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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 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 <stdint.h>
30 
31 #include "libavutil/internal.h"
32 
33 /* prototypes for static functions in ac3enc_fixed.c and ac3enc_float.c */
34 
36 
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 
44  const CoefType *coef0, const CoefType *coef1,
45  int len);
46 
48 {
49  int ch;
50 
51  FF_ALLOC_OR_GOTO(s->avctx, s->windowed_samples, AC3_WINDOW_SIZE *
52  sizeof(*s->windowed_samples), alloc_fail);
53  FF_ALLOC_OR_GOTO(s->avctx, s->planar_samples, s->channels * sizeof(*s->planar_samples),
54  alloc_fail);
55  for (ch = 0; ch < s->channels; ch++) {
56  FF_ALLOCZ_OR_GOTO(s->avctx, s->planar_samples[ch],
57  (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),
58  alloc_fail);
59  }
60 
61  return 0;
62 alloc_fail:
63  return AVERROR(ENOMEM);
64 }
65 
66 
67 /*
68  * Copy input samples.
69  * Channels are reordered from FFmpeg's default order to AC-3 order.
70  */
72 {
73  int ch;
74 
75  /* copy and remap input samples */
76  for (ch = 0; ch < s->channels; ch++) {
77  /* copy last 256 samples of previous frame to the start of the current frame */
78  memcpy(&s->planar_samples[ch][0], &s->planar_samples[ch][AC3_BLOCK_SIZE * s->num_blocks],
79  AC3_BLOCK_SIZE * sizeof(s->planar_samples[0][0]));
80 
81  /* copy new samples for current frame */
82  memcpy(&s->planar_samples[ch][AC3_BLOCK_SIZE],
83  samples[s->channel_map[ch]],
84  AC3_BLOCK_SIZE * s->num_blocks * sizeof(s->planar_samples[0][0]));
85  }
86 }
87 
88 
89 /*
90  * Apply the MDCT to input samples to generate frequency coefficients.
91  * This applies the KBD window and normalizes the input to reduce precision
92  * loss due to fixed-point calculations.
93  */
95 {
96  int blk, ch;
97 
98  for (ch = 0; ch < s->channels; ch++) {
99  for (blk = 0; blk < s->num_blocks; blk++) {
100  AC3Block *block = &s->blocks[blk];
101  const SampleType *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE];
102 
103 #if CONFIG_AC3ENC_FLOAT
104  s->fdsp.vector_fmul(s->windowed_samples, input_samples,
106 #else
107  s->ac3dsp.apply_window_int16(s->windowed_samples, input_samples,
109 #endif
110 
111  if (s->fixed_point)
112  block->coeff_shift[ch+1] = normalize_samples(s);
113 
114  s->mdct.mdct_calcw(&s->mdct, block->mdct_coef[ch+1],
115  s->windowed_samples);
116  }
117  }
118 }
119 
120 
121 /*
122  * Calculate coupling channel and coupling coordinates.
123  */
125 {
127 #if CONFIG_AC3ENC_FLOAT
128  LOCAL_ALIGNED_16(int32_t, fixed_cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
129 #else
130  int32_t (*fixed_cpl_coords)[AC3_MAX_CHANNELS][16] = cpl_coords;
131 #endif
132  int av_uninit(blk), ch, bnd, i, j;
133  CoefSumType energy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}};
134  int cpl_start, num_cpl_coefs;
135 
136  memset(cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
137 #if CONFIG_AC3ENC_FLOAT
138  memset(fixed_cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
139 #endif
140 
141  /* align start to 16-byte boundary. align length to multiple of 32.
