flacdec: When there is not enough data to read the next header block,
[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 "golomb.h"
43 #include "flac.h"
44
45 #undef NDEBUG
46 #include <assert.h>
47
48 #define MAX_CHANNELS 8
49 #define MAX_BLOCKSIZE 65535
50
51 enum decorrelation_type {
52 INDEPENDENT,
53 LEFT_SIDE,
54 RIGHT_SIDE,
55 MID_SIDE,
56 };
57
58 typedef struct FLACContext {
59 FLACSTREAMINFO
60
61 AVCodecContext *avctx; ///< parent AVCodecContext
62 GetBitContext gb; ///< GetBitContext initialized to start at the current frame
63
64 int blocksize; ///< number of samples in the current frame
65 int curr_bps; ///< bps for current subframe, adjusted for channel correlation and wasted bits
66 int sample_shift; ///< shift required to make output samples 16-bit or 32-bit
67 int is32; ///< flag to indicate if output should be 32-bit instead of 16-bit
68 enum decorrelation_type decorrelation; ///< channel decorrelation type in the current frame
69 int got_streaminfo; ///< indicates if the STREAMINFO has been read
70
71 int32_t *decoded[MAX_CHANNELS]; ///< decoded samples
72 uint8_t *bitstream;
73 unsigned int bitstream_size;
74 unsigned int bitstream_index;
75 unsigned int allocated_bitstream_size;
76 } FLACContext;
77
78 static const int sample_rate_table[] =
79 { 0,
80 88200, 176400, 192000,
81 8000, 16000, 22050, 24000, 32000, 44100, 48000, 96000,
82 0, 0, 0, 0 };
83
84 static const int sample_size_table[] =
85 { 0, 8, 12, 0, 16, 20, 24, 0 };
86
87 static const int blocksize_table[] = {
88 0, 192, 576<<0, 576<<1, 576<<2, 576<<3, 0, 0,
89 256<<0, 256<<1, 256<<2, 256<<3, 256<<4, 256<<5, 256<<6, 256<<7
90 };
91
92 static int64_t get_utf8(GetBitContext *gb)
93 {
94 int64_t val;
95 GET_UTF8(val, get_bits(gb, 8), return -1;)
96 return val;
97 }
98
99 static void allocate_buffers(FLACContext *s);
100
101 int ff_flac_is_extradata_valid(AVCodecContext *avctx,
102 enum FLACExtradataFormat *format,
103 uint8_t **streaminfo_start)
104 {
105 if (!avctx->extradata || avctx->extradata_size < FLAC_STREAMINFO_SIZE) {
106 av_log(avctx, AV_LOG_ERROR, "extradata NULL or too small.\n");
107 return 0;
108 }
109 if (AV_RL32(avctx->extradata) != MKTAG('f','L','a','C')) {
110 /* extradata contains STREAMINFO only */
111 if (avctx->extradata_size != FLAC_STREAMINFO_SIZE) {
112 av_log(avctx, AV_LOG_WARNING, "extradata contains %d bytes too many.\n",
113 FLAC_STREAMINFO_SIZE-avctx->extradata_size);
114 }
115 *format = FLAC_EXTRADATA_FORMAT_STREAMINFO;
116 *streaminfo_start = avctx->extradata;
117 } else {
118 if (avctx->extradata_size < 8+FLAC_STREAMINFO_SIZE) {
119 av_log(avctx, AV_LOG_ERROR, "extradata too small.\n");
120 return 0;
121 }
122 *format = FLAC_EXTRADATA_FORMAT_FULL_HEADER;
123 *streaminfo_start = &avctx->extradata[8];
124 }
125 return 1;
126 }
127
128 static av_cold int flac_decode_init(AVCodecContext *avctx)
129 {
