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flacenc.c
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1 /*
2  * FLAC audio encoder
3  * Copyright (c) 2006 Justin Ruggles <justin.ruggles@gmail.com>
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #include "libavutil/avassert.h"
23 #include "libavutil/crc.h"
24 #include "libavutil/intmath.h"
25 #include "libavutil/md5.h"
26 #include "libavutil/opt.h"
27 #include "avcodec.h"
28 #include "bswapdsp.h"
29 #include "put_bits.h"
30 #include "golomb.h"
31 #include "internal.h"
32 #include "lpc.h"
33 #include "flac.h"
34 #include "flacdata.h"
35 #include "flacdsp.h"
36 
37 #define FLAC_SUBFRAME_CONSTANT 0
38 #define FLAC_SUBFRAME_VERBATIM 1
39 #define FLAC_SUBFRAME_FIXED 8
40 #define FLAC_SUBFRAME_LPC 32
41 
42 #define MAX_FIXED_ORDER 4
43 #define MAX_PARTITION_ORDER 8
44 #define MAX_PARTITIONS (1 << MAX_PARTITION_ORDER)
45 #define MAX_LPC_PRECISION 15
46 #define MAX_LPC_SHIFT 15
47 
48 enum CodingMode {
51 };
52 
53 typedef struct CompressionOptions {
64  int ch_mode;
66 
67 typedef struct RiceContext {
69  int porder;
71 } RiceContext;
72 
73 typedef struct FlacSubframe {
74  int type;
75  int type_code;
76  int obits;
77  int wasted;
78  int order;
80  int shift;
84 } FlacSubframe;
85 
86 typedef struct FlacFrame {
88  int blocksize;
89  int bs_code[2];
91  int ch_mode;
93 } FlacFrame;
94 
95 typedef struct FlacEncodeContext {
96  AVClass *class;
98  int channels;
100  int sr_code[2];
101  int bps_code;
106  uint32_t frame_count;
107  uint64_t sample_count;
113  struct AVMD5 *md5ctx;
115  unsigned int md5_buffer_size;
118 
119  int flushed;
120  int64_t next_pts;
122 
123 
124 /**
125  * Write streaminfo metadata block to byte array.
126  */
128 {
129  PutBitContext pb;
130 
131  memset(header, 0, FLAC_STREAMINFO_SIZE);
132  init_put_bits(&pb, header, FLAC_STREAMINFO_SIZE);
133 
134  /* streaminfo metadata block */
135  put_bits(&pb, 16, s->max_blocksize);
136  put_bits(&pb, 16, s->max_blocksize);
137  put_bits(&pb, 24, s->min_framesize);
138  put_bits(&pb, 24, s->max_framesize);
139  put_bits(&pb, 20, s->samplerate);
140  put_bits(&pb, 3, s->channels-1);
141  put_bits(&pb, 5, s->avctx->bits_per_raw_sample - 1);
142  /* write 36-bit sample count in 2 put_bits() calls */
143  put_bits(&pb, 24, (s->sample_count & 0xFFFFFF000LL) >> 12);
144  put_bits(&pb, 12, s->sample_count & 0x000000FFFLL);
145  flush_put_bits(&pb);
146  memcpy(&header[18], s->md5sum, 16);
147 }
148 
149 
150 /**
151  * Set blocksize based on samplerate.
152  * Choose the closest predefined blocksize >= BLOCK_TIME_MS milliseconds.
153  */
154 static int select_blocksize(int samplerate, int block_time_ms)
155 {
156  int i;
157  int target;
158  int blocksize;
159 
160  av_assert0(samplerate > 0);
161  blocksize = ff_flac_blocksize_table[1];
162  target = (samplerate * block_time_ms) / 1000;
163  for (i = 0; i < 16; i++) {
164  if (target >= ff_flac_blocksize_table[i] &&
165  ff_flac_blocksize_table[i] > blocksize) {
166  blocksize = ff_flac_blocksize_table[i];
167  }
168  }
169  return blocksize;
170 }
171 
172 
174 {
175  AVCodecContext *avctx = s->avctx;
176  CompressionOptions *opt = &s->options;
177 
178  av_log(avctx, AV_LOG_DEBUG, " compression: %d\n", opt->compression_level);
179 
180  switch (opt->lpc_type) {
181  case FF_LPC_TYPE_NONE:
182  av_log(avctx, AV_LOG_DEBUG, " lpc type: None\n");
183  break;
184  case FF_LPC_TYPE_FIXED:
185  av_log(avctx, AV_LOG_DEBUG, " lpc type: Fixed pre-defined coefficients\n");
186  break;
188  av_log(avctx, AV_LOG_DEBUG, " lpc type: Levinson-Durbin recursion with Welch window\n");
189  break;
191  av_log(avctx, AV_LOG_DEBUG, " lpc type: Cholesky factorization, %d pass%s\n",
192  opt->lpc_passes, opt->lpc_passes == 1 ? "" : "es");
193  break;
194  }
195 
196  av_log(avctx, AV_LOG_DEBUG, " prediction order: %d, %d\n",
198 
199  switch (opt->prediction_order_method) {
200  case ORDER_METHOD_EST:
201  av_log(avctx, AV_LOG_DEBUG, " order method: %s\n", "estimate");
202  break;
203  case ORDER_METHOD_2LEVEL:
204  av_log(avctx, AV_LOG_DEBUG, " order method: %s\n", "2-level");
205  break;
206  case ORDER_METHOD_4LEVEL:
207  av_log(avctx, AV_LOG_DEBUG, " order method: %s\n", "4-level");
208  break;
209  case ORDER_METHOD_8LEVEL:
210  av_log(avctx, AV_LOG_DEBUG, " order method: %s\n", "8-level");
211  break;
212  case ORDER_METHOD_SEARCH:
213  av_log(avctx, AV_LOG_DEBUG, " order method: %s\n", "full search");
214  break;
215  case ORDER_METHOD_LOG:
216  av_log(avctx, AV_LOG_DEBUG, " order method: %s\n", "log search");
217  break;
218  }
219 
220 
221  av_log(avctx, AV_LOG_DEBUG, " partition order: %d, %d\n",
223 
224  av_log(avctx, AV_LOG_DEBUG, " block size: %d\n", avctx->frame_size);
225 
226  av_log(avctx, AV_LOG_DEBUG, " lpc precision: %d\n",
227  opt->lpc_coeff_precision);
228 }
229 
230 
232 {
233  int freq = avctx->sample_rate;
234  int channels = avctx->channels;
235  FlacEncodeContext *s = avctx->priv_data;
236  int i, level, ret;
237  uint8_t *streaminfo;
238 
239  s->avctx = avctx;
240 
241  switch (avctx->sample_fmt) {
242  case AV_SAMPLE_FMT_S16:
243  avctx->bits_per_raw_sample = 16;
244  s->bps_code = 4;
245  break;
246  case AV_SAMPLE_FMT_S32:
247  if (avctx->bits_per_raw_sample != 24)
248  av_log(avctx, AV_LOG_WARNING, "encoding as 24 bits-per-sample\n");
249  avctx->bits_per_raw_sample = 24;
250  s->bps_code = 6;
251  break;
252  }
253 
254  if (channels < 1 || channels > FLAC_MAX_CHANNELS) {
255  av_log(avctx, AV_LOG_ERROR, "%d channels not supported (max %d)\n",
256  channels, FLAC_MAX_CHANNELS);
257  return AVERROR(EINVAL);
258  }
259  s->channels = channels;
260 
261  /* find samplerate in table */
262  if (freq < 1)
263  return -1;
264  for (i = 4; i < 12; i++) {
265  if (freq == ff_flac_sample_rate_table[i]) {
267  s->sr_code[0] = i;
268  s->sr_code[1] = 0;
269  break;
270  }
271  }
272  /* if not in table, samplerate is non-standard */
273  if (i == 12) {
274  if (freq % 1000 == 0 && freq < 255000) {
275  s->sr_code[0] = 12;
276  s->sr_code[1] = freq / 1000;
277  } else if (freq % 10 == 0 && freq < 655350) {
278  s->sr_code[0] = 14;
279  s->sr_code[1] = freq / 10;
280  } else if (freq < 65535) {
281  s->sr_code[0] = 13;
282  s->sr_code[1] = freq;
283  } else {
284  av_log(avctx, AV_LOG_ERROR, "%d Hz not supported\n", freq);
285  return AVERROR(EINVAL);
286  }
287  s->samplerate = freq;
288  }
289 
290  /* set compression option defaults based on avctx->compression_level */
291  if (avctx->compression_level < 0)
292  s->options.compression_level = 5;
293  else
295 
296  level = s->options.compression_level;
297  if (level > 12) {
298  av_log(avctx, AV_LOG_ERROR, "invalid compression level: %d\n",
300  return AVERROR(EINVAL);
301  }
302 
303  s->options.block_time_ms = ((int[]){ 27, 27, 27,105,105,105,105,105,105,105,105,105,105})[level];
304 
310  FF_LPC_TYPE_LEVINSON})[level];
311 
312  s->options.min_prediction_order = ((int[]){ 2, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1})[level];
313  s->options.max_prediction_order = ((int[]){ 3, 4, 4, 6, 8, 8, 8, 8, 12, 12, 12, 32, 32})[level];
314 
315  if (s->options.prediction_order_method < 0)
320  ORDER_METHOD_SEARCH})[level];
321 
323  av_log(avctx, AV_LOG_ERROR, "invalid partition orders: min=%d max=%d\n",
325  return AVERROR(EINVAL);
326  }
327  if (s->options.min_partition_order < 0)
328  s->options.min_partition_order = ((int[]){ 2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0})[level];
329  if (s->options.max_partition_order < 0)
330  s->options.max_partition_order = ((int[]){ 2, 2, 3, 3, 3, 8, 8, 8, 8, 8, 8, 8, 8})[level];
331 
332  if (s->options.lpc_type == FF_LPC_TYPE_NONE) {
334  } else if (avctx->min_prediction_order >= 0) {
335  if (s->options.lpc_type == FF_LPC_TYPE_FIXED) {
336  if (avctx->min_prediction_order > MAX_FIXED_ORDER) {
337  av_log(avctx, AV_LOG_ERROR, "invalid min prediction order: %d\n",
338  avctx->min_prediction_order);
339  return AVERROR(EINVAL);
340  }
341  } else if (avctx->min_prediction_order < MIN_LPC_ORDER ||
343  av_log(avctx, AV_LOG_ERROR, "invalid min prediction order: %d\n",
344  avctx->min_prediction_order);
345  return AVERROR(EINVAL);
346  }
348  }
349  if (s->options.lpc_type == FF_LPC_TYPE_NONE) {
351  } else if (avctx->max_prediction_order >= 0) {
352  if (s->options.lpc_type == FF_LPC_TYPE_FIXED) {
353  if (avctx->max_prediction_order > MAX_FIXED_ORDER) {
354  av_log(avctx, AV_LOG_ERROR, "invalid max prediction order: %d\n",
355  avctx->max_prediction_order);
356  return AVERROR(EINVAL);
357  }
358  } else if (avctx->max_prediction_order < MIN_LPC_ORDER ||
360  av_log(avctx, AV_LOG_ERROR, "invalid max prediction order: %d\n",
361  avctx->max_prediction_order);
362  return AVERROR(EINVAL);
363  }
365  }
367  av_log(avctx, AV_LOG_ERROR, "invalid prediction orders: min=%d max=%d\n",
369  return AVERROR(EINVAL);
370  }
371 
372  if (avctx->frame_size > 0) {
373  if (avctx->frame_size < FLAC_MIN_BLOCKSIZE ||