142  note: coupling start bin % 4 will always be 1 */
143  cpl_start = s->start_freq[CPL_CH] - 1;
144  num_cpl_coefs = FFALIGN(s->num_cpl_subbands * 12 + 1, 32);
145  cpl_start = FFMIN(256, cpl_start + num_cpl_coefs) - num_cpl_coefs;
146 
147  /* calculate coupling channel from fbw channels */
148  for (blk = 0; blk < s->num_blocks; blk++) {
149  AC3Block *block = &s->blocks[blk];
150  CoefType *cpl_coef = &block->mdct_coef[CPL_CH][cpl_start];
151  if (!block->cpl_in_use)
152  continue;
153  memset(cpl_coef, 0, num_cpl_coefs * sizeof(*cpl_coef));
154  for (ch = 1; ch <= s->fbw_channels; ch++) {
155  CoefType *ch_coef = &block->mdct_coef[ch][cpl_start];
156  if (!block->channel_in_cpl[ch])
157  continue;
158  for (i = 0; i < num_cpl_coefs; i++)
159  cpl_coef[i] += ch_coef[i];
160  }
161 
162  /* coefficients must be clipped in order to be encoded */
163  clip_coefficients(&s->dsp, cpl_coef, num_cpl_coefs);
164  }
165 
166  /* calculate energy in each band in coupling channel and each fbw channel */
167  /* TODO: possibly use SIMD to speed up energy calculation */
168  bnd = 0;
169  i = s->start_freq[CPL_CH];
170  while (i < s->cpl_end_freq) {
171  int band_size = s->cpl_band_sizes[bnd];
172  for (ch = CPL_CH; ch <= s->fbw_channels; ch++) {
173  for (blk = 0; blk < s->num_blocks; blk++) {
174  AC3Block *block = &s->blocks[blk];
175  if (!block->cpl_in_use || (ch > CPL_CH && !block->channel_in_cpl[ch]))
176  continue;
177  for (j = 0; j < band_size; j++) {
178  CoefType v = block->mdct_coef[ch][i+j];
179  MAC_COEF(energy[blk][ch][bnd], v, v);
180  }
181  }
182  }
183  i += band_size;
184  bnd++;
185  }
186 
187  /* calculate coupling coordinates for all blocks for all channels */
188  for (blk = 0; blk < s->num_blocks; blk++) {
189  AC3Block *block = &s->blocks[blk];
190  if (!block->cpl_in_use)
191  continue;
192  for (ch = 1; ch <= s->fbw_channels; ch++) {
193  if (!block->channel_in_cpl[ch])
194  continue;
195  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
196  cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy[blk][ch][bnd],
197  energy[blk][CPL_CH][bnd]);
198  }
199  }
200  }
201 
202  /* determine which blocks to send new coupling coordinates for */
203  for (blk = 0; blk < s->num_blocks; blk++) {
204  AC3Block *block = &s->blocks[blk];
205  AC3Block *block0 = blk ? &s->blocks[blk-1] : NULL;
206 
207  memset(block->new_cpl_coords, 0, sizeof(block->new_cpl_coords));
208 
209  if (block->cpl_in_use) {
210  /* send new coordinates if this is the first block, if previous
211  * block did not use coupling but this block does, the channels
212  * using coupling has changed from the previous block, or the
213  * coordinate difference from the last block for any channel is
214  * greater than a threshold value. */
215  if (blk == 0 || !block0->cpl_in_use) {
216  for (ch = 1; ch <= s->fbw_channels; ch++)
217  block->new_cpl_coords[ch] = 1;
218  } else {
219  for (ch = 1; ch <= s->fbw_channels; ch++) {
220  if (!block->channel_in_cpl[ch])
221  continue;
222  if (!block0->channel_in_cpl[ch]) {
223  block->new_cpl_coords[ch] = 1;
224  } else {
225  CoefSumType coord_diff = 0;
226  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
227  coord_diff += FFABS(cpl_coords[blk-1][ch][bnd] -
228  cpl_coords[blk ][ch][bnd]);
229  }
230  coord_diff /= s->num_cpl_bands;
231  if (coord_diff > NEW_CPL_COORD_THRESHOLD)
232  block->new_cpl_coords[ch] = 1;
233  }
234  }
235  }
236  }
237  }
238 
239  /* calculate final coupling coordinates, taking into account reusing of
240  coordinates in successive blocks */
241  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
242  blk = 0;
243  while (blk < s->num_blocks) {
244  int av_uninit(blk1);
245  AC3Block *block = &s->blocks[blk];
246 
247  if (!block->cpl_in_use) {
248  blk++;
249  continue;
250  }
251 
252  for (ch = 1; ch <= s->fbw_channels; ch++) {
253  CoefSumType energy_ch, energy_cpl;
254  if (!block->channel_in_cpl[ch])
255  continue;
256  energy_cpl = energy[blk][CPL_CH][bnd];
257  energy_ch = energy[blk][ch][bnd];
258  blk1 = blk+1;
259  while (!s->blocks[blk1].new_cpl_coords[ch] && blk1 < s->num_blocks) {
260  if (s->blocks[blk1].cpl_in_use) {
261  energy_cpl += energy[blk1][CPL_CH][bnd];
262  energy_ch += energy[blk1][ch][bnd];
263  }
264  blk1++;
265  }
