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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 
37 static void apply_window(void *dsp, SampleType *output,
38  const SampleType *input, const SampleType *window,
39  unsigned int len);
40 
42 
43 static void clip_coefficients(DSPContext *dsp, CoefType *coef, unsigned int len);
44 
45 static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl);
46 
48  const CoefType *coef0, const CoefType *coef1,
49  int len);
50 
52 {
53  int ch;
54 
55  FF_ALLOC_OR_GOTO(s->avctx, s->windowed_samples, AC3_WINDOW_SIZE *
56  sizeof(*s->windowed_samples), alloc_fail);
57  FF_ALLOC_OR_GOTO(s->avctx, s->planar_samples, s->channels * sizeof(*s->planar_samples),
58  alloc_fail);
59  for (ch = 0; ch < s->channels; ch++) {
60  FF_ALLOCZ_OR_GOTO(s->avctx, s->planar_samples[ch],
61  (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),
62  alloc_fail);
63  }
64 
65  return 0;
66 alloc_fail:
67  return AVERROR(ENOMEM);
68 }
69 
70 
71 /*
72  * Copy input samples.
73  * Channels are reordered from FFmpeg's default order to AC-3 order.
74  */
76 {
77  int ch;
78 
79  /* copy and remap input samples */
80  for (ch = 0; ch < s->channels; ch++) {
81  /* copy last 256 samples of previous frame to the start of the current frame */
82  memcpy(&s->planar_samples[ch][0], &s->planar_samples[ch][AC3_BLOCK_SIZE * s->num_blocks],
83  AC3_BLOCK_SIZE * sizeof(s->planar_samples[0][0]));
84 
85  /* copy new samples for current frame */
86  memcpy(&s->planar_samples[ch][AC3_BLOCK_SIZE],
87  samples[s->channel_map[ch]],
88  AC3_BLOCK_SIZE * s->num_blocks * sizeof(s->planar_samples[0][0]));
89  }
90 }
91 
92 
93 /*
94  * Apply the MDCT to input samples to generate frequency coefficients.
95  * This applies the KBD window and normalizes the input to reduce precision
96  * loss due to fixed-point calculations.
97  */
99 {
100  int blk, ch;
101 
102  for (ch = 0; ch < s->channels; ch++) {
103  for (blk = 0; blk < s->num_blocks; blk++) {
104  AC3Block *block = &s->blocks[blk];
105  const SampleType *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE];
106 
107 #if CONFIG_AC3ENC_FLOAT
108  apply_window(&s->fdsp, s->windowed_samples, input_samples,
110 #else
111  apply_window(&s->dsp, s->windowed_samples, input_samples,
113 #endif
114 
115  if (s->fixed_point)
116  block->coeff_shift[ch+1] = normalize_samples(s);
117 
118  s->mdct.mdct_calcw(&s->mdct, block->mdct_coef[ch+1],
119  s->windowed_samples);
120  }
121  }
122 }
123 
124 
125 /*
126  * Calculate coupling channel and coupling coordinates.
127  */
129 {
131 #if CONFIG_AC3ENC_FLOAT
132  LOCAL_ALIGNED_16(int32_t, fixed_cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
133 #else
134  int32_t (*fixed_cpl_coords)[AC3_MAX_CHANNELS][16] = cpl_coords;
135 #endif
136  int av_uninit(blk), ch, bnd, i, j;
137  CoefSumType energy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}};
138  int cpl_start, num_cpl_coefs;
139 
140  memset(cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
141 #if CONFIG_AC3ENC_FLOAT
142  memset(fixed_cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
143 #endif
144 
145  /* align start to 16-byte boundary. align length to multiple of 32.
