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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).
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 * Copyright (c) 2007 Justin Ruggles
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 *
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 * Portions of this code are derived from liba52
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 * http://liba52.sourceforge.net
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 * Copyright (C) 2000-2003 Michel Lespinasse <walken@zoy.org>
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 * Copyright (C) 1999-2000 Aaron Holtzman <aholtzma@ess.engr.uvic.ca>
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU General Public
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 * License as published by the Free Software Foundation; either
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 * version 2 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,
21
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * General Public License for more details.
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 *
25
 * You should have received a copy of the GNU 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
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 "dsputil.h"
39
#include "random.h"
40

    
41
/**
42
 * Table of bin locations for rematrixing bands
43
 * reference: Section 7.5.2 Rematrixing : Frequency Band Definitions
44
 */
45
static const uint8_t rematrix_band_tbl[5] = { 13, 25, 37, 61, 253 };
46

    
47
/* table for exponent to scale_factor mapping
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 * scale_factor[i] = 2 ^ -(i + 15)
49
 */
50
static float scale_factors[25];
51

    
52
/** table for grouping exponents */
53
static uint8_t exp_ungroup_tbl[128][3];
54

    
55
static int16_t l3_quantizers_1[32];
56
static int16_t l3_quantizers_2[32];
57
static int16_t l3_quantizers_3[32];
58

    
59
static int16_t l5_quantizers_1[128];
60
static int16_t l5_quantizers_2[128];
61
static int16_t l5_quantizers_3[128];
62

    
63
static int16_t l7_quantizers[7];
64

    
65
static int16_t l11_quantizers_1[128];
66
static int16_t l11_quantizers_2[128];
67

    
68
static int16_t l15_quantizers[15];
69

    
70
static const uint8_t qntztab[16] = { 0, 5, 7, 3, 7, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16 };
71

    
72
/* Adjustmens in dB gain */
73
#define LEVEL_MINUS_3DB         0.7071067811865476
74
#define LEVEL_MINUS_4POINT5DB   0.5946035575013605
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#define LEVEL_MINUS_6DB         0.5000000000000000
76
#define LEVEL_PLUS_3DB          1.4142135623730951
77
#define LEVEL_PLUS_6DB          2.0000000000000000
78
#define LEVEL_ZERO              0.0000000000000000
79

    
80
static const float clevs[4] = { LEVEL_MINUS_3DB, LEVEL_MINUS_4POINT5DB,
81
    LEVEL_MINUS_6DB, LEVEL_MINUS_4POINT5DB };
82

    
83
static const float slevs[4] = { LEVEL_MINUS_3DB, LEVEL_MINUS_6DB, LEVEL_ZERO, LEVEL_MINUS_6DB };
84

    
85
#define AC3_OUTPUT_LFEON  8
86

    
87
typedef struct {
88
    int acmod;
89
    int cmixlev;
90
    int surmixlev;
91
    int dsurmod;
92

    
93
    int blksw[AC3_MAX_CHANNELS];
94
    int dithflag[AC3_MAX_CHANNELS];
95
    int cplinu;
96
    int chincpl[AC3_MAX_CHANNELS];
97
    int phsflginu;
98
    int cplcoe;
99
    uint32_t cplbndstrc;
100
    int rematstr;
101
    int nrematbnd;
102
    int rematflg[AC3_MAX_CHANNELS];
103
    int cplexpstr;
104
    int lfeexpstr;
105
    int chexpstr[5];
106
    int cplsnroffst;
107
    int cplfgain;
108
    int snroffst[5];
109
    int fgain[5];
110
    int lfesnroffst;
111
    int lfefgain;
112
    int cpldeltbae;
113
    int deltbae[5];
114
    int cpldeltnseg;
115
    uint8_t  cpldeltoffst[8];
116
    uint8_t  cpldeltlen[8];
117
    uint8_t  cpldeltba[8];
118
    int deltnseg[5];
119
    uint8_t  deltoffst[5][8];
120
    uint8_t  deltlen[5][8];
121
    uint8_t  deltba[5][8];
122

    
123
    /* Derived Attributes. */
124
    int      sampling_rate;
125
    int      bit_rate;
126
    int      frame_size;
127

    
128
    int      nchans;            //number of total channels
129
    int      nfchans;           //number of full-bandwidth channels
130
    int      lfeon;             //lfe channel in use
131
    int      output_mode;       ///< output channel configuration
132
    int      out_channels;      ///< number of output channels
133

    
134
    float    dynrng;            //dynamic range gain
135
    float    dynrng2;           //dynamic range gain for 1+1 mode
136
    float    cplco[5][18];      //coupling coordinates
137
    int      ncplbnd;           //number of coupling bands
138
    int      ncplsubnd;         //number of coupling sub bands
139
    int      cplstrtmant;       //coupling start mantissa
140
    int      cplendmant;        //coupling end mantissa
141
    int      endmant[5];        //channel end mantissas
142
    AC3BitAllocParameters bit_alloc_params; ///< bit allocation parameters
143

    
144
    int8_t   dcplexps[256];     //decoded coupling exponents
145
    int8_t   dexps[5][256];     //decoded fbw channel exponents
146
    int8_t   dlfeexps[256];     //decoded lfe channel exponents
147
    uint8_t  cplbap[256];       //coupling bit allocation pointers
148
    uint8_t  bap[5][256];       //fbw channel bit allocation pointers
149
    uint8_t  lfebap[256];       //lfe channel bit allocation pointers
150

    
151
    DECLARE_ALIGNED_16(float, transform_coeffs[AC3_MAX_CHANNELS][256]);  //transform coefficients
152

    
153
    /* For IMDCT. */
154
    MDCTContext imdct_512;  //for 512 sample imdct transform
155
    MDCTContext imdct_256;  //for 256 sample imdct transform
156
    DSPContext  dsp;        //for optimization
157

    
158
    DECLARE_ALIGNED_16(float, output[AC3_MAX_CHANNELS][256]);   //output after imdct transform and windowing
159
    DECLARE_ALIGNED_16(float, delay[AC3_MAX_CHANNELS][256]);    //delay - added to the next block
160
    DECLARE_ALIGNED_16(float, tmp_imdct[256]);                  //temporary storage for imdct transform
161
    DECLARE_ALIGNED_16(float, tmp_output[512]);                 //temporary storage for output before windowing
162
    DECLARE_ALIGNED_16(float, window[256]);                     //window coefficients
163

