Statistics
| Branch: | Revision:

ffmpeg / libavcodec / ac3dec.c @ 9d10e6e6

History | View | Annotate | Download (40.1 KB)

1
/*
2
 * AC-3 Audio Decoder
3
 * This code is developed as part of Google Summer of Code 2006 Program.
4
 *
5
 * Copyright (c) 2006 Kartikey Mahendra BHATT (bhattkm at gmail dot com).
6
 * Copyright (c) 2007 Justin Ruggles
7
 *
8
 * Portions of this code are derived from liba52
9
 * http://liba52.sourceforge.net
10
 * Copyright (C) 2000-2003 Michel Lespinasse <walken@zoy.org>
11
 * Copyright (C) 1999-2000 Aaron Holtzman <aholtzma@ess.engr.uvic.ca>
12
 *
13
 * This file is part of FFmpeg.
14
 *
15
 * FFmpeg is free software; you can redistribute it and/or
16
 * modify it under the terms of the GNU General Public
17
 * License as published by the Free Software Foundation; either
18
 * version 2 of the License, or (at your option) any later version.
19
 *
20
 * FFmpeg is distributed in the hope that it will be useful,
21
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
22
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
23
 * General Public License for more details.
24
 *
25
 * You should have received a copy of the GNU General Public
26
 * License along with FFmpeg; if not, write to the Free Software
27
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
28
 */
29

    
30
#include <stdio.h>
31
#include <stddef.h>
32
#include <math.h>
33
#include <string.h>
34

    
35
#include "avcodec.h"
36
#include "ac3_parser.h"
37
#include "bitstream.h"
38
#include "crc.h"
39
#include "dsputil.h"
40
#include "random.h"
41

    
42
/**
43
 * Table of bin locations for rematrixing bands
44
 * reference: Section 7.5.2 Rematrixing : Frequency Band Definitions
45
 */
46
static const uint8_t rematrix_band_tab[5] = { 13, 25, 37, 61, 253 };
47

    
48
/** table for grouping exponents */
49
static uint8_t exp_ungroup_tab[128][3];
50

    
51

    
52
/** tables for ungrouping mantissas */
53
static int b1_mantissas[32][3];
54
static int b2_mantissas[128][3];
55
static int b3_mantissas[8];
56
static int b4_mantissas[128][2];
57
static int b5_mantissas[16];
58

    
59
/**
60
 * Quantization table: levels for symmetric. bits for asymmetric.
61
 * reference: Table 7.18 Mapping of bap to Quantizer
62
 */
63
static const uint8_t quantization_tab[16] = {
64
    0, 3, 5, 7, 11, 15,
65
    5, 6, 7, 8, 9, 10, 11, 12, 14, 16
66
};
67

    
68
/** dynamic range table. converts codes to scale factors. */
69
static float dynamic_range_tab[256];
70

    
71
/** Adjustments in dB gain */
72
#define LEVEL_MINUS_3DB         0.7071067811865476
73
#define LEVEL_MINUS_4POINT5DB   0.5946035575013605
74
#define LEVEL_MINUS_6DB         0.5000000000000000
75
#define LEVEL_MINUS_9DB         0.3535533905932738
76
#define LEVEL_ZERO              0.0000000000000000
77
#define LEVEL_ONE               1.0000000000000000
78

    
79
static const float gain_levels[6] = {
80
    LEVEL_ZERO,
81
    LEVEL_ONE,
82
    LEVEL_MINUS_3DB,
83
    LEVEL_MINUS_4POINT5DB,
84
    LEVEL_MINUS_6DB,
85
    LEVEL_MINUS_9DB
86
};
87

    
88
/**
89
 * Table for center mix levels
90
 * reference: Section 5.4.2.4 cmixlev
91
 */
92
static const uint8_t center_levels[4] = { 2, 3, 4, 3 };
93

    
94
/**
95
 * Table for surround mix levels
96
 * reference: Section 5.4.2.5 surmixlev
97
 */
98
static const uint8_t surround_levels[4] = { 2, 4, 0, 4 };
99

    
100
/**
101
 * Table for default stereo downmixing coefficients
102
 * reference: Section 7.8.2 Downmixing Into Two Channels
103
 */
104
static const uint8_t ac3_default_coeffs[8][5][2] = {
105
    { { 1, 0 }, { 0, 1 },                               },
106
    { { 2, 2 },                                         },
107
    { { 1, 0 }, { 0, 1 },                               },
108
    { { 1, 0 }, { 3, 3 }, { 0, 1 },                     },
109
    { { 1, 0 }, { 0, 1 }, { 4, 4 },                     },
110
    { { 1, 0 }, { 3, 3 }, { 0, 1 }, { 5, 5 },           },
111
    { { 1, 0 }, { 0, 1 }, { 4, 0 }, { 0, 4 },           },
112
    { { 1, 0 }, { 3, 3 }, { 0, 1 }, { 4, 0 }, { 0, 4 }, },
113
};
114

    
115
/* override ac3.h to include coupling channel */
116
#undef AC3_MAX_CHANNELS
117
#define AC3_MAX_CHANNELS 7
118
#define CPL_CH 0
119

    
120
#define AC3_OUTPUT_LFEON  8
121

    
122
typedef struct {
123
    int channel_mode;                       ///< channel mode (acmod)
124
    int block_switch[AC3_MAX_CHANNELS];     ///< block switch flags
125
    int dither_flag[AC3_MAX_CHANNELS];      ///< dither flags
126
    int dither_all;                         ///< true if all channels are dithered
127
    int cpl_in_use;                         ///< coupling in use
128
    int channel_in_cpl[AC3_MAX_CHANNELS];   ///< channel in coupling
129
    int phase_flags_in_use;                 ///< phase flags in use
130
    int phase_flags[18];                    ///< phase flags
131
    int cpl_band_struct[18];                ///< coupling band structure
132
    int num_rematrixing_bands;              ///< number of rematrixing bands
133
    int rematrixing_flags[4];               ///< rematrixing flags
134
    int exp_strategy[AC3_MAX_CHANNELS];     ///< exponent strategies
135
    int snr_offset[AC3_MAX_CHANNELS];       ///< signal-to-noise ratio offsets
136
    int fast_gain[AC3_MAX_CHANNELS];        ///< fast gain values (signal-to-mask ratio)
137
    int dba_mode[AC3_MAX_CHANNELS];         ///< delta bit allocation mode
138
    int dba_nsegs[AC3_MAX_CHANNELS];        ///< number of delta segments
139
    uint8_t dba_offsets[AC3_MAX_CHANNELS][8]; ///< delta segment offsets
140
    uint8_t dba_lengths[AC3_MAX_CHANNELS][8]; ///< delta segment lengths
141
    uint8_t dba_values[AC3_MAX_CHANNELS][8];  ///< delta values for each segment
142

