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1
/*
2
 * AC-3 Audio Decoder
3
 * This code was developed as part of Google Summer of Code 2006.
4
 * E-AC-3 support was added as part of Google Summer of Code 2007.
5
 *
6
 * Copyright (c) 2006 Kartikey Mahendra BHATT (bhattkm at gmail dot com)
7
 * Copyright (c) 2007-2008 Bartlomiej Wolowiec <bartek.wolowiec@gmail.com>
8
 * Copyright (c) 2007 Justin Ruggles <justin.ruggles@gmail.com>
9
 *
10
 * This file is part of Libav.
11
 *
12
 * Libav is free software; you can redistribute it and/or
13
 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * Libav is distributed in the hope that it will be useful,
18
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
20
 * Lesser General Public License for more details.
21
 *
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 * You should have received a copy of the GNU Lesser General Public
23
 * License along with Libav; if not, write to the Free Software
24
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
25
 */
26

    
27
#include <stdio.h>
28
#include <stddef.h>
29
#include <math.h>
30
#include <string.h>
31

    
32
#include "libavutil/crc.h"
33
#include "internal.h"
34
#include "aac_ac3_parser.h"
35
#include "ac3_parser.h"
36
#include "ac3dec.h"
37
#include "ac3dec_data.h"
38
#include "kbdwin.h"
39

    
40
/** Large enough for maximum possible frame size when the specification limit is ignored */
41
#define AC3_FRAME_BUFFER_SIZE 32768
42

    
43
/**
44
 * table for ungrouping 3 values in 7 bits.
45
 * used for exponents and bap=2 mantissas
46
 */
47
static uint8_t ungroup_3_in_7_bits_tab[128][3];
48

    
49

    
50
/** tables for ungrouping mantissas */
51
static int b1_mantissas[32][3];
52
static int b2_mantissas[128][3];
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static int b3_mantissas[8];
54
static int b4_mantissas[128][2];
55
static int b5_mantissas[16];
56

    
57
/**
58
 * Quantization table: levels for symmetric. bits for asymmetric.
59
 * reference: Table 7.18 Mapping of bap to Quantizer
60
 */
61
static const uint8_t quantization_tab[16] = {
62
    0, 3, 5, 7, 11, 15,
63
    5, 6, 7, 8, 9, 10, 11, 12, 14, 16
64
};
65

    
66
/** dynamic range table. converts codes to scale factors. */
67
static float dynamic_range_tab[256];
68

    
69
/** Adjustments in dB gain */
70
#define LEVEL_PLUS_3DB          1.4142135623730950
71
#define LEVEL_PLUS_1POINT5DB    1.1892071150027209
72
#define LEVEL_MINUS_1POINT5DB   0.8408964152537145
73
#define LEVEL_MINUS_3DB         0.7071067811865476
74
#define LEVEL_MINUS_4POINT5DB   0.5946035575013605
75
#define LEVEL_MINUS_6DB         0.5000000000000000
76
#define LEVEL_MINUS_9DB         0.3535533905932738
77
#define LEVEL_ZERO              0.0000000000000000
78
#define LEVEL_ONE               1.0000000000000000
79

    
80
static const float gain_levels[9] = {
81
    LEVEL_PLUS_3DB,
82
    LEVEL_PLUS_1POINT5DB,
83
    LEVEL_ONE,
84
    LEVEL_MINUS_1POINT5DB,
85
    LEVEL_MINUS_3DB,
86
    LEVEL_MINUS_4POINT5DB,
87
    LEVEL_MINUS_6DB,
88
    LEVEL_ZERO,
89
    LEVEL_MINUS_9DB
90
};
91

    
92
/**
93
 * Table for center mix levels
94
 * reference: Section 5.4.2.4 cmixlev
95
 */
96
static const uint8_t center_levels[4] = { 4, 5, 6, 5 };
97

    
98
/**
99
 * Table for surround mix levels
100
 * reference: Section 5.4.2.5 surmixlev
101
 */
102
static const uint8_t surround_levels[4] = { 4, 6, 7, 6 };
103

    
104
/**
105
 * Table for default stereo downmixing coefficients
106
 * reference: Section 7.8.2 Downmixing Into Two Channels
107
 */
108
static const uint8_t ac3_default_coeffs[8][5][2] = {
109
    { { 2, 7 }, { 7, 2 },                               },
110
    { { 4, 4 },                                         },
111
    { { 2, 7 }, { 7, 2 },                               },
112
    { { 2, 7 }, { 5, 5 }, { 7, 2 },                     },
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    { { 2, 7 }, { 7, 2 }, { 6, 6 },                     },
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    { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 8, 8 },           },
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    { { 2, 7 }, { 7, 2 }, { 6, 7 }, { 7, 6 },           },
116