    
164
    /* Miscellaneous. */
165
    GetBitContext gb;
166
    AVRandomState dith_state;   //for dither generation
167
} AC3DecodeContext;
168

    
169
/*********** BEGIN INIT HELPER FUNCTIONS ***********/
170
/**
171
 * Generate a Kaiser-Bessel Derived Window.
172
 */
173
static void ac3_window_init(float *window)
174
{
175
   int i, j;
176
   double sum = 0.0, bessel, tmp;
177
   double local_window[256];
178
   double alpha2 = (5.0 * M_PI / 256.0) * (5.0 * M_PI / 256.0);
179

    
180
   for (i = 0; i < 256; i++) {
181
       tmp = i * (256 - i) * alpha2;
182
       bessel = 1.0;
183
       for (j = 100; j > 0; j--) /* defaul to 100 iterations */
184
           bessel = bessel * tmp / (j * j) + 1;
185
       sum += bessel;
186
       local_window[i] = sum;
187
   }
188

    
189
   sum++;
190
   for (i = 0; i < 256; i++)
191
       window[i] = sqrt(local_window[i] / sum);
192
}
193

    
194
/*
195
 * Generate quantizer tables.
196
 */
197
static void generate_quantizers_table(int16_t quantizers[], int level, int length)
198
{
199
    int i;
200

    
201
    for (i = 0; i < length; i++)
202
        quantizers[i] = ((2 * i - level + 1) << 15) / level;
203
}
204

    
205
static void generate_quantizers_table_1(int16_t quantizers[], int level, int length1, int length2, int size)
206
{
207
    int i, j;
208
    int16_t v;
209

    
210
    for (i = 0; i < length1; i++) {
211
        v = ((2 * i - level + 1) << 15) / level;
212
        for (j = 0; j < length2; j++)
213
            quantizers[i * length2 + j] = v;
214
    }
215

    
216
    for (i = length1 * length2; i < size; i++)
217
        quantizers[i] = 0;
218
}
219

    
220
static void generate_quantizers_table_2(int16_t quantizers[], int level, int length1, int length2, int size)
221
{
222
    int i, j;
223
    int16_t v;
224

    
225
    for (i = 0; i < length1; i++) {
226
        v = ((2 * (i % level) - level + 1) << 15) / level;
227
        for (j = 0; j < length2; j++)
228
            quantizers[i * length2 + j] = v;
229
    }
230

    
231
    for (i = length1 * length2; i < size; i++)
232
        quantizers[i] = 0;
233

    
234
}
235

    
236
static void generate_quantizers_table_3(int16_t quantizers[], int level, int length1, int length2, int size)
237
{
238
    int i, j;
239

    
240
    for (i = 0; i < length1; i++)
241
        for (j = 0; j < length2; j++)
242
            quantizers[i * length2 + j] = ((2 * (j % level) - level + 1) << 15) / level;
243

    
244
    for (i = length1 * length2; i < size; i++)
245
        quantizers[i] = 0;
246
}
247

    
248
/*
249
 * Initialize tables at runtime.
250
 */
251
static void ac3_tables_init(void)
252
{
253
    int i;
254

    
255
    /* Quantizer ungrouping tables. */
256
    // for level-3 quantizers
257
    generate_quantizers_table_1(l3_quantizers_1, 3, 3, 9, 32);
258
    generate_quantizers_table_2(l3_quantizers_2, 3, 9, 3, 32);
259
    generate_quantizers_table_3(l3_quantizers_3, 3, 9, 3, 32);
260

    
261
    //for level-5 quantizers
262
    generate_quantizers_table_1(l5_quantizers_1, 5, 5, 25, 128);
263
    generate_quantizers_table_2(l5_quantizers_2, 5, 25, 5, 128);
264
    generate_quantizers_table_3(l5_quantizers_3, 5, 25, 5, 128);
265

    
266
    //for level-7 quantizers
267
    generate_quantizers_table(l7_quantizers, 7, 7);
268

    
269
    //for level-4 quantizers
270
    generate_quantizers_table_2(l11_quantizers_1, 11, 11, 11, 128);
271
    generate_quantizers_table_3(l11_quantizers_2, 11, 11, 11, 128);
272

    
273
    //for level-15 quantizers
274
    generate_quantizers_table(l15_quantizers, 15, 15);
275
    /* End Quantizer ungrouping tables. */
276

    
277
    //generate scale factors
278
    for (i = 0; i < 25; i++)
279
        scale_factors[i] = pow(2.0, -(i + 15));
280

    
281
    /* generate exponent tables
282
       reference: Section 7.1.3 Exponent Decoding */
283
    for(i=0; i<128; i++) {
284
        exp_ungroup_tbl[i][0] =  i / 25;
285
        exp_ungroup_tbl[i][1] = (i % 25) / 5;
286
        exp_ungroup_tbl[i][2] = (i % 25) % 5;
287
    }
288
}
289

    
290

    
291
static int ac3_decode_init(AVCodecContext *avctx)
292
{
293
    AC3DecodeContext *ctx = avctx->priv_data;
294

    
295
    ac3_common_init();
296
    ac3_tables_init();
297
    ff_mdct_init(&ctx->imdct_256, 8, 1);
298
    ff_mdct_init(&ctx->imdct_512, 9, 1);
299
    ac3_window_init(ctx->window);
300
    dsputil_init(&ctx->dsp, avctx);
301
    av_init_random(0, &ctx->dith_state);
302

    
303
    return 0;
304
}
305
/*********** END INIT FUNCTIONS ***********/
306

    
307
/**
308
 * Parses the 'sync info' and 'bit stream info' from the AC-3 bitstream.
309
 * GetBitContext within AC3DecodeContext must point to
310
 * start of the synchronized ac3 bitstream.
311
 */
312
static int ac3_parse_header(AC3DecodeContext *ctx)
313
{
314
    AC3HeaderInfo hdr;
315
    GetBitContext *gb = &ctx->gb;
316
    int err, i;
317

    
318
    err = ff_ac3_parse_header(gb->buffer, &hdr);
319
    if(err)
320
        return err;
321