    
143
    int sample_rate;                        ///< sample frequency, in Hz
144
    int bit_rate;                           ///< stream bit rate, in bits-per-second
145
    int frame_size;                         ///< current frame size, in bytes
146

    
147
    int channels;                           ///< number of total channels
148
    int fbw_channels;                       ///< number of full-bandwidth channels
149
    int lfe_on;                             ///< lfe channel in use
150
    int lfe_ch;                             ///< index of LFE channel
151
    int output_mode;                        ///< output channel configuration
152
    int out_channels;                       ///< number of output channels
153

    
154
    int center_mix_level;                   ///< Center mix level index
155
    int surround_mix_level;                 ///< Surround mix level index
156
    float downmix_coeffs[AC3_MAX_CHANNELS][2];  ///< stereo downmix coefficients
157
    float downmix_coeff_sum[2];             ///< sum of downmix coeffs for each output channel
158
    float dynamic_range[2];                 ///< dynamic range
159
    int   cpl_coords[AC3_MAX_CHANNELS][18]; ///< coupling coordinates
160
    int   num_cpl_bands;                    ///< number of coupling bands
161
    int   num_cpl_subbands;                 ///< number of coupling sub bands
162
    int   start_freq[AC3_MAX_CHANNELS];     ///< start frequency bin
163
    int   end_freq[AC3_MAX_CHANNELS];       ///< end frequency bin
164
    AC3BitAllocParameters bit_alloc_params; ///< bit allocation parameters
165

    
166
    int8_t  dexps[AC3_MAX_CHANNELS][256];   ///< decoded exponents
167
    uint8_t bap[AC3_MAX_CHANNELS][256];     ///< bit allocation pointers
168
    int16_t psd[AC3_MAX_CHANNELS][256];     ///< scaled exponents
169
    int16_t band_psd[AC3_MAX_CHANNELS][50]; ///< interpolated exponents
170
    int16_t mask[AC3_MAX_CHANNELS][50];     ///< masking curve values
171

    
172
    int fixed_coeffs[AC3_MAX_CHANNELS][256];    ///> fixed-point transform coefficients
173
    DECLARE_ALIGNED_16(float, transform_coeffs[AC3_MAX_CHANNELS][256]);  ///< transform coefficients
174

    
175
    /* For IMDCT. */
176
    MDCTContext imdct_512;                  ///< for 512 sample IMDCT
177
    MDCTContext imdct_256;                  ///< for 256 sample IMDCT
178
    DSPContext  dsp;                        ///< for optimization
179
    float       add_bias;                   ///< offset for float_to_int16 conversion
180
    float       mul_bias;                   ///< scaling for float_to_int16 conversion
181

    
182
    DECLARE_ALIGNED_16(float, output[AC3_MAX_CHANNELS-1][256]);     ///< output after imdct transform and windowing
183
    DECLARE_ALIGNED_16(short, int_output[AC3_MAX_CHANNELS-1][256]); ///< final 16-bit integer output
184
    DECLARE_ALIGNED_16(float, delay[AC3_MAX_CHANNELS-1][256]);      ///< delay - added to the next block
185
    DECLARE_ALIGNED_16(float, tmp_imdct[256]);                      ///< temporary storage for imdct transform
186
    DECLARE_ALIGNED_16(float, tmp_output[512]);                     ///< temporary storage for output before windowing
187
    DECLARE_ALIGNED_16(float, window[256]);                         ///< window coefficients
188

    
189
    /* Miscellaneous. */
190
    GetBitContext gbc;                      ///< bitstream reader
191
    AVRandomState dith_state;               ///< for dither generation
192
    AVCodecContext *avctx;                  ///< parent context
193
} AC3DecodeContext;
194

    
195
/**
196
 * Symmetrical Dequantization
197
 * reference: Section 7.3.3 Expansion of Mantissas for Symmetrical Quantization
198
 *            Tables 7.19 to 7.23
199
 */
200
static inline int
201
symmetric_dequant(int code, int levels)
202
{
203
    return ((code - (levels >> 1)) << 24) / levels;
204
}
205

    
206
/*
207
 * Initialize tables at runtime.
208
 */
209
static void ac3_tables_init(void)
210
{
211
    int i;
212

    
213
    /* generate grouped mantissa tables
214
       reference: Section 7.3.5 Ungrouping of Mantissas */
215
    for(i=0; i<32; i++) {
216
        /* bap=1 mantissas */
217
        b1_mantissas[i][0] = symmetric_dequant( i / 9     , 3);
218
        b1_mantissas[i][1] = symmetric_dequant((i % 9) / 3, 3);
219
        b1_mantissas[i][2] = symmetric_dequant((i % 9) % 3, 3);
220
    }
221
    for(i=0; i<128; i++) {
222
        /* bap=2 mantissas */
223
        b2_mantissas[i][0] = symmetric_dequant( i / 25     , 5);
224
        b2_mantissas[i][1] = symmetric_dequant((i % 25) / 5, 5);
225
        b2_mantissas[i][2] = symmetric_dequant((i % 25) % 5, 5);
226

    
227
        /* bap=4 mantissas */
228
        b4_mantissas[i][0] = symmetric_dequant(i / 11, 11);
229
        b4_mantissas[i][1] = symmetric_dequant(i % 11, 11);
230
    }
231
    /* generate ungrouped mantissa tables
232
       reference: Tables 7.21 and 7.23 */
233
    for(i=0; i<7; i++) {
234
        /* bap=3 mantissas */
235
        b3_mantissas[i] = symmetric_dequant(i, 7);
236
    }
237
    for(i=0; i<15; i++) {
238
        /* bap=5 mantissas */
239
        b5_mantissas[i] = symmetric_dequant(i, 15);
240
    }
241