146  note: coupling start bin % 4 will always be 1 */
147  cpl_start = s->start_freq[CPL_CH] - 1;
148  num_cpl_coefs = FFALIGN(s->num_cpl_subbands * 12 + 1, 32);
149  cpl_start = FFMIN(256, cpl_start + num_cpl_coefs) - num_cpl_coefs;
150 
151  /* calculate coupling channel from fbw channels */
152  for (blk = 0; blk < s->num_blocks; blk++) {
153  AC3Block *block = &s->blocks[blk];
154  CoefType *cpl_coef = &block->mdct_coef[CPL_CH][cpl_start];
155  if (!block->cpl_in_use)
156  continue;
157  memset(cpl_coef, 0, num_cpl_coefs * sizeof(*cpl_coef));
158  for (ch = 1; ch <= s->fbw_channels; ch++) {
159  CoefType *ch_coef = &block->mdct_coef[ch][cpl_start];
160  if (!block->channel_in_cpl[ch])
161  continue;
162  for (i = 0; i < num_cpl_coefs; i++)
163  cpl_coef[i] += ch_coef[i];
164  }
165 
166  /* coefficients must be clipped in order to be encoded */
167  clip_coefficients(&s->dsp, cpl_coef, num_cpl_coefs);
168  }
169 
170  /* calculate energy in each band in coupling channel and each fbw channel */
171  /* TODO: possibly use SIMD to speed up energy calculation */
172  bnd = 0;
173  i = s->start_freq[CPL_CH];
174  while (i < s->cpl_end_freq) {
175  int band_size = s->cpl_band_sizes[bnd];
176  for (ch = CPL_CH; ch <= s->fbw_channels; ch++) {
177  for (blk = 0; blk < s->num_blocks; blk++) {
178  AC3Block *block = &s->blocks[blk];
179  if (!block->cpl_in_use || (ch > CPL_CH && !block->channel_in_cpl[ch]))
180  continue;
181  for (j = 0; j < band_size; j++) {
182  CoefType v = block->mdct_coef[ch][i+j];
183  MAC_COEF(energy[blk][ch][bnd], v, v);
184  }
185  }
186  }
187  i += band_size;
188  bnd++;
189  }
190 
191  /* calculate coupling coordinates for all blocks for all channels */
192  for (blk = 0; blk < s->num_blocks; blk++) {
193  AC3Block *block = &s->blocks[blk];
194  if (!block->cpl_in_use)
195  continue;
196  for (ch = 1; ch <= s->fbw_channels; ch++) {
197  if (!block->channel_in_cpl[ch])
198  continue;
199  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
200  cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy[blk][ch][bnd],
201  energy[blk][CPL_CH][bnd]);
202  }
203  }
204  }
205 
206  /* determine which blocks to send new coupling coordinates for */
207  for (blk = 0; blk < s->num_blocks; blk++) {
208  AC3Block *block = &s->blocks[blk];
209  AC3Block *block0 = blk ? &s->blocks[blk-1] : NULL;
210 
211  memset(block->new_cpl_coords, 0, sizeof(block->new_cpl_coords));
212 
213  if (block->cpl_in_use) {
214  /* send new coordinates if this is the first block, if previous
215  * block did not use coupling but this block does, the channels
216  * using coupling has changed from the previous block, or the
217  * coordinate difference from the last block for any channel is
218  * greater than a threshold value. */
219  if (blk == 0 || !block0->cpl_in_use) {
220  for (ch = 1; ch <= s->fbw_channels; ch++)
221  block->new_cpl_coords[ch] = 1;
222  } else {
223  for (ch = 1; ch <= s->fbw_channels; ch++) {
224  if (!block->channel_in_cpl[ch])
225  continue;
226  if (!block0->channel_in_cpl[ch]) {
227  block->new_cpl_coords[ch] = 1;
228  } else {
229  CoefSumType coord_diff = 0;
230  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
231  coord_diff += FFABS(cpl_coords[blk-1][ch][bnd] -
232  cpl_coords[blk ][ch][bnd]);
233  }
234  coord_diff /= s->num_cpl_bands;
235  if (coord_diff > NEW_CPL_COORD_THRESHOLD)
236  block->new_cpl_coords[ch] = 1;
237  }
238  }
239  }
240  }
241  }
242 
243  /* calculate final coupling coordinates, taking into account reusing of
244  coordinates in successive blocks */
245  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
246  blk = 0;
247  while (blk < s->num_blocks) {
248  int av_uninit(blk1);
249  AC3Block *block = &s->blocks[blk];
250 
251  if (!block->cpl_in_use) {
252  blk++;
253  continue;
254  }
255 
256  for (ch = 1; ch <= s->fbw_channels; ch++) {
257  CoefSumType energy_ch, energy_cpl;
258  if (!block->channel_in_cpl[ch])
259  continue;
260  energy_cpl = energy[blk][CPL_CH][bnd];
261  energy_ch = energy[blk][ch][bnd];
262  blk1 = blk+1;
263  while (!s->blocks[blk1].new_cpl_coords[ch] && blk1 < s->num_blocks) {
264  if (s->blocks[blk1].cpl_in_use) {
265  energy_cpl += energy[blk1][CPL_CH][bnd];
266  energy_ch += energy[blk1][ch][bnd];
267  }
268  blk1++;
269  }
