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1
/*
2
 * FLAC (Free Lossless Audio Codec) decoder
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 * Copyright (c) 2003 Alex Beregszaszi
4
 *
5
 * This file is part of FFmpeg.
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 *
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 * 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.
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 *
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 * 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
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
21

    
22
/**
23
 * @file libavcodec/flacdec.c
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 * FLAC (Free Lossless Audio Codec) decoder
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 * @author Alex Beregszaszi
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 *
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 * For more information on the FLAC format, visit:
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 *  http://flac.sourceforge.net/
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 *
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 * This decoder can be used in 1 of 2 ways: Either raw FLAC data can be fed
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 * through, starting from the initial 'fLaC' signature; or by passing the
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 * 34-byte streaminfo structure through avctx->extradata[_size] followed
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 * by data starting with the 0xFFF8 marker.
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 */
35

    
36
#include <limits.h>
37

    
38
#define ALT_BITSTREAM_READER
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#include "libavutil/crc.h"
40
#include "avcodec.h"
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#include "bitstream.h"
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#include "golomb.h"
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#include "flac.h"
44

    
45
#undef NDEBUG
46
#include <assert.h>
47

    
48
#define MAX_CHANNELS 8
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#define MAX_BLOCKSIZE 65535
50

    
51
enum decorrelation_type {
52
    INDEPENDENT,
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    LEFT_SIDE,
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    RIGHT_SIDE,
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    MID_SIDE,
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};
57

    
58
typedef struct FLACContext {
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    FLACSTREAMINFO
60

    
61
    AVCodecContext *avctx;                  ///< parent AVCodecContext
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    GetBitContext gb;                       ///< GetBitContext initialized to start at the current frame
63

    
64
    int blocksize;                          ///< number of samples in the current frame
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    int curr_bps;                           ///< bps for current subframe, adjusted for channel correlation and wasted bits
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    int sample_shift;                       ///< shift required to make output samples 16-bit or 32-bit
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    int is32;                               ///< flag to indicate if output should be 32-bit instead of 16-bit
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    enum decorrelation_type decorrelation;  ///< channel decorrelation type in the current frame
69

    
70
    int32_t *decoded[MAX_CHANNELS];         ///< decoded samples
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    uint8_t *bitstream;
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    unsigned int bitstream_size;
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    unsigned int bitstream_index;
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    unsigned int allocated_bitstream_size;
75
} FLACContext;
76

    
77
static const int sample_rate_table[] =
78
{ 0,
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  88200, 176400, 192000,
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  8000, 16000, 22050, 24000, 32000, 44100, 48000, 96000,
81
  0, 0, 0, 0 };
82

    
83
static const int sample_size_table[] =
84
{ 0, 8, 12, 0, 16, 20, 24, 0 };
85

    
86
static const int blocksize_table[] = {
87
     0,    192, 576<<0, 576<<1, 576<<2, 576<<3,      0,      0,
88
256<<0, 256<<1, 256<<2, 256<<3, 256<<4, 256<<5, 256<<6, 256<<7
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};
90

    
91
static int64_t get_utf8(GetBitContext *gb)
92
{
93
    int64_t val;
94
    GET_UTF8(val, get_bits(gb, 8), return -1;)
95
    return val;
96
}
97

    
98
static void allocate_buffers(FLACContext *s);
99

    
100
int ff_flac_is_extradata_valid(AVCodecContext *avctx,
101
                               enum FLACExtradataFormat *format,
102
                               uint8_t **streaminfo_start)
103
{
104
    if (!avctx->extradata || avctx->extradata_size < FLAC_STREAMINFO_SIZE) {
105
        av_log(avctx, AV_LOG_ERROR, "extradata NULL or too small.\n");
106
        return 0;
107
    }
108
    if (AV_RL32(avctx->extradata) != MKTAG('f','L','a','C')) {
109
        /* extradata contains STREAMINFO only */
110
        if (avctx->extradata_size != FLAC_STREAMINFO_SIZE) {
111
            av_log(avctx, AV_LOG_WARNING, "extradata contains %d bytes too many.\n",
112
                   FLAC_STREAMINFO_SIZE-avctx->extradata_size);
113
        }
114
        *format = FLAC_EXTRADATA_FORMAT_STREAMINFO;
115
        *streaminfo_start = avctx->extradata;
116
    } else {
117
        if (avctx->extradata_size < 8+FLAC_STREAMINFO_SIZE) {
118
            av_log(avctx, AV_LOG_ERROR, "extradata too small.\n");
119
            return 0;
120
        }
121
        *format = FLAC_EXTRADATA_FORMAT_FULL_HEADER;
122
        *streaminfo_start = &avctx->extradata[8];
123
    }
124
    return 1;
125
}
126

