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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 
32 /* prototypes for static functions in ac3enc_fixed.c and ac3enc_float.c */
33 
34 static void scale_coefficients(AC3EncodeContext *s);
35 
36 static void apply_window(void *dsp, SampleType *output,
37  const SampleType *input, const SampleType *window,
38  unsigned int len);
39 
40 static int normalize_samples(AC3EncodeContext *s);
41 
42 static void clip_coefficients(DSPContext *dsp, CoefType *coef, unsigned int len);
43 
44 static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl);
45 
47  const CoefType *coef0, const CoefType *coef1,
48  int len);
49 
51 {
52  int ch;
53 
54  FF_ALLOC_OR_GOTO(s->avctx, s->windowed_samples, AC3_WINDOW_SIZE *
55  sizeof(*s->windowed_samples), alloc_fail);
56  FF_ALLOC_OR_GOTO(s->avctx, s->planar_samples, s->channels * sizeof(*s->planar_samples),
57  alloc_fail);
58  for (ch = 0; ch < s->channels; ch++) {
59  FF_ALLOCZ_OR_GOTO(s->avctx, s->planar_samples[ch],
60  (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),
61  alloc_fail);
62  }
63 
64  return 0;
65 alloc_fail:
66  return AVERROR(ENOMEM);
67 }
68 
69 
70 /*
71  * Copy input samples.
72  * Channels are reordered from FFmpeg's default order to AC-3 order.
73  */
75 {
76  int ch;
77 
78  /* copy and remap input samples */
79  for (ch = 0; ch < s->channels; ch++) {
80  /* copy last 256 samples of previous frame to the start of the current frame */
81  memcpy(&s->planar_samples[ch][0], &s->planar_samples[ch][AC3_BLOCK_SIZE * s->num_blocks],
82  AC3_BLOCK_SIZE * sizeof(s->planar_samples[0][0]));
83 
84  /* copy new samples for current frame */
85  memcpy(&s->planar_samples[ch][AC3_BLOCK_SIZE],
86  samples[s->channel_map[ch]],
87  AC3_BLOCK_SIZE * s->num_blocks * sizeof(s->planar_samples[0][0]));
88  }
89 }
90 
91 
92 /*
93  * Apply the MDCT to input samples to generate frequency coefficients.
94  * This applies the KBD window and normalizes the input to reduce precision
95  * loss due to fixed-point calculations.
96  */
98 {
99  int blk, ch;
100 
101  for (ch = 0; ch < s->channels; ch++) {
102  for (blk = 0; blk < s->num_blocks; blk++) {
103  AC3Block *block = &s->blocks[blk];
104  const SampleType *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE];
105 
106 #if CONFIG_AC3ENC_FLOAT
107  apply_window(&s->fdsp, s->windowed_samples, input_samples,
109 #else
110  apply_window(&s->dsp, s->windowed_samples, input_samples,
112 #endif
113 
114  if (s->fixed_point)
115  block->coeff_shift[ch+1] = normalize_samples(s);
116 
117  s->mdct.mdct_calcw(&s->mdct, block->mdct_coef[ch+1],
118  s->windowed_samples);
119  }
120  }
121 }
122 
123 
124 /*
125  * Calculate coupling channel and coupling coordinates.
126  */
128 {
130 #if CONFIG_AC3ENC_FLOAT
131  LOCAL_ALIGNED_16(int32_t, fixed_cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
132 #else
133  int32_t (*fixed_cpl_coords)[AC3_MAX_CHANNELS][16] = cpl_coords;
134 #endif
135  int blk, ch, bnd, i, j;
136  CoefSumType energy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}};
137  int cpl_start, num_cpl_coefs;
138 
139  memset(cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
140 #if CONFIG_AC3ENC_FLOAT
141  memset(fixed_cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
142 #endif
143 
144  /* align start to 16-byte boundary. align length to multiple of 32.