    
322
    /* get decoding parameters from header info */
323
    ctx->bit_alloc_params.fscod       = hdr.fscod;
324
    ctx->acmod                        = hdr.acmod;
325
    ctx->cmixlev                      = hdr.cmixlev;
326
    ctx->surmixlev                    = hdr.surmixlev;
327
    ctx->dsurmod                      = hdr.dsurmod;
328
    ctx->lfeon                        = hdr.lfeon;
329
    ctx->bit_alloc_params.halfratecod = hdr.halfratecod;
330
    ctx->sampling_rate                = hdr.sample_rate;
331
    ctx->bit_rate                     = hdr.bit_rate;
332
    ctx->nchans                       = hdr.channels;
333
    ctx->nfchans                      = ctx->nchans - ctx->lfeon;
334
    ctx->frame_size                   = hdr.frame_size;
335

    
336
    /* set default output to all source channels */
337
    ctx->out_channels = ctx->nchans;
338
    ctx->output_mode = ctx->acmod;
339
    if(ctx->lfeon)
340
        ctx->output_mode |= AC3_OUTPUT_LFEON;
341

    
342
    /* skip over portion of header which has already been read */
343
    skip_bits(gb, 16); //skip the sync_word, sync_info->sync_word = get_bits(gb, 16);
344
    skip_bits(gb, 16); // skip crc1
345
    skip_bits(gb, 8);  // skip fscod and frmsizecod
346
    skip_bits(gb, 11); // skip bsid, bsmod, and acmod
347
    if(ctx->acmod == AC3_ACMOD_STEREO) {
348
        skip_bits(gb, 2); // skip dsurmod
349
    } else {
350
        if((ctx->acmod & 1) && ctx->acmod != AC3_ACMOD_MONO)
351
            skip_bits(gb, 2); // skip cmixlev
352
        if(ctx->acmod & 4)
353
            skip_bits(gb, 2); // skip surmixlev
354
    }
355
    skip_bits1(gb); // skip lfeon
356

    
357
    /* read the rest of the bsi. read twice for dual mono mode. */
358
    i = !(ctx->acmod);
359
    do {
360
        skip_bits(gb, 5); //skip dialog normalization
361
        if (get_bits1(gb))
362
            skip_bits(gb, 8); //skip compression
363
        if (get_bits1(gb))
364
            skip_bits(gb, 8); //skip language code
365
        if (get_bits1(gb))
366
            skip_bits(gb, 7); //skip audio production information
367
    } while (i--);
368

    
369
    skip_bits(gb, 2); //skip copyright bit and original bitstream bit
370

    
371
    /* FIXME: read & use the xbsi1 downmix levels */
372
    if (get_bits1(gb))
373
        skip_bits(gb, 14); //skip timecode1
374
    if (get_bits1(gb))
375
        skip_bits(gb, 14); //skip timecode2
376

    
377
    if (get_bits1(gb)) {
378
        i = get_bits(gb, 6); //additional bsi length
379
        do {
380
            skip_bits(gb, 8);
381
        } while(i--);
382
    }
383

    
384
    return 0;
385
}
386

    
387
/**
388
 * Decodes the grouped exponents.
389
 * This function decodes the coded exponents according to exponent strategy
390
 * and stores them in the decoded exponents buffer.
391
 *
392
 * @param[in]  gb      GetBitContext which points to start of coded exponents
393
 * @param[in]  expstr  Exponent coding strategy
394
 * @param[in]  ngrps   Number of grouped exponents
395
 * @param[in]  absexp  Absolute exponent or DC exponent
396
 * @param[out] dexps   Decoded exponents are stored in dexps
397
 */
398
static void decode_exponents(GetBitContext *gb, int expstr, int ngrps,
399
                             uint8_t absexp, int8_t *dexps)
400
{
401
    int i, j, grp, grpsize;
402
    int dexp[256];
403
    int expacc, prevexp;
404

    
405
    /* unpack groups */
406
    grpsize = expstr + (expstr == EXP_D45);
407
    for(grp=0,i=0; grp<ngrps; grp++) {
408
        expacc = get_bits(gb, 7);
409
        dexp[i++] = exp_ungroup_tbl[expacc][0];
410
        dexp[i++] = exp_ungroup_tbl[expacc][1];
411
        dexp[i++] = exp_ungroup_tbl[expacc][2];
412
    }
413

    
414
    /* convert to absolute exps and expand groups */
415
    prevexp = absexp;
416
    for(i=0; i<ngrps*3; i++) {
417
        prevexp = av_clip(prevexp + dexp[i]-2, 0, 24);
418
        for(j=0; j<grpsize; j++) {
419
            dexps[(i*grpsize)+j] = prevexp;
420
        }
421
    }
422
}
423

    
424
typedef struct { /* grouped mantissas for 3-level 5-leve and 11-level quantization */
425
    int16_t l3_quantizers[3];
426
    int16_t l5_quantizers[3];
427
    int16_t l11_quantizers[2];
428
    int l3ptr;
429
    int l5ptr;
430
    int l11ptr;
431
} mant_groups;
432

    
433
/* Get the transform coefficients for coupling channel and uncouple channels.
434
 * The coupling transform coefficients starts at the the cplstrtmant, which is
435
 * equal to endmant[ch] for fbw channels. Hence we can uncouple channels before
436
 * getting transform coefficients for the channel.
437
 */
438
static int get_transform_coeffs_cpling(AC3DecodeContext *ctx, mant_groups *m)
439
{
440
    GetBitContext *gb = &ctx->gb;
441
    int ch, start, end, cplbndstrc, bnd, gcode, tbap;
442
    float cplcos[5], cplcoeff;
443
    uint8_t *exps = ctx->dcplexps;
444
    uint8_t *bap = ctx->cplbap;
445

    
446
    cplbndstrc = ctx->cplbndstrc;
447
    start = ctx->cplstrtmant;
448
    bnd = 0;
449

    
450
    while (start < ctx->cplendmant) {
451
        end = start + 12;
452
        while (cplbndstrc & 1) {
453
            end += 12;
454
            cplbndstrc >>= 1;
455
        }
456
        cplbndstrc >>= 1;
457
        for (ch = 0; ch < ctx->nfchans; ch++)
458
            cplcos[ch] = ctx->cplco[ch][bnd];
459
        bnd++;
460

