FFmpeg: libavcodec/ac3enc_template.c Source File

FFmpeg
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/attributes.h"
32 #include "libavutil/internal.h"
33 
34 #include "audiodsp.h"
35 #include "internal.h"
36 #include "ac3enc.h"
37 #include "eac3enc.h"
38 
39 /* prototypes for static functions in ac3enc_fixed.c and ac3enc_float.c */
40 
41 static void scale_coefficients(AC3EncodeContext *s);
42 
43 static int normalize_samples(AC3EncodeContext *s);
44 
45 static void clip_coefficients(AudioDSPContext *adsp, CoefType *coef,
46  unsigned int len);
47 
48 static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl);
49 
50 static void sum_square_butterfly(AC3EncodeContext *s, CoefSumType sum[4],
51  const CoefType *coef0, const CoefType *coef1,
52  int len);
53 
54  int AC3_NAME(allocate_sample_buffers)(AC3EncodeContext *s)
55 {
56  int ch;
57 
58  FF_ALLOC_OR_GOTO(s->avctx, s->windowed_samples, AC3_WINDOW_SIZE *
59  sizeof(*s->windowed_samples), alloc_fail);
60  FF_ALLOC_ARRAY_OR_GOTO(s->avctx, s->planar_samples, s->channels, sizeof(*s->planar_samples),
61  alloc_fail);
62  for (ch = 0; ch < s->channels; ch++) {
63  FF_ALLOCZ_OR_GOTO(s->avctx, s->planar_samples[ch],
64  (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),
65  alloc_fail);
66  }
67 
68  return 0;
69 alloc_fail:
70  return AVERROR(ENOMEM);
71 }
72 
73 
74 /*
75  * Copy input samples.
76  * Channels are reordered from FFmpeg's default order to AC-3 order.
77  */
78  static void copy_input_samples(AC3EncodeContext *s, SampleType **samples)
79 {
80  int ch;
81 
82  /* copy and remap input samples */
83  for (ch = 0; ch < s->channels; ch++) {
84  /* copy last 256 samples of previous frame to the start of the current frame */
85  memcpy(&s->planar_samples[ch][0], &s->planar_samples[ch][AC3_BLOCK_SIZE * s->num_blocks],
86  AC3_BLOCK_SIZE * sizeof(s->planar_samples[0][0]));
87 
88  /* copy new samples for current frame */
89  memcpy(&s->planar_samples[ch][AC3_BLOCK_SIZE],
90  samples[s->channel_map[ch]],
91  AC3_BLOCK_SIZE * s->num_blocks * sizeof(s->planar_samples[0][0]));
92  }
93 }
94 
95 
96 /*
97  * Apply the MDCT to input samples to generate frequency coefficients.
98  * This applies the KBD window and normalizes the input to reduce precision
99  * loss due to fixed-point calculations.
100  */
101  static void apply_mdct(AC3EncodeContext *s)
102 {
103  int blk, ch;
104 
105  for (ch = 0; ch < s->channels; ch++) {
106  for (blk = 0; blk < s->num_blocks; blk++) {
107  AC3Block *block = &s->blocks[blk];
108  const SampleType *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE];
109 
110 #if CONFIG_AC3ENC_FLOAT
111  s->fdsp->vector_fmul(s->windowed_samples, input_samples,
112  s->mdct_window, AC3_WINDOW_SIZE);
113 #else
114  s->ac3dsp.apply_window_int16(s->windowed_samples, input_samples,
115  s->mdct_window, AC3_WINDOW_SIZE);
116 #endif
117 
118  if (s->fixed_point)
119  block->coeff_shift[ch+1] = normalize_samples(s);
120 
121  s->mdct.mdct_calcw(&s->mdct, block->mdct_coef[ch+1],
122  s->windowed_samples);
123  }
124  }
125 }
126 
127 
128 /*
129  * Calculate coupling channel and coupling coordinates.