145  note: coupling start bin % 4 will always be 1 */
146  cpl_start = s->start_freq[CPL_CH] - 1;
147  num_cpl_coefs = FFALIGN(s->num_cpl_subbands * 12 + 1, 32);
148  cpl_start = FFMIN(256, cpl_start + num_cpl_coefs) - num_cpl_coefs;
149 
150  /* calculate coupling channel from fbw channels */
151  for (blk = 0; blk < s->num_blocks; blk++) {
152  AC3Block *block = &s->blocks[blk];
153  CoefType *cpl_coef = &block->mdct_coef[CPL_CH][cpl_start];
154  if (!block->cpl_in_use)
155  continue;
156  memset(cpl_coef, 0, num_cpl_coefs * sizeof(*cpl_coef));
157  for (ch = 1; ch <= s->fbw_channels; ch++) {
158  CoefType *ch_coef = &block->mdct_coef[ch][cpl_start];
159  if (!block->channel_in_cpl[ch])
160  continue;
161  for (i = 0; i < num_cpl_coefs; i++)
162  cpl_coef[i] += ch_coef[i];
163  }
164 
165  /* coefficients must be clipped in order to be encoded */
166  clip_coefficients(&s->dsp, cpl_coef, num_cpl_coefs);
167  }
168 
169  /* calculate energy in each band in coupling channel and each fbw channel */
170  /* TODO: possibly use SIMD to speed up energy calculation */
171  bnd = 0;
172  i = s->start_freq[CPL_CH];
173  while (i < s->cpl_end_freq) {
174  int band_size = s->cpl_band_sizes[bnd];
175  for (ch = CPL_CH; ch <= s->fbw_channels; ch++) {
176  for (blk = 0; blk < s->num_blocks; blk++) {
177  AC3Block *block = &s->blocks[blk];
178  if (!block->cpl_in_use || (ch > CPL_CH && !block->channel_in_cpl[ch]))
179  continue;
180  for (j = 0; j < band_size; j++) {
181  CoefType v = block->mdct_coef[ch][i+j];
182  MAC_COEF(energy[blk][ch][bnd], v, v);
183  }
184  }
185  }
186  i += band_size;
187  bnd++;
188  }
189 
190  /* calculate coupling coordinates for all blocks for all channels */
191  for (blk = 0; blk < s->num_blocks; blk++) {
192  AC3Block *block = &s->blocks[blk];
193  if (!block->cpl_in_use)
194  continue;
195  for (ch = 1; ch <= s->fbw_channels; ch++) {
196  if (!block->channel_in_cpl[ch])
197  continue;
198  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
199  cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy[blk][ch][bnd],
200  energy[blk][CPL_CH][bnd]);
201  }
202  }
203  }
204 
205  /* determine which blocks to send new coupling coordinates for */
206  for (blk = 0; blk < s->num_blocks; blk++) {
207  AC3Block *block = &s->blocks[blk];
208  AC3Block *block0 = blk ? &s->blocks[blk-1] : NULL;
209 
210  memset(block->new_cpl_coords, 0, sizeof(block->new_cpl_coords));
211 
212  if (block->cpl_in_use) {
213  /* send new coordinates if this is the first block, if previous
214  * block did not use coupling but this block does, the channels
215  * using coupling has changed from the previous block, or the
216  * coordinate difference from the last block for any channel is
217  * greater than a threshold value. */
218  if (blk == 0 || !block0->cpl_in_use) {
219  for (ch = 1; ch <= s->fbw_channels; ch++)
220  block->new_cpl_coords[ch] = 1;
221  } else {
222  for (ch = 1; ch <= s->fbw_channels; ch++) {
223  if (!block->channel_in_cpl[ch])
224  continue;
225  if (!block0->channel_in_cpl[ch]) {
226  block->new_cpl_coords[ch] = 1;
227  } else {
228  CoefSumType coord_diff = 0;
229  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
230  coord_diff += FFABS(cpl_coords[blk-1][ch][bnd] -
231  cpl_coords[blk ][ch][bnd]);
232  }
233  coord_diff /= s->num_cpl_bands;
234  if (coord_diff > NEW_CPL_COORD_THRESHOLD)
235  block->new_cpl_coords[ch] = 1;
236  }
237  }
238  }
239  }
240  }
241 
242  /* calculate final coupling coordinates, taking into account reusing of
243  coordinates in successive blocks */
244  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
245  blk = 0;
246  while (blk < s->num_blocks) {
247  int av_uninit(blk1);
248  AC3Block *block = &s->blocks[blk];
249 
250  if (!block->cpl_in_use) {
251  blk++;
252  continue;
253  }
254 
255  for (ch = 1; ch <= s->fbw_channels; ch++) {
256  CoefSumType energy_ch, energy_cpl;
257  if (!block->channel_in_cpl[ch])
258  continue;
259  energy_cpl = energy[blk][CPL_CH][bnd];
260  energy_ch = energy[blk][ch][bnd];
261  blk1 = blk+1;
262  while (!s->blocks[blk1].new_cpl_coords[ch] && blk1 < s->num_blocks) {
263  if (s->blocks[blk1].cpl_in_use) {
264  energy_cpl += energy[blk1][CPL_CH][bnd];
265  energy_ch += energy[blk1][ch][bnd];
266  }
267  blk1++;
268  }
