
200  for (blk = 0; blk < s->num_blocks; blk++) {
201  AC3Block *block = &s->blocks[blk];
202  AC3Block *block0 = blk ? &s->blocks[blk-1] : NULL;
203 
204  memset(block->new_cpl_coords, 0, sizeof(block->new_cpl_coords));
205 
206  if (block->cpl_in_use) {
207  /* send new coordinates if this is the first block, if previous
208  * block did not use coupling but this block does, the channels
209  * using coupling has changed from the previous block, or the
210  * coordinate difference from the last block for any channel is
211  * greater than a threshold value. */
212  if (blk == 0 || !block0->cpl_in_use) {
213  for (ch = 1; ch <= s->fbw_channels; ch++)
214  block->new_cpl_coords[ch] = 1;
215  } else {
216  for (ch = 1; ch <= s->fbw_channels; ch++) {
217  if (!block->channel_in_cpl[ch])
218  continue;
219  if (!block0->channel_in_cpl[ch]) {
220  block->new_cpl_coords[ch] = 1;
221  } else {
222  CoefSumType coord_diff = 0;
223  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
224  coord_diff += FFABS(cpl_coords[blk-1][ch][bnd] -
225  cpl_coords[blk ][ch][bnd]);
226  }
227  coord_diff /= s->num_cpl_bands;
228  if (coord_diff > NEW_CPL_COORD_THRESHOLD)
229  block->new_cpl_coords[ch] = 1;
230  }
231  }
232  }
233  }
234  }
235 
236  /* calculate final coupling coordinates, taking into account reusing of
237  coordinates in successive blocks */
238  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
239  blk = 0;
240  while (blk < s->num_blocks) {
241  int av_uninit(blk1);
242  AC3Block *block = &s->blocks[blk];
243 
244  if (!block->cpl_in_use) {
245  blk++;
246  continue;
247  }
248 
249  for (ch = 1; ch <= s->fbw_channels; ch++) {
250  CoefSumType energy_ch, energy_cpl;
251  if (!block->channel_in_cpl[ch])
252  continue;
253  energy_cpl = energy[blk][CPL_CH][bnd];
254  energy_ch = energy[blk][ch][bnd];
255  blk1 = blk+1;
256  while (!s->blocks[blk1].new_cpl_coords[ch] && blk1 < s->num_blocks) {
257  if (s->blocks[blk1].cpl_in_use) {
258  energy_cpl += energy[blk1][CPL_CH][bnd];
259  energy_ch += energy[blk1][ch][bnd];
260  }
261  blk1++;
262  }
263  cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy_ch, energy_cpl);
264  }
265  blk = blk1;
266  }
267  }
268 
269  /* calculate exponents/mantissas for coupling coordinates */
270  for (blk = 0; blk < s->num_blocks; blk++) {
271  AC3Block *block = &s->blocks[blk];
272  if (!block->cpl_in_use)
273  continue;
274 
275 #if CONFIG_AC3ENC_FLOAT
276  s->ac3dsp.float_to_fixed24(fixed_cpl_coords[blk][1],
277  cpl_coords[blk][1],
278  s->fbw_channels * 16);
279 #endif
281  fixed_cpl_coords[blk][1],
282  s->fbw_channels * 16);
283 
284  for (ch = 1; ch <= s->fbw_channels; ch++) {
285  int bnd, min_exp, max_exp, master_exp;
286 
287  if (!block->new_cpl_coords[ch])
288  continue;
289 
290  /* determine master exponent */
291  min_exp = max_exp = block->cpl_coord_exp[ch][0];
292  for (bnd = 1; bnd < s->num_cpl_bands; bnd++) {
293  int exp = block->cpl_coord_exp[ch][bnd];
294  min_exp = FFMIN(exp, min_exp);
295  max_exp = FFMAX(exp, max_exp);
296  }
297  master_exp = ((max_exp - 15) + 2) / 3;
298  master_exp = FFMAX(master_exp, 0);
299  while (min_exp < master_exp * 3)
300  master_exp--;
301  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
302  block->cpl_coord_exp[ch][bnd] = av_clip(block->cpl_coord_exp[ch][bnd] -
303  master_exp * 3, 0, 15);
304  }
305  block->cpl_master_exp[ch] = master_exp;
306 
307  /* quantize mantissas */
308  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
309  int cpl_exp = block->cpl_coord_exp[ch][bnd];
310  int cpl_mant = (fixed_cpl_coords[blk][ch][bnd] << (5 + cpl_exp + master_exp * 3)) >> 24;
311  if (cpl_exp == 15)
312  cpl_mant >>= 1;
313  else
314  cpl_mant -= 16;
315 
316  block->cpl_coord_mant[ch][bnd] = cpl_mant;
317  }
318  }
319  }
320 
321  if (CONFIG_EAC3_ENCODER && s->eac3)
323 }
324 
325 
326 /*
327  * Determine rematrixing flags for each block and band.