    
461
        while (start < end) {
462
            tbap = bap[start];
463
            switch(tbap) {
464
                case 0:
465
                    for (ch = 0; ch < ctx->nfchans; ch++)
466
                        if (ctx->chincpl[ch]) {
467
                            if (ctx->dithflag[ch]) {
468
                                cplcoeff = (av_random(&ctx->dith_state) & 0xFFFF) * scale_factors[exps[start]];
469
                                ctx->transform_coeffs[ch + 1][start] = cplcoeff * cplcos[ch] * LEVEL_MINUS_3DB;
470
                            } else
471
                                ctx->transform_coeffs[ch + 1][start] = 0;
472
                        }
473
                    start++;
474
                    continue;
475
                case 1:
476
                    if (m->l3ptr > 2) {
477
                        gcode = get_bits(gb, 5);
478
                        m->l3_quantizers[0] = l3_quantizers_1[gcode];
479
                        m->l3_quantizers[1] = l3_quantizers_2[gcode];
480
                        m->l3_quantizers[2] = l3_quantizers_3[gcode];
481
                        m->l3ptr = 0;
482
                    }
483
                    cplcoeff = m->l3_quantizers[m->l3ptr++] * scale_factors[exps[start]];
484
                    break;
485

    
486
                case 2:
487
                    if (m->l5ptr > 2) {
488
                        gcode = get_bits(gb, 7);
489
                        m->l5_quantizers[0] = l5_quantizers_1[gcode];
490
                        m->l5_quantizers[1] = l5_quantizers_2[gcode];
491
                        m->l5_quantizers[2] = l5_quantizers_3[gcode];
492
                        m->l5ptr = 0;
493
                    }
494
                    cplcoeff = m->l5_quantizers[m->l5ptr++] * scale_factors[exps[start]];
495
                    break;
496

    
497
                case 3:
498
                    cplcoeff = l7_quantizers[get_bits(gb, 3)] * scale_factors[exps[start]];
499
                    break;
500

    
501
                case 4:
502
                    if (m->l11ptr > 1) {
503
                        gcode = get_bits(gb, 7);
504
                        m->l11_quantizers[0] = l11_quantizers_1[gcode];
505
                        m->l11_quantizers[1] = l11_quantizers_2[gcode];
506
                        m->l11ptr = 0;
507
                    }
508
                    cplcoeff = m->l11_quantizers[m->l11ptr++] * scale_factors[exps[start]];
509
                    break;
510

    
511
                case 5:
512
                    cplcoeff = l15_quantizers[get_bits(gb, 4)] * scale_factors[exps[start]];
513
                    break;
514

    
515
                default:
516
                    cplcoeff = (get_sbits(gb, qntztab[tbap]) << (16 - qntztab[tbap])) * scale_factors[exps[start]];
517
            }
518
            for (ch = 0; ch < ctx->nfchans; ch++)
519
                if (ctx->chincpl[ch])
520
                    ctx->transform_coeffs[ch + 1][start] = cplcoeff * cplcos[ch];
521
            start++;
522
        }
523
    }
524

    
525
    return 0;
526
}
527

    
528
/* Get the transform coefficients for particular channel */
529
static int get_transform_coeffs_ch(AC3DecodeContext *ctx, int ch_index, mant_groups *m)
530
{
531
    GetBitContext *gb = &ctx->gb;
532
    int i, gcode, tbap, dithflag, end;
533
    uint8_t *exps;
534
    uint8_t *bap;
535
    float *coeffs;
536

    
537
    if (ch_index != -1) { /* fbw channels */
538
        dithflag = ctx->dithflag[ch_index];
539
        exps = ctx->dexps[ch_index];
540
        bap = ctx->bap[ch_index];
541
        coeffs = ctx->transform_coeffs[ch_index + 1];
542
        end = ctx->endmant[ch_index];
543
    } else if (ch_index == -1) {
544
        dithflag = 0;
545
        exps = ctx->dlfeexps;
546
        bap = ctx->lfebap;
547
        coeffs = ctx->transform_coeffs[0];
548
        end = 7;
549
    }
550

    
551

    
552
    for (i = 0; i < end; i++) {
553
        tbap = bap[i];
554
        switch (tbap) {
555
            case 0:
556
                if (!dithflag) {
557
                    coeffs[i] = 0;
558
                    continue;
559
                }
560
                else {
561
                    coeffs[i] = (av_random(&ctx->dith_state) & 0xFFFF) * scale_factors[exps[i]];
562
                    coeffs[i] *= LEVEL_MINUS_3DB;
563
                    continue;
564
                }
565

    
566
            case 1:
567
                if (m->l3ptr > 2) {
568
                    gcode = get_bits(gb, 5);
569
                    m->l3_quantizers[0] = l3_quantizers_1[gcode];
570
                    m->l3_quantizers[1] = l3_quantizers_2[gcode];
571
                    m->l3_quantizers[2] = l3_quantizers_3[gcode];
572
                    m->l3ptr = 0;
573
                }
574
                coeffs[i] = m->l3_quantizers[m->l3ptr++] * scale_factors[exps[i]];
575
                continue;
576

    
577
            case 2:
578
                if (m->l5ptr > 2) {
579
                    gcode = get_bits(gb, 7);
580
                    m->l5_quantizers[0] = l5_quantizers_1[gcode];
581
                    m->l5_quantizers[1] = l5_quantizers_2[gcode];
582
                    m->l5_quantizers[2] = l5_quantizers_3[gcode];
583
                    m->l5ptr = 0;
584
                }
585
                coeffs[i] = m->l5_quantizers[m->l5ptr++] * scale_factors[exps[i]];
586
                continue;
587

    
588
            case 3:
589
                coeffs[i] = l7_quantizers[get_bits(gb, 3)] * scale_factors[exps[i]];
590
                continue;
591

    
592
            case 4:
593
                if (m->l11ptr > 1) {
594
                    gcode = get_bits(gb, 7);
595
                    m->l11_quantizers[0] = l11_quantizers_1[gcode];
596
                    m->l11_quantizers[1] = l11_quantizers_2[gcode];
597
                    m->l11ptr = 0;
598
                }
599
                coeffs[i] = m->l11_quantizers[m->l11ptr++] * scale_factors[exps[i]];
600
                continue;
601

    
602
            case 5:
603
                coeffs[i] = l15_quantizers[get_bits(gb, 4)] * scale_factors[exps[i]];
604
                continue;
605

    
606
            default:
607
                coeffs[i] = (get_sbits(gb, qntztab[tbap]) << (16 - qntztab[tbap])) * scale_factors[exps[i]];
608
                continue;
609
        }
610
    }
611

