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 
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(DSPContext *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 
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  * Deinterleave input samples.
69  * Channels are reordered from Libav's default order to AC-3 order.
70  */
72  const SampleType *samples)
73 {
74  int ch, i;
75 
76  /* deinterleave and remap input samples */
77  for (ch = 0; ch < s->channels; ch++) {
78  const SampleType *sptr;
79  int sinc;
80 
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  /* deinterleave */
86  sinc = s->channels;
87  sptr = samples + s->channel_map[ch];
88  for (i = AC3_BLOCK_SIZE; i < AC3_BLOCK_SIZE * (s->num_blocks + 1); i++) {
89  s->planar_samples[ch][i] = *sptr;
90  sptr += sinc;
91  }
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  */
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  apply_window(&s->dsp, s->windowed_samples, input_samples,
112 
113  if (s->fixed_point)
114  block->coeff_shift[ch+1] = normalize_samples(s);
115 
116  s->mdct.mdct_calcw(&s->mdct, block->mdct_coef[ch+1],
117  s->windowed_samples);
118  }
119  }
120 }
121 
122 
123 /*
124  * Calculate coupling channel and coupling coordinates.
125  */
127 {
129 #if CONFIG_AC3ENC_FLOAT
130  LOCAL_ALIGNED_16(int32_t, fixed_cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
131 #else
132  int32_t (*fixed_cpl_coords)[AC3_MAX_CHANNELS][16] = cpl_coords;
133 #endif
134  int blk, ch, bnd, i, j;
135  CoefSumType energy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}};
136  int cpl_start, num_cpl_coefs;
137 
138  memset(cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
139 #if CONFIG_AC3ENC_FLOAT
140  memset(fixed_cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
141 #endif
142 
143  /* align start to 16-byte boundary. align length to multiple of 32.
144  note: coupling start bin % 4 will always be 1 */
145  cpl_start = s->start_freq[CPL_CH] - 1;
146  num_cpl_coefs = FFALIGN(s->num_cpl_subbands * 12 + 1, 32);
147  cpl_start = FFMIN(256, cpl_start + num_cpl_coefs) - num_cpl_coefs;
148 
149  /* calculate coupling channel from fbw channels */
150  for (blk = 0; blk < s->num_blocks; blk++) {
151  AC3Block *block = &s->blocks[blk];
152  CoefType *cpl_coef = &block->mdct_coef[CPL_CH][cpl_start];
153  if (!block->cpl_in_use)
154  continue;
155  memset(cpl_coef, 0, num_cpl_coefs * sizeof(*cpl_coef));
156  for (ch = 1; ch <= s->fbw_channels; ch++) {
157  CoefType *ch_coef = &block->mdct_coef[ch][cpl_start];
158  if (!block->channel_in_cpl[ch])
159  continue;
160  for (i = 0; i < num_cpl_coefs; i++)
161  cpl_coef[i] += ch_coef[i];
162  }
163 
164  /* coefficients must be clipped in order to be encoded */
165  clip_coefficients(&s->dsp, cpl_coef, num_cpl_coefs);
166  }
167 
168  /* calculate energy in each band in coupling channel and each fbw channel */
169  /* TODO: possibly use SIMD to speed up energy calculation */
170  bnd = 0;
171  i = s->start_freq[CPL_CH];
172  while (i < s->cpl_end_freq) {
173  int band_size = s->cpl_band_sizes[bnd];
174  for (ch = CPL_CH; ch <= s->fbw_channels; ch++) {
175  for (blk = 0; blk < s->num_blocks; blk++) {
176  AC3Block *block = &s->blocks[blk];
177  if (!block->cpl_in_use || (ch > CPL_CH && !block->channel_in_cpl[ch]))
178  continue;
179  for (j = 0; j < band_size; j++) {
180  CoefType v = block->mdct_coef[ch][i+j];
181  MAC_COEF(energy[blk][ch][bnd], v, v);
182  }
183  }
184  }
185  i += band_size;
186  bnd++;
187  }
188 
189  /* calculate coupling coordinates for all blocks for all channels */
190  for (blk = 0; blk < s->num_blocks; blk++) {
191  AC3Block *block = &s->blocks[blk];
192  if (!block->cpl_in_use)
193  continue;
194  for (ch = 1; ch <= s->fbw_channels; ch++) {
195  if (!block->channel_in_cpl[ch])
196  continue;
197  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
198  cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy[blk][ch][bnd],
199  energy[blk][CPL_CH][bnd]);
200  }
201  }