    
242
    /* generate dynamic range table
243
       reference: Section 7.7.1 Dynamic Range Control */
244
    for(i=0; i<256; i++) {
245
        int v = (i >> 5) - ((i >> 7) << 3) - 5;
246
        dynamic_range_tab[i] = powf(2.0f, v) * ((i & 0x1F) | 0x20);
247
    }
248

    
249
    /* generate exponent tables
250
       reference: Section 7.1.3 Exponent Decoding */
251
    for(i=0; i<128; i++) {
252
        exp_ungroup_tab[i][0] =  i / 25;
253
        exp_ungroup_tab[i][1] = (i % 25) / 5;
254
        exp_ungroup_tab[i][2] = (i % 25) % 5;
255
    }
256
}
257

    
258

    
259
/**
260
 * AVCodec initialization
261
 */
262
static int ac3_decode_init(AVCodecContext *avctx)
263
{
264
    AC3DecodeContext *s = avctx->priv_data;
265
    s->avctx = avctx;
266

    
267
    ac3_common_init();
268
    ac3_tables_init();
269
    ff_mdct_init(&s->imdct_256, 8, 1);
270
    ff_mdct_init(&s->imdct_512, 9, 1);
271
    ff_kbd_window_init(s->window, 5.0, 256);
272
    dsputil_init(&s->dsp, avctx);
273
    av_init_random(0, &s->dith_state);
274

    
275
    /* set bias values for float to int16 conversion */
276
    if(s->dsp.float_to_int16 == ff_float_to_int16_c) {
277
        s->add_bias = 385.0f;
278
        s->mul_bias = 1.0f;
279
    } else {
280
        s->add_bias = 0.0f;
281
        s->mul_bias = 32767.0f;
282
    }
283

    
284
    /* allow downmixing to stereo or mono */
285
    if (avctx->channels > 0 && avctx->request_channels > 0 &&
286
            avctx->request_channels < avctx->channels &&
287
            avctx->request_channels <= 2) {
288
        avctx->channels = avctx->request_channels;
289
    }
290

    
291
    return 0;
292
}
293

    
294
/**
295
 * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
296
 * GetBitContext within AC3DecodeContext must point to
297
 * start of the synchronized ac3 bitstream.
298
 */
299
static int ac3_parse_header(AC3DecodeContext *s)
300
{
301
    AC3HeaderInfo hdr;
302
    GetBitContext *gbc = &s->gbc;
303
    int err, i;
304

    
305
    err = ff_ac3_parse_header(gbc->buffer, &hdr);
306
    if(err)
307
        return err;
308

    
309
    if(hdr.bitstream_id > 10)
310
        return AC3_PARSE_ERROR_BSID;
311

    
312
    /* get decoding parameters from header info */
313
    s->bit_alloc_params.sr_code     = hdr.sr_code;
314
    s->channel_mode                 = hdr.channel_mode;
315
    s->lfe_on                       = hdr.lfe_on;
316
    s->bit_alloc_params.sr_shift    = hdr.sr_shift;
317
    s->sample_rate                  = hdr.sample_rate;
318
    s->bit_rate                     = hdr.bit_rate;
319
    s->channels                     = hdr.channels;
320
    s->fbw_channels                 = s->channels - s->lfe_on;
321
    s->lfe_ch                       = s->fbw_channels + 1;
322
    s->frame_size                   = hdr.frame_size;
323

    
324
    /* set default output to all source channels */
325
    s->out_channels = s->channels;
326
    s->output_mode = s->channel_mode;
327
    if(s->lfe_on)
328
        s->output_mode |= AC3_OUTPUT_LFEON;
329

    
330
    /* set default mix levels */
331
    s->center_mix_level   = 3;  // -4.5dB
332
    s->surround_mix_level = 4;  // -6.0dB
333

    
334
    /* skip over portion of header which has already been read */
335
    skip_bits(gbc, 16); // skip the sync_word
336
    skip_bits(gbc, 16); // skip crc1
337
    skip_bits(gbc, 8);  // skip fscod and frmsizecod
338
    skip_bits(gbc, 11); // skip bsid, bsmod, and acmod
339
    if(s->channel_mode == AC3_CHMODE_STEREO) {
340
        skip_bits(gbc, 2); // skip dsurmod
341
    } else {
342
        if((s->channel_mode & 1) && s->channel_mode != AC3_CHMODE_MONO)
343
            s->center_mix_level = center_levels[get_bits(gbc, 2)];
344
        if(s->channel_mode & 4)
345
            s->surround_mix_level = surround_levels[get_bits(gbc, 2)];
346
    }
347
    skip_bits1(gbc); // skip lfeon
348

    
349
    /* read the rest of the bsi. read twice for dual mono mode. */
350
    i = !(s->channel_mode);
351
    do {
352
        skip_bits(gbc, 5); // skip dialog normalization
353
        if (get_bits1(gbc))
354
            skip_bits(gbc, 8); //skip compression
355
        if (get_bits1(gbc))
356
            skip_bits(gbc, 8); //skip language code
357
        if (get_bits1(gbc))
358
            skip_bits(gbc, 7); //skip audio production information
359
    } while (i--);
360

    
361
    skip_bits(gbc, 2); //skip copyright bit and original bitstream bit
362

    
363
    /* skip the timecodes (or extra bitstream information for Alternate Syntax)
364
       TODO: read & use the xbsi1 downmix levels */
365
    if (get_bits1(gbc))
366
        skip_bits(gbc, 14); //skip timecode1 / xbsi1
367
    if (get_bits1(gbc))
368
        skip_bits(gbc, 14); //skip timecode2 / xbsi2
369

    
370
    /* skip additional bitstream info */
371
    if (get_bits1(gbc)) {
372
        i = get_bits(gbc, 6);
373
        do {
374
            skip_bits(gbc, 8);
375
        } while(i--);
376
    }
377

    
378
    return 0;
379
}
380

    
381
/**
382
 * Set stereo downmixing coefficients based on frame header info.
383
 * reference: Section 7.8.2 Downmixing Into Two Channels
384
 */
385
static void set_downmix_coeffs(AC3DecodeContext *s)
386
{
387
    int i;
388
    float cmix = gain_levels[s->center_mix_level];
389
    float smix = gain_levels[s->surround_mix_level];
390