269  cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy_ch, energy_cpl);
270  }
271  blk = blk1;
272  }
273  }
274 
275  /* calculate exponents/mantissas for coupling coordinates */
276  for (blk = 0; blk < s->num_blocks; blk++) {
277  AC3Block *block = &s->blocks[blk];
278  if (!block->cpl_in_use)
279  continue;
280 
281 #if CONFIG_AC3ENC_FLOAT
282  s->ac3dsp.float_to_fixed24(fixed_cpl_coords[blk][1],
283  cpl_coords[blk][1],
284  s->fbw_channels * 16);
285 #endif
287  fixed_cpl_coords[blk][1],
288  s->fbw_channels * 16);
289 
290  for (ch = 1; ch <= s->fbw_channels; ch++) {
291  int bnd, min_exp, max_exp, master_exp;
292 
293  if (!block->new_cpl_coords[ch])
294  continue;
295 
296  /* determine master exponent */
297  min_exp = max_exp = block->cpl_coord_exp[ch][0];
298  for (bnd = 1; bnd < s->num_cpl_bands; bnd++) {
299  int exp = block->cpl_coord_exp[ch][bnd];
300  min_exp = FFMIN(exp, min_exp);
301  max_exp = FFMAX(exp, max_exp);
302  }
303  master_exp = ((max_exp - 15) + 2) / 3;
304  master_exp = FFMAX(master_exp, 0);
305  while (min_exp < master_exp * 3)
306  master_exp--;
307  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
308  block->cpl_coord_exp[ch][bnd] = av_clip(block->cpl_coord_exp[ch][bnd] -
309  master_exp * 3, 0, 15);
310  }
311  block->cpl_master_exp[ch] = master_exp;
312 
313  /* quantize mantissas */
314  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
315  int cpl_exp = block->cpl_coord_exp[ch][bnd];
316  int cpl_mant = (fixed_cpl_coords[blk][ch][bnd] << (5 + cpl_exp + master_exp * 3)) >> 24;
317  if (cpl_exp == 15)
318  cpl_mant >>= 1;
319  else
320  cpl_mant -= 16;
321 
322  block->cpl_coord_mant[ch][bnd] = cpl_mant;
323  }
324  }
325  }
326 
327  if (CONFIG_EAC3_ENCODER && s->eac3)
329 }
330 
331 
332 /*
333  * Determine rematrixing flags for each block and band.
334  */
336 {
337  int nb_coefs;
338  int blk, bnd;
339  AC3Block *block, *block0;
340 
342  return;
343 
344  for (blk = 0; blk < s->num_blocks; blk++) {
345  block = &s->blocks[blk];
346  block->new_rematrixing_strategy = !blk;
347 
348  block->num_rematrixing_bands = 4;
349  if (block->cpl_in_use) {
350  block->num_rematrixing_bands -= (s->start_freq[CPL_CH] <= 61);
351  block->num_rematrixing_bands -= (s->start_freq[CPL_CH] == 37);
352  if (blk && block->num_rematrixing_bands != block0->num_rematrixing_bands)
353  block->new_rematrixing_strategy = 1;
354  }
355  nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]);
356 
357  if (!s->rematrixing_enabled) {
358  block0 = block;
359  continue;
360  }
361 
362  for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) {
363  /* calculate calculate sum of squared coeffs for one band in one block */
364  int start = ff_ac3_rematrix_band_tab[bnd];
365  int end = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
366  CoefSumType sum[4];
367  sum_square_butterfly(s, sum, block->mdct_coef[1] + start,
368  block->mdct_coef[2] + start, end - start);
369 
370  /* compare sums to determine if rematrixing will be used for this band */
371  if (FFMIN(sum[2], sum[3]) < FFMIN(sum[0], sum[1]))
372  block->rematrixing_flags[bnd] = 1;
373  else
374  block->rematrixing_flags[bnd] = 0;
375 
376  /* determine if new rematrixing flags will be sent */
377  if (blk &&
378  block->rematrixing_flags[bnd] != block0->rematrixing_flags[bnd]) {
379  block->new_rematrixing_strategy = 1;
380  }
381  }
382  block0 = block;
383  }
384 }
385 
386 
388  const AVFrame *frame, int *got_packet_ptr)
389 {
391  int ret;
392 
394  ret = ff_ac3_validate_metadata(s);
395  if (ret)
396  return ret;
397  }
398 
399  if (s->bit_alloc.sr_code == 1 || s->eac3)
401 
403 
404  apply_mdct(s);
405 
406  if (s->fixed_point)
408 
409  clip_coefficients(&s->dsp, s->blocks[0].mdct_coef[1],
410  AC3_MAX_COEFS * s->num_blocks * s->channels);
411 
412  s->cpl_on = s->cpl_enabled;
414 
415  if (s->cpl_on)
417 
419 
420  if (!s->fixed_point)
422 
424 
426 
428  if (ret) {
429  av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
430  return ret;
431  }
432 
434 
436 
437  if ((ret = ff_alloc_packet2(avctx, avpkt, s->frame_size)))
438  return ret;
439  ff_ac3_output_frame(s, avpkt->data);
440 
441  if (frame->pts != AV_NOPTS_VALUE)
442  avpkt->pts = frame->pts - ff_samples_to_time_base(avctx, avctx->delay);
443 
444  *got_packet_ptr = 1;
445  return 0;
446 }