374  avctx->frame_size > FLAC_MAX_BLOCKSIZE) {
375  av_log(avctx, AV_LOG_ERROR, "invalid block size: %d\n",
376  avctx->frame_size);
377  return AVERROR(EINVAL);
378  }
379  } else {
381  }
382  s->max_blocksize = s->avctx->frame_size;
383 
384  /* set maximum encoded frame size in verbatim mode */
386  s->channels,
388 
389  /* initialize MD5 context */
390  s->md5ctx = av_md5_alloc();
391  if (!s->md5ctx)
392  return AVERROR(ENOMEM);
393  av_md5_init(s->md5ctx);
394 
395  streaminfo = av_malloc(FLAC_STREAMINFO_SIZE);
396  if (!streaminfo)
397  return AVERROR(ENOMEM);
398  write_streaminfo(s, streaminfo);
399  avctx->extradata = streaminfo;
401 
402  s->frame_count = 0;
404 
405  if (channels == 3 &&
407  channels == 4 &&
408  avctx->channel_layout != AV_CH_LAYOUT_2_2 &&
409  avctx->channel_layout != AV_CH_LAYOUT_QUAD ||
410  channels == 5 &&
413  channels == 6 &&
416  if (avctx->channel_layout) {
417  av_log(avctx, AV_LOG_ERROR, "Channel layout not supported by Flac, "
418  "output stream will have incorrect "
419  "channel layout.\n");
420  } else {
421  av_log(avctx, AV_LOG_WARNING, "No channel layout specified. The encoder "
422  "will use Flac channel layout for "
423  "%d channels.\n", channels);
424  }
425  }
426 
427  ret = ff_lpc_init(&s->lpc_ctx, avctx->frame_size,
429 
430  ff_bswapdsp_init(&s->bdsp);
431  ff_flacdsp_init(&s->flac_dsp, avctx->sample_fmt, channels,
432  avctx->bits_per_raw_sample);
433 
435 
436  return ret;
437 }
438 
439 
440 static void init_frame(FlacEncodeContext *s, int nb_samples)
441 {
442  int i, ch;
443  FlacFrame *frame;
444 
445  frame = &s->frame;
446 
447  for (i = 0; i < 16; i++) {
448  if (nb_samples == ff_flac_blocksize_table[i]) {
450  frame->bs_code[0] = i;
451  frame->bs_code[1] = 0;
452  break;
453  }
454  }
455  if (i == 16) {
456  frame->blocksize = nb_samples;
457  if (frame->blocksize <= 256) {
458  frame->bs_code[0] = 6;
459  frame->bs_code[1] = frame->blocksize-1;
460  } else {
461  frame->bs_code[0] = 7;
462  frame->bs_code[1] = frame->blocksize-1;
463  }
464  }
465 
466  for (ch = 0; ch < s->channels; ch++) {
467  FlacSubframe *sub = &frame->subframes[ch];
468 
469  sub->wasted = 0;
470  sub->obits = s->avctx->bits_per_raw_sample;
471 
472  if (sub->obits > 16)
474  else
476  }
477 
478  frame->verbatim_only = 0;
479 }
480 
481 
482 /**
483  * Copy channel-interleaved input samples into separate subframes.
484  */
485 static void copy_samples(FlacEncodeContext *s, const void *samples)
486 {
487  int i, j, ch;
488  FlacFrame *frame;
491 
492 #define COPY_SAMPLES(bits) do { \
493  const int ## bits ## _t *samples0 = samples; \
494  frame = &s->frame; \
495  for (i = 0, j = 0; i < frame->blocksize; i++) \
496  for (ch = 0; ch < s->channels; ch++, j++) \
497  frame->subframes[ch].samples[i] = samples0[j] >> shift; \
498 } while (0)
499 
501  COPY_SAMPLES(16);
502  else
503  COPY_SAMPLES(32);
504 }
505 
506 
507 static uint64_t rice_count_exact(int32_t *res, int n, int k)
508 {
509  int i;
510  uint64_t count = 0;
511 
512  for (i = 0; i < n; i++) {
513  int32_t v = -2 * res[i] - 1;
514  v ^= v >> 31;
515  count += (v >> k) + 1 + k;
516  }
517  return count;
518 }
519 
520 
522  int pred_order)
523 {
524  int p, porder, psize;
525  int i, part_end;
526  uint64_t count = 0;
527 
528  /* subframe header */
529  count += 8;
530 
531  /* subframe */
532  if (sub->type == FLAC_SUBFRAME_CONSTANT) {
533  count += sub->obits;
534  } else if (sub->type == FLAC_SUBFRAME_VERBATIM) {
535  count += s->frame.blocksize * sub->obits;
536  } else {
537  /* warm-up samples */
538  count += pred_order * sub->obits;
539 
540  /* LPC coefficients */
541  if (sub->type == FLAC_SUBFRAME_LPC)
542  count += 4 + 5 + pred_order * s->options.lpc_coeff_precision;
543 
544  /* rice-encoded block */
545  count += 2;
546 
547  /* partition order */
548  porder = sub->rc.porder;
549  psize = s->frame.blocksize >> porder;
550  count += 4;
551 
552  /* residual */
553  i = pred_order;
554  part_end = psize;
555  for (p = 0; p < 1 << porder; p++) {
556  int k = sub->rc.params[p];
557  count += sub->rc.coding_mode;
558  count += rice_count_exact(&sub->residual[i], part_end - i, k);
559  i = part_end;
560  part_end = FFMIN(s->frame.blocksize, part_end + psize);
561  }
562  }
563 
564  return count;
565 }
566 
567 
568 #define rice_encode_count(sum, n, k) (((n)*((k)+1))+((sum-(n>>1))>>(k)))
569 
570 /**
571  * Solve for d/dk(rice_encode_count) = n-((sum-(n>>1))>>(k+1)) = 0.