    
391
    for(i=0; i<s->fbw_channels; i++) {
392
        s->downmix_coeffs[i][0] = gain_levels[ac3_default_coeffs[s->channel_mode][i][0]];
393
        s->downmix_coeffs[i][1] = gain_levels[ac3_default_coeffs[s->channel_mode][i][1]];
394
    }
395
    if(s->channel_mode > 1 && s->channel_mode & 1) {
396
        s->downmix_coeffs[1][0] = s->downmix_coeffs[1][1] = cmix;
397
    }
398
    if(s->channel_mode == AC3_CHMODE_2F1R || s->channel_mode == AC3_CHMODE_3F1R) {
399
        int nf = s->channel_mode - 2;
400
        s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf][1] = smix * LEVEL_MINUS_3DB;
401
    }
402
    if(s->channel_mode == AC3_CHMODE_2F2R || s->channel_mode == AC3_CHMODE_3F2R) {
403
        int nf = s->channel_mode - 4;
404
        s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf+1][1] = smix;
405
    }
406

    
407
    s->downmix_coeff_sum[0] = s->downmix_coeff_sum[1] = 0.0f;
408
    for(i=0; i<s->fbw_channels; i++) {
409
        s->downmix_coeff_sum[0] += s->downmix_coeffs[i][0];
410
        s->downmix_coeff_sum[1] += s->downmix_coeffs[i][1];
411
    }
412
}
413

    
414
/**
415
 * Decode the grouped exponents according to exponent strategy.
416
 * reference: Section 7.1.3 Exponent Decoding
417
 */
418
static void decode_exponents(GetBitContext *gbc, int exp_strategy, int ngrps,
419
                             uint8_t absexp, int8_t *dexps)
420
{
421
    int i, j, grp, group_size;
422
    int dexp[256];
423
    int expacc, prevexp;
424

    
425
    /* unpack groups */
426
    group_size = exp_strategy + (exp_strategy == EXP_D45);
427
    for(grp=0,i=0; grp<ngrps; grp++) {
428
        expacc = get_bits(gbc, 7);
429
        dexp[i++] = exp_ungroup_tab[expacc][0];
430
        dexp[i++] = exp_ungroup_tab[expacc][1];
431
        dexp[i++] = exp_ungroup_tab[expacc][2];
432
    }
433

    
434
    /* convert to absolute exps and expand groups */
435
    prevexp = absexp;
436
    for(i=0; i<ngrps*3; i++) {
437
        prevexp = av_clip(prevexp + dexp[i]-2, 0, 24);
438
        for(j=0; j<group_size; j++) {
439
            dexps[(i*group_size)+j] = prevexp;
440
        }
441
    }
442
}
443

    
444
/**
445
 * Generate transform coefficients for each coupled channel in the coupling
446
 * range using the coupling coefficients and coupling coordinates.
447
 * reference: Section 7.4.3 Coupling Coordinate Format
448
 */
449
static void uncouple_channels(AC3DecodeContext *s)
450
{
451
    int i, j, ch, bnd, subbnd;
452

    
453
    subbnd = -1;
454
    i = s->start_freq[CPL_CH];
455
    for(bnd=0; bnd<s->num_cpl_bands; bnd++) {
456
        do {
457
            subbnd++;
458
            for(j=0; j<12; j++) {
459
                for(ch=1; ch<=s->fbw_channels; ch++) {
460
                    if(s->channel_in_cpl[ch]) {
461
                        s->fixed_coeffs[ch][i] = ((int64_t)s->fixed_coeffs[CPL_CH][i] * (int64_t)s->cpl_coords[ch][bnd]) >> 23;
462
                        if (ch == 2 && s->phase_flags[bnd])
463
                            s->fixed_coeffs[ch][i] = -s->fixed_coeffs[ch][i];
464
                    }
465
                }
466
                i++;
467
            }
468
        } while(s->cpl_band_struct[subbnd]);
469
    }
470
}
471

    
472
/**
473
 * Grouped mantissas for 3-level 5-level and 11-level quantization
474
 */
475
typedef struct {
476
    int b1_mant[3];
477
    int b2_mant[3];
478
    int b4_mant[2];
479
    int b1ptr;
480
    int b2ptr;
481
    int b4ptr;
482
} mant_groups;
483

    
484
/**
485
 * Get the transform coefficients for a particular channel
486
 * reference: Section 7.3 Quantization and Decoding of Mantissas
487
 */
488
static int get_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m)
489
{
490
    GetBitContext *gbc = &s->gbc;
491
    int i, gcode, tbap, start, end;
492
    uint8_t *exps;
493
    uint8_t *bap;
494
    int *coeffs;
495

    
496
    exps = s->dexps[ch_index];
497
    bap = s->bap[ch_index];
498
    coeffs = s->fixed_coeffs[ch_index];
499
    start = s->start_freq[ch_index];
500
    end = s->end_freq[ch_index];
501

    
502
    for (i = start; i < end; i++) {
503
        tbap = bap[i];
504
        switch (tbap) {
505
            case 0:
506
                coeffs[i] = (av_random(&s->dith_state) & 0x7FFFFF) - 4194304;
507
                break;
508

    
509
            case 1:
510
                if(m->b1ptr > 2) {
511
                    gcode = get_bits(gbc, 5);
512
                    m->b1_mant[0] = b1_mantissas[gcode][0];
513
                    m->b1_mant[1] = b1_mantissas[gcode][1];
514
                    m->b1_mant[2] = b1_mantissas[gcode][2];
515
                    m->b1ptr = 0;
516
                }
517
                coeffs[i] = m->b1_mant[m->b1ptr++];
518
                break;
519

    
520
            case 2:
521
                if(m->b2ptr > 2) {
522
                    gcode = get_bits(gbc, 7);
523
                    m->b2_mant[0] = b2_mantissas[gcode][0];
524
                    m->b2_mant[1] = b2_mantissas[gcode][1];
525
                    m->b2_mant[2] = b2_mantissas[gcode][2];
526
                    m->b2ptr = 0;
527
                }
528
                coeffs[i] = m->b2_mant[m->b2ptr++];
529
                break;
530

    
531
            case 3:
532
                coeffs[i] = b3_mantissas[get_bits(gbc, 3)];
533
                break;
534

    
535
            case 4:
536
                if(m->b4ptr > 1) {
537
                    gcode = get_bits(gbc, 7);
538
                    m->b4_mant[0] = b4_mantissas[gcode][0];
539
                    m->b4_mant[1] = b4_mantissas[gcode][1];
540
                    m->b4ptr = 0;
541
                }
542
                coeffs[i] = m->b4_mant[m->b4ptr++];
543
                break;
544