    
612
    return 0;
613
}
614

    
615
/* Get the transform coefficients.
616
 * This function extracts the tranform coefficients form the ac3 bitstream.
617
 * This function is called after bit allocation is performed.
618
 */
619
static int get_transform_coeffs(AC3DecodeContext * ctx)
620
{
621
    int i, end;
622
    int got_cplchan = 0;
623
    mant_groups m;
624

    
625
    m.l3ptr = m.l5ptr = m.l11ptr = 3;
626

    
627
    for (i = 0; i < ctx->nfchans; i++) {
628
        /* transform coefficients for individual channel */
629
        if (get_transform_coeffs_ch(ctx, i, &m))
630
            return -1;
631
        /* tranform coefficients for coupling channels */
632
        if (ctx->chincpl[i])  {
633
            if (!got_cplchan) {
634
                if (get_transform_coeffs_cpling(ctx, &m)) {
635
                    av_log(NULL, AV_LOG_ERROR, "error in decoupling channels\n");
636
                    return -1;
637
                }
638
                got_cplchan = 1;
639
            }
640
            end = ctx->cplendmant;
641
        } else
642
            end = ctx->endmant[i];
643
        do
644
            ctx->transform_coeffs[i + 1][end] = 0;
645
        while(++end < 256);
646
    }
647
    if (ctx->lfeon) {
648
        if (get_transform_coeffs_ch(ctx, -1, &m))
649
                return -1;
650
        for (i = 7; i < 256; i++) {
651
            ctx->transform_coeffs[0][i] = 0;
652
        }
653
    }
654

    
655
    return 0;
656
}
657

    
658
/**
659
 * Performs stereo rematrixing.
660
 * reference: Section 7.5.4 Rematrixing : Decoding Technique
661
 */
662
static void do_rematrixing(AC3DecodeContext *ctx)
663
{
664
    int bnd, i;
665
    int end, bndend;
666
    float tmp0, tmp1;
667

    
668
    end = FFMIN(ctx->endmant[0], ctx->endmant[1]);
669

    
670
    for(bnd=0; bnd<ctx->nrematbnd; bnd++) {
671
        if(ctx->rematflg[bnd]) {
672
            bndend = FFMIN(end, rematrix_band_tbl[bnd+1]);
673
            for(i=rematrix_band_tbl[bnd]; i<bndend; i++) {
674
                tmp0 = ctx->transform_coeffs[1][i];
675
                tmp1 = ctx->transform_coeffs[2][i];
676
                ctx->transform_coeffs[1][i] = tmp0 + tmp1;
677
                ctx->transform_coeffs[2][i] = tmp0 - tmp1;
678
            }
679
        }
680
    }
681
}
682

    
683
/* This function performs the imdct on 256 sample transform
684
 * coefficients.
685
 */
686
static void do_imdct_256(AC3DecodeContext *ctx, int chindex)
687
{
688
    int i, k;
689
    float x[128];
690
    FFTComplex z[2][64];
691
    float *o_ptr = ctx->tmp_output;
692

    
693
    for(i=0; i<2; i++) {
694
        /* de-interleave coefficients */
695
        for(k=0; k<128; k++) {
696
            x[k] = ctx->transform_coeffs[chindex][2*k+i];
697
        }
698

    
699
        /* run standard IMDCT */
700
        ctx->imdct_256.fft.imdct_calc(&ctx->imdct_256, o_ptr, x, ctx->tmp_imdct);
701

    
702
        /* reverse the post-rotation & reordering from standard IMDCT */
703
        for(k=0; k<32; k++) {
704
            z[i][32+k].re = -o_ptr[128+2*k];
705
            z[i][32+k].im = -o_ptr[2*k];
706
            z[i][31-k].re =  o_ptr[2*k+1];
707
            z[i][31-k].im =  o_ptr[128+2*k+1];
708
        }
709
    }
710

    
711
    /* apply AC-3 post-rotation & reordering */
712
    for(k=0; k<64; k++) {
713
        o_ptr[    2*k  ] = -z[0][   k].im;
714
        o_ptr[    2*k+1] =  z[0][63-k].re;
715
        o_ptr[128+2*k  ] = -z[0][   k].re;
716
        o_ptr[128+2*k+1] =  z[0][63-k].im;
717
        o_ptr[256+2*k  ] = -z[1][   k].re;
718
        o_ptr[256+2*k+1] =  z[1][63-k].im;
719
        o_ptr[384+2*k  ] =  z[1][   k].im;
720
        o_ptr[384+2*k+1] = -z[1][63-k].re;
721
    }
722
}
723

    
724
/* IMDCT Transform. */
725
static inline void do_imdct(AC3DecodeContext *ctx)
726
{
727
    int ch;
728

    
729
    if (ctx->output_mode & AC3_OUTPUT_LFEON) {
730
        ctx->imdct_512.fft.imdct_calc(&ctx->imdct_512, ctx->tmp_output,
731
                                      ctx->transform_coeffs[0], ctx->tmp_imdct);
732
        ctx->dsp.vector_fmul_add_add(ctx->output[0], ctx->tmp_output,
733
                                     ctx->window, ctx->delay[0], 384, 256, 1);
734
        ctx->dsp.vector_fmul_reverse(ctx->delay[0], ctx->tmp_output+256,
735
                                     ctx->window, 256);
736
    }
737
    for (ch=1; ch<=ctx->nfchans; ch++) {
738
        if (ctx->blksw[ch-1])
739
            do_imdct_256(ctx, ch);
740
        else
741
            ctx->imdct_512.fft.imdct_calc(&ctx->imdct_512, ctx->tmp_output,
742
                                          ctx->transform_coeffs[ch],
743
                                          ctx->tmp_imdct);
744

    
745
        ctx->dsp.vector_fmul_add_add(ctx->output[ch], ctx->tmp_output,
746
                                     ctx->window, ctx->delay[ch], 384, 256, 1);
747
        ctx->dsp.vector_fmul_reverse(ctx->delay[ch], ctx->tmp_output+256,
748
                                     ctx->window, 256);
749
    }
750
}
751

