8dbe8c91b472ae302e06cabbf3cf007c9fe37c3f
[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, int alloc_data_size)
484 {
485 int blocksize_code, sample_rate_code, sample_size_code, i, crc8;
486 int ch_mode, bps, blocksize, samplerate;
487
488 blocksize_code = get_bits(&s->gb, 4);
489
490 sample_rate_code = get_bits(&s->gb, 4);
491
492 ch_mode = get_bits(&s->gb, 4); /* channel assignment */
493 if (ch_mode < FLAC_MAX_CHANNELS && s->channels == ch_mode+1) {
494 ch_mode = FLAC_CHMODE_INDEPENDENT;
495 } else if (ch_mode > FLAC_CHMODE_MID_SIDE || s->channels != 2) {
496 av_log(s->avctx, AV_LOG_ERROR, "unsupported channel assignment %d (channels=%d)\n",
497 ch_mode, s->channels);
498 return -1;
499 }
500
501 sample_size_code = get_bits(&s->gb, 3);
502 if (sample_size_code == 0)
503 bps= s->bps;
504 else if ((sample_size_code != 3) && (sample_size_code != 7))
505 bps = sample_size_table[sample_size_code];
506 else {
507 av_log(s->avctx, AV_LOG_ERROR, "invalid sample size code (%d)\n",
508 sample_size_code);
509 return -1;
510 }
511 if (bps > 16) {
512 s->avctx->sample_fmt = SAMPLE_FMT_S32;
513 s->sample_shift = 32 - bps;
514 s->is32 = 1;
515 } else {
516 s->avctx->sample_fmt = SAMPLE_FMT_S16;
517 s->sample_shift = 16 - bps;
518 s->is32 = 0;
519 }
520 s->bps = s->avctx->bits_per_raw_sample = bps;
521
522 if (get_bits1(&s->gb)) {
523 av_log(s->avctx, AV_LOG_ERROR, "broken stream, invalid padding\n");
524 return -1;
525 }
526
527 if (get_utf8(&s->gb) < 0) {
528 av_log(s->avctx, AV_LOG_ERROR, "utf8 fscked\n");
529 return -1;
530 }
531
532 if (blocksize_code == 0) {
533 av_log(s->avctx, AV_LOG_ERROR, "reserved blocksize code: 0\n");
534 return -1;
535 } else if (blocksize_code == 6)
536 blocksize = get_bits(&s->gb, 8)+1;
537 else if (blocksize_code == 7)
538 blocksize = get_bits(&s->gb, 16)+1;
539 else
540 blocksize = ff_flac_blocksize_table[blocksize_code];
541
542 if (blocksize > s->max_blocksize) {
543 av_log(s->avctx, AV_LOG_ERROR, "blocksize %d > %d\n", blocksize,
544 s->max_blocksize);
545 return -1;
546 }
547
548 if (blocksize * s->channels * (s->is32 ? 4 : 2) > alloc_data_size)
549 return -1;
550
551 if (sample_rate_code == 0)
552 samplerate= s->samplerate;
553 else if (sample_rate_code < 12)
554 samplerate = ff_flac_sample_rate_table[sample_rate_code];
555 else if (sample_rate_code == 12)
556 samplerate = get_bits(&s->gb, 8) * 1000;
557 else if (sample_rate_code == 13)
558 samplerate = get_bits(&s->gb, 16);
559 else if (sample_rate_code == 14)
560 samplerate = get_bits(&s->gb, 16) * 10;
561 else {
562 av_log(s->avctx, AV_LOG_ERROR, "illegal sample rate code %d\n",
563 sample_rate_code);
564 return -1;
565 }
566
567 skip_bits(&s->gb, 8);
568 crc8 = av_crc(av_crc_get_table(AV_CRC_8_ATM), 0,
569 s->gb.buffer, get_bits_count(&s->gb)/8);
570 if (crc8) {
571 av_log(s->avctx, AV_LOG_ERROR, "header crc mismatch crc=%2X\n", crc8);
572 return -1;
573 }
574
575 s->blocksize = blocksize;
576 s->samplerate = samplerate;
577 s->bps = bps;
578 s->ch_mode = ch_mode;
579
580 // dump_headers(s->avctx, (FLACStreaminfo *)s);
581
582 /* subframes */
583 for (i = 0; i < s->channels; i++) {
584 if (decode_subframe(s, i) < 0)
585 return -1;
586 }
587
588 align_get_bits(&s->gb);
589
590 /* frame footer */
591 skip_bits(&s->gb, 16); /* data crc */
592
593 return 0;
594 }
595
596 static int flac_decode_frame(AVCodecContext *avctx,
597 void *data, int *data_size,
598 const uint8_t *buf, int buf_size)
599 {
600 FLACContext *s = avctx->priv_data;
601 int i, j = 0, input_buf_size = 0, bytes_read = 0;
602 int16_t *samples_16 = data;
603 int32_t *samples_32 = data;
604 int alloc_data_size= *data_size;
605
606 *data_size=0;
607
608 if (s->max_framesize == 0) {
609 s->max_framesize= FFMAX(4, buf_size); // should hopefully be enough for the first header
610 s->bitstream= av_fast_realloc(s->bitstream, &s->allocated_bitstream_size, s->max_framesize);
611 }
612
613 if (1 && s->max_framesize) { //FIXME truncated
614 if (s->bitstream_size < 4 || AV_RL32(s->bitstream) != MKTAG('f','L','a','C'))
615 buf_size= FFMIN(buf_size, s->max_framesize - FFMIN(s->bitstream_size, s->max_framesize));
616 input_buf_size= buf_size;
617
618 if (s->bitstream_size + buf_size < buf_size || s->bitstream_index + s->bitstream_size + buf_size < s->bitstream_index)
619 return -1;
620
621 if (s->allocated_bitstream_size < s->bitstream_size + buf_size)
622 s->bitstream= av_fast_realloc(s->bitstream, &s->allocated_bitstream_size, s->bitstream_size + buf_size);
623
624 if (s->bitstream_index + s->bitstream_size + buf_size > s->allocated_bitstream_size) {
625 memmove(s->bitstream, &s->bitstream[s->bitstream_index],
626 s->bitstream_size);
627 s->bitstream_index=0;
628 }
629 memcpy(&s->bitstream[s->bitstream_index + s->bitstream_size],
630 buf, buf_size);
631 buf= &s->bitstream[s->bitstream_index];
632 buf_size += s->bitstream_size;
633 s->bitstream_size= buf_size;
634
635 if (buf_size < s->max_framesize && input_buf_size) {
636 return input_buf_size;
637 }
638 }
639
640 /* check that there is at least the smallest decodable amount of data.