    
545
            case 5:
546
                coeffs[i] = b5_mantissas[get_bits(gbc, 4)];
547
                break;
548

    
549
            default: {
550
                /* asymmetric dequantization */
551
                int qlevel = quantization_tab[tbap];
552
                coeffs[i] = get_sbits(gbc, qlevel) << (24 - qlevel);
553
                break;
554
            }
555
        }
556
        coeffs[i] >>= exps[i];
557
    }
558

    
559
    return 0;
560
}
561

    
562
/**
563
 * Remove random dithering from coefficients with zero-bit mantissas
564
 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
565
 */
566
static void remove_dithering(AC3DecodeContext *s) {
567
    int ch, i;
568
    int end=0;
569
    int *coeffs;
570
    uint8_t *bap;
571

    
572
    for(ch=1; ch<=s->fbw_channels; ch++) {
573
        if(!s->dither_flag[ch]) {
574
            coeffs = s->fixed_coeffs[ch];
575
            bap = s->bap[ch];
576
            if(s->channel_in_cpl[ch])
577
                end = s->start_freq[CPL_CH];
578
            else
579
                end = s->end_freq[ch];
580
            for(i=0; i<end; i++) {
581
                if(!bap[i])
582
                    coeffs[i] = 0;
583
            }
584
            if(s->channel_in_cpl[ch]) {
585
                bap = s->bap[CPL_CH];
586
                for(; i<s->end_freq[CPL_CH]; i++) {
587
                    if(!bap[i])
588
                        coeffs[i] = 0;
589
                }
590
            }
591
        }
592
    }
593
}
594

    
595
/**
596
 * Get the transform coefficients.
597
 */
598
static int get_transform_coeffs(AC3DecodeContext *s)
599
{
600
    int ch, end;
601
    int got_cplchan = 0;
602
    mant_groups m;
603

    
604
    m.b1ptr = m.b2ptr = m.b4ptr = 3;
605

    
606
    for (ch = 1; ch <= s->channels; ch++) {
607
        /* transform coefficients for full-bandwidth channel */
608
        if (get_transform_coeffs_ch(s, ch, &m))
609
            return -1;
610
        /* tranform coefficients for coupling channel come right after the
611
           coefficients for the first coupled channel*/
612
        if (s->channel_in_cpl[ch])  {
613
            if (!got_cplchan) {
614
                if (get_transform_coeffs_ch(s, CPL_CH, &m)) {
615
                    av_log(s->avctx, AV_LOG_ERROR, "error in decoupling channels\n");
616
                    return -1;
617
                }
618
                uncouple_channels(s);
619
                got_cplchan = 1;
620
            }
621
            end = s->end_freq[CPL_CH];
622
        } else {
623
            end = s->end_freq[ch];
624
        }
625
        do
626
            s->transform_coeffs[ch][end] = 0;
627
        while(++end < 256);
628
    }
629

    
630
    /* if any channel doesn't use dithering, zero appropriate coefficients */
631
    if(!s->dither_all)
632
        remove_dithering(s);
633

    
634
    return 0;
635
}
636

    
637
/**
638
 * Stereo rematrixing.
639
 * reference: Section 7.5.4 Rematrixing : Decoding Technique
640
 */
641
static void do_rematrixing(AC3DecodeContext *s)
642
{
643
    int bnd, i;
644
    int end, bndend;
645
    int tmp0, tmp1;
646

    
647
    end = FFMIN(s->end_freq[1], s->end_freq[2]);
648

    
649
    for(bnd=0; bnd<s->num_rematrixing_bands; bnd++) {
650
        if(s->rematrixing_flags[bnd]) {
651
            bndend = FFMIN(end, rematrix_band_tab[bnd+1]);
652
            for(i=rematrix_band_tab[bnd]; i<bndend; i++) {
653
                tmp0 = s->fixed_coeffs[1][i];
654
                tmp1 = s->fixed_coeffs[2][i];
655
                s->fixed_coeffs[1][i] = tmp0 + tmp1;
656
                s->fixed_coeffs[2][i] = tmp0 - tmp1;
657
            }
658
        }
659
    }
660
}
661

    
662
/**
663
 * Perform the 256-point IMDCT
664
 */
665
static void do_imdct_256(AC3DecodeContext *s, int chindex)
666
{
667
    int i, k;
668
    DECLARE_ALIGNED_16(float, x[128]);
669
    FFTComplex z[2][64];
670
    float *o_ptr = s->tmp_output;
671

    
672
    for(i=0; i<2; i++) {
673
        /* de-interleave coefficients */
674
        for(k=0; k<128; k++) {
675
            x[k] = s->transform_coeffs[chindex][2*k+i];
676
        }
677

    
678
        /* run standard IMDCT */
679
        s->imdct_256.fft.imdct_calc(&s->imdct_256, o_ptr, x, s->tmp_imdct);
680

    
681
        /* reverse the post-rotation & reordering from standard IMDCT */
682
        for(k=0; k<32; k++) {
683
            z[i][32+k].re = -o_ptr[128+2*k];
684
            z[i][32+k].im = -o_ptr[2*k];
685
            z[i][31-k].re =  o_ptr[2*k+1];
686
            z[i][31-k].im =  o_ptr[128+2*k+1];
687
        }
688
    }
689

    
690
    /* apply AC-3 post-rotation & reordering */
691
    for(k=0; k<64; k++) {
692
        o_ptr[    2*k  ] = -z[0][   k].im;
693
        o_ptr[    2*k+1] =  z[0][63-k].re;
694
        o_ptr[128+2*k  ] = -z[0][   k].re;
695
        o_ptr[128+2*k+1] =  z[0][63-k].im;
696
        o_ptr[256+2*k  ] = -z[1][   k].re;
697
        o_ptr[256+2*k+1] =  z[1][63-k].im;
698
        o_ptr[384+2*k  ] =  z[1][   k].im;
699
        o_ptr[384+2*k+1] = -z[1][63-k].re;
700
    }
701
}
702

    
703
/**
704
 * Inverse MDCT Transform.
705
 * Convert frequency domain coefficients to time-domain audio samples.
706
 * reference: Section 7.9.4 Transformation Equations
707
 */
708
static inline void do_imdct(AC3DecodeContext *s)
709
{
710
    int ch;
711
    int channels;
712