    
127
static av_cold int flac_decode_init(AVCodecContext *avctx)
128
{
129
    enum FLACExtradataFormat format;
130
    uint8_t *streaminfo;
131
    FLACContext *s = avctx->priv_data;
132
    s->avctx = avctx;
133

    
134
    avctx->sample_fmt = SAMPLE_FMT_S16;
135

    
136
    /* for now, the raw FLAC header is allowed to be passed to the decoder as
137
       frame data instead of extradata. */
138
    if (!avctx->extradata)
139
        return 0;
140

    
141
    if (!ff_flac_is_extradata_valid(avctx, &format, &streaminfo))
142
        return -1;
143

    
144
    /* initialize based on the demuxer-supplied streamdata header */
145
    ff_flac_parse_streaminfo(avctx, (FLACStreaminfo *)s, streaminfo);
146
    allocate_buffers(s);
147

    
148
    return 0;
149
}
150

    
151
static void dump_headers(AVCodecContext *avctx, FLACStreaminfo *s)
152
{
153
    av_log(avctx, AV_LOG_DEBUG, "  Blocksize: %d .. %d\n", s->min_blocksize,
154
           s->max_blocksize);
155
    av_log(avctx, AV_LOG_DEBUG, "  Max Framesize: %d\n", s->max_framesize);
156
    av_log(avctx, AV_LOG_DEBUG, "  Samplerate: %d\n", s->samplerate);
157
    av_log(avctx, AV_LOG_DEBUG, "  Channels: %d\n", s->channels);
158
    av_log(avctx, AV_LOG_DEBUG, "  Bits: %d\n", s->bps);
159
}
160

    
161
static void allocate_buffers(FLACContext *s)
162
{
163
    int i;
164

    
165
    assert(s->max_blocksize);
166

    
167
    if (s->max_framesize == 0 && s->max_blocksize) {
168
        // FIXME header overhead
169
        s->max_framesize= (s->channels * s->bps * s->max_blocksize + 7)/ 8;
170
    }
171

    
172
    for (i = 0; i < s->channels; i++) {
173
        s->decoded[i] = av_realloc(s->decoded[i],
174
                                   sizeof(int32_t)*s->max_blocksize);
175
    }
176

    
177
    if (s->allocated_bitstream_size < s->max_framesize)
178
        s->bitstream= av_fast_realloc(s->bitstream,
179
                                      &s->allocated_bitstream_size,
180
                                      s->max_framesize);
181
}
182

    
183
void ff_flac_parse_streaminfo(AVCodecContext *avctx, struct FLACStreaminfo *s,
184
                              const uint8_t *buffer)
185
{
186
    GetBitContext gb;
187
    init_get_bits(&gb, buffer, FLAC_STREAMINFO_SIZE*8);
188

    
189
    /* mandatory streaminfo */
190
    s->min_blocksize = get_bits(&gb, 16);
191
    s->max_blocksize = get_bits(&gb, 16);
192

    
193
    skip_bits(&gb, 24); /* skip min frame size */
194
    s->max_framesize = get_bits_long(&gb, 24);
195

    
196
    s->samplerate = get_bits_long(&gb, 20);
197
    s->channels = get_bits(&gb, 3) + 1;
198
    s->bps = get_bits(&gb, 5) + 1;
199

    
200
    avctx->channels = s->channels;
201
    avctx->sample_rate = s->samplerate;
202
    avctx->bits_per_raw_sample = s->bps;
203
    if (s->bps > 16)
204
        avctx->sample_fmt = SAMPLE_FMT_S32;
205
    else
206
        avctx->sample_fmt = SAMPLE_FMT_S16;
207

    
208
    s->samples  = get_bits_long(&gb, 32) << 4;
209
    s->samples |= get_bits(&gb, 4);
210