    
752
/* Parse the audio block from ac3 bitstream.
753
 * This function extract the audio block from the ac3 bitstream
754
 * and produces the output for the block. This function must
755
 * be called for each of the six audio block in the ac3 bitstream.
756
 */
757
static int ac3_parse_audio_block(AC3DecodeContext *ctx, int blk)
758
{
759
    int nfchans = ctx->nfchans;
760
    int acmod = ctx->acmod;
761
    int i, bnd, seg, grpsize, ch;
762
    GetBitContext *gb = &ctx->gb;
763
    int bit_alloc_flags = 0;
764
    int8_t *dexps;
765
    int mstrcplco, cplcoexp, cplcomant;
766
    int dynrng, chbwcod, ngrps, cplabsexp, skipl;
767

    
768
    for (i = 0; i < nfchans; i++) /*block switch flag */
769
        ctx->blksw[i] = get_bits1(gb);
770

    
771
    for (i = 0; i < nfchans; i++) /* dithering flag */
772
        ctx->dithflag[i] = get_bits1(gb);
773

    
774
    if (get_bits1(gb)) { /* dynamic range */
775
        dynrng = get_sbits(gb, 8);
776
        ctx->dynrng = ((((dynrng & 0x1f) | 0x20) << 13) * scale_factors[3 - (dynrng >> 5)]);
777
    } else if(blk == 0) {
778
        ctx->dynrng = 1.0;
779
    }
780

    
781
    if(acmod == AC3_ACMOD_DUALMONO) { /* dynamic range 1+1 mode */
782
        if(get_bits1(gb)) {
783
            dynrng = get_sbits(gb, 8);
784
            ctx->dynrng2 = ((((dynrng & 0x1f) | 0x20) << 13) * scale_factors[3 - (dynrng >> 5)]);
785
        } else if(blk == 0) {
786
            ctx->dynrng2 = 1.0;
787
        }
788
    }
789

    
790
    if (get_bits1(gb)) { /* coupling strategy */
791
        ctx->cplinu = get_bits1(gb);
792
        ctx->cplbndstrc = 0;
793
        if (ctx->cplinu) { /* coupling in use */
794
            int cplbegf, cplendf;
795

    
796
            for (i = 0; i < nfchans; i++)
797
                ctx->chincpl[i] = get_bits1(gb);
798

    
799
            if (acmod == AC3_ACMOD_STEREO)
800
                ctx->phsflginu = get_bits1(gb); //phase flag in use
801

    
802
            cplbegf = get_bits(gb, 4);
803
            cplendf = get_bits(gb, 4);
804

    
805
            if (3 + cplendf - cplbegf < 0) {
806
                av_log(NULL, AV_LOG_ERROR, "cplendf = %d < cplbegf = %d\n", cplendf, cplbegf);
807
                return -1;
808
            }
809

    
810
            ctx->ncplbnd = ctx->ncplsubnd = 3 + cplendf - cplbegf;
811
            ctx->cplstrtmant = cplbegf * 12 + 37;
812
            ctx->cplendmant = cplendf * 12 + 73;
813
            for (i = 0; i < ctx->ncplsubnd - 1; i++) /* coupling band structure */
814
                if (get_bits1(gb)) {
815
                    ctx->cplbndstrc |= 1 << i;
816
                    ctx->ncplbnd--;
817
                }
818
        } else {
819
            for (i = 0; i < nfchans; i++)
820
                ctx->chincpl[i] = 0;
821
        }
822
    }
823

    
824
    if (ctx->cplinu) {
825
        ctx->cplcoe = 0;
826

    
827
        for (i = 0; i < nfchans; i++)
828
            if (ctx->chincpl[i])
829
                if (get_bits1(gb)) { /* coupling co-ordinates */
830
                    ctx->cplcoe |= 1 << i;
831
                    mstrcplco = 3 * get_bits(gb, 2);
832
                    for (bnd = 0; bnd < ctx->ncplbnd; bnd++) {
833
                        cplcoexp = get_bits(gb, 4);
834
                        cplcomant = get_bits(gb, 4);
835
                        if (cplcoexp == 15)
836
                            cplcomant <<= 14;
837
                        else
838
                            cplcomant = (cplcomant | 0x10) << 13;
839
                        ctx->cplco[i][bnd] = cplcomant * scale_factors[cplcoexp + mstrcplco];
840
                    }
841
                }
842

    
843
        if (acmod == AC3_ACMOD_STEREO && ctx->phsflginu && (ctx->cplcoe & 1 || ctx->cplcoe & 2))
844
            for (bnd = 0; bnd < ctx->ncplbnd; bnd++)
845
                if (get_bits1(gb))
846
                    ctx->cplco[1][bnd] = -ctx->cplco[1][bnd];
847
    }
848

    
849
    if (acmod == AC3_ACMOD_STEREO) {/* rematrixing */
850
        ctx->rematstr = get_bits1(gb);
851
        if (ctx->rematstr) {
852
            ctx->nrematbnd = 4;
853
            if(ctx->cplinu && ctx->cplstrtmant <= 61)
854
                ctx->nrematbnd -= 1 + (ctx->cplstrtmant == 37);
855
            for(bnd=0; bnd<ctx->nrematbnd; bnd++)
856
                ctx->rematflg[bnd] = get_bits1(gb);
857
        }
858
    }
859

    
860
    ctx->cplexpstr = EXP_REUSE;
861
    ctx->lfeexpstr = EXP_REUSE;
862
    if (ctx->cplinu) /* coupling exponent strategy */
863
        ctx->cplexpstr = get_bits(gb, 2);
864
    for (i = 0; i < nfchans; i++)  /* channel exponent strategy */
865
        ctx->chexpstr[i] = get_bits(gb, 2);
866
    if (ctx->lfeon)  /* lfe exponent strategy */
867
        ctx->lfeexpstr = get_bits1(gb);
868

    
869
    for (i = 0; i < nfchans; i++) /* channel bandwidth code */
870
        if (ctx->chexpstr[i] != EXP_REUSE) {
871
            if (ctx->chincpl[i])
872
                ctx->endmant[i] = ctx->cplstrtmant;
873
            else {
874
                chbwcod = get_bits(gb, 6);
875
                if (chbwcod > 60) {
876
                    av_log(NULL, AV_LOG_ERROR, "chbwcod = %d > 60", chbwcod);
877
                    return -1;
878
                }
879
                ctx->endmant[i] = chbwcod * 3 + 73;
880
            }
881
        }
882

