8b730d0b5186b3cc125a2e9e113a9ae301244a4c
[libav.git] / libavcodec / flacdec.c
1 /*
2 * FLAC (Free Lossless Audio Codec) decoder
3 * Copyright (c) 2003 Alex Beregszaszi
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 /**
23 * @file libavcodec/flacdec.c
24 * FLAC (Free Lossless Audio Codec) decoder
25 * @author Alex Beregszaszi
26 *
27 * For more information on the FLAC format, visit:
28 * http://flac.sourceforge.net/
29 *
30 * This decoder can be used in 1 of 2 ways: Either raw FLAC data can be fed
31 * through, starting from the initial 'fLaC' signature; or by passing the
32 * 34-byte streaminfo structure through avctx->extradata[_size] followed
33 * by data starting with the 0xFFF8 marker.
34 */
35
36 #include <limits.h>
37
38 #include "libavutil/crc.h"
39 #include "avcodec.h"
40 #include "internal.h"
41 #include "bitstream.h"
42 #include "bytestream.h"
43 #include "golomb.h"
44 #include "flac.h"
45 #include "flacdata.h"
46
47 #undef NDEBUG
48 #include <assert.h>
49
50 typedef struct FLACContext {
51 FLACSTREAMINFO
52
53 AVCodecContext *avctx; ///< parent AVCodecContext
54 GetBitContext gb; ///< GetBitContext initialized to start at the current frame
55
56 int blocksize; ///< number of samples in the current frame
57 int curr_bps; ///< bps for current subframe, adjusted for channel correlation and wasted bits
58 int sample_shift; ///< shift required to make output samples 16-bit or 32-bit
59 int is32; ///< flag to indicate if output should be 32-bit instead of 16-bit
60 int ch_mode; ///< channel decorrelation type in the current frame
61 int got_streaminfo; ///< indicates if the STREAMINFO has been read
62
63 int32_t *decoded[FLAC_MAX_CHANNELS]; ///< decoded samples
64 uint8_t *bitstream;
65 unsigned int bitstream_size;
66 unsigned int bitstream_index;
67 unsigned int allocated_bitstream_size;
68 } FLACContext;
69
70 static const int sample_size_table[] =
71 { 0, 8, 12, 0, 16, 20, 24, 0 };
72
73 static int64_t get_utf8(GetBitContext *gb)
74 {
75 int64_t val;
76 GET_UTF8(val, get_bits(gb, 8), return -1;)
77 return val;
78 }
79
80 static void allocate_buffers(FLACContext *s);
81
82 int ff_flac_is_extradata_valid(AVCodecContext *avctx,
83 enum FLACExtradataFormat *format,
84 uint8_t **streaminfo_start)
85 {
86 if (!avctx->extradata || avctx->extradata_size < FLAC_STREAMINFO_SIZE) {
87 av_log(avctx, AV_LOG_ERROR, "extradata NULL or too small.\n");
88 return 0;
89 }
90 if (AV_RL32(avctx->extradata) != MKTAG('f','L','a','C')) {
91 /* extradata contains STREAMINFO only */
92 if (avctx->extradata_size != FLAC_STREAMINFO_SIZE) {
93 av_log(avctx, AV_LOG_WARNING, "extradata contains %d bytes too many.\n",
94 FLAC_STREAMINFO_SIZE-avctx->extradata_size);
95 }
96 *format = FLAC_EXTRADATA_FORMAT_STREAMINFO;
97 *streaminfo_start = avctx->extradata;
98 } else {
99 if (avctx->extradata_size < 8+FLAC_STREAMINFO_SIZE) {
100 av_log(avctx, AV_LOG_ERROR, "extradata too small.\n");
101 return 0;
102 }
103 *format = FLAC_EXTRADATA_FORMAT_FULL_HEADER;
104 *streaminfo_start = &avctx->extradata[8];
105 }
106 return 1;
107 }
108
109 static av_cold int flac_decode_init(AVCodecContext *avctx)
110 {