    
713
    /* Don't perform the IMDCT on the LFE channel unless it's used in the output */
714
    channels = s->fbw_channels;
715
    if(s->output_mode & AC3_OUTPUT_LFEON)
716
        channels++;
717

    
718
    for (ch=1; ch<=channels; ch++) {
719
        if (s->block_switch[ch]) {
720
            do_imdct_256(s, ch);
721
        } else {
722
            s->imdct_512.fft.imdct_calc(&s->imdct_512, s->tmp_output,
723
                                        s->transform_coeffs[ch], s->tmp_imdct);
724
        }
725
        /* For the first half of the block, apply the window, add the delay
726
           from the previous block, and send to output */
727
        s->dsp.vector_fmul_add_add(s->output[ch-1], s->tmp_output,
728
                                     s->window, s->delay[ch-1], 0, 256, 1);
729
        /* For the second half of the block, apply the window and store the
730
           samples to delay, to be combined with the next block */
731
        s->dsp.vector_fmul_reverse(s->delay[ch-1], s->tmp_output+256,
732
                                   s->window, 256);
733
    }
734
}
735

    
736
/**
737
 * Downmix the output to mono or stereo.
738
 */
739
static void ac3_downmix(AC3DecodeContext *s)
740
{
741
    int i, j;
742
    float v0, v1;
743

    
744
    for(i=0; i<256; i++) {
745
        v0 = v1 = 0.0f;
746
        for(j=0; j<s->fbw_channels; j++) {
747
            v0 += s->output[j][i] * s->downmix_coeffs[j][0];
748
            v1 += s->output[j][i] * s->downmix_coeffs[j][1];
749
        }
750
        v0 /= s->downmix_coeff_sum[0];
751
        v1 /= s->downmix_coeff_sum[1];
752
        if(s->output_mode == AC3_CHMODE_MONO) {
753
            s->output[0][i] = (v0 + v1) * LEVEL_MINUS_3DB;
754
        } else if(s->output_mode == AC3_CHMODE_STEREO) {
755
            s->output[0][i] = v0;
756
            s->output[1][i] = v1;
757
        }
758
    }
759
}
760

    
761
/**
762
 * Parse an audio block from AC-3 bitstream.
763
 */
764
static int ac3_parse_audio_block(AC3DecodeContext *s, int blk)
765
{
766
    int fbw_channels = s->fbw_channels;
767
    int channel_mode = s->channel_mode;
768
    int i, bnd, seg, ch;
769
    GetBitContext *gbc = &s->gbc;
770
    uint8_t bit_alloc_stages[AC3_MAX_CHANNELS];
771

    
772
    memset(bit_alloc_stages, 0, AC3_MAX_CHANNELS);
773

    
774
    /* block switch flags */
775
    for (ch = 1; ch <= fbw_channels; ch++)
776
        s->block_switch[ch] = get_bits1(gbc);
777

    
778
    /* dithering flags */
779
    s->dither_all = 1;
780
    for (ch = 1; ch <= fbw_channels; ch++) {
781
        s->dither_flag[ch] = get_bits1(gbc);
782
        if(!s->dither_flag[ch])
783
            s->dither_all = 0;
784
    }
785

    
786
    /* dynamic range */
787
    i = !(s->channel_mode);
788
    do {
789
        if(get_bits1(gbc)) {
790
            s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)]-1.0) *
791
                                  s->avctx->drc_scale)+1.0;
792
        } else if(blk == 0) {
793
            s->dynamic_range[i] = 1.0f;
794
        }
795
    } while(i--);
796

    
797
    /* coupling strategy */
798
    if (get_bits1(gbc)) {
799
        memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
800
        s->cpl_in_use = get_bits1(gbc);
801
        if (s->cpl_in_use) {
802
            /* coupling in use */
803
            int cpl_begin_freq, cpl_end_freq;
804

    
805
            /* determine which channels are coupled */
806
            for (ch = 1; ch <= fbw_channels; ch++)
807
                s->channel_in_cpl[ch] = get_bits1(gbc);
808

    
809
            /* phase flags in use */
810
            if (channel_mode == AC3_CHMODE_STEREO)
811
                s->phase_flags_in_use = get_bits1(gbc);
812

    
813
            /* coupling frequency range and band structure */
814
            cpl_begin_freq = get_bits(gbc, 4);
815
            cpl_end_freq = get_bits(gbc, 4);
816
            if (3 + cpl_end_freq - cpl_begin_freq < 0) {
817
                av_log(s->avctx, AV_LOG_ERROR, "3+cplendf = %d < cplbegf = %d\n", 3+cpl_end_freq, cpl_begin_freq);
818
                return -1;
819
            }
820
            s->num_cpl_bands = s->num_cpl_subbands = 3 + cpl_end_freq - cpl_begin_freq;
821
            s->start_freq[CPL_CH] = cpl_begin_freq * 12 + 37;
822
            s->end_freq[CPL_CH] = cpl_end_freq * 12 + 73;
823
            for (bnd = 0; bnd < s->num_cpl_subbands - 1; bnd++) {
824
                if (get_bits1(gbc)) {
825
                    s->cpl_band_struct[bnd] = 1;
826
                    s->num_cpl_bands--;
827
                }
828
            }
829
            s->cpl_band_struct[s->num_cpl_subbands-1] = 0;
830
        } else {
831
            /* coupling not in use */
832
            for (ch = 1; ch <= fbw_channels; ch++)
833
                s->channel_in_cpl[ch] = 0;
834
        }
835
    }
836

    
837
    /* coupling coordinates */
838
    if (s->cpl_in_use) {
839
        int cpl_coords_exist = 0;
840

    
841
        for (ch = 1; ch <= fbw_channels; ch++) {
842
            if (s->channel_in_cpl[ch]) {
843
                if (get_bits1(gbc)) {
844
                    int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
845
                    cpl_coords_exist = 1;
846
                    master_cpl_coord = 3 * get_bits(gbc, 2);
847
                    for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
848
                        cpl_coord_exp = get_bits(gbc, 4);
849
                        cpl_coord_mant = get_bits(gbc, 4);
850
                        if (cpl_coord_exp == 15)
851
                            s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
852
                        else
853
                            s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
854
                        s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
855
                    }
856
                }
857
            }
858
        }
859
        /* phase flags */
860
        if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
861
            for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
862
                s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
863
            }
864
        }
865
    }
866