130 enum FLACExtradataFormat format;
131 uint8_t *streaminfo;
132 FLACContext *s = avctx->priv_data;
133 s->avctx = avctx;
134
135 avctx->sample_fmt = SAMPLE_FMT_S16;
136
137 /* for now, the raw FLAC header is allowed to be passed to the decoder as
138 frame data instead of extradata. */
139 if (!avctx->extradata)
140 return 0;
141
142 if (!ff_flac_is_extradata_valid(avctx, &format, &streaminfo))
143 return -1;
144
145 /* initialize based on the demuxer-supplied streamdata header */
146 ff_flac_parse_streaminfo(avctx, (FLACStreaminfo *)s, streaminfo);
147 allocate_buffers(s);
148 s->got_streaminfo = 1;
149
150 return 0;
151 }
152
153 static void dump_headers(AVCodecContext *avctx, FLACStreaminfo *s)
154 {
155 av_log(avctx, AV_LOG_DEBUG, " Max Blocksize: %d\n", s->max_blocksize);
156 av_log(avctx, AV_LOG_DEBUG, " Max Framesize: %d\n", s->max_framesize);
157 av_log(avctx, AV_LOG_DEBUG, " Samplerate: %d\n", s->samplerate);
158 av_log(avctx, AV_LOG_DEBUG, " Channels: %d\n", s->channels);
159 av_log(avctx, AV_LOG_DEBUG, " Bits: %d\n", s->bps);
160 }
161
162 static void allocate_buffers(FLACContext *s)
163 {
164 int i;
165
166 assert(s->max_blocksize);
167
168 if (s->max_framesize == 0 && s->max_blocksize) {
169 // FIXME header overhead
170 s->max_framesize= (s->channels * s->bps * s->max_blocksize + 7)/ 8;
171 }
172
173 for (i = 0; i < s->channels; i++) {
174 s->decoded[i] = av_realloc(s->decoded[i],
175 sizeof(int32_t)*s->max_blocksize);
176 }
177
178 if (s->allocated_bitstream_size < s->max_framesize)
179 s->bitstream= av_fast_realloc(s->bitstream,
180 &s->allocated_bitstream_size,
181 s->max_framesize);
182 }
183
184 void ff_flac_parse_streaminfo(AVCodecContext *avctx, struct FLACStreaminfo *s,
185 const uint8_t *buffer)
186 {
187 GetBitContext gb;
188 init_get_bits(&gb, buffer, FLAC_STREAMINFO_SIZE*8);
189
190 skip_bits(&gb, 16); /* skip min blocksize */
191 s->max_blocksize = get_bits(&gb, 16);
192 if (s->max_blocksize < 16) {
193 av_log(avctx, AV_LOG_WARNING, "invalid max blocksize: %d\n",
194 s->max_blocksize);
195 s->max_blocksize = 16;
196 }
197
198 skip_bits(&gb, 24); /* skip min frame size */
199 s->max_framesize = get_bits_long(&gb, 24);
200
201 s->samplerate = get_bits_long(&gb, 20);
202 s->channels = get_bits(&gb, 3) + 1;
203 s->bps = get_bits(&gb, 5) + 1;
204
205 avctx->channels = s->channels;
206 avctx->sample_rate = s->samplerate;
207 avctx->bits_per_raw_sample = s->bps;
208 if (s->bps > 16)
209 avctx->sample_fmt = SAMPLE_FMT_S32;
210 else
211 avctx->sample_fmt = SAMPLE_FMT_S16;
212
213 s->samples = get_bits_long(&gb, 32) << 4;
214 s->samples |= get_bits(&gb, 4);
215
216 skip_bits_long(&gb, 64); /* md5 sum */
217 skip_bits_long(&gb, 64); /* md5 sum */
218
219 dump_headers(avctx, s);
220 }
221
222 /**
223 * Parse a list of metadata blocks. This list of blocks must begin with
224 * the fLaC marker.