111 enum FLACExtradataFormat format;
112 uint8_t *streaminfo;
113 FLACContext *s = avctx->priv_data;
114 s->avctx = avctx;
115
116 avctx->sample_fmt = SAMPLE_FMT_S16;
117
118 /* for now, the raw FLAC header is allowed to be passed to the decoder as
119 frame data instead of extradata. */
120 if (!avctx->extradata)
121 return 0;
122
123 if (!ff_flac_is_extradata_valid(avctx, &format, &streaminfo))
124 return -1;
125
126 /* initialize based on the demuxer-supplied streamdata header */
127 ff_flac_parse_streaminfo(avctx, (FLACStreaminfo *)s, streaminfo);
128 allocate_buffers(s);
129 s->got_streaminfo = 1;
130
131 return 0;
132 }
133
134 static void dump_headers(AVCodecContext *avctx, FLACStreaminfo *s)
135 {
136 av_log(avctx, AV_LOG_DEBUG, " Max Blocksize: %d\n", s->max_blocksize);
137 av_log(avctx, AV_LOG_DEBUG, " Max Framesize: %d\n", s->max_framesize);
138 av_log(avctx, AV_LOG_DEBUG, " Samplerate: %d\n", s->samplerate);
139 av_log(avctx, AV_LOG_DEBUG, " Channels: %d\n", s->channels);
140 av_log(avctx, AV_LOG_DEBUG, " Bits: %d\n", s->bps);
141 }
142
143 static void allocate_buffers(FLACContext *s)
144 {
145 int i;
146
147 assert(s->max_blocksize);
148
149 if (s->max_framesize == 0 && s->max_blocksize) {
150 s->max_framesize = ff_flac_get_max_frame_size(s->max_blocksize,
151 s->channels, s->bps);
152 }
153
154 for (i = 0; i < s->channels; i++) {
155 s->decoded[i] = av_realloc(s->decoded[i],
156 sizeof(int32_t)*s->max_blocksize);
157 }
158
159 if (s->allocated_bitstream_size < s->max_framesize)
160 s->bitstream= av_fast_realloc(s->bitstream,
161 &s->allocated_bitstream_size,
162 s->max_framesize);
163 }
164
165 void ff_flac_parse_streaminfo(AVCodecContext *avctx, struct FLACStreaminfo *s,
166 const uint8_t *buffer)
167 {
168 GetBitContext gb;
169 init_get_bits(&gb, buffer, FLAC_STREAMINFO_SIZE*8);
170
171 skip_bits(&gb, 16); /* skip min blocksize */
172 s->max_blocksize = get_bits(&gb, 16);
173 if (s->max_blocksize < FLAC_MIN_BLOCKSIZE) {
174 av_log(avctx, AV_LOG_WARNING, "invalid max blocksize: %d\n",
175 s->max_blocksize);
176 s->max_blocksize = 16;
177 }
178
179 skip_bits(&gb, 24); /* skip min frame size */
180 s->max_framesize = get_bits_long(&gb, 24);
181
182 s->samplerate = get_bits_long(&gb, 20);
183 s->channels = get_bits(&gb, 3) + 1;
184 s->bps = get_bits(&gb, 5) + 1;
185
186 avctx->channels = s->channels;
187 avctx->sample_rate = s->samplerate;
188 avctx->bits_per_raw_sample = s->bps;
189 if (s->bps > 16)
190 avctx->sample_fmt = SAMPLE_FMT_S32;
191 else
192 avctx->sample_fmt = SAMPLE_FMT_S16;
193
194 s->samples = get_bits_long(&gb, 32) << 4;
195 s->samples |= get_bits(&gb, 4);
196
197 skip_bits_long(&gb, 64); /* md5 sum */
198 skip_bits_long(&gb, 64); /* md5 sum */
199
200 dump_headers(avctx, s);
201 }
202
203 void ff_flac_parse_block_header(const uint8_t *block_header,
204 int *last, int *type, int *size)
205 {
206 int tmp = bytestream_get_byte(&block_header);
207 if (last)
208 *last = tmp & 0x80;
209 if (type)
210 *type = tmp & 0x7F;
211 if (size)
212 *size = bytestream_get_be24(&block_header);
213 }
214
215 /**
216 * Parse the STREAMINFO from an inline header.