    
211
    skip_bits_long(&gb, 64); /* md5 sum */
212
    skip_bits_long(&gb, 64); /* md5 sum */
213

    
214
    dump_headers(avctx, s);
215
}
216

    
217
/**
218
 * Parse a list of metadata blocks. This list of blocks must begin with
219
 * the fLaC marker.
220
 * @param s the flac decoding context containing the gb bit reader used to
221
 *          parse metadata
222
 * @return 1 if some metadata was read, 0 if no fLaC marker was found
223
 */
224
static int metadata_parse(FLACContext *s)
225
{
226
    int i, metadata_last, metadata_type, metadata_size, streaminfo_updated=0;
227
    int initial_pos= get_bits_count(&s->gb);
228

    
229
    if (show_bits_long(&s->gb, 32) == MKBETAG('f','L','a','C')) {
230
        skip_bits_long(&s->gb, 32);
231

    
232
        do {
233
            metadata_last = get_bits1(&s->gb);
234
            metadata_type = get_bits(&s->gb, 7);
235
            metadata_size = get_bits_long(&s->gb, 24);
236

    
237
            if (get_bits_count(&s->gb) + 8*metadata_size > s->gb.size_in_bits) {
238
                skip_bits_long(&s->gb, initial_pos - get_bits_count(&s->gb));
239
                break;
240
            }
241

    
242
            if (metadata_size) {
243
                switch (metadata_type) {
244
                case FLAC_METADATA_TYPE_STREAMINFO:
245
                    ff_flac_parse_streaminfo(s->avctx, (FLACStreaminfo *)s,
246
                                             s->gb.buffer+get_bits_count(&s->gb)/8);
247
                    streaminfo_updated = 1;
248

    
249
                default:
250
                    for (i = 0; i < metadata_size; i++)
251
                        skip_bits(&s->gb, 8);
252
                }
253
            }
254
        } while (!metadata_last);
255

    
256
        if (streaminfo_updated)
257
            allocate_buffers(s);
258
        return 1;
259
    }
260
    return 0;
261
}
262

    
263
static int decode_residuals(FLACContext *s, int channel, int pred_order)
264
{
265
    int i, tmp, partition, method_type, rice_order;
266
    int sample = 0, samples;
267

    
268
    method_type = get_bits(&s->gb, 2);
269
    if (method_type > 1) {
270
        av_log(s->avctx, AV_LOG_ERROR, "illegal residual coding method %d\n",
271
               method_type);
272
        return -1;
273
    }
274

    
275
    rice_order = get_bits(&s->gb, 4);
276

    
277
    samples= s->blocksize >> rice_order;
278
    if (pred_order > samples) {
279
        av_log(s->avctx, AV_LOG_ERROR, "invalid predictor order: %i > %i\n",
280
               pred_order, samples);
281
        return -1;
282
    }
283

    
284
    sample=
285
    i= pred_order;
286
    for (partition = 0; partition < (1 << rice_order); partition++) {
287
        tmp = get_bits(&s->gb, method_type == 0 ? 4 : 5);
288
        if (tmp == (method_type == 0 ? 15 : 31)) {
289
            tmp = get_bits(&s->gb, 5);
290
            for (; i < samples; i++, sample++)
291
                s->decoded[channel][sample] = get_sbits(&s->gb, tmp);
292
        } else {
293
            for (; i < samples; i++, sample++) {
294
                s->decoded[channel][sample] = get_sr_golomb_flac(&s->gb, tmp, INT_MAX, 0);
295
            }
296
        }
297
        i= 0;
298
    }
299

    
300
    return 0;
301
}
302

    
303
static int decode_subframe_fixed(FLACContext *s, int channel, int pred_order)
304
{
305
    const int blocksize = s->blocksize;
306
    int32_t *decoded = s->decoded[channel];
307
    int av_uninit(a), av_uninit(b), av_uninit(c), av_uninit(d), i;
308

    
309
    /* warm up samples */
310
    for (i = 0; i < pred_order; i++) {
311
        decoded[i] = get_sbits(&s->gb, s->curr_bps);
312
    }
313

    
314
    if (decode_residuals(s, channel, pred_order) < 0)
315
        return -1;
316