328  */
330 {
331  int nb_coefs;
332  int blk, bnd, i;
333  AC3Block *block, *block0;
334 
336  return;
337 
338  for (blk = 0; blk < s->num_blocks; blk++) {
339  block = &s->blocks[blk];
340  block->new_rematrixing_strategy = !blk;
341 
342  block->num_rematrixing_bands = 4;
343  if (block->cpl_in_use) {
344  block->num_rematrixing_bands -= (s->start_freq[CPL_CH] <= 61);
345  block->num_rematrixing_bands -= (s->start_freq[CPL_CH] == 37);
346  if (blk && block->num_rematrixing_bands != block0->num_rematrixing_bands)
347  block->new_rematrixing_strategy = 1;
348  }
349  nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]);
350 
351  if (!s->rematrixing_enabled) {
352  block0 = block;
353  continue;
354  }
355 
356  for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) {
357  /* calculate calculate sum of squared coeffs for one band in one block */
358  int start = ff_ac3_rematrix_band_tab[bnd];
359  int end = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
360  CoefSumType sum[4] = {0,};
361  for (i = start; i < end; i++) {
362  CoefType lt = block->mdct_coef[1][i];
363  CoefType rt = block->mdct_coef[2][i];
364  CoefType md = lt + rt;
365  CoefType sd = lt - rt;
366  MAC_COEF(sum[0], lt, lt);
367  MAC_COEF(sum[1], rt, rt);
368  MAC_COEF(sum[2], md, md);
369  MAC_COEF(sum[3], sd, sd);
370  }
371 
372  /* compare sums to determine if rematrixing will be used for this band */
373  if (FFMIN(sum[2], sum[3]) < FFMIN(sum[0], sum[1]))
374  block->rematrixing_flags[bnd] = 1;
375  else
376  block->rematrixing_flags[bnd] = 0;
377 
378  /* determine if new rematrixing flags will be sent */
379  if (blk &&
380  block->rematrixing_flags[bnd] != block0->rematrixing_flags[bnd]) {
381  block->new_rematrixing_strategy = 1;
382  }
383  }
384  block0 = block;
385  }
386 }
387 
388 
390  const AVFrame *frame, int *got_packet_ptr)
391 {
393  int ret;
394 
396  ret = ff_ac3_validate_metadata(s);
397  if (ret)
398  return ret;
399  }
400 
401  if (s->bit_alloc.sr_code == 1 || s->eac3)
403 
404  copy_input_samples(s, (SampleType **)frame->extended_data);
405 
406  apply_mdct(s);
407 
408  if (s->fixed_point)
410 
411  clip_coefficients(&s->dsp, s->blocks[0].mdct_coef[1],
412  AC3_MAX_COEFS * s->num_blocks * s->channels);
413 
414  s->cpl_on = s->cpl_enabled;
416 
417  if (s->cpl_on)
419 
421 
422  if (!s->fixed_point)
424 
426 
428 
430  if (ret) {
431  av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
432  return ret;
433  }
434 
436 
438 
439  if ((ret = ff_alloc_packet(avpkt, s->frame_size))) {
440  av_log(avctx, AV_LOG_ERROR, "Error getting output packet\n");
441  return ret;
442  }
443  ff_ac3_output_frame(s, avpkt->data);
444 
445  if (frame->pts != AV_NOPTS_VALUE)
446  avpkt->pts = frame->pts - ff_samples_to_time_base(avctx, avctx->delay);
447 
448  *got_packet_ptr = 1;
449  return 0;
450 }