217 * @param s the flac decoding context
218 * @param buf input buffer, starting with the "fLaC" marker
219 * @param buf_size buffer size
220 * @return non-zero if metadata is invalid
221 */
222 static int parse_streaminfo(FLACContext *s, const uint8_t *buf, int buf_size)
223 {
224 int metadata_type, metadata_size;
225
226 if (buf_size < FLAC_STREAMINFO_SIZE+8) {
227 /* need more data */
228 return 0;
229 }
230 ff_flac_parse_block_header(&buf[4], NULL, &metadata_type, &metadata_size);
231 if (metadata_type != FLAC_METADATA_TYPE_STREAMINFO ||
232 metadata_size != FLAC_STREAMINFO_SIZE) {
233 return AVERROR_INVALIDDATA;
234 }
235 ff_flac_parse_streaminfo(s->avctx, (FLACStreaminfo *)s, &buf[8]);
236 allocate_buffers(s);
237 s->got_streaminfo = 1;
238
239 return 0;
240 }
241
242 /**
243 * Determine the size of an inline header.
244 * @param buf input buffer, starting with the "fLaC" marker
245 * @param buf_size buffer size
246 * @return number of bytes in the header, or 0 if more data is needed
247 */
248 static int get_metadata_size(const uint8_t *buf, int buf_size)
249 {
250 int metadata_last, metadata_size;
251 const uint8_t *buf_end = buf + buf_size;
252
253 buf += 4;
254 do {
255 ff_flac_parse_block_header(buf, &metadata_last, NULL, &metadata_size);
256 buf += 4;
257 if (buf + metadata_size > buf_end) {
258 /* need more data in order to read the complete header */
259 return 0;
260 }
261 buf += metadata_size;
262 } while (!metadata_last);
263
264 return buf_size - (buf_end - buf);
265 }
266
267 static int decode_residuals(FLACContext *s, int channel, int pred_order)
268 {
269 int i, tmp, partition, method_type, rice_order;
270 int sample = 0, samples;
271
272 method_type = get_bits(&s->gb, 2);
273 if (method_type > 1) {
274 av_log(s->avctx, AV_LOG_ERROR, "illegal residual coding method %d\n",
275 method_type);
276 return -1;
277 }
278
279 rice_order = get_bits(&s->gb, 4);
280
281 samples= s->blocksize >> rice_order;
282 if (pred_order > samples) {
283 av_log(s->avctx, AV_LOG_ERROR, "invalid predictor order: %i > %i\n",
284 pred_order, samples);
285 return -1;
286 }
287
288 sample=
289 i= pred_order;
290 for (partition = 0; partition < (1 << rice_order); partition++) {
291 tmp = get_bits(&s->gb, method_type == 0 ? 4 : 5);
292 if (tmp == (method_type == 0 ? 15 : 31)) {
293 tmp = get_bits(&s->gb, 5);
294 for (; i < samples; i++, sample++)
295 s->decoded[channel][sample] = get_sbits_long(&s->gb, tmp);
296 } else {
297 for (; i < samples; i++, sample++) {
298 s->decoded[channel][sample] = get_sr_golomb_flac(&s->gb, tmp, INT_MAX, 0);
299 }
300 }
301 i= 0;
302 }
303
304 return 0;
305 }
306
307 static int decode_subframe_fixed(FLACContext *s, int channel, int pred_order)
308 {
309 const int blocksize = s->blocksize;
310 int32_t *decoded = s->decoded[channel];
311 int av_uninit(a), av_uninit(b), av_uninit(c), av_uninit(d), i;
312
313 /* warm up samples */
314 for (i = 0; i < pred_order; i++) {
315 decoded[i] = get_sbits_long(&s->gb, s->curr_bps);
316 }
317
318 if (decode_residuals(s, channel, pred_order) < 0)
319 return -1;
320
321 if (pred_order > 0)
322 a = decoded[pred_order-1];
323 if (pred_order > 1)