572  */
573 static int find_optimal_param(uint64_t sum, int n, int max_param)
574 {
575  int k;
576  uint64_t sum2;
577 
578  if (sum <= n >> 1)
579  return 0;
580  sum2 = sum - (n >> 1);
581  k = av_log2(av_clipl_int32(sum2 / n));
582  return FFMIN(k, max_param);
583 }
584 
585 
586 static uint64_t calc_optimal_rice_params(RiceContext *rc, int porder,
587  uint64_t *sums, int n, int pred_order)
588 {
589  int i;
590  int k, cnt, part, max_param;
591  uint64_t all_bits;
592 
593  max_param = (1 << rc->coding_mode) - 2;
594 
595  part = (1 << porder);
596  all_bits = 4 * part;
597 
598  cnt = (n >> porder) - pred_order;
599  for (i = 0; i < part; i++) {
600  k = find_optimal_param(sums[i], cnt, max_param);
601  rc->params[i] = k;
602  all_bits += rice_encode_count(sums[i], cnt, k);
603  cnt = n >> porder;
604  }
605 
606  rc->porder = porder;
607 
608  return all_bits;
609 }
610 
611 
612 static void calc_sum_top(int pmax, uint32_t *data, int n, int pred_order,
613  uint64_t sums[MAX_PARTITIONS])
614 {
615  int i;
616  int parts;
617  uint32_t *res, *res_end;
618 
619  /* sums for highest level */
620  parts = (1 << pmax);
621  res = &data[pred_order];
622  res_end = &data[n >> pmax];
623  for (i = 0; i < parts; i++) {
624  uint64_t sum = 0;
625  while (res < res_end)
626  sum += *(res++);
627  sums[i] = sum;
628  res_end += n >> pmax;
629  }
630 }
631 
632 static void calc_sum_next(int level, uint64_t sums[MAX_PARTITIONS])
633 {
634  int i;
635  int parts = (1 << level);
636  for (i = 0; i < parts; i++)
637  sums[i] = sums[2*i] + sums[2*i+1];
638 }
639 
640 static uint64_t calc_rice_params(RiceContext *rc, int pmin, int pmax,
641  int32_t *data, int n, int pred_order)
642 {
643  int i;
644  uint64_t bits[MAX_PARTITION_ORDER+1];
645  int opt_porder;
646  RiceContext tmp_rc;
647  uint32_t *udata;
648  uint64_t sums[MAX_PARTITIONS];
649 
650  av_assert1(pmin >= 0 && pmin <= MAX_PARTITION_ORDER);
651  av_assert1(pmax >= 0 && pmax <= MAX_PARTITION_ORDER);
652  av_assert1(pmin <= pmax);
653 
654  tmp_rc.coding_mode = rc->coding_mode;
655 
656  udata = av_malloc_array(n, sizeof(uint32_t));
657  for (i = 0; i < n; i++)
658  udata[i] = (2*data[i]) ^ (data[i]>>31);
659 
660  calc_sum_top(pmax, udata, n, pred_order, sums);
661 
662  opt_porder = pmin;
663  bits[pmin] = UINT32_MAX;
664  for (i = pmax; ; ) {
665  bits[i] = calc_optimal_rice_params(&tmp_rc, i, sums, n, pred_order);
666  if (bits[i] < bits[opt_porder]) {
667  opt_porder = i;
668  *rc = tmp_rc;
669  }
670  if (i == pmin)
671  break;
672  calc_sum_next(--i, sums);
673  }
674 
675  av_freep(&udata);
676  return bits[opt_porder];
677 }
678 
679 
680 static int get_max_p_order(int max_porder, int n, int order)
681 {
682  int porder = FFMIN(max_porder, av_log2(n^(n-1)));
683  if (order > 0)
684  porder = FFMIN(porder, av_log2(n/order));
685  return porder;
686 }
687 
688 
690  FlacSubframe *sub, int pred_order)
691 {
693  s->frame.blocksize, pred_order);
695  s->frame.blocksize, pred_order);
696 
697  uint64_t bits = 8 + pred_order * sub->obits + 2 + sub->rc.coding_mode;
698  if (sub->type == FLAC_SUBFRAME_LPC)
699  bits += 4 + 5 + pred_order * s->options.lpc_coeff_precision;
700  bits += calc_rice_params(&sub->rc, pmin, pmax, sub->residual,
701  s->frame.blocksize, pred_order);
702  return bits;
703 }
704 
705 
706 static void encode_residual_fixed(int32_t *res, const int32_t *smp, int n,
707  int order)
708 {
709  int i;
710 
711  for (i = 0; i < order; i++)
712  res[i] = smp[i];
713 
714  if (order == 0) {
715  for (i = order; i < n; i++)
716  res[i] = smp[i];
717  } else if (order == 1) {
718  for (i = order; i < n; i++)
719  res[i] = smp[i] - smp[i-1];
720  } else if (order == 2) {
721  int a = smp[order-1] - smp[order-2];
722  for (i = order; i < n; i += 2) {
723  int b = smp[i ] - smp[i-1];
724  res[i] = b - a;
725  a = smp[i+1] - smp[i ];
726  res[i+1] = a - b;
727  }
728  } else if (order == 3) {
729  int a = smp[order-1] - smp[order-2];
730  int c = smp[order-1] - 2*smp[order-2] + smp[order-3];
731  for (i = order; i < n; i += 2) {
732  int b = smp[i ] - smp[i-1];
733  int d = b - a;
734  res[i] = d - c;
735  a = smp[i+1] - smp[i ];
736  c = a - b;
737  res[i+1] = c - d;
738  }
739  } else {
740  int a = smp[order-1] - smp[order-2];
741  int c = smp[order-1] - 2*smp[order-2] + smp[order-3];
742  int e = smp[order-1] - 3*smp[order-2] + 3*smp[order-3] - smp[order-4];
743  for (i = order; i < n; i += 2) {
744  int b = smp[i ] - smp[i-1];
745  int d = b - a;
746  int f = d - c;
747  res[i ] = f - e;
748  a = smp[i+1] - smp[i ];
749  c = a - b;
750  e = c - d;
751  res[i+1] = e - f;
752  }
753  }
754 }
755 
756 
758 {
759  int i, n;
760  int min_order, max_order, opt_order, omethod;
761  FlacFrame *frame;
762  FlacSubframe *sub;
764  int shift[MAX_LPC_ORDER];