130  */
131  static void apply_channel_coupling(AC3EncodeContext *s)
132 {
133  LOCAL_ALIGNED_16(CoefType, cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
134 #if CONFIG_AC3ENC_FLOAT
135  LOCAL_ALIGNED_16(int32_t, fixed_cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
136 #else
137  int32_t (*fixed_cpl_coords)[AC3_MAX_CHANNELS][16] = cpl_coords;
138 #endif
139  int av_uninit(blk), ch, bnd, i, j;
140  CoefSumType energy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}};
141  int cpl_start, num_cpl_coefs;
142 
143  memset(cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
144 #if CONFIG_AC3ENC_FLOAT
145  memset(fixed_cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
146 #endif
147 
148  /* align start to 16-byte boundary. align length to multiple of 32.
149  note: coupling start bin % 4 will always be 1 */
150  cpl_start = s->start_freq[CPL_CH] - 1;
151  num_cpl_coefs = FFALIGN(s->num_cpl_subbands * 12 + 1, 32);
152  cpl_start = FFMIN(256, cpl_start + num_cpl_coefs) - num_cpl_coefs;
153 
154  /* calculate coupling channel from fbw channels */
155  for (blk = 0; blk < s->num_blocks; blk++) {
156  AC3Block *block = &s->blocks[blk];
157  CoefType *cpl_coef = &block->mdct_coef[CPL_CH][cpl_start];
158  if (!block->cpl_in_use)
159  continue;
160  memset(cpl_coef, 0, num_cpl_coefs * sizeof(*cpl_coef));
161  for (ch = 1; ch <= s->fbw_channels; ch++) {
162  CoefType *ch_coef = &block->mdct_coef[ch][cpl_start];
163  if (!block->channel_in_cpl[ch])
164  continue;
165  for (i = 0; i < num_cpl_coefs; i++)
166  cpl_coef[i] += ch_coef[i];
167  }
168 
169  /* coefficients must be clipped in order to be encoded */
170  clip_coefficients(&s->adsp, cpl_coef, num_cpl_coefs);
171  }
172 
173  /* calculate energy in each band in coupling channel and each fbw channel */
174  /* TODO: possibly use SIMD to speed up energy calculation */
175  bnd = 0;
176  i = s->start_freq[CPL_CH];
177  while (i < s->cpl_end_freq) {
178  int band_size = s->cpl_band_sizes[bnd];
179  for (ch = CPL_CH; ch <= s->fbw_channels; ch++) {
180  for (blk = 0; blk < s->num_blocks; blk++) {
181  AC3Block *block = &s->blocks[blk];
182  if (!block->cpl_in_use || (ch > CPL_CH && !block->channel_in_cpl[ch]))
183  continue;
184  for (j = 0; j < band_size; j++) {
185  CoefType v = block->mdct_coef[ch][i+j];
186  MAC_COEF(energy[blk][ch][bnd], v, v);
187  }
188  }
189  }
190  i += band_size;
191  bnd++;
192  }
193 
194  /* calculate coupling coordinates for all blocks for all channels */
195  for (blk = 0; blk < s->num_blocks; blk++) {
196  AC3Block *block = &s->blocks[blk];
197  if (!block->cpl_in_use)
198  continue;
199  for (ch = 1; ch <= s->fbw_channels; ch++) {
200  if (!block->channel_in_cpl[ch])
201  continue;
202  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
203  cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy[blk][ch][bnd],
204  energy[blk][CPL_CH][bnd]);
205  }
206  }
207  }
208 
209  /* determine which blocks to send new coupling coordinates for */
210  for (blk = 0; blk < s->num_blocks; blk++) {
211  AC3Block *block = &s->blocks[blk];
212  AC3Block *block0 = blk ? &s->blocks[blk-1] : NULL;
213 
214  memset(block->new_cpl_coords, 0, sizeof(block->new_cpl_coords));
215 
216  if (block->cpl_in_use) {
217  /* send new coordinates if this is the first block, if previous
218  * block did not use coupling but this block does, the channels
219  * using coupling has changed from the previous block, or the
220  * coordinate difference from the last block for any channel is