324 b = a - decoded[pred_order-2];
325 if (pred_order > 2)
326 c = b - decoded[pred_order-2] + decoded[pred_order-3];
327 if (pred_order > 3)
328 d = c - decoded[pred_order-2] + 2*decoded[pred_order-3] - decoded[pred_order-4];
329
330 switch (pred_order) {
331 case 0:
332 break;
333 case 1:
334 for (i = pred_order; i < blocksize; i++)
335 decoded[i] = a += decoded[i];
336 break;
337 case 2:
338 for (i = pred_order; i < blocksize; i++)
339 decoded[i] = a += b += decoded[i];
340 break;
341 case 3:
342 for (i = pred_order; i < blocksize; i++)
343 decoded[i] = a += b += c += decoded[i];
344 break;
345 case 4:
346 for (i = pred_order; i < blocksize; i++)
347 decoded[i] = a += b += c += d += decoded[i];
348 break;
349 default:
350 av_log(s->avctx, AV_LOG_ERROR, "illegal pred order %d\n", pred_order);
351 return -1;
352 }
353
354 return 0;
355 }
356
357 static int decode_subframe_lpc(FLACContext *s, int channel, int pred_order)
358 {
359 int i, j;
360 int coeff_prec, qlevel;
361 int coeffs[pred_order];
362 int32_t *decoded = s->decoded[channel];
363
364 /* warm up samples */
365 for (i = 0; i < pred_order; i++) {
366 decoded[i] = get_sbits_long(&s->gb, s->curr_bps);
367 }
368
369 coeff_prec = get_bits(&s->gb, 4) + 1;
370 if (coeff_prec == 16) {
371 av_log(s->avctx, AV_LOG_ERROR, "invalid coeff precision\n");
372 return -1;
373 }
374 qlevel = get_sbits(&s->gb, 5);
375 if (qlevel < 0) {
376 av_log(s->avctx, AV_LOG_ERROR, "qlevel %d not supported, maybe buggy stream\n",
377 qlevel);
378 return -1;
379 }
380
381 for (i = 0; i < pred_order; i++) {
382 coeffs[i] = get_sbits(&s->gb, coeff_prec);
383 }
384
385 if (decode_residuals(s, channel, pred_order) < 0)
386 return -1;
387
388 if (s->bps > 16) {
389 int64_t sum;
390 for (i = pred_order; i < s->blocksize; i++) {
391 sum = 0;
392 for (j = 0; j < pred_order; j++)
393 sum += (int64_t)coeffs[j] * decoded[i-j-1];
394 decoded[i] += sum >> qlevel;
395 }
396 } else {
397 for (i = pred_order; i < s->blocksize-1; i += 2) {
398 int c;
399 int d = decoded[i-pred_order];
400 int s0 = 0, s1 = 0;
401 for (j = pred_order-1; j > 0; j--) {
402 c = coeffs[j];
403 s0 += c*d;
404 d = decoded[i-j];
405 s1 += c*d;
406 }
407 c = coeffs[0];
408 s0 += c*d;
409 d = decoded[i] += s0 >> qlevel;
410 s1 += c*d;
411 decoded[i+1] += s1 >> qlevel;
412 }
413 if (i < s->blocksize) {
414 int sum = 0;
415 for (j = 0; j < pred_order; j++)
416 sum += coeffs[j] * decoded[i-j-1];
417 decoded[i] += sum >> qlevel;
418 }
419 }
420
421 return 0;
422 }
423
424 static inline int decode_subframe(FLACContext *s, int channel)
425 {
426 int type, wasted = 0;
427 int i, tmp;
428
429 s->curr_bps = s->bps;
430 if (channel == 0) {
431 if (s->ch_mode == FLAC_CHMODE_RIGHT_SIDE)
432 s->curr_bps++;
433 } else {
434 if (s->ch_mode == FLAC_CHMODE_LEFT_SIDE || s->ch_mode == FLAC_CHMODE_MID_SIDE)
435 s->curr_bps++;
436 }
437
438 if (get_bits1(&s->gb)) {
439 av_log(s->avctx, AV_LOG_ERROR, "invalid subframe padding\n");
440 return -1;
441 }
442 type = get_bits(&s->gb, 6);
443
444 if (get_bits1(&s->gb)) {
445 wasted = 1;
446 while (!get_bits1(&s->gb))
447 wasted++;
448 s->curr_bps -= wasted;
449 }