    
317
    if (pred_order > 0)
318
        a = decoded[pred_order-1];
319
    if (pred_order > 1)
320
        b = a - decoded[pred_order-2];
321
    if (pred_order > 2)
322
        c = b - decoded[pred_order-2] + decoded[pred_order-3];
323
    if (pred_order > 3)
324
        d = c - decoded[pred_order-2] + 2*decoded[pred_order-3] - decoded[pred_order-4];
325

    
326
    switch (pred_order) {
327
    case 0:
328
        break;
329
    case 1:
330
        for (i = pred_order; i < blocksize; i++)
331
            decoded[i] = a += decoded[i];
332
        break;
333
    case 2:
334
        for (i = pred_order; i < blocksize; i++)
335
            decoded[i] = a += b += decoded[i];
336
        break;
337
    case 3:
338
        for (i = pred_order; i < blocksize; i++)
339
            decoded[i] = a += b += c += decoded[i];
340
        break;
341
    case 4:
342
        for (i = pred_order; i < blocksize; i++)
343
            decoded[i] = a += b += c += d += decoded[i];
344
        break;
345
    default:
346
        av_log(s->avctx, AV_LOG_ERROR, "illegal pred order %d\n", pred_order);
347
        return -1;
348
    }
349

    
350
    return 0;
351
}
352

    
353
static int decode_subframe_lpc(FLACContext *s, int channel, int pred_order)
354
{
355
    int i, j;
356
    int coeff_prec, qlevel;
357
    int coeffs[pred_order];
358
    int32_t *decoded = s->decoded[channel];
359

    
360
    /* warm up samples */
361
    for (i = 0; i < pred_order; i++) {
362
        decoded[i] = get_sbits(&s->gb, s->curr_bps);
363
    }
364

    
365
    coeff_prec = get_bits(&s->gb, 4) + 1;
366
    if (coeff_prec == 16) {
367
        av_log(s->avctx, AV_LOG_ERROR, "invalid coeff precision\n");
368
        return -1;
369
    }
370
    qlevel = get_sbits(&s->gb, 5);
371
    if (qlevel < 0) {
372
        av_log(s->avctx, AV_LOG_ERROR, "qlevel %d not supported, maybe buggy stream\n",
373
               qlevel);
374
        return -1;
375
    }
376

    
377
    for (i = 0; i < pred_order; i++) {
378
        coeffs[i] = get_sbits(&s->gb, coeff_prec);
379
    }
380

    
381
    if (decode_residuals(s, channel, pred_order) < 0)
382
        return -1;
383

    
384
    if (s->bps > 16) {
385
        int64_t sum;
386
        for (i = pred_order; i < s->blocksize; i++) {
387
            sum = 0;
388
            for (j = 0; j < pred_order; j++)
389
                sum += (int64_t)coeffs[j] * decoded[i-j-1];
390
            decoded[i] += sum >> qlevel;
391
        }
392
    } else {
393
        for (i = pred_order; i < s->blocksize-1; i += 2) {
394
            int c;
395
            int d = decoded[i-pred_order];
396
            int s0 = 0, s1 = 0;
397
            for (j = pred_order-1; j > 0; j--) {
398
                c = coeffs[j];
399
                s0 += c*d;
400
                d = decoded[i-j];
401
                s1 += c*d;
402
            }
403
            c = coeffs[0];
404
            s0 += c*d;
405
            d = decoded[i] += s0 >> qlevel;
406
            s1 += c*d;
407
            decoded[i+1] += s1 >> qlevel;
408
        }
409
        if (i < s->blocksize) {
410
            int sum = 0;
411
            for (j = 0; j < pred_order; j++)
412
                sum += coeffs[j] * decoded[i-j-1];
413
            decoded[i] += sum >> qlevel;
414
        }
415
    }
416

    
417
    return 0;
418
}
419

    
420
static inline int decode_subframe(FLACContext *s, int channel)
421
{
422
    int type, wasted = 0;
423
    int i, tmp;
424

    
425
    s->curr_bps = s->bps;
426
    if (channel == 0) {
427
        if (s->decorrelation == RIGHT_SIDE)
428
            s->curr_bps++;
429
    } else {
430
        if (s->decorrelation == LEFT_SIDE || s->decorrelation == MID_SIDE)
431
            s->curr_bps++;
432
    }
433