765  int32_t *res, *smp;
766 
767  frame = &s->frame;
768  sub = &frame->subframes[ch];
769  res = sub->residual;
770  smp = sub->samples;
771  n = frame->blocksize;
772 
773  /* CONSTANT */
774  for (i = 1; i < n; i++)
775  if(smp[i] != smp[0])
776  break;
777  if (i == n) {
778  sub->type = sub->type_code = FLAC_SUBFRAME_CONSTANT;
779  res[0] = smp[0];
780  return subframe_count_exact(s, sub, 0);
781  }
782 
783  /* VERBATIM */
784  if (frame->verbatim_only || n < 5) {
785  sub->type = sub->type_code = FLAC_SUBFRAME_VERBATIM;
786  memcpy(res, smp, n * sizeof(int32_t));
787  return subframe_count_exact(s, sub, 0);
788  }
789 
790  min_order = s->options.min_prediction_order;
791  max_order = s->options.max_prediction_order;
792  omethod = s->options.prediction_order_method;
793 
794  /* FIXED */
795  sub->type = FLAC_SUBFRAME_FIXED;
796  if (s->options.lpc_type == FF_LPC_TYPE_NONE ||
797  s->options.lpc_type == FF_LPC_TYPE_FIXED || n <= max_order) {
798  uint64_t bits[MAX_FIXED_ORDER+1];
799  if (max_order > MAX_FIXED_ORDER)
800  max_order = MAX_FIXED_ORDER;
801  opt_order = 0;
802  bits[0] = UINT32_MAX;
803  for (i = min_order; i <= max_order; i++) {
804  encode_residual_fixed(res, smp, n, i);
805  bits[i] = find_subframe_rice_params(s, sub, i);
806  if (bits[i] < bits[opt_order])
807  opt_order = i;
808  }
809  sub->order = opt_order;
810  sub->type_code = sub->type | sub->order;
811  if (sub->order != max_order) {
812  encode_residual_fixed(res, smp, n, sub->order);
813  find_subframe_rice_params(s, sub, sub->order);
814  }
815  return subframe_count_exact(s, sub, sub->order);
816  }
817 
818  /* LPC */
819  sub->type = FLAC_SUBFRAME_LPC;
820  opt_order = ff_lpc_calc_coefs(&s->lpc_ctx, smp, n, min_order, max_order,
821  s->options.lpc_coeff_precision, coefs, shift, s->options.lpc_type,
822  s->options.lpc_passes, omethod,
823  MAX_LPC_SHIFT, 0);
824 
825  if (omethod == ORDER_METHOD_2LEVEL ||
826  omethod == ORDER_METHOD_4LEVEL ||
827  omethod == ORDER_METHOD_8LEVEL) {
828  int levels = 1 << omethod;
829  uint64_t bits[1 << ORDER_METHOD_8LEVEL];
830  int order = -1;
831  int opt_index = levels-1;
832  opt_order = max_order-1;
833  bits[opt_index] = UINT32_MAX;
834  for (i = levels-1; i >= 0; i--) {
835  int last_order = order;
836  order = min_order + (((max_order-min_order+1) * (i+1)) / levels)-1;
837  order = av_clip(order, min_order - 1, max_order - 1);
838  if (order == last_order)
839  continue;
840  s->flac_dsp.lpc_encode(res, smp, n, order+1, coefs[order],
841  shift[order]);
842  bits[i] = find_subframe_rice_params(s, sub, order+1);
843  if (bits[i] < bits[opt_index]) {
844  opt_index = i;
845  opt_order = order;
846  }
847  }
848  opt_order++;
849  } else if (omethod == ORDER_METHOD_SEARCH) {
850  // brute-force optimal order search
851  uint64_t bits[MAX_LPC_ORDER];
852  opt_order = 0;
853  bits[0] = UINT32_MAX;
854  for (i = min_order-1; i < max_order; i++) {
855  s->flac_dsp.lpc_encode(res, smp, n, i+1, coefs[i], shift[i]);
856  bits[i] = find_subframe_rice_params(s, sub, i+1);
857  if (bits[i] < bits[opt_order])
858  opt_order = i;
859  }
860  opt_order++;
861  } else if (omethod == ORDER_METHOD_LOG) {
862  uint64_t bits[MAX_LPC_ORDER];
863  int step;
864 
865  opt_order = min_order - 1 + (max_order-min_order)/3;
866  memset(bits, -1, sizeof(bits));
867 
868  for (step = 16; step; step >>= 1) {
869  int last = opt_order;
870  for (i = last-step; i <= last+step; i += step) {
871  if (i < min_order-1 || i >= max_order || bits[i] < UINT32_MAX)
872  continue;
873  s->flac_dsp.lpc_encode(res, smp, n, i+1, coefs[i], shift[i]);
874  bits[i] = find_subframe_rice_params(s, sub, i+1);
875  if (bits[i] < bits[opt_order])
876  opt_order = i;
877  }
878  }
879  opt_order++;
880  }
881 
882  sub->order = opt_order;
883  sub->type_code = sub->type | (sub->order-1);
884  sub->shift = shift[sub->order-1];
885  for (i = 0; i < sub->order; i++)
886  sub->coefs[i] = coefs[sub->order-1][i];
887 
888  s->flac_dsp.lpc_encode(res, smp, n, sub->order, sub->coefs, sub->shift);
889 
890  find_subframe_rice_params(s, sub, sub->order);
891 
892  return subframe_count_exact(s, sub, sub->order);
893 }
894 
895 
897 {
898  uint8_t av_unused tmp;
899  int count;
900 
901  /*
902  <14> Sync code
903  <1> Reserved
904  <1> Blocking strategy
905  <4> Block size in inter-channel samples
906  <4> Sample rate
907  <4> Channel assignment
908  <3> Sample size in bits
909  <1> Reserved
910  */
911  count = 32;
912 
913  /* coded frame number */
914  PUT_UTF8(s->frame_count, tmp, count += 8;)
915 
916  /* explicit block size */
917  if (s->frame.bs_code[0] == 6)
918  count += 8;
919  else if (s->frame.bs_code[0] == 7)
920  count += 16;
921 
922  /* explicit sample rate */
923  count += ((s->sr_code[0] == 12) + (s->sr_code[0] > 12)) * 8;