450 if (s->curr_bps > 32) {
451 ff_log_missing_feature(s->avctx, "decorrelated bit depth > 32", 0);
452 return -1;
453 }
454
455 //FIXME use av_log2 for types
456 if (type == 0) {
457 tmp = get_sbits_long(&s->gb, s->curr_bps);
458 for (i = 0; i < s->blocksize; i++)
459 s->decoded[channel][i] = tmp;
460 } else if (type == 1) {
461 for (i = 0; i < s->blocksize; i++)
462 s->decoded[channel][i] = get_sbits_long(&s->gb, s->curr_bps);
463 } else if ((type >= 8) && (type <= 12)) {
464 if (decode_subframe_fixed(s, channel, type & ~0x8) < 0)
465 return -1;
466 } else if (type >= 32) {
467 if (decode_subframe_lpc(s, channel, (type & ~0x20)+1) < 0)
468 return -1;
469 } else {
470 av_log(s->avctx, AV_LOG_ERROR, "invalid coding type\n");
471 return -1;
472 }
473
474 if (wasted) {
475 int i;
476 for (i = 0; i < s->blocksize; i++)
477 s->decoded[channel][i] <<= wasted;
478 }
479
480 return 0;
481 }
482
483 static int decode_frame(FLACContext *s)
484 {
485 int bs_code, sr_code, bps_code, i;
486 int ch_mode, bps, blocksize, samplerate, channels;
487 GetBitContext *gb = &s->gb;
488
489 /* frame sync code */
490 skip_bits(&s->gb, 16);
491
492 /* block size and sample rate codes */
493 bs_code = get_bits(gb, 4);
494 sr_code = get_bits(gb, 4);
495
496 /* channels and decorrelation */
497 ch_mode = get_bits(gb, 4);
498 if (ch_mode < FLAC_MAX_CHANNELS) {
499 channels = ch_mode + 1;
500 ch_mode = FLAC_CHMODE_INDEPENDENT;
501 } else if (ch_mode <= FLAC_CHMODE_MID_SIDE) {
502 channels = 2;
503 } else {
504 av_log(s->avctx, AV_LOG_ERROR, "invalid channel mode: %d\n", ch_mode);
505 return -1;
506 }
507
508 /* bits per sample */
509 bps_code = get_bits(gb, 3);
510 if (bps_code == 3 || bps_code == 7) {
511 av_log(s->avctx, AV_LOG_ERROR, "invalid sample size code (%d)\n",
512 bps_code);
513 return -1;
514 }
515 bps = sample_size_table[bps_code];
516
517 /* reserved bit */
518 if (get_bits1(gb)) {
519 av_log(s->avctx, AV_LOG_ERROR, "broken stream, invalid padding\n");
520 return -1;
521 }
522
523 /* sample or frame count */
524 if (get_utf8(gb) < 0) {
525 av_log(s->avctx, AV_LOG_ERROR, "utf8 fscked\n");
526 return -1;
527 }
528
529 /* blocksize */
530 if (bs_code == 0) {
531 av_log(s->avctx, AV_LOG_ERROR, "reserved blocksize code: 0\n");
532 return -1;
533 } else if (bs_code == 6) {
534 blocksize = get_bits(gb, 8) + 1;
535 } else if (bs_code == 7) {
536 blocksize = get_bits(gb, 16) + 1;
537 } else {
538 blocksize = ff_flac_blocksize_table[bs_code];
539 }
540
541 /* sample rate */
542 if (sr_code < 12) {
543 samplerate = ff_flac_sample_rate_table[sr_code];
544 } else if (sr_code == 12) {
545 samplerate = get_bits(gb, 8) * 1000;
546 } else if (sr_code == 13) {
547 samplerate = get_bits(gb, 16);
548 } else if (sr_code == 14) {
549 samplerate = get_bits(gb, 16) * 10;
550 } else {
551 av_log(s->avctx, AV_LOG_ERROR, "illegal sample rate code %d\n",
552 sr_code);
553 return -1;
554 }
555
556 /* header CRC-8 check */
557 skip_bits(gb, 8);
558 if (av_crc(av_crc_get_table(AV_CRC_8_ATM), 0, gb->buffer,
559 get_bits_count(gb)/8)) {
560 av_log(s->avctx, AV_LOG_ERROR, "header crc mismatch\n");
561 return -1;
562 }
563
564 if (channels != s->channels) {