    
434
    if (get_bits1(&s->gb)) {
435
        av_log(s->avctx, AV_LOG_ERROR, "invalid subframe padding\n");
436
        return -1;
437
    }
438
    type = get_bits(&s->gb, 6);
439

    
440
    if (get_bits1(&s->gb)) {
441
        wasted = 1;
442
        while (!get_bits1(&s->gb))
443
            wasted++;
444
        s->curr_bps -= wasted;
445
    }
446

    
447
//FIXME use av_log2 for types
448
    if (type == 0) {
449
        tmp = get_sbits(&s->gb, s->curr_bps);
450
        for (i = 0; i < s->blocksize; i++)
451
            s->decoded[channel][i] = tmp;
452
    } else if (type == 1) {
453
        for (i = 0; i < s->blocksize; i++)
454
            s->decoded[channel][i] = get_sbits(&s->gb, s->curr_bps);
455
    } else if ((type >= 8) && (type <= 12)) {
456
        if (decode_subframe_fixed(s, channel, type & ~0x8) < 0)
457
            return -1;
458
    } else if (type >= 32) {
459
        if (decode_subframe_lpc(s, channel, (type & ~0x20)+1) < 0)
460
            return -1;
461
    } else {
462
        av_log(s->avctx, AV_LOG_ERROR, "invalid coding type\n");
463
        return -1;
464
    }
465

    
466
    if (wasted) {
467
        int i;
468
        for (i = 0; i < s->blocksize; i++)
469
            s->decoded[channel][i] <<= wasted;
470
    }
471

    
472
    return 0;
473
}
474

    
475
static int decode_frame(FLACContext *s, int alloc_data_size)
476
{
477
    int blocksize_code, sample_rate_code, sample_size_code, assignment, i, crc8;
478
    int decorrelation, bps, blocksize, samplerate;
479

    
480
    blocksize_code = get_bits(&s->gb, 4);
481

    
482
    sample_rate_code = get_bits(&s->gb, 4);
483

    
484
    assignment = get_bits(&s->gb, 4); /* channel assignment */
485
    if (assignment < 8 && s->channels == assignment+1)
486
        decorrelation = INDEPENDENT;
487
    else if (assignment >=8 && assignment < 11 && s->channels == 2)
488
        decorrelation = LEFT_SIDE + assignment - 8;
489
    else {
490
        av_log(s->avctx, AV_LOG_ERROR, "unsupported channel assignment %d (channels=%d)\n",
491
               assignment, s->channels);
492
        return -1;
493
    }
494

    
495
    sample_size_code = get_bits(&s->gb, 3);
496
    if (sample_size_code == 0)
497
        bps= s->bps;
498
    else if ((sample_size_code != 3) && (sample_size_code != 7))
499
        bps = sample_size_table[sample_size_code];
500
    else {
501
        av_log(s->avctx, AV_LOG_ERROR, "invalid sample size code (%d)\n",
502
               sample_size_code);
503
        return -1;
504
    }
505
    if (bps > 16) {
506
        s->avctx->sample_fmt = SAMPLE_FMT_S32;
507
        s->sample_shift = 32 - bps;
508
        s->is32 = 1;
509
    } else {
510
        s->avctx->sample_fmt = SAMPLE_FMT_S16;
511
        s->sample_shift = 16 - bps;
512
        s->is32 = 0;
513
    }
514
    s->bps = s->avctx->bits_per_raw_sample = bps;
515

    
516
    if (get_bits1(&s->gb)) {
517
        av_log(s->avctx, AV_LOG_ERROR, "broken stream, invalid padding\n");
518
        return -1;
519
    }
520

    
521
    if (get_utf8(&s->gb) < 0) {
522
        av_log(s->avctx, AV_LOG_ERROR, "utf8 fscked\n");
523
        return -1;
524
    }
525

    
526
    if (blocksize_code == 0)
527
        blocksize = s->min_blocksize;
528
    else if (blocksize_code == 6)
529
        blocksize = get_bits(&s->gb, 8)+1;
530
    else if (blocksize_code == 7)
531
        blocksize = get_bits(&s->gb, 16)+1;
532
    else
533
        blocksize = blocksize_table[blocksize_code];
534