641 this amount corresponds to the smallest valid FLAC frame possible.
642 FF F8 69 02 00 00 9A 00 00 34 46 */
643 if (buf_size < 11)
644 goto end;
645
646 /* check for inline header */
647 if (AV_RB32(buf) == MKBETAG('f','L','a','C')) {
648 if (!s->got_streaminfo && parse_streaminfo(s, buf, buf_size)) {
649 av_log(s->avctx, AV_LOG_ERROR, "invalid header\n");
650 return -1;
651 }
652 bytes_read = get_metadata_size(buf, buf_size);
653 goto end;
654 }
655
656 /* check for frame sync code and resync stream if necessary */
657 if ((AV_RB16(buf) & 0xFFFE) != 0xFFF8) {
658 const uint8_t *buf_end = buf + buf_size;
659 av_log(s->avctx, AV_LOG_ERROR, "FRAME HEADER not here\n");
660 while (buf+2 < buf_end && (AV_RB16(buf) & 0xFFFE) != 0xFFF8)
661 buf++;
662 bytes_read = buf_size - (buf_end - buf);
663 goto end; // we may not have enough bits left to decode a frame, so try next time
664 }
665
666 /* decode frame */
667 init_get_bits(&s->gb, buf, buf_size*8);
668 skip_bits(&s->gb, 16);
669 if (decode_frame(s, alloc_data_size) < 0) {
670 av_log(s->avctx, AV_LOG_ERROR, "decode_frame() failed\n");
671 s->bitstream_size=0;
672 s->bitstream_index=0;
673 return -1;
674 }
675 *data_size = s->blocksize * s->channels * (s->is32 ? 4 : 2);
676 bytes_read = (get_bits_count(&s->gb)+7)/8;
677
678 #define DECORRELATE(left, right)\
679 assert(s->channels == 2);\
680 for (i = 0; i < s->blocksize; i++) {\
681 int a= s->decoded[0][i];\
682 int b= s->decoded[1][i];\
683 if (s->is32) {\
684 *samples_32++ = (left) << s->sample_shift;\
685 *samples_32++ = (right) << s->sample_shift;\
686 } else {\
687 *samples_16++ = (left) << s->sample_shift;\
688 *samples_16++ = (right) << s->sample_shift;\
689 }\
690 }\
691 break;
692
693 switch (s->ch_mode) {
694 case FLAC_CHMODE_INDEPENDENT:
695 for (j = 0; j < s->blocksize; j++) {
696 for (i = 0; i < s->channels; i++) {
697 if (s->is32)
698 *samples_32++ = s->decoded[i][j] << s->sample_shift;
699 else
700 *samples_16++ = s->decoded[i][j] << s->sample_shift;
701 }
702 }
703 break;
704 case FLAC_CHMODE_LEFT_SIDE:
705 DECORRELATE(a,a-b)
706 case FLAC_CHMODE_RIGHT_SIDE:
707 DECORRELATE(a+b,b)
708 case FLAC_CHMODE_MID_SIDE:
709 DECORRELATE( (a-=b>>1) + b, a)
710 }
711
712 end:
713 if (bytes_read > buf_size) {
714 av_log(s->avctx, AV_LOG_ERROR, "overread: %d\n", bytes_read - buf_size);
715 s->bitstream_size=0;
716 s->bitstream_index=0;
717 return -1;
718 }
719
720 if (s->bitstream_size) {
721 s->bitstream_index += bytes_read;
722 s->bitstream_size -= bytes_read;
723 return input_buf_size;
724 } else
725 return bytes_read;
726 }
727
728 static av_cold int flac_decode_close(AVCodecContext *avctx)
729 {
730 FLACContext *s = avctx->priv_data;
731 int i;
732
733 for (i = 0; i < s->channels; i++) {
734 av_freep(&s->decoded[i]);
735 }
736 av_freep(&s->bitstream);
737
738 return 0;
739 }
740
741 static void flac_flush(AVCodecContext *avctx)
742 {
743 FLACContext *s = avctx->priv_data;
744
745 s->bitstream_size=
746 s->bitstream_index= 0;
747 }
748
749 AVCodec flac_decoder = {
750 "flac",
751 CODEC_TYPE_AUDIO,
752 CODEC_ID_FLAC,
753 sizeof(FLACContext),
754 flac_decode_init,
755 NULL,
756 flac_decode_close,
757 flac_decode_frame,
758 CODEC_CAP_DELAY,
759 .flush= flac_flush,
760 .long_name= NULL_IF_CONFIG_SMALL("FLAC (Free Lossless Audio Codec)"),
761 };