565 av_log(s->avctx, AV_LOG_ERROR, "switching channel layout mid-stream "
566 "is not supported\n");
567 return -1;
568 }
569 s->ch_mode = ch_mode;
570
571 if (bps && bps != s->bps) {
572 av_log(s->avctx, AV_LOG_ERROR, "switching bps mid-stream is not "
573 "supported\n");
574 return -1;
575 }
576 if (s->bps > 16) {
577 s->avctx->sample_fmt = SAMPLE_FMT_S32;
578 s->sample_shift = 32 - s->bps;
579 s->is32 = 1;
580 } else {
581 s->avctx->sample_fmt = SAMPLE_FMT_S16;
582 s->sample_shift = 16 - s->bps;
583 s->is32 = 0;
584 }
585
586 if (blocksize > s->max_blocksize) {
587 av_log(s->avctx, AV_LOG_ERROR, "blocksize %d > %d\n", blocksize,
588 s->max_blocksize);
589 return -1;
590 }
591 s->blocksize = blocksize;
592
593 if (samplerate == 0) {
594 samplerate = s->samplerate;
595 } else if (samplerate != s->samplerate) {
596 av_log(s->avctx, AV_LOG_WARNING, "sample rate changed from %d to %d\n",
597 s->samplerate, samplerate);
598 }
599 s->samplerate = s->avctx->sample_rate = samplerate;
600
601 // dump_headers(s->avctx, (FLACStreaminfo *)s);
602
603 /* subframes */
604 for (i = 0; i < s->channels; i++) {
605 if (decode_subframe(s, i) < 0)
606 return -1;
607 }
608
609 align_get_bits(gb);
610
611 /* frame footer */
612 skip_bits(gb, 16); /* data crc */
613
614 return 0;
615 }
616
617 static int flac_decode_frame(AVCodecContext *avctx,
618 void *data, int *data_size,
619 const uint8_t *buf, int buf_size)
620 {
621 FLACContext *s = avctx->priv_data;
622 int i, j = 0, input_buf_size = 0, bytes_read = 0;
623 int16_t *samples_16 = data;
624 int32_t *samples_32 = data;
625 int alloc_data_size= *data_size;
626 int output_size;
627
628 *data_size=0;
629
630 if (s->max_framesize == 0) {
631 s->max_framesize= FFMAX(4, buf_size); // should hopefully be enough for the first header
632 s->bitstream= av_fast_realloc(s->bitstream, &s->allocated_bitstream_size, s->max_framesize);
633 }
634
635 if (1 && s->max_framesize) { //FIXME truncated
636 if (s->bitstream_size < 4 || AV_RL32(s->bitstream) != MKTAG('f','L','a','C'))
637 buf_size= FFMIN(buf_size, s->max_framesize - FFMIN(s->bitstream_size, s->max_framesize));
638 input_buf_size= buf_size;
639
640 if (s->bitstream_size + buf_size < buf_size || s->bitstream_index + s->bitstream_size + buf_size < s->bitstream_index)
641 return -1;
642
643 if (s->allocated_bitstream_size < s->bitstream_size + buf_size)
644 s->bitstream= av_fast_realloc(s->bitstream, &s->allocated_bitstream_size, s->bitstream_size + buf_size);
645
646 if (s->bitstream_index + s->bitstream_size + buf_size > s->allocated_bitstream_size) {
647 memmove(s->bitstream, &s->bitstream[s->bitstream_index],
648 s->bitstream_size);
649 s->bitstream_index=0;
650 }
651 memcpy(&s->bitstream[s->bitstream_index + s->bitstream_size],
652 buf, buf_size);
653 buf= &s->bitstream[s->bitstream_index];
654 buf_size += s->bitstream_size;
655 s->bitstream_size= buf_size;
656
657 if (buf_size < s->max_framesize && input_buf_size) {
658 return input_buf_size;
659 }
660 }
661
662 /* check that there is at least the smallest decodable amount of data.
663 this amount corresponds to the smallest valid FLAC frame possible.