    
867
    /* stereo rematrixing strategy and band structure */
868
    if (channel_mode == AC3_CHMODE_STEREO) {
869
        if (get_bits1(gbc)) {
870
            s->num_rematrixing_bands = 4;
871
            if(s->cpl_in_use && s->start_freq[CPL_CH] <= 61)
872
                s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
873
            for(bnd=0; bnd<s->num_rematrixing_bands; bnd++)
874
                s->rematrixing_flags[bnd] = get_bits1(gbc);
875
        }
876
    }
877

    
878
    /* exponent strategies for each channel */
879
    s->exp_strategy[CPL_CH] = EXP_REUSE;
880
    s->exp_strategy[s->lfe_ch] = EXP_REUSE;
881
    for (ch = !s->cpl_in_use; ch <= s->channels; ch++) {
882
        if(ch == s->lfe_ch)
883
            s->exp_strategy[ch] = get_bits(gbc, 1);
884
        else
885
            s->exp_strategy[ch] = get_bits(gbc, 2);
886
        if(s->exp_strategy[ch] != EXP_REUSE)
887
            bit_alloc_stages[ch] = 3;
888
    }
889

    
890
    /* channel bandwidth */
891
    for (ch = 1; ch <= fbw_channels; ch++) {
892
        s->start_freq[ch] = 0;
893
        if (s->exp_strategy[ch] != EXP_REUSE) {
894
            int prev = s->end_freq[ch];
895
            if (s->channel_in_cpl[ch])
896
                s->end_freq[ch] = s->start_freq[CPL_CH];
897
            else {
898
                int bandwidth_code = get_bits(gbc, 6);
899
                if (bandwidth_code > 60) {
900
                    av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60", bandwidth_code);
901
                    return -1;
902
                }
903
                s->end_freq[ch] = bandwidth_code * 3 + 73;
904
            }
905
            if(blk > 0 && s->end_freq[ch] != prev)
906
                memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
907
        }
908
    }
909
    s->start_freq[s->lfe_ch] = 0;
910
    s->end_freq[s->lfe_ch] = 7;
911

    
912
    /* decode exponents for each channel */
913
    for (ch = !s->cpl_in_use; ch <= s->channels; ch++) {
914
        if (s->exp_strategy[ch] != EXP_REUSE) {
915
            int group_size, num_groups;
916
            group_size = 3 << (s->exp_strategy[ch] - 1);
917
            if(ch == CPL_CH)
918
                num_groups = (s->end_freq[ch] - s->start_freq[ch]) / group_size;
919
            else if(ch == s->lfe_ch)
920
                num_groups = 2;
921
            else
922
                num_groups = (s->end_freq[ch] + group_size - 4) / group_size;
923
            s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
924
            decode_exponents(gbc, s->exp_strategy[ch], num_groups, s->dexps[ch][0],
925
                             &s->dexps[ch][s->start_freq[ch]+!!ch]);
926
            if(ch != CPL_CH && ch != s->lfe_ch)
927
                skip_bits(gbc, 2); /* skip gainrng */
928
        }
929
    }
930

    
931
    /* bit allocation information */
932
    if (get_bits1(gbc)) {
933
        s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
934
        s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
935
        s->bit_alloc_params.slow_gain  = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
936
        s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
937
        s->bit_alloc_params.floor  = ff_ac3_floor_tab[get_bits(gbc, 3)];
938
        for(ch=!s->cpl_in_use; ch<=s->channels; ch++) {
939
            bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
940
        }
941
    }
942

    
943
    /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
944
    if (get_bits1(gbc)) {
945
        int csnr;
946
        csnr = (get_bits(gbc, 6) - 15) << 4;
947
        for (ch = !s->cpl_in_use; ch <= s->channels; ch++) { /* snr offset and fast gain */
948
            s->snr_offset[ch] = (csnr + get_bits(gbc, 4)) << 2;
949
            s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
950
        }
951
        memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
952
    }
953

    
954
    /* coupling leak information */
955
    if (s->cpl_in_use && get_bits1(gbc)) {
956
        s->bit_alloc_params.cpl_fast_leak = get_bits(gbc, 3);
957
        s->bit_alloc_params.cpl_slow_leak = get_bits(gbc, 3);
958
        bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
959
    }
960

    
961
    /* delta bit allocation information */
962
    if (get_bits1(gbc)) {
963
        /* delta bit allocation exists (strategy) */
964
        for (ch = !s->cpl_in_use; ch <= fbw_channels; ch++) {
965
            s->dba_mode[ch] = get_bits(gbc, 2);
966
            if (s->dba_mode[ch] == DBA_RESERVED) {
967
                av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
968
                return -1;
969
            }
970
            bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
971
        }
972
        /* channel delta offset, len and bit allocation */
973
        for (ch = !s->cpl_in_use; ch <= fbw_channels; ch++) {
974
            if (s->dba_mode[ch] == DBA_NEW) {
975
                s->dba_nsegs[ch] = get_bits(gbc, 3);
976
                for (seg = 0; seg <= s->dba_nsegs[ch]; seg++) {
977
                    s->dba_offsets[ch][seg] = get_bits(gbc, 5);
978
                    s->dba_lengths[ch][seg] = get_bits(gbc, 4);
979
                    s->dba_values[ch][seg] = get_bits(gbc, 3);
980
                }
981
            }
982
        }
983
    } else if(blk == 0) {
984
        for(ch=0; ch<=s->channels; ch++) {
985
            s->dba_mode[ch] = DBA_NONE;
986
        }
987
    }
988

    
989
    /* Bit allocation */
990
    for(ch=!s->cpl_in_use; ch<=s->channels; ch++) {
991
        if(bit_alloc_stages[ch] > 2) {
992
            /* Exponent mapping into PSD and PSD integration */
993
            ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
994
                                      s->start_freq[ch], s->end_freq[ch],
995
                                      s->psd[ch], s->band_psd[ch]);
996
        }
997
        if(bit_alloc_stages[ch] > 1) {
998
            /* Compute excitation function, Compute masking curve, and
999
               Apply delta bit allocation */
1000
            ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1001
                                       s->start_freq[ch], s->end_freq[ch],
1002
                                       s->fast_gain[ch], (ch == s->lfe_ch),
1003
                                       s->dba_mode[ch], s->dba_nsegs[ch],
1004
                                       s->dba_offsets[ch], s->dba_lengths[ch],
1005
                                       s->dba_values[ch], s->mask[ch]);
1006
        }
1007
        if(bit_alloc_stages[ch] > 0) {
1008
            /* Compute bit allocation */
1009
            ff_ac3_bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1010
                                      s->start_freq[ch], s->end_freq[ch],
1011
                                      s->snr_offset[ch],
1012
                                      s->bit_alloc_params.floor,
1013
                                      s->bap[ch]);
1014
        }
1015
    }
1016