225 * @param s the flac decoding context containing the gb bit reader used to
226 * parse metadata
227 * @return non-zero if metadata is invalid
228 */
229 static int metadata_parse(FLACContext *s)
230 {
231 int i, metadata_last, metadata_type, metadata_size;
232
233 skip_bits_long(&s->gb, 32);
234
235 do {
236 metadata_last = get_bits1(&s->gb);
237 metadata_type = get_bits(&s->gb, 7);
238 metadata_size = get_bits_long(&s->gb, 24);
239
240 if (get_bits_count(&s->gb) + 8*metadata_size > s->gb.size_in_bits) {
241 /* need more data. reset the bitstream reader and return. */
242 init_get_bits(&s->gb, s->gb.buffer, s->gb.size_in_bits);
243 break;
244 }
245
246 if (metadata_size) {
247 switch (metadata_type) {
248 case FLAC_METADATA_TYPE_STREAMINFO:
249 if (!s->got_streaminfo) {
250 ff_flac_parse_streaminfo(s->avctx, (FLACStreaminfo *)s,
251 s->gb.buffer+get_bits_count(&s->gb)/8);
252 allocate_buffers(s);
253 s->got_streaminfo = 1;
254 }
255 default:
256 for (i = 0; i < metadata_size; i++)
257 skip_bits(&s->gb, 8);
258 }
259 }
260 } while (!metadata_last);
261
262 return 0;
263 }
264
265 static int decode_residuals(FLACContext *s, int channel, int pred_order)
266 {
267 int i, tmp, partition, method_type, rice_order;
268 int sample = 0, samples;
269
270 method_type = get_bits(&s->gb, 2);
271 if (method_type > 1) {
272 av_log(s->avctx, AV_LOG_ERROR, "illegal residual coding method %d\n",
273 method_type);
274 return -1;
275 }
276
277 rice_order = get_bits(&s->gb, 4);
278
279 samples= s->blocksize >> rice_order;
280 if (pred_order > samples) {
281 av_log(s->avctx, AV_LOG_ERROR, "invalid predictor order: %i > %i\n",
282 pred_order, samples);
283 return -1;
284 }
285
286 sample=
287 i= pred_order;
288 for (partition = 0; partition < (1 << rice_order); partition++) {
289 tmp = get_bits(&s->gb, method_type == 0 ? 4 : 5);
290 if (tmp == (method_type == 0 ? 15 : 31)) {
291 tmp = get_bits(&s->gb, 5);
292 for (; i < samples; i++, sample++)
293 s->decoded[channel][sample] = get_sbits_long(&s->gb, tmp);
294 } else {
295 for (; i < samples; i++, sample++) {
296 s->decoded[channel][sample] = get_sr_golomb_flac(&s->gb, tmp, INT_MAX, 0);
297 }
298 }
299 i= 0;
300 }
301
302 return 0;
303 }
304
305 static int decode_subframe_fixed(FLACContext *s, int channel, int pred_order)
306 {
307 const int blocksize = s->blocksize;
308 int32_t *decoded = s->decoded[channel];
309 int av_uninit(a), av_uninit(b), av_uninit(c), av_uninit(d), i;
310
311 /* warm up samples */
312 for (i = 0; i < pred_order; i++) {
313 decoded[i] = get_sbits_long(&s->gb, s->curr_bps);
314 }
315
316 if (decode_residuals(s, channel, pred_order) < 0)
317 return -1;
318
319 if (pred_order > 0)
320 a = decoded[pred_order-1];
321 if (pred_order > 1)
322 b = a - decoded[pred_order-2];
323 if (pred_order > 2)
324 c = b - decoded[pred_order-2] + decoded[pred_order-3];
325 if (pred_order > 3)
326 d = c - decoded[pred_order-2] + 2*decoded[pred_order-3] - decoded[pred_order-4];
327
328 switch (pred_order) {
329 case 0:
330 break;
331 case 1:
332 for (i = pred_order; i < blocksize; i++)
333 decoded[i] = a += decoded[i];
334 break;
335 case 2:
336 for (i = pred_order; i < blocksize; i++)
337 decoded[i] = a += b += decoded[i];
338 break;
339 case 3:
340 for (i = pred_order; i < blocksize; i++)
341 decoded[i] = a += b += c += decoded[i];
342 break;
343 case 4:
344 for (i = pred_order; i < blocksize; i++)
345 decoded[i] = a += b += c += d += decoded[i];
346 break;
347 default:
348 av_log(s->avctx, AV_LOG_ERROR, "illegal pred order %d\n", pred_order);
349 return -1;
350 }
351