    
883
    if (ctx->cplexpstr != EXP_REUSE) {/* coupling exponents */
884
        bit_alloc_flags = 64;
885
        cplabsexp = get_bits(gb, 4) << 1;
886
        ngrps = (ctx->cplendmant - ctx->cplstrtmant) / (3 << (ctx->cplexpstr - 1));
887
        decode_exponents(gb, ctx->cplexpstr, ngrps, cplabsexp, ctx->dcplexps + ctx->cplstrtmant);
888
    }
889

    
890
    for (i = 0; i < nfchans; i++) /* fbw channel exponents */
891
        if (ctx->chexpstr[i] != EXP_REUSE) {
892
            bit_alloc_flags |= 1 << i;
893
            grpsize = 3 << (ctx->chexpstr[i] - 1);
894
            ngrps = (ctx->endmant[i] + grpsize - 4) / grpsize;
895
            dexps = ctx->dexps[i];
896
            dexps[0] = get_bits(gb, 4);
897
            decode_exponents(gb, ctx->chexpstr[i], ngrps, dexps[0], dexps + 1);
898
            skip_bits(gb, 2); /* skip gainrng */
899
        }
900

    
901
    if (ctx->lfeexpstr != EXP_REUSE) { /* lfe exponents */
902
        bit_alloc_flags |= 32;
903
        ctx->dlfeexps[0] = get_bits(gb, 4);
904
        decode_exponents(gb, ctx->lfeexpstr, 2, ctx->dlfeexps[0], ctx->dlfeexps + 1);
905
    }
906

    
907
    if (get_bits1(gb)) { /* bit allocation information */
908
        bit_alloc_flags = 127;
909
        ctx->bit_alloc_params.sdecay = ff_sdecaytab[get_bits(gb, 2)];
910
        ctx->bit_alloc_params.fdecay = ff_fdecaytab[get_bits(gb, 2)];
911
        ctx->bit_alloc_params.sgain  = ff_sgaintab[get_bits(gb, 2)];
912
        ctx->bit_alloc_params.dbknee = ff_dbkneetab[get_bits(gb, 2)];
913
        ctx->bit_alloc_params.floor  = ff_floortab[get_bits(gb, 3)];
914
    }
915

    
916
    if (get_bits1(gb)) { /* snroffset */
917
        int csnr;
918
        bit_alloc_flags = 127;
919
        csnr = (get_bits(gb, 6) - 15) << 4;
920
        if (ctx->cplinu) { /* coupling fine snr offset and fast gain code */
921
            ctx->cplsnroffst = (csnr + get_bits(gb, 4)) << 2;
922
            ctx->cplfgain = ff_fgaintab[get_bits(gb, 3)];
923
        }
924
        for (i = 0; i < nfchans; i++) { /* channel fine snr offset and fast gain code */
925
            ctx->snroffst[i] = (csnr + get_bits(gb, 4)) << 2;
926
            ctx->fgain[i] = ff_fgaintab[get_bits(gb, 3)];
927
        }
928
        if (ctx->lfeon) { /* lfe fine snr offset and fast gain code */
929
            ctx->lfesnroffst = (csnr + get_bits(gb, 4)) << 2;
930
            ctx->lfefgain = ff_fgaintab[get_bits(gb, 3)];
931
        }
932
    }
933

    
934
    if (ctx->cplinu && get_bits1(gb)) { /* coupling leak information */
935
        bit_alloc_flags |= 64;
936
        ctx->bit_alloc_params.cplfleak = get_bits(gb, 3);
937
        ctx->bit_alloc_params.cplsleak = get_bits(gb, 3);
938
    }
939

    
940
    if (get_bits1(gb)) { /* delta bit allocation information */
941
        bit_alloc_flags = 127;
942

    
943
        if (ctx->cplinu) {
944
            ctx->cpldeltbae = get_bits(gb, 2);
945
            if (ctx->cpldeltbae == DBA_RESERVED) {
946
                av_log(NULL, AV_LOG_ERROR, "coupling delta bit allocation strategy reserved\n");
947
                return -1;
948
            }
949
        }
950

    
951
        for (i = 0; i < nfchans; i++) {
952
            ctx->deltbae[i] = get_bits(gb, 2);
953
            if (ctx->deltbae[i] == DBA_RESERVED) {
954
                av_log(NULL, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
955
                return -1;
956
            }
957
        }
958

    
959
        if (ctx->cplinu)
960
            if (ctx->cpldeltbae == DBA_NEW) { /*coupling delta offset, len and bit allocation */
961
                ctx->cpldeltnseg = get_bits(gb, 3);
962
                for (seg = 0; seg <= ctx->cpldeltnseg; seg++) {
963
                    ctx->cpldeltoffst[seg] = get_bits(gb, 5);
964
                    ctx->cpldeltlen[seg] = get_bits(gb, 4);
965
                    ctx->cpldeltba[seg] = get_bits(gb, 3);
966
                }
967
            }
968

    
969
        for (i = 0; i < nfchans; i++)
970
            if (ctx->deltbae[i] == DBA_NEW) {/*channel delta offset, len and bit allocation */
971
                ctx->deltnseg[i] = get_bits(gb, 3);
972
                for (seg = 0; seg <= ctx->deltnseg[i]; seg++) {
973
                    ctx->deltoffst[i][seg] = get_bits(gb, 5);
974
                    ctx->deltlen[i][seg] = get_bits(gb, 4);
975
                    ctx->deltba[i][seg] = get_bits(gb, 3);
976
                }
977
            }
978
    } else if(blk == 0) {
979
        if(ctx->cplinu)
980
            ctx->cpldeltbae = DBA_NONE;
981
        for(i=0; i<nfchans; i++) {
982
            ctx->deltbae[i] = DBA_NONE;
983
        }
984
    }
985