924 
925  /* frame header CRC-8 */
926  count += 8;
927 
928  return count;
929 }
930 
931 
933 {
934  int ch;
935  uint64_t count;
936 
937  count = count_frame_header(s);
938 
939  for (ch = 0; ch < s->channels; ch++)
940  count += encode_residual_ch(s, ch);
941 
942  count += (8 - (count & 7)) & 7; // byte alignment
943  count += 16; // CRC-16
944 
945  count >>= 3;
946  if (count > INT_MAX)
947  return AVERROR_BUG;
948  return count;
949 }
950 
951 
953 {
954  int ch, i;
955 
956  for (ch = 0; ch < s->channels; ch++) {
957  FlacSubframe *sub = &s->frame.subframes[ch];
958  int32_t v = 0;
959 
960  for (i = 0; i < s->frame.blocksize; i++) {
961  v |= sub->samples[i];
962  if (v & 1)
963  break;
964  }
965 
966  if (v && !(v & 1)) {
967  v = av_ctz(v);
968 
969  for (i = 0; i < s->frame.blocksize; i++)
970  sub->samples[i] >>= v;
971 
972  sub->wasted = v;
973  sub->obits -= v;
974 
975  /* for 24-bit, check if removing wasted bits makes the range better
976  suited for using RICE instead of RICE2 for entropy coding */
977  if (sub->obits <= 17)
979  }
980  }
981 }
982 
983 
984 static int estimate_stereo_mode(int32_t *left_ch, int32_t *right_ch, int n,
985  int max_rice_param)
986 {
987  int i, best;
988  int32_t lt, rt;
989  uint64_t sum[4];
990  uint64_t score[4];
991  int k;
992 
993  /* calculate sum of 2nd order residual for each channel */
994  sum[0] = sum[1] = sum[2] = sum[3] = 0;
995  for (i = 2; i < n; i++) {
996  lt = left_ch[i] - 2*left_ch[i-1] + left_ch[i-2];
997  rt = right_ch[i] - 2*right_ch[i-1] + right_ch[i-2];
998  sum[2] += FFABS((lt + rt) >> 1);
999  sum[3] += FFABS(lt - rt);
1000  sum[0] += FFABS(lt);
1001  sum[1] += FFABS(rt);
1002  }
1003  /* estimate bit counts */
1004  for (i = 0; i < 4; i++) {
1005  k = find_optimal_param(2 * sum[i], n, max_rice_param);
1006  sum[i] = rice_encode_count( 2 * sum[i], n, k);
1007  }
1008 
1009  /* calculate score for each mode */
1010  score[0] = sum[0] + sum[1];
1011  score[1] = sum[0] + sum[3];
1012  score[2] = sum[1] + sum[3];
1013  score[3] = sum[2] + sum[3];
1014 
1015  /* return mode with lowest score */
1016  best = 0;
1017  for (i = 1; i < 4; i++)
1018  if (score[i] < score[best])
1019  best = i;
1020 
1021  return best;
1022 }
1023 
1024 
1025 /**
1026  * Perform stereo channel decorrelation.
1027  */
1029 {
1030  FlacFrame *frame;
1031  int32_t *left, *right;
1032  int i, n;
1033 
1034  frame = &s->frame;
1035  n = frame->blocksize;
1036  left = frame->subframes[0].samples;
1037  right = frame->subframes[1].samples;
1038 
1039  if (s->channels != 2) {
1041  return;
1042  }
1043 
1044  if (s->options.ch_mode < 0) {
1045  int max_rice_param = (1 << frame->subframes[0].rc.coding_mode) - 2;
1046  frame->ch_mode = estimate_stereo_mode(left, right, n, max_rice_param);
1047  } else
1048  frame->ch_mode = s->options.ch_mode;
1049 
1050  /* perform decorrelation and adjust bits-per-sample */
1051  if (frame->ch_mode == FLAC_CHMODE_INDEPENDENT)
1052  return;
1053  if (frame->ch_mode == FLAC_CHMODE_MID_SIDE) {
1054  int32_t tmp;
1055  for (i = 0; i < n; i++) {
1056  tmp = left[i];
1057  left[i] = (tmp + right[i]) >> 1;
1058  right[i] = tmp - right[i];
1059  }
1060  frame->subframes[1].obits++;
1061  } else if (frame->ch_mode == FLAC_CHMODE_LEFT_SIDE) {
1062  for (i = 0; i < n; i++)
1063  right[i] = left[i] - right[i];
1064  frame->subframes[1].obits++;
1065  } else {
1066  for (i = 0; i < n; i++)
1067  left[i] -= right[i];
1068  frame->subframes[0].obits++;
1069  }
1070 }
1071 
1072 
1073 static void write_utf8(PutBitContext *pb, uint32_t val)
1074 {
1075  uint8_t tmp;
1076  PUT_UTF8(val, tmp, put_bits(pb, 8, tmp);)
1077 }
1078 
1079 
1081 {
1082  FlacFrame *frame;
1083  int crc;
1084 
1085  frame = &s->frame;
1086 
1087  put_bits(&s->pb, 16, 0xFFF8);
1088  put_bits(&s->pb, 4, frame->bs_code[0]);
1089  put_bits(&s->pb, 4, s->sr_code[0]);
1090 
1091  if (frame->ch_mode == FLAC_CHMODE_INDEPENDENT)
1092  put_bits(&s->pb, 4, s->channels-1);
1093  else
1094  put_bits(&s->pb, 4, frame->ch_mode + FLAC_MAX_CHANNELS - 1);
1095 
1096  put_bits(&s->pb, 3, s->bps_code);
1097  put_bits(&s->pb, 1, 0);
1098  write_utf8(&s->pb, s->frame_count);
1099 
1100  if (frame->bs_code[0] == 6)
1101  put_bits(&s->pb, 8, frame->bs_code[1]);
1102  else if (frame->bs_code[0] == 7)
1103  put_bits(&s->pb, 16, frame->bs_code[1]);
1104 
1105  if (s->sr_code[0] == 12)
1106  put_bits(&s->pb, 8, s->sr_code[1]);
1107  else if (s->sr_code[0] > 12)
1108  put_bits(&s->pb, 16, s->sr_code[1]);
1109 
1110  flush_put_bits(&s->pb);
1111  crc = av_crc(av_crc_get_table(AV_CRC_8_ATM), 0, s->pb.buf,
1112  put_bits_count(&s->pb) >> 3);
1113  put_bits(&s->pb, 8, crc);
1114 }
1115 
1116 
1118 {
1119  int ch;
1120 
1121  for (ch = 0; ch < s->channels; ch++) {