221  * greater than a threshold value. */
222  if (blk == 0 || !block0->cpl_in_use) {
223  for (ch = 1; ch <= s->fbw_channels; ch++)
224  block->new_cpl_coords[ch] = 1;
225  } else {
226  for (ch = 1; ch <= s->fbw_channels; ch++) {
227  if (!block->channel_in_cpl[ch])
228  continue;
229  if (!block0->channel_in_cpl[ch]) {
230  block->new_cpl_coords[ch] = 1;
231  } else {
232  CoefSumType coord_diff = 0;
233  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
234  coord_diff += FFABS(cpl_coords[blk-1][ch][bnd] -
235  cpl_coords[blk ][ch][bnd]);
236  }
237  coord_diff /= s->num_cpl_bands;
238  if (coord_diff > NEW_CPL_COORD_THRESHOLD)
239  block->new_cpl_coords[ch] = 1;
240  }
241  }
242  }
243  }
244  }
245 
246  /* calculate final coupling coordinates, taking into account reusing of
247  coordinates in successive blocks */
248  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
249  blk = 0;
250  while (blk < s->num_blocks) {
251  int av_uninit(blk1);
252  AC3Block *block = &s->blocks[blk];
253 
254  if (!block->cpl_in_use) {
255  blk++;
256  continue;
257  }
258 
259  for (ch = 1; ch <= s->fbw_channels; ch++) {
260  CoefSumType energy_ch, energy_cpl;
261  if (!block->channel_in_cpl[ch])
262  continue;
263  energy_cpl = energy[blk][CPL_CH][bnd];
264  energy_ch = energy[blk][ch][bnd];
265  blk1 = blk+1;
266  while (blk1 < s->num_blocks && !s->blocks[blk1].new_cpl_coords[ch]) {
267  if (s->blocks[blk1].cpl_in_use) {
268  energy_cpl += energy[blk1][CPL_CH][bnd];
269  energy_ch += energy[blk1][ch][bnd];
270  }
271  blk1++;
272  }
273  cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy_ch, energy_cpl);
274  }
275  blk = blk1;
276  }
277  }
278 
279  /* calculate exponents/mantissas for coupling coordinates */
280  for (blk = 0; blk < s->num_blocks; blk++) {
281  AC3Block *block = &s->blocks[blk];
282  if (!block->cpl_in_use)
283  continue;
284 
285 #if CONFIG_AC3ENC_FLOAT
286  s->ac3dsp.float_to_fixed24(fixed_cpl_coords[blk][1],
287  cpl_coords[blk][1],
288  s->fbw_channels * 16);
289 #endif
290  s->ac3dsp.extract_exponents(block->cpl_coord_exp[1],
291  fixed_cpl_coords[blk][1],
292  s->fbw_channels * 16);
293 
294  for (ch = 1; ch <= s->fbw_channels; ch++) {
295  int bnd, min_exp, max_exp, master_exp;
296 
297  if (!block->new_cpl_coords[ch])
298  continue;
299 
300  /* determine master exponent */
301  min_exp = max_exp = block->cpl_coord_exp[ch][0];
302  for (bnd = 1; bnd < s->num_cpl_bands; bnd++) {
303  int exp = block->cpl_coord_exp[ch][bnd];
304  min_exp = FFMIN(exp, min_exp);
305  max_exp = FFMAX(exp, max_exp);
306  }
307  master_exp = ((max_exp - 15) + 2) / 3;
308  master_exp = FFMAX(master_exp, 0);
309  while (min_exp < master_exp * 3)
310  master_exp--;
311  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
312  block->cpl_coord_exp[ch][bnd] = av_clip(block->cpl_coord_exp[ch][bnd] -
313  master_exp * 3, 0, 15);
314  }
315  block->cpl_master_exp[ch] = master_exp;
316 
317  /* quantize mantissas */
318  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
319  int cpl_exp = block->cpl_coord_exp[ch][bnd];
320  int cpl_mant = (fixed_cpl_coords[blk][ch][bnd] << (5 + cpl_exp + master_exp * 3)) >> 24;
321  if (cpl_exp == 15)
322  cpl_mant >>= 1;
323  else
324  cpl_mant -= 16;
325 
326  block->cpl_coord_mant[ch][bnd] = cpl_mant;
327  }
328  }
329  }
330 
331  if (CONFIG_EAC3_ENCODER && s->eac3)
332  ff_eac3_set_cpl_states(s);
333 }
334 
335 
336 /*
337  * Determine rematrixing flags for each block and band.