270  cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy_ch, energy_cpl);
271  }
272  blk = blk1;
273  }
274  }
275 
276  /* calculate exponents/mantissas for coupling coordinates */
277  for (blk = 0; blk < s->num_blocks; blk++) {
278  AC3Block *block = &s->blocks[blk];
279  if (!block->cpl_in_use)
280  continue;
281 
282 #if CONFIG_AC3ENC_FLOAT
283  s->ac3dsp.float_to_fixed24(fixed_cpl_coords[blk][1],
284  cpl_coords[blk][1],
285  s->fbw_channels * 16);
286 #endif
288  fixed_cpl_coords[blk][1],
289  s->fbw_channels * 16);
290 
291  for (ch = 1; ch <= s->fbw_channels; ch++) {
292  int bnd, min_exp, max_exp, master_exp;
293 
294  if (!block->new_cpl_coords[ch])
295  continue;
296 
297  /* determine master exponent */
298  min_exp = max_exp = block->cpl_coord_exp[ch][0];
299  for (bnd = 1; bnd < s->num_cpl_bands; bnd++) {
300  int exp = block->cpl_coord_exp[ch][bnd];
301  min_exp = FFMIN(exp, min_exp);
302  max_exp = FFMAX(exp, max_exp);
303  }
304  master_exp = ((max_exp - 15) + 2) / 3;
305  master_exp = FFMAX(master_exp, 0);
306  while (min_exp < master_exp * 3)
307  master_exp--;
308  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
309  block->cpl_coord_exp[ch][bnd] = av_clip(block->cpl_coord_exp[ch][bnd] -
310  master_exp * 3, 0, 15);
311  }
312  block->cpl_master_exp[ch] = master_exp;
313 
314  /* quantize mantissas */
315  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
316  int cpl_exp = block->cpl_coord_exp[ch][bnd];
317  int cpl_mant = (fixed_cpl_coords[blk][ch][bnd] << (5 + cpl_exp + master_exp * 3)) >> 24;
318  if (cpl_exp == 15)
319  cpl_mant >>= 1;
320  else
321  cpl_mant -= 16;
322 
323  block->cpl_coord_mant[ch][bnd] = cpl_mant;
324  }
325  }
326  }
327 
328  if (CONFIG_EAC3_ENCODER && s->eac3)
330 }
331 
332 
333 /*
334  * Determine rematrixing flags for each block and band.
335  */
337 {
338  int nb_coefs;
339  int blk, bnd;
340  AC3Block *block, *block0 = NULL;
341 
343  return;
344 
345  for (blk = 0; blk < s->num_blocks; blk++) {
346  block = &s->blocks[blk];
347  block->new_rematrixing_strategy = !blk;
348 
349  block->num_rematrixing_bands = 4;
350  if (block->cpl_in_use) {
351  block->num_rematrixing_bands -= (s->start_freq[CPL_CH] <= 61);
352  block->num_rematrixing_bands -= (s->start_freq[CPL_CH] == 37);
353  if (blk && block->num_rematrixing_bands != block0->num_rematrixing_bands)
354  block->new_rematrixing_strategy = 1;
355  }
356  nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]);
357 
358  if (!s->rematrixing_enabled) {
359  block0 = block;
360  continue;
361  }
362 
363  for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) {
364  /* calculate calculate sum of squared coeffs for one band in one block */
365  int start = ff_ac3_rematrix_band_tab[bnd];
366  int end = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
367  CoefSumType sum[4];
368  sum_square_butterfly(s, sum, block->mdct_coef[1] + start,
369  block->mdct_coef[2] + start, end - start);
370 
371  /* compare sums to determine if rematrixing will be used for this band */
372  if (FFMIN(sum[2], sum[3]) < FFMIN(sum[0], sum[1]))
373  block->rematrixing_flags[bnd] = 1;
374  else
375  block->rematrixing_flags[bnd] = 0;
376 
377  /* determine if new rematrixing flags will be sent */
378  if (blk &&
379  block->rematrixing_flags[bnd] != block0->rematrixing_flags[bnd]) {
380  block->new_rematrixing_strategy = 1;
381  }
382  }
383  block0 = block;
384  }
385 }
386 
387 
389  const AVFrame *frame, int *got_packet_ptr)
390 {
392  int ret;
393 
395  ret = ff_ac3_validate_metadata(s);
396  if (ret)
397  return ret;
398  }
399 
400  if (s->bit_alloc.sr_code == 1 || s->eac3)
402 
404 
405  apply_mdct(s);
406 
407  if (s->fixed_point)
409 
410  clip_coefficients(&s->dsp, s->blocks[0].mdct_coef[1],
411  AC3_MAX_COEFS * s->num_blocks * s->channels);
412 
413  s->cpl_on = s->cpl_enabled;
415 
416  if (s->cpl_on)
418 
420 
421  if (!s->fixed_point)
423 
425 
427 
429  if (ret) {
430  av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
431  return ret;
432  }
433 
435 
437 
438  if ((ret = ff_alloc_packet2(avctx, avpkt, s->frame_size)) < 0)
439  return ret;
440  ff_ac3_output_frame(s, avpkt->data);
441 
442  if (frame->pts != AV_NOPTS_VALUE)
443  avpkt->pts = frame->pts - ff_samples_to_time_base(avctx, avctx->delay);
444 
445  *got_packet_ptr = 1;
446  return 0;
447 }