352 return 0;
353 }
354
355 static int decode_subframe_lpc(FLACContext *s, int channel, int pred_order)
356 {
357 int i, j;
358 int coeff_prec, qlevel;
359 int coeffs[pred_order];
360 int32_t *decoded = s->decoded[channel];
361
362 /* warm up samples */
363 for (i = 0; i < pred_order; i++) {
364 decoded[i] = get_sbits_long(&s->gb, s->curr_bps);
365 }
366
367 coeff_prec = get_bits(&s->gb, 4) + 1;
368 if (coeff_prec == 16) {
369 av_log(s->avctx, AV_LOG_ERROR, "invalid coeff precision\n");
370 return -1;
371 }
372 qlevel = get_sbits(&s->gb, 5);
373 if (qlevel < 0) {
374 av_log(s->avctx, AV_LOG_ERROR, "qlevel %d not supported, maybe buggy stream\n",
375 qlevel);
376 return -1;
377 }
378
379 for (i = 0; i < pred_order; i++) {
380 coeffs[i] = get_sbits(&s->gb, coeff_prec);
381 }
382
383 if (decode_residuals(s, channel, pred_order) < 0)
384 return -1;
385
386 if (s->bps > 16) {
387 int64_t sum;
388 for (i = pred_order; i < s->blocksize; i++) {
389 sum = 0;
390 for (j = 0; j < pred_order; j++)
391 sum += (int64_t)coeffs[j] * decoded[i-j-1];
392 decoded[i] += sum >> qlevel;
393 }
394 } else {
395 for (i = pred_order; i < s->blocksize-1; i += 2) {
396 int c;
397 int d = decoded[i-pred_order];
398 int s0 = 0, s1 = 0;
399 for (j = pred_order-1; j > 0; j--) {
400 c = coeffs[j];
401 s0 += c*d;
402 d = decoded[i-j];
403 s1 += c*d;
404 }
405 c = coeffs[0];
406 s0 += c*d;
407 d = decoded[i] += s0 >> qlevel;
408 s1 += c*d;
409 decoded[i+1] += s1 >> qlevel;
410 }
411 if (i < s->blocksize) {
412 int sum = 0;
413 for (j = 0; j < pred_order; j++)
414 sum += coeffs[j] * decoded[i-j-1];
415 decoded[i] += sum >> qlevel;
416 }
417 }
418
419 return 0;
420 }
421
422 static inline int decode_subframe(FLACContext *s, int channel)
423 {
424 int type, wasted = 0;
425 int i, tmp;
426
427 s->curr_bps = s->bps;
428 if (channel == 0) {
429 if (s->decorrelation == RIGHT_SIDE)
430 s->curr_bps++;
431 } else {
432 if (s->decorrelation == LEFT_SIDE || s->decorrelation == MID_SIDE)
433 s->curr_bps++;
434 }
435 if (s->curr_bps > 32) {
436 ff_log_missing_feature(s->avctx, "decorrelated bit depth > 32", 0);
437 return -1;
438 }
439
440 if (get_bits1(&s->gb)) {
441 av_log(s->avctx, AV_LOG_ERROR, "invalid subframe padding\n");
442 return -1;
443 }
444 type = get_bits(&s->gb, 6);
445
446 if (get_bits1(&s->gb)) {
447 wasted = 1;
448 while (!get_bits1(&s->gb))
449 wasted++;
450 s->curr_bps -= wasted;
451 }
452
453 //FIXME use av_log2 for types
454 if (type == 0) {
455 tmp = get_sbits_long(&s->gb, s->curr_bps);
456 for (i = 0; i < s->blocksize; i++)
457 s->decoded[channel][i] = tmp;
458 } else if (type == 1) {
459 for (i = 0; i < s->blocksize; i++)
460 s->decoded[channel][i] = get_sbits_long(&s->gb, s->curr_bps);
461 } else if ((type >= 8) && (type <= 12)) {
462 if (decode_subframe_fixed(s, channel, type & ~0x8) < 0)
463 return -1;
464 } else if (type >= 32) {
465 if (decode_subframe_lpc(s, channel, (type & ~0x20)+1) < 0)
466 return -1;
467 } else {
468 av_log(s->avctx, AV_LOG_ERROR, "invalid coding type\n");
469 return -1;
470 }
471
472 if (wasted) {
473 int i;
474 for (i = 0; i < s->blocksize; i++)
475 s->decoded[channel][i] <<= wasted;
476 }
477
478 return 0;
479 }
480
481 static int decode_frame(FLACContext *s, int alloc_data_size)
482 {
483 int blocksize_code, sample_rate_code, sample_size_code, assignment, i, crc8;
484 int decorrelation, bps, blocksize, samplerate;
485
486 blocksize_code = get_bits(&s->gb, 4);
487
488 sample_rate_code = get_bits(&s->gb, 4);
489
490 assignment = get_bits(&s->gb, 4); /* channel assignment */
491 if (assignment < 8 && s->channels == assignment+1)
492 decorrelation = INDEPENDENT;
493 else if (assignment >=8 && assignment < 11 && s->channels == 2)
494 decorrelation = LEFT_SIDE + assignment - 8;
495 else {
496 av_log(s->avctx, AV_LOG_ERROR, "unsupported channel assignment %d (channels=%d)\n",
497 assignment, 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 = 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 * sizeof(int16_t) > 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 = 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->decorrelation= decorrelation;
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 tmp = 0, i, j = 0, input_buf_size = 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 init_get_bits(&s->gb, buf, buf_size*8);
641
642 /* check for inline header */
643 if (show_bits_long(&s->gb, 32) == MKBETAG('f','L','a','C')) {
644 if (metadata_parse(s)) {
645 av_log(s->avctx, AV_LOG_ERROR, "invalid header\n");
646 return -1;
647 }
648 goto end;
649 }
650
651 tmp = show_bits(&s->gb, 16);
652 if ((tmp & 0xFFFE) != 0xFFF8) {
653 av_log(s->avctx, AV_LOG_ERROR, "FRAME HEADER not here\n");
654 while (get_bits_count(&s->gb)/8+2 < buf_size && (show_bits(&s->gb, 16) & 0xFFFE) != 0xFFF8)
655 skip_bits(&s->gb, 8);
656 goto end; // we may not have enough bits left to decode a frame, so try next time
657 }
658 skip_bits(&s->gb, 16);
659 if (decode_frame(s, alloc_data_size) < 0) {
660 av_log(s->avctx, AV_LOG_ERROR, "decode_frame() failed\n");
661 s->bitstream_size=0;
662 s->bitstream_index=0;
663 return -1;
664 }
665
666 #define DECORRELATE(left, right)\
667 assert(s->channels == 2);\
668 for (i = 0; i < s->blocksize; i++) {\
669 int a= s->decoded[0][i];\
670 int b= s->decoded[1][i];\
671 if (s->is32) {\
672 *samples_32++ = (left) << s->sample_shift;\
673 *samples_32++ = (right) << s->sample_shift;\
674 } else {\
675 *samples_16++ = (left) << s->sample_shift;\
676 *samples_16++ = (right) << s->sample_shift;\
677 }\
678 }\
679 break;
680
681 switch (s->decorrelation) {
682 case INDEPENDENT:
683 for (j = 0; j < s->blocksize; j++) {
684 for (i = 0; i < s->channels; i++) {
685 if (s->is32)
686 *samples_32++ = s->decoded[i][j] << s->sample_shift;
687 else
688 *samples_16++ = s->decoded[i][j] << s->sample_shift;
689 }
690 }
691 break;
692 case LEFT_SIDE:
693 DECORRELATE(a,a-b)
694 case RIGHT_SIDE:
695 DECORRELATE(a+b,b)
696 case MID_SIDE:
697 DECORRELATE( (a-=b>>1) + b, a)
698 }
699
700 *data_size = s->blocksize * s->channels * (s->is32 ? 4 : 2);
701
702 end:
703 i= (get_bits_count(&s->gb)+7)/8;
704 if (i > buf_size) {
705 av_log(s->avctx, AV_LOG_ERROR, "overread: %d\n", i - buf_size);
706 s->bitstream_size=0;
707 s->bitstream_index=0;
708 return -1;
709 }
710
711 if (s->bitstream_size) {
712 s->bitstream_index += i;
713 s->bitstream_size -= i;
714 return input_buf_size;
715 } else
716 return i;
717 }
718
719 static av_cold int flac_decode_close(AVCodecContext *avctx)
720 {
721 FLACContext *s = avctx->priv_data;
722 int i;
723
724 for (i = 0; i < s->channels; i++) {
725 av_freep(&s->decoded[i]);
726 }
727 av_freep(&s->bitstream);
728
729 return 0;
730 }
731
732 static void flac_flush(AVCodecContext *avctx)
733 {
734 FLACContext *s = avctx->priv_data;
735
736 s->bitstream_size=
737 s->bitstream_index= 0;
738 }
739
740 AVCodec flac_decoder = {
741 "flac",
742 CODEC_TYPE_AUDIO,
743 CODEC_ID_FLAC,
744 sizeof(FLACContext),
745 flac_decode_init,
746 NULL,
747 flac_decode_close,
748 flac_decode_frame,
749 CODEC_CAP_DELAY,
750 .flush= flac_flush,
751 .long_name= NULL_IF_CONFIG_SMALL("FLAC (Free Lossless Audio Codec)"),
752 };