338  */
339  static void compute_rematrixing_strategy(AC3EncodeContext *s)
340 {
341  int nb_coefs;
342  int blk, bnd;
343  AC3Block *block, *block0 = NULL;
344 
345  if (s->channel_mode != AC3_CHMODE_STEREO)
346  return;
347 
348  for (blk = 0; blk < s->num_blocks; blk++) {
349  block = &s->blocks[blk];
350  block->new_rematrixing_strategy = !blk;
351 
352  block->num_rematrixing_bands = 4;
353  if (block->cpl_in_use) {
354  block->num_rematrixing_bands -= (s->start_freq[CPL_CH] <= 61);
355  block->num_rematrixing_bands -= (s->start_freq[CPL_CH] == 37);
356  if (blk && block->num_rematrixing_bands != block0->num_rematrixing_bands)
357  block->new_rematrixing_strategy = 1;
358  }
359  nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]);
360 
361  if (!s->rematrixing_enabled) {
362  block0 = block;
363  continue;
364  }
365 
366  for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) {
367  /* calculate sum of squared coeffs for one band in one block */
368  int start = ff_ac3_rematrix_band_tab[bnd];
369  int end = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
370  CoefSumType sum[4];
371  sum_square_butterfly(s, sum, block->mdct_coef[1] + start,
372  block->mdct_coef[2] + start, end - start);
373 
374  /* compare sums to determine if rematrixing will be used for this band */
375  if (FFMIN(sum[2], sum[3]) < FFMIN(sum[0], sum[1]))
376  block->rematrixing_flags[bnd] = 1;
377  else
378  block->rematrixing_flags[bnd] = 0;
379 
380  /* determine if new rematrixing flags will be sent */
381  if (blk &&
382  block->rematrixing_flags[bnd] != block0->rematrixing_flags[bnd]) {
383  block->new_rematrixing_strategy = 1;
384  }
385  }
386  block0 = block;
387  }
388 }
389 
390 
391  int AC3_NAME(encode_frame)(AVCodecContext *avctx, AVPacket *avpkt,
392  const AVFrame *frame, int *got_packet_ptr)
393 {
394  AC3EncodeContext *s = avctx->priv_data;
395  int ret;
396 
397  if (s->options.allow_per_frame_metadata) {
398  ret = ff_ac3_validate_metadata(s);
399  if (ret)
400  return ret;
401  }
402 
403  if (s->bit_alloc.sr_code == 1 || s->eac3)
404  ff_ac3_adjust_frame_size(s);
405 
406  copy_input_samples(s, (SampleType **)frame->extended_data);
407 
408  apply_mdct(s);
409 
410  if (s->fixed_point)
411  scale_coefficients(s);
412 
413  clip_coefficients(&s->adsp, s->blocks[0].mdct_coef[1],
414  AC3_MAX_COEFS * s->num_blocks * s->channels);
415 
416  s->cpl_on = s->cpl_enabled;
417  ff_ac3_compute_coupling_strategy(s);
418 
419  if (s->cpl_on)
420  apply_channel_coupling(s);
421 
422  compute_rematrixing_strategy(s);
423 
424  if (!s->fixed_point)
425  scale_coefficients(s);
426 
427  ff_ac3_apply_rematrixing(s);
428 
429  ff_ac3_process_exponents(s);
430 
431  ret = ff_ac3_compute_bit_allocation(s);
432  if (ret) {
433  av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
434  return ret;
435  }
436 
437  ff_ac3_group_exponents(s);
438 
439  ff_ac3_quantize_mantissas(s);
440 
441  if ((ret = ff_alloc_packet2(avctx, avpkt, s->frame_size)) < 0)
442  return ret;
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->initial_padding);
447 
448  *got_packet_ptr = 1;
449  return 0;
450 }
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