1122  FlacSubframe *sub = &s->frame.subframes[ch];
1123  int i, p, porder, psize;
1124  int32_t *part_end;
1125  int32_t *res = sub->residual;
1126  int32_t *frame_end = &sub->residual[s->frame.blocksize];
1127 
1128  /* subframe header */
1129  put_bits(&s->pb, 1, 0);
1130  put_bits(&s->pb, 6, sub->type_code);
1131  put_bits(&s->pb, 1, !!sub->wasted);
1132  if (sub->wasted)
1133  put_bits(&s->pb, sub->wasted, 1);
1134 
1135  /* subframe */
1136  if (sub->type == FLAC_SUBFRAME_CONSTANT) {
1137  put_sbits(&s->pb, sub->obits, res[0]);
1138  } else if (sub->type == FLAC_SUBFRAME_VERBATIM) {
1139  while (res < frame_end)
1140  put_sbits(&s->pb, sub->obits, *res++);
1141  } else {
1142  /* warm-up samples */
1143  for (i = 0; i < sub->order; i++)
1144  put_sbits(&s->pb, sub->obits, *res++);
1145 
1146  /* LPC coefficients */
1147  if (sub->type == FLAC_SUBFRAME_LPC) {
1148  int cbits = s->options.lpc_coeff_precision;
1149  put_bits( &s->pb, 4, cbits-1);
1150  put_sbits(&s->pb, 5, sub->shift);
1151  for (i = 0; i < sub->order; i++)
1152  put_sbits(&s->pb, cbits, sub->coefs[i]);
1153  }
1154 
1155  /* rice-encoded block */
1156  put_bits(&s->pb, 2, sub->rc.coding_mode - 4);
1157 
1158  /* partition order */
1159  porder = sub->rc.porder;
1160  psize = s->frame.blocksize >> porder;
1161  put_bits(&s->pb, 4, porder);
1162 
1163  /* residual */
1164  part_end = &sub->residual[psize];
1165  for (p = 0; p < 1 << porder; p++) {
1166  int k = sub->rc.params[p];
1167  put_bits(&s->pb, sub->rc.coding_mode, k);
1168  while (res < part_end)
1169  set_sr_golomb_flac(&s->pb, *res++, k, INT32_MAX, 0);
1170  part_end = FFMIN(frame_end, part_end + psize);
1171  }
1172  }
1173  }
1174 }
1175 
1176 
1178 {
1179  int crc;
1180  flush_put_bits(&s->pb);
1182  put_bits_count(&s->pb)>>3));
1183  put_bits(&s->pb, 16, crc);
1184  flush_put_bits(&s->pb);
1185 }
1186 
1187 
1189 {
1190  init_put_bits(&s->pb, avpkt->data, avpkt->size);
1191  write_frame_header(s);
1192  write_subframes(s);
1193  write_frame_footer(s);
1194  return put_bits_count(&s->pb) >> 3;
1195 }
1196 
1197 
1198 static int update_md5_sum(FlacEncodeContext *s, const void *samples)
1199 {
1200  const uint8_t *buf;
1201  int buf_size = s->frame.blocksize * s->channels *
1202  ((s->avctx->bits_per_raw_sample + 7) / 8);
1203 
1204  if (s->avctx->bits_per_raw_sample > 16 || HAVE_BIGENDIAN) {
1205  av_fast_malloc(&s->md5_buffer, &s->md5_buffer_size, buf_size);
1206  if (!s->md5_buffer)
1207  return AVERROR(ENOMEM);
1208  }
1209 
1210  if (s->avctx->bits_per_raw_sample <= 16) {
1211  buf = (const uint8_t *)samples;
1212 #if HAVE_BIGENDIAN
1213  s->bdsp.bswap16_buf((uint16_t *) s->md5_buffer,
1214  (const uint16_t *) samples, buf_size / 2);
1215  buf = s->md5_buffer;
1216 #endif
1217  } else {
1218  int i;
1219  const int32_t *samples0 = samples;
1220  uint8_t *tmp = s->md5_buffer;
1221 
1222  for (i = 0; i < s->frame.blocksize * s->channels; i++) {
1223  int32_t v = samples0[i] >> 8;
1224  *tmp++ = (v ) & 0xFF;
1225  *tmp++ = (v >> 8) & 0xFF;
1226  *tmp++ = (v >> 16) & 0xFF;
1227  }
1228  buf = s->md5_buffer;
1229  }
1230  av_md5_update(s->md5ctx, buf, buf_size);
1231 
1232  return 0;
1233 }
1234 
1235 
1236 static int flac_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
1237  const AVFrame *frame, int *got_packet_ptr)
1238 {
1240  int frame_bytes, out_bytes, ret;
1241 
1242  s = avctx->priv_data;
1243 
1244  /* when the last block is reached, update the header in extradata */
1245  if (!frame) {
1247  av_md5_final(s->md5ctx, s->md5sum);
1248  write_streaminfo(s, avctx->extradata);
1249 
1250  if (avctx->side_data_only_packets && !s->flushed) {
1252  avctx->extradata_size);
1253  if (!side_data)
1254  return AVERROR(ENOMEM);
1255  memcpy(side_data, avctx->extradata, avctx->extradata_size);
1256 
1257  avpkt->pts = s->next_pts;
1258 
1259  *got_packet_ptr = 1;
1260  s->flushed = 1;
1261  }
1262 
1263  return 0;
1264  }
1265 
1266  /* change max_framesize for small final frame */
1267  if (frame->nb_samples < s->frame.blocksize) {
1269  s->channels,
1270  avctx->bits_per_raw_sample);
1271  }
1272 
1273  init_frame(s, frame->nb_samples);
1274 
1275  copy_samples(s, frame->data[0]);
1276 
1278 
1279  remove_wasted_bits(s);
1280 
1281  frame_bytes = encode_frame(s);
1282 
1283  /* Fall back on verbatim mode if the compressed frame is larger than it
1284  would be if encoded uncompressed. */
1285  if (frame_bytes < 0 || frame_bytes > s->max_framesize) {
1286  s->frame.verbatim_only = 1;
1287  frame_bytes = encode_frame(s);
1288  if (frame_bytes < 0) {
1289  av_log(avctx, AV_LOG_ERROR, "Bad frame count\n");
1290  return frame_bytes;
1291  }
1292  }
1293 
1294  if ((ret = ff_alloc_packet2(avctx, avpkt, frame_bytes)) < 0)
1295  return ret;
1296 
1297  out_bytes = write_frame(s, avpkt);
1298 