    
1017
    /* unused dummy data */
1018
    if (get_bits1(gbc)) {
1019
        int skipl = get_bits(gbc, 9);
1020
        while(skipl--)
1021
            skip_bits(gbc, 8);
1022
    }
1023

    
1024
    /* unpack the transform coefficients
1025
       this also uncouples channels if coupling is in use. */
1026
    if (get_transform_coeffs(s)) {
1027
        av_log(s->avctx, AV_LOG_ERROR, "Error in routine get_transform_coeffs\n");
1028
        return -1;
1029
    }
1030

    
1031
    /* recover coefficients if rematrixing is in use */
1032
    if(s->channel_mode == AC3_CHMODE_STEREO)
1033
        do_rematrixing(s);
1034

    
1035
    /* apply scaling to coefficients (headroom, dynrng) */
1036
    for(ch=1; ch<=s->channels; ch++) {
1037
        float gain = s->mul_bias / 4194304.0f;
1038
        if(s->channel_mode == AC3_CHMODE_DUALMONO) {
1039
            gain *= s->dynamic_range[ch-1];
1040
        } else {
1041
            gain *= s->dynamic_range[0];
1042
        }
1043
        for(i=0; i<256; i++) {
1044
            s->transform_coeffs[ch][i] = s->fixed_coeffs[ch][i] * gain;
1045
        }
1046
    }
1047

    
1048
    do_imdct(s);
1049

    
1050
    /* downmix output if needed */
1051
    if(s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1052
            s->fbw_channels == s->out_channels)) {
1053
        ac3_downmix(s);
1054
    }
1055

    
1056
    /* convert float to 16-bit integer */
1057
    for(ch=0; ch<s->out_channels; ch++) {
1058
        for(i=0; i<256; i++) {
1059
            s->output[ch][i] += s->add_bias;
1060
        }
1061
        s->dsp.float_to_int16(s->int_output[ch], s->output[ch], 256);
1062
    }
1063

    
1064
    return 0;
1065
}
1066

    
1067
/**
1068
 * Decode a single AC-3 frame.
1069
 */
1070
static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size, uint8_t *buf, int buf_size)
1071
{
1072
    AC3DecodeContext *s = avctx->priv_data;
1073
    int16_t *out_samples = (int16_t *)data;
1074
    int i, blk, ch, err;
1075

    
1076
    /* initialize the GetBitContext with the start of valid AC-3 Frame */
1077
    init_get_bits(&s->gbc, buf, buf_size * 8);
1078

    
1079
    /* parse the syncinfo */
1080
    err = ac3_parse_header(s);
1081
    if(err) {
1082
        switch(err) {
1083
            case AC3_PARSE_ERROR_SYNC:
1084
                av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1085
                break;
1086
            case AC3_PARSE_ERROR_BSID:
1087
                av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1088
                break;
1089
            case AC3_PARSE_ERROR_SAMPLE_RATE:
1090
                av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1091
                break;
1092
            case AC3_PARSE_ERROR_FRAME_SIZE:
1093
                av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1094
                break;
1095
            default:
1096
                av_log(avctx, AV_LOG_ERROR, "invalid header\n");
1097
                break;
1098
        }
1099
        return -1;
1100
    }
1101

    
1102
    /* check that reported frame size fits in input buffer */
1103
    if(s->frame_size > buf_size) {
1104
        av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1105
        return -1;
1106
    }
1107

    
1108
    /* check for crc mismatch */
1109
    if(avctx->error_resilience >= FF_ER_CAREFUL) {
1110
        if(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2], s->frame_size-2)) {
1111
            av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1112
            return -1;
1113
        }
1114
        /* TODO: error concealment */
1115
    }
1116

    
1117
    avctx->sample_rate = s->sample_rate;
1118
    avctx->bit_rate = s->bit_rate;
1119

    
1120
    /* channel config */
1121
    s->out_channels = s->channels;
1122
    if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
1123
            avctx->request_channels < s->channels) {
1124
        s->out_channels = avctx->request_channels;
1125
        s->output_mode  = avctx->request_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1126
    }
1127
    avctx->channels = s->out_channels;
1128

    
1129
    /* set downmixing coefficients if needed */
1130
    if(s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1131
            s->fbw_channels == s->out_channels)) {
1132
        set_downmix_coeffs(s);
1133
    }
1134

    
1135
    /* parse the audio blocks */
1136
    for (blk = 0; blk < NB_BLOCKS; blk++) {
1137
        if (ac3_parse_audio_block(s, blk)) {
1138
            av_log(avctx, AV_LOG_ERROR, "error parsing the audio block\n");
1139
            *data_size = 0;
1140
            return s->frame_size;
1141
        }
1142
        for (i = 0; i < 256; i++)
1143
            for (ch = 0; ch < s->out_channels; ch++)
1144
                *(out_samples++) = s->int_output[ch][i];
1145
    }
1146
    *data_size = NB_BLOCKS * 256 * avctx->channels * sizeof (int16_t);
1147
    return s->frame_size;
1148
}
1149

    
1150
/**
1151
 * Uninitialize the AC-3 decoder.
1152
 */
1153
static int ac3_decode_end(AVCodecContext *avctx)
1154
{
1155
    AC3DecodeContext *s = avctx->priv_data;
1156
    ff_mdct_end(&s->imdct_512);
1157
    ff_mdct_end(&s->imdct_256);
1158

    
1159
    return 0;
1160
}
1161

    
1162
AVCodec ac3_decoder = {
1163
    .name = "ac3",
1164
    .type = CODEC_TYPE_AUDIO,
1165
    .id = CODEC_ID_AC3,
1166
    .priv_data_size = sizeof (AC3DecodeContext),
1167
    .init = ac3_decode_init,
1168
    .close = ac3_decode_end,
1169
    .decode = ac3_decode_frame,
1170
};