266  cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy_ch, energy_cpl);
267  }
268  blk = blk1;
269  }
270  }
271 
272  /* calculate exponents/mantissas for coupling coordinates */
273  for (blk = 0; blk < s->num_blocks; blk++) {
274  AC3Block *block = &s->blocks[blk];
275  if (!block->cpl_in_use)
276  continue;
277 
278 #if CONFIG_AC3ENC_FLOAT
279  s->ac3dsp.float_to_fixed24(fixed_cpl_coords[blk][1],
280  cpl_coords[blk][1],
281  s->fbw_channels * 16);
282 #endif
284  fixed_cpl_coords[blk][1],
285  s->fbw_channels * 16);
286 
287  for (ch = 1; ch <= s->fbw_channels; ch++) {
288  int bnd, min_exp, max_exp, master_exp;
289 
290  if (!block->new_cpl_coords[ch])
291  continue;
292 
293  /* determine master exponent */
294  min_exp = max_exp = block->cpl_coord_exp[ch][0];
295  for (bnd = 1; bnd < s->num_cpl_bands; bnd++) {
296  int exp = block->cpl_coord_exp[ch][bnd];
297  min_exp = FFMIN(exp, min_exp);
298  max_exp = FFMAX(exp, max_exp);
299  }
300  master_exp = ((max_exp - 15) + 2) / 3;
301  master_exp = FFMAX(master_exp, 0);
302  while (min_exp < master_exp * 3)
303  master_exp--;
304  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
305  block->cpl_coord_exp[ch][bnd] = av_clip(block->cpl_coord_exp[ch][bnd] -
306  master_exp * 3, 0, 15);
307  }
308  block->cpl_master_exp[ch] = master_exp;
309 
310  /* quantize mantissas */
311  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
312  int cpl_exp = block->cpl_coord_exp[ch][bnd];
313  int cpl_mant = (fixed_cpl_coords[blk][ch][bnd] << (5 + cpl_exp + master_exp * 3)) >> 24;
314  if (cpl_exp == 15)
315  cpl_mant >>= 1;
316  else
317  cpl_mant -= 16;
318 
319  block->cpl_coord_mant[ch][bnd] = cpl_mant;
320  }
321  }
322  }
323 
324  if (CONFIG_EAC3_ENCODER && s->eac3)
326 }
327 
328 
329 /*
330  * Determine rematrixing flags for each block and band.
331  */
333 {
334  int nb_coefs;
335  int blk, bnd;
336  AC3Block *block, *block0 = NULL;
337 
339  return;
340 
341  for (blk = 0; blk < s->num_blocks; blk++) {
342  block = &s->blocks[blk];
343  block->new_rematrixing_strategy = !blk;
344 
345  block->num_rematrixing_bands = 4;
346  if (block->cpl_in_use) {
347  block->num_rematrixing_bands -= (s->start_freq[CPL_CH] <= 61);
348  block->num_rematrixing_bands -= (s->start_freq[CPL_CH] == 37);
349  if (blk && block->num_rematrixing_bands != block0->num_rematrixing_bands)
350  block->new_rematrixing_strategy = 1;
351  }
352  nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]);
353 
354  if (!s->rematrixing_enabled) {
355  block0 = block;
356  continue;
357  }
358 
359  for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) {
360  /* calculate sum of squared coeffs for one band in one block */
361  int start = ff_ac3_rematrix_band_tab[bnd];
362  int end = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
363  CoefSumType sum[4];
364  sum_square_butterfly(s, sum, block->mdct_coef[1] + start,
365  block->mdct_coef[2] + start, end - start);
366 
367  /* compare sums to determine if rematrixing will be used for this band */
368  if (FFMIN(sum[2], sum[3]) < FFMIN(sum[0], sum[1]))
369  block->rematrixing_flags[bnd] = 1;
370  else
371  block->rematrixing_flags[bnd] = 0;
372 
373  /* determine if new rematrixing flags will be sent */
374  if (blk &&
375  block->rematrixing_flags[bnd] != block0->rematrixing_flags[bnd]) {
376  block->new_rematrixing_strategy = 1;
377  }
378  }
379  block0 = block;
380  }
381 }
382 
383 
385  const AVFrame *frame, int *got_packet_ptr)
386 {
388  int ret;
389 
391  ret = ff_ac3_validate_metadata(s);
392  if (ret)
393  return ret;
394  }
395 
396  if (s->bit_alloc.sr_code == 1 || s->eac3)
398 
400 
401  apply_mdct(s);
402 
403  if (s->fixed_point)
405 
406  clip_coefficients(&s->dsp, s->blocks[0].mdct_coef[1],
407  AC3_MAX_COEFS * s->num_blocks * s->channels);
408 
409  s->cpl_on = s->cpl_enabled;
411 
412  if (s->cpl_on)
414 
416 
417  if (!s->fixed_point)
419 
421 
423 
425  if (ret) {
426  av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
427  return ret;
428  }
429 
431 
433 
434  if ((ret = ff_alloc_packet2(avctx, avpkt, s->frame_size)) < 0)
435  return ret;
436  ff_ac3_output_frame(s, avpkt->data);
437 
438  if (frame->pts != AV_NOPTS_VALUE)
439  avpkt->pts = frame->pts - ff_samples_to_time_base(avctx, avctx->delay);
440 
441  *got_packet_ptr = 1;
442  return 0;
443 }