1299  s->frame_count++;
1300  s->sample_count += frame->nb_samples;
1301  if ((ret = update_md5_sum(s, frame->data[0])) < 0) {
1302  av_log(avctx, AV_LOG_ERROR, "Error updating MD5 checksum\n");
1303  return ret;
1304  }
1305  if (out_bytes > s->max_encoded_framesize)
1306  s->max_encoded_framesize = out_bytes;
1307  if (out_bytes < s->min_framesize)
1308  s->min_framesize = out_bytes;
1309 
1310  avpkt->pts = frame->pts;
1311  avpkt->duration = ff_samples_to_time_base(avctx, frame->nb_samples);
1312  avpkt->size = out_bytes;
1313 
1314  s->next_pts = avpkt->pts + avpkt->duration;
1315 
1316  *got_packet_ptr = 1;
1317  return 0;
1318 }
1319 
1320 
1322 {
1323  if (avctx->priv_data) {
1324  FlacEncodeContext *s = avctx->priv_data;
1325  av_freep(&s->md5ctx);
1326  av_freep(&s->md5_buffer);
1327  ff_lpc_end(&s->lpc_ctx);
1328  }
1329  av_freep(&avctx->extradata);
1330  avctx->extradata_size = 0;
1331  return 0;
1332 }
1333 
1334 #define FLAGS AV_OPT_FLAG_ENCODING_PARAM | AV_OPT_FLAG_AUDIO_PARAM
1335 static const AVOption options[] = {
1336 { "lpc_coeff_precision", "LPC coefficient precision", offsetof(FlacEncodeContext, options.lpc_coeff_precision), AV_OPT_TYPE_INT, {.i64 = 15 }, 0, MAX_LPC_PRECISION, FLAGS },
1337 { "lpc_type", "LPC algorithm", offsetof(FlacEncodeContext, options.lpc_type), AV_OPT_TYPE_INT, {.i64 = FF_LPC_TYPE_DEFAULT }, FF_LPC_TYPE_DEFAULT, FF_LPC_TYPE_NB-1, FLAGS, "lpc_type" },
1338 { "none", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = FF_LPC_TYPE_NONE }, INT_MIN, INT_MAX, FLAGS, "lpc_type" },
1339 { "fixed", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = FF_LPC_TYPE_FIXED }, INT_MIN, INT_MAX, FLAGS, "lpc_type" },
1340 { "levinson", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = FF_LPC_TYPE_LEVINSON }, INT_MIN, INT_MAX, FLAGS, "lpc_type" },
1341 { "cholesky", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = FF_LPC_TYPE_CHOLESKY }, INT_MIN, INT_MAX, FLAGS, "lpc_type" },
1342 { "lpc_passes", "Number of passes to use for Cholesky factorization during LPC analysis", offsetof(FlacEncodeContext, options.lpc_passes), AV_OPT_TYPE_INT, {.i64 = 2 }, 1, INT_MAX, FLAGS },
1343 { "min_partition_order", NULL, offsetof(FlacEncodeContext, options.min_partition_order), AV_OPT_TYPE_INT, {.i64 = -1 }, -1, MAX_PARTITION_ORDER, FLAGS },
1344 { "max_partition_order", NULL, offsetof(FlacEncodeContext, options.max_partition_order), AV_OPT_TYPE_INT, {.i64 = -1 }, -1, MAX_PARTITION_ORDER, FLAGS },
1345 { "prediction_order_method", "Search method for selecting prediction order", offsetof(FlacEncodeContext, options.prediction_order_method), AV_OPT_TYPE_INT, {.i64 = -1 }, -1, ORDER_METHOD_LOG, FLAGS, "predm" },
1346 { "estimation", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = ORDER_METHOD_EST }, INT_MIN, INT_MAX, FLAGS, "predm" },
1347 { "2level", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = ORDER_METHOD_2LEVEL }, INT_MIN, INT_MAX, FLAGS, "predm" },
1348 { "4level", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = ORDER_METHOD_4LEVEL }, INT_MIN, INT_MAX, FLAGS, "predm" },
1349 { "8level", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = ORDER_METHOD_8LEVEL }, INT_MIN, INT_MAX, FLAGS, "predm" },
1350 { "search", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = ORDER_METHOD_SEARCH }, INT_MIN, INT_MAX, FLAGS, "predm" },
1351 { "log", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = ORDER_METHOD_LOG }, INT_MIN, INT_MAX, FLAGS, "predm" },
1352 { "ch_mode", "Stereo decorrelation mode", offsetof(FlacEncodeContext, options.ch_mode), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, FLAC_CHMODE_MID_SIDE, FLAGS, "ch_mode" },
1353 { "auto", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = -1 }, INT_MIN, INT_MAX, FLAGS, "ch_mode" },
1354 { "indep", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = FLAC_CHMODE_INDEPENDENT }, INT_MIN, INT_MAX, FLAGS, "ch_mode" },
1355 { "left_side", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = FLAC_CHMODE_LEFT_SIDE }, INT_MIN, INT_MAX, FLAGS, "ch_mode" },
1356 { "right_side", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = FLAC_CHMODE_RIGHT_SIDE }, INT_MIN, INT_MAX, FLAGS, "ch_mode" },
1357 { "mid_side", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = FLAC_CHMODE_MID_SIDE }, INT_MIN, INT_MAX, FLAGS, "ch_mode" },
1358 { NULL },
1359 };
1360 
1361 static const AVClass flac_encoder_class = {
1362  "FLAC encoder",
1364  options,
1366 };
1367 
1369  .name = "flac",
1370  .long_name = NULL_IF_CONFIG_SMALL("FLAC (Free Lossless Audio Codec)"),
1371  .type = AVMEDIA_TYPE_AUDIO,
1372  .id = AV_CODEC_ID_FLAC,
1373  .priv_data_size = sizeof(FlacEncodeContext),
1375  .encode2 = flac_encode_frame,
1378  .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16,
1381  .priv_class = &flac_encoder_class,
1382 };