    
535
    if (blocksize > s->max_blocksize) {
536
        av_log(s->avctx, AV_LOG_ERROR, "blocksize %d > %d\n", blocksize,
537
               s->max_blocksize);
538
        return -1;
539
    }
540

    
541
    if (blocksize * s->channels * sizeof(int16_t) > alloc_data_size)
542
        return -1;
543

    
544
    if (sample_rate_code == 0)
545
        samplerate= s->samplerate;
546
    else if (sample_rate_code < 12)
547
        samplerate = sample_rate_table[sample_rate_code];
548
    else if (sample_rate_code == 12)
549
        samplerate = get_bits(&s->gb, 8) * 1000;
550
    else if (sample_rate_code == 13)
551
        samplerate = get_bits(&s->gb, 16);
552
    else if (sample_rate_code == 14)
553
        samplerate = get_bits(&s->gb, 16) * 10;
554
    else {
555
        av_log(s->avctx, AV_LOG_ERROR, "illegal sample rate code %d\n",
556
               sample_rate_code);
557
        return -1;
558
    }
559

    
560
    skip_bits(&s->gb, 8);
561
    crc8 = av_crc(av_crc_get_table(AV_CRC_8_ATM), 0,
562
                  s->gb.buffer, get_bits_count(&s->gb)/8);
563
    if (crc8) {
564
        av_log(s->avctx, AV_LOG_ERROR, "header crc mismatch crc=%2X\n", crc8);
565
        return -1;
566
    }
567

    
568
    s->blocksize    = blocksize;
569
    s->samplerate   = samplerate;
570
    s->bps          = bps;
571
    s->decorrelation= decorrelation;
572

    
573
//    dump_headers(s->avctx, (FLACStreaminfo *)s);
574

    
575
    /* subframes */
576
    for (i = 0; i < s->channels; i++) {
577
        if (decode_subframe(s, i) < 0)
578
            return -1;
579
    }
580

    
581
    align_get_bits(&s->gb);
582

    
583
    /* frame footer */
584
    skip_bits(&s->gb, 16); /* data crc */
585

    
586
    return 0;
587
}
588

    
589
static int flac_decode_frame(AVCodecContext *avctx,
590
                            void *data, int *data_size,
591
                            const uint8_t *buf, int buf_size)
592
{
593
    FLACContext *s = avctx->priv_data;
594
    int tmp = 0, i, j = 0, input_buf_size = 0;
595
    int16_t *samples_16 = data;
596
    int32_t *samples_32 = data;
597
    int alloc_data_size= *data_size;
598

    
599
    *data_size=0;
600

    
601
    if (s->max_framesize == 0) {
602
        s->max_framesize= FFMAX(4, buf_size); // should hopefully be enough for the first header
603
        s->bitstream= av_fast_realloc(s->bitstream, &s->allocated_bitstream_size, s->max_framesize);
604
    }
605

    
606
    if (1 && s->max_framesize) { //FIXME truncated
607
        if (s->bitstream_size < 4 || AV_RL32(s->bitstream) != MKTAG('f','L','a','C'))
608
            buf_size= FFMIN(buf_size, s->max_framesize - FFMIN(s->bitstream_size, s->max_framesize));
609
        input_buf_size= buf_size;
610

    
611
        if (s->bitstream_size + buf_size < buf_size || s->bitstream_index + s->bitstream_size + buf_size < s->bitstream_index)
612
            return -1;
613

    
614
        if (s->allocated_bitstream_size < s->bitstream_size + buf_size)
615
            s->bitstream= av_fast_realloc(s->bitstream, &s->allocated_bitstream_size, s->bitstream_size + buf_size);
616

    
617
        if (s->bitstream_index + s->bitstream_size + buf_size > s->allocated_bitstream_size) {
618
            memmove(s->bitstream, &s->bitstream[s->bitstream_index],
619
                    s->bitstream_size);
620
            s->bitstream_index=0;
621
        }
622
        memcpy(&s->bitstream[s->bitstream_index + s->bitstream_size],
623
               buf, buf_size);
624
        buf= &s->bitstream[s->bitstream_index];
625
        buf_size += s->bitstream_size;
626
        s->bitstream_size= buf_size;
627