664 FF F8 69 02 00 00 9A 00 00 34 46 */
665 if (buf_size < 11)
666 goto end;
667
668 /* check for inline header */
669 if (AV_RB32(buf) == MKBETAG('f','L','a','C')) {
670 if (!s->got_streaminfo && parse_streaminfo(s, buf, buf_size)) {
671 av_log(s->avctx, AV_LOG_ERROR, "invalid header\n");
672 return -1;
673 }
674 bytes_read = get_metadata_size(buf, buf_size);
675 goto end;
676 }
677
678 /* check for frame sync code and resync stream if necessary */
679 if ((AV_RB16(buf) & 0xFFFE) != 0xFFF8) {
680 const uint8_t *buf_end = buf + buf_size;
681 av_log(s->avctx, AV_LOG_ERROR, "FRAME HEADER not here\n");
682 while (buf+2 < buf_end && (AV_RB16(buf) & 0xFFFE) != 0xFFF8)
683 buf++;
684 bytes_read = buf_size - (buf_end - buf);
685 goto end; // we may not have enough bits left to decode a frame, so try next time
686 }
687
688 /* decode frame */
689 init_get_bits(&s->gb, buf, buf_size*8);
690 if (decode_frame(s) < 0) {
691 av_log(s->avctx, AV_LOG_ERROR, "decode_frame() failed\n");
692 s->bitstream_size=0;
693 s->bitstream_index=0;
694 return -1;
695 }
696 bytes_read = (get_bits_count(&s->gb)+7)/8;
697
698 /* check if allocated data size is large enough for output */
699 output_size = s->blocksize * s->channels * (s->is32 ? 4 : 2);
700 if (output_size > alloc_data_size) {
701 av_log(s->avctx, AV_LOG_ERROR, "output data size is larger than "
702 "allocated data size\n");
703 goto end;
704 }
705 *data_size = output_size;
706
707 #define DECORRELATE(left, right)\
708 assert(s->channels == 2);\
709 for (i = 0; i < s->blocksize; i++) {\
710 int a= s->decoded[0][i];\
711 int b= s->decoded[1][i];\
712 if (s->is32) {\
713 *samples_32++ = (left) << s->sample_shift;\
714 *samples_32++ = (right) << s->sample_shift;\
715 } else {\
716 *samples_16++ = (left) << s->sample_shift;\
717 *samples_16++ = (right) << s->sample_shift;\
718 }\
719 }\
720 break;
721
722 switch (s->ch_mode) {
723 case FLAC_CHMODE_INDEPENDENT:
724 for (j = 0; j < s->blocksize; j++) {
725 for (i = 0; i < s->channels; i++) {
726 if (s->is32)
727 *samples_32++ = s->decoded[i][j] << s->sample_shift;
728 else
729 *samples_16++ = s->decoded[i][j] << s->sample_shift;
730 }
731 }
732 break;
733 case FLAC_CHMODE_LEFT_SIDE:
734 DECORRELATE(a,a-b)
735 case FLAC_CHMODE_RIGHT_SIDE:
736 DECORRELATE(a+b,b)
737 case FLAC_CHMODE_MID_SIDE:
738 DECORRELATE( (a-=b>>1) + b, a)
739 }
740
741 end:
742 if (bytes_read > buf_size) {
743 av_log(s->avctx, AV_LOG_ERROR, "overread: %d\n", bytes_read - buf_size);
744 s->bitstream_size=0;
745 s->bitstream_index=0;
746 return -1;
747 }
748
749 if (s->bitstream_size) {
750 s->bitstream_index += bytes_read;
751 s->bitstream_size -= bytes_read;
752 return input_buf_size;
753 } else
754 return bytes_read;
755 }
756
757 static av_cold int flac_decode_close(AVCodecContext *avctx)
758 {
759 FLACContext *s = avctx->priv_data;
760 int i;
761
762 for (i = 0; i < s->channels; i++) {
763 av_freep(&s->decoded[i]);
764 }
765 av_freep(&s->bitstream);
766
767 return 0;
768 }
769
770 static void flac_flush(AVCodecContext *avctx)
771 {
772 FLACContext *s = avctx->priv_data;
773
774 s->bitstream_size=
775 s->bitstream_index= 0;
776 }
777
778 AVCodec flac_decoder = {
779 "flac",
780 CODEC_TYPE_AUDIO,
781 CODEC_ID_FLAC,
782 sizeof(FLACContext),
783 flac_decode_init,
784 NULL,
785 flac_decode_close,
786 flac_decode_frame,
787 CODEC_CAP_DELAY,
788 .flush= flac_flush,
789 .long_name= NULL_IF_CONFIG_SMALL("FLAC (Free Lossless Audio Codec)"),
790 };