202  }
203 
204  /* determine which blocks to send new coupling coordinates for */
205  for (blk = 0; blk < s->num_blocks; blk++) {
206  AC3Block *block = &s->blocks[blk];
207  AC3Block *block0 = blk ? &s->blocks[blk-1] : NULL;
208 
209  memset(block->new_cpl_coords, 0, sizeof(block->new_cpl_coords));
210 
211  if (block->cpl_in_use) {
212  /* send new coordinates if this is the first block, if previous
213  * block did not use coupling but this block does, the channels
214  * using coupling has changed from the previous block, or the
215  * coordinate difference from the last block for any channel is
216  * greater than a threshold value. */
217  if (blk == 0 || !block0->cpl_in_use) {
218  for (ch = 1; ch <= s->fbw_channels; ch++)
219  block->new_cpl_coords[ch] = 1;
220  } else {
221  for (ch = 1; ch <= s->fbw_channels; ch++) {
222  if (!block->channel_in_cpl[ch])
223  continue;
224  if (!block0->channel_in_cpl[ch]) {
225  block->new_cpl_coords[ch] = 1;
226  } else {
227  CoefSumType coord_diff = 0;
228  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
229  coord_diff += FFABS(cpl_coords[blk-1][ch][bnd] -
230  cpl_coords[blk ][ch][bnd]);
231  }
232  coord_diff /= s->num_cpl_bands;
233  if (coord_diff > NEW_CPL_COORD_THRESHOLD)
234  block->new_cpl_coords[ch] = 1;
235  }
236  }
237  }
238  }
239  }
240 
241  /* calculate final coupling coordinates, taking into account reusing of
242  coordinates in successive blocks */
243  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
244  blk = 0;
245  while (blk < s->num_blocks) {
246  int av_uninit(blk1);
247  AC3Block *block = &s->blocks[blk];
248 
249  if (!block->cpl_in_use) {
250  blk++;
251  continue;
252  }
253 
254  for (ch = 1; ch <= s->fbw_channels; ch++) {
255  CoefSumType energy_ch, energy_cpl;
256  if (!block->channel_in_cpl[ch])
257  continue;
258  energy_cpl = energy[blk][CPL_CH][bnd];
259  energy_ch = energy[blk][ch][bnd];
260  blk1 = blk+1;
261  while (!s->blocks[blk1].new_cpl_coords[ch] && blk1 < s->num_blocks) {
262  if (s->blocks[blk1].cpl_in_use) {
263  energy_cpl += energy[blk1][CPL_CH][bnd];
264  energy_ch += energy[blk1][ch][bnd];
265  }
266  blk1++;
267  }
268  cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy_ch, energy_cpl);
269  }
270  blk = blk1;
271  }
272  }
273 
274  /* calculate exponents/mantissas for coupling coordinates */
275  for (blk = 0; blk < s->num_blocks; blk++) {
276  AC3Block *block = &s->blocks[blk];
277  if (!block->cpl_in_use)
278  continue;
279 
280 #if CONFIG_AC3ENC_FLOAT
281  s->ac3dsp.float_to_fixed24(fixed_cpl_coords[blk][1],
282  cpl_coords[blk][1],
283  s->fbw_channels * 16);
284 #endif
286  fixed_cpl_coords[blk][1],
287  s->fbw_channels * 16);
288 
289  for (ch = 1; ch <= s->fbw_channels; ch++) {
290  int bnd, min_exp, max_exp, master_exp;
291 
292  if (!block->new_cpl_coords[ch])
293  continue;
294 
295  /* determine master exponent */
296  min_exp = max_exp = block->cpl_coord_exp[ch][0];
297  for (bnd = 1; bnd < s->num_cpl_bands; bnd++) {
298  int exp = block->cpl_coord_exp[ch][bnd];
299  min_exp = FFMIN(exp, min_exp);
300  max_exp = FFMAX(exp, max_exp);
301  }
302  master_exp = ((max_exp - 15) + 2) / 3;
303  master_exp = FFMAX(master_exp, 0);
304  while (min_exp < master_exp * 3)
305  master_exp--;
306  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
307  block->cpl_coord_exp[ch][bnd] = av_clip(block->cpl_coord_exp[ch][bnd] -
308  master_exp * 3, 0, 15);
309  }
310  block->cpl_master_exp[ch] = master_exp;
311 
312  /* quantize mantissas */
313  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
314  int cpl_exp = block->cpl_coord_exp[ch][bnd];
315  int cpl_mant = (fixed_cpl_coords[blk][ch][bnd] << (5 + cpl_exp + master_exp * 3)) >> 24;
316  if (cpl_exp == 15)
317  cpl_mant >>= 1;
318  else
319  cpl_mant -= 16;
320 
321  block->cpl_coord_mant[ch][bnd] = cpl_mant;
322  }
323  }
324  }
325 
326  if (CONFIG_EAC3_ENCODER && s->eac3)
328 }
329 
330 
331 /*
332  * Determine rematrixing flags for each block and band.