    
628
        if (buf_size < s->max_framesize && input_buf_size) {
629
            return input_buf_size;
630
        }
631
    }
632

    
633
    init_get_bits(&s->gb, buf, buf_size*8);
634

    
635
    if (metadata_parse(s))
636
        goto end;
637

    
638
    tmp = show_bits(&s->gb, 16);
639
    if ((tmp & 0xFFFE) != 0xFFF8) {
640
        av_log(s->avctx, AV_LOG_ERROR, "FRAME HEADER not here\n");
641
        while (get_bits_count(&s->gb)/8+2 < buf_size && (show_bits(&s->gb, 16) & 0xFFFE) != 0xFFF8)
642
            skip_bits(&s->gb, 8);
643
        goto end; // we may not have enough bits left to decode a frame, so try next time
644
    }
645
    skip_bits(&s->gb, 16);
646
    if (decode_frame(s, alloc_data_size) < 0) {
647
        av_log(s->avctx, AV_LOG_ERROR, "decode_frame() failed\n");
648
        s->bitstream_size=0;
649
        s->bitstream_index=0;
650
        return -1;
651
    }
652

    
653
#define DECORRELATE(left, right)\
654
            assert(s->channels == 2);\
655
            for (i = 0; i < s->blocksize; i++) {\
656
                int a= s->decoded[0][i];\
657
                int b= s->decoded[1][i];\
658
                if (s->is32) {\
659
                    *samples_32++ = (left)  << s->sample_shift;\
660
                    *samples_32++ = (right) << s->sample_shift;\
661
                } else {\
662
                    *samples_16++ = (left)  << s->sample_shift;\
663
                    *samples_16++ = (right) << s->sample_shift;\
664
                }\
665
            }\
666
            break;
667

    
668
    switch (s->decorrelation) {
669
    case INDEPENDENT:
670
        for (j = 0; j < s->blocksize; j++) {
671
            for (i = 0; i < s->channels; i++) {
672
                if (s->is32)
673
                    *samples_32++ = s->decoded[i][j] << s->sample_shift;
674
                else
675
                    *samples_16++ = s->decoded[i][j] << s->sample_shift;
676
            }
677
        }
678
        break;
679
    case LEFT_SIDE:
680
        DECORRELATE(a,a-b)
681
    case RIGHT_SIDE:
682
        DECORRELATE(a+b,b)
683
    case MID_SIDE:
684
        DECORRELATE( (a-=b>>1) + b, a)
685
    }
686

    
687
    *data_size = s->blocksize * s->channels * (s->is32 ? 4 : 2);
688

    
689
end:
690
    i= (get_bits_count(&s->gb)+7)/8;
691
    if (i > buf_size) {
692
        av_log(s->avctx, AV_LOG_ERROR, "overread: %d\n", i - buf_size);
693
        s->bitstream_size=0;
694
        s->bitstream_index=0;
695
        return -1;
696
    }
697

    
698
    if (s->bitstream_size) {
699
        s->bitstream_index += i;
700
        s->bitstream_size  -= i;
701
        return input_buf_size;
702
    } else
703
        return i;
704
}
705

    
706
static av_cold int flac_decode_close(AVCodecContext *avctx)
707
{
708
    FLACContext *s = avctx->priv_data;
709
    int i;
710

    
711
    for (i = 0; i < s->channels; i++) {
712
        av_freep(&s->decoded[i]);
713
    }
714
    av_freep(&s->bitstream);
715

    
716
    return 0;
717
}
718

    
719
static void flac_flush(AVCodecContext *avctx)
720
{
721
    FLACContext *s = avctx->priv_data;
722

    
723
    s->bitstream_size=
724
    s->bitstream_index= 0;
725
}
726

    
727
AVCodec flac_decoder = {
728
    "flac",
729
    CODEC_TYPE_AUDIO,
730
    CODEC_ID_FLAC,
731
    sizeof(FLACContext),
732
    flac_decode_init,
733
    NULL,
734
    flac_decode_close,
735
    flac_decode_frame,
736
    CODEC_CAP_DELAY,
737
    .flush= flac_flush,
738
    .long_name= NULL_IF_CONFIG_SMALL("FLAC (Free Lossless Audio Codec)"),
739
};