    
986
    if (bit_alloc_flags) {
987
        if (ctx->cplinu && (bit_alloc_flags & 64))
988
            ac3_parametric_bit_allocation(&ctx->bit_alloc_params, ctx->cplbap,
989
                                          ctx->dcplexps, ctx->cplstrtmant,
990
                                          ctx->cplendmant, ctx->cplsnroffst,
991
                                          ctx->cplfgain, 0,
992
                                          ctx->cpldeltbae, ctx->cpldeltnseg,
993
                                          ctx->cpldeltoffst, ctx->cpldeltlen,
994
                                          ctx->cpldeltba);
995
        for (i = 0; i < nfchans; i++)
996
            if ((bit_alloc_flags >> i) & 1)
997
                ac3_parametric_bit_allocation(&ctx->bit_alloc_params,
998
                                              ctx->bap[i], ctx->dexps[i], 0,
999
                                              ctx->endmant[i], ctx->snroffst[i],
1000
                                              ctx->fgain[i], 0, ctx->deltbae[i],
1001
                                              ctx->deltnseg[i], ctx->deltoffst[i],
1002
                                              ctx->deltlen[i], ctx->deltba[i]);
1003
        if (ctx->lfeon && (bit_alloc_flags & 32))
1004
            ac3_parametric_bit_allocation(&ctx->bit_alloc_params, ctx->lfebap,
1005
                                          ctx->dlfeexps, 0, 7, ctx->lfesnroffst,
1006
                                          ctx->lfefgain, 1,
1007
                                          DBA_NONE, 0, NULL, NULL, NULL);
1008
    }
1009

    
1010
    if (get_bits1(gb)) { /* unused dummy data */
1011
        skipl = get_bits(gb, 9);
1012
        while(skipl--)
1013
            skip_bits(gb, 8);
1014
    }
1015
    /* unpack the transform coefficients
1016
     * * this also uncouples channels if coupling is in use.
1017
     */
1018
    if (get_transform_coeffs(ctx)) {
1019
        av_log(NULL, AV_LOG_ERROR, "Error in routine get_transform_coeffs\n");
1020
        return -1;
1021
    }
1022

    
1023
    /* recover coefficients if rematrixing is in use */
1024
    if(ctx->acmod == AC3_ACMOD_STEREO)
1025
        do_rematrixing(ctx);
1026

    
1027
    /* apply scaling to coefficients (headroom, dynrng) */
1028
    if(ctx->lfeon) {
1029
        for(i=0; i<7; i++) {
1030
            ctx->transform_coeffs[0][i] *= 2.0f * ctx->dynrng;
1031
        }
1032
    }
1033
    for(ch=1; ch<=ctx->nfchans; ch++) {
1034
        float gain = 2.0f;
1035
        if(ctx->acmod == AC3_ACMOD_DUALMONO && ch == 2) {
1036
            gain *= ctx->dynrng2;
1037
        } else {
1038
            gain *= ctx->dynrng;
1039
        }
1040
        for(i=0; i<ctx->endmant[ch-1]; i++) {
1041
            ctx->transform_coeffs[ch][i] *= gain;
1042
        }
1043
    }
1044

    
1045
    do_imdct(ctx);
1046

    
1047
    return 0;
1048
}
1049

    
1050
static inline int16_t convert(int32_t i)
1051
{
1052
    if (i > 0x43c07fff)
1053
        return 32767;
1054
    else if (i <= 0x43bf8000)
1055
        return -32768;
1056
    else
1057
        return (i - 0x43c00000);
1058
}
1059

    
1060
/* Decode ac3 frame.
1061
 *
1062
 * @param avctx Pointer to AVCodecContext
1063
 * @param data Pointer to pcm smaples
1064
 * @param data_size Set to number of pcm samples produced by decoding
1065
 * @param buf Data to be decoded
1066
 * @param buf_size Size of the buffer
1067
 */
1068
static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size, uint8_t *buf, int buf_size)
1069
{
1070
    AC3DecodeContext *ctx = (AC3DecodeContext *)avctx->priv_data;
1071
    int16_t *out_samples = (int16_t *)data;
1072
    int i, j, k, start;
1073
    int32_t *int_ptr[6];
1074

    
1075
    for (i = 0; i < 6; i++)
1076
        int_ptr[i] = (int32_t *)(&ctx->output[i]);
1077

    
1078
    //Initialize the GetBitContext with the start of valid AC3 Frame.
1079
    init_get_bits(&ctx->gb, buf, buf_size * 8);
1080

    
1081
    //Parse the syncinfo.
1082
    if (ac3_parse_header(ctx)) {
1083
        av_log(avctx, AV_LOG_ERROR, "\n");
1084
        *data_size = 0;
1085
        return buf_size;
1086
    }
1087

    
1088
    avctx->sample_rate = ctx->sampling_rate;
1089
    avctx->bit_rate = ctx->bit_rate;
1090

    
1091
    /* channel config */
1092
    if (avctx->channels == 0) {
1093
        avctx->channels = ctx->out_channels;
1094
    }
1095
    if(avctx->channels != ctx->out_channels) {
1096
        av_log(avctx, AV_LOG_ERROR, "Cannot mix AC3 to %d channels.\n",
1097
               avctx->channels);
1098
        return -1;
1099
    }
1100

    
1101
    //av_log(avctx, AV_LOG_INFO, "channels = %d \t bit rate = %d \t sampling rate = %d \n", avctx->channels, avctx->bit_rate * 1000, avctx->sample_rate);
1102

    
1103
    //Parse the Audio Blocks.
1104
    for (i = 0; i < NB_BLOCKS; i++) {
1105
        if (ac3_parse_audio_block(ctx, i)) {
1106
            av_log(avctx, AV_LOG_ERROR, "error parsing the audio block\n");
1107
            *data_size = 0;
1108
            return ctx->frame_size;
1109
        }
1110
        start = (ctx->output_mode & AC3_OUTPUT_LFEON) ? 0 : 1;
1111
        for (k = 0; k < 256; k++)
1112
            for (j = start; j <= ctx->nfchans; j++)
1113
                *(out_samples++) = convert(int_ptr[j][k]);
1114
    }
1115
    *data_size = NB_BLOCKS * 256 * avctx->channels * sizeof (int16_t);
1116
    return ctx->frame_size;
1117
}
1118

    
1119
/* Uninitialize ac3 decoder.
1120
 */
1121
static int ac3_decode_end(AVCodecContext *avctx)
1122
{
1123
    AC3DecodeContext *ctx = (AC3DecodeContext *)avctx->priv_data;
1124
    ff_mdct_end(&ctx->imdct_512);
1125
    ff_mdct_end(&ctx->imdct_256);
1126

    
1127
    return 0;
1128
}
1129

    
1130
AVCodec ac3_decoder = {
1131
    .name = "ac3",
1132
    .type = CODEC_TYPE_AUDIO,
1133
    .id = CODEC_ID_AC3,
1134
    .priv_data_size = sizeof (AC3DecodeContext),
1135
    .init = ac3_decode_init,
1136
    .close = ac3_decode_end,
1137
    .decode = ac3_decode_frame,
1138
};
1139