333  */
335 {
336  int nb_coefs;
337  int blk, bnd, i;
338  AC3Block *block, *av_uninit(block0);
339 
341  return;
342 
343  for (blk = 0; blk < s->num_blocks; blk++) {
344  block = &s->blocks[blk];
345  block->new_rematrixing_strategy = !blk;
346 
347  block->num_rematrixing_bands = 4;
348  if (block->cpl_in_use) {
349  block->num_rematrixing_bands -= (s->start_freq[CPL_CH] <= 61);
350  block->num_rematrixing_bands -= (s->start_freq[CPL_CH] == 37);
351  if (blk && block->num_rematrixing_bands != block0->num_rematrixing_bands)
352  block->new_rematrixing_strategy = 1;
353  }
354  nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]);
355 
356  if (!s->rematrixing_enabled) {
357  block0 = block;
358  continue;
359  }
360 
361  for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) {
362  /* calculate calculate sum of squared coeffs for one band in one block */
363  int start = ff_ac3_rematrix_band_tab[bnd];
364  int end = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
365  CoefSumType sum[4] = {0,};
366  for (i = start; i < end; i++) {
367  CoefType lt = block->mdct_coef[1][i];
368  CoefType rt = block->mdct_coef[2][i];
369  CoefType md = lt + rt;
370  CoefType sd = lt - rt;
371  MAC_COEF(sum[0], lt, lt);
372  MAC_COEF(sum[1], rt, rt);
373  MAC_COEF(sum[2], md, md);
374  MAC_COEF(sum[3], sd, sd);
375  }
376 
377  /* compare sums to determine if rematrixing will be used for this band */
378  if (FFMIN(sum[2], sum[3]) < FFMIN(sum[0], sum[1]))
379  block->rematrixing_flags[bnd] = 1;
380  else
381  block->rematrixing_flags[bnd] = 0;
382 
383  /* determine if new rematrixing flags will be sent */
384  if (blk &&
385  block->rematrixing_flags[bnd] != block0->rematrixing_flags[bnd]) {
386  block->new_rematrixing_strategy = 1;
387  }
388  }
389  block0 = block;
390  }
391 }
392 
393 
394 int AC3_NAME(encode_frame)(AVCodecContext *avctx, unsigned char *frame,
395  int buf_size, void *data)
396 {
398  const SampleType *samples = data;
399  int ret;
400 
402  ret = ff_ac3_validate_metadata(s);
403  if (ret)
404  return ret;
405  }
406 
407  if (s->bit_alloc.sr_code == 1 || s->eac3)
409 
410  deinterleave_input_samples(s, samples);
411 
412  apply_mdct(s);
413 
414  if (s->fixed_point)
416 
417  clip_coefficients(&s->dsp, s->blocks[0].mdct_coef[1],
418  AC3_MAX_COEFS * s->num_blocks * s->channels);
419 
420  s->cpl_on = s->cpl_enabled;
422 
423  if (s->cpl_on)
425 
427 
428  if (!s->fixed_point)
430 
432 
434 
436  if (ret) {
437  av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
438  return ret;
439  }
440 
442 
444 
445  ff_ac3_output_frame(s, frame);
446 
447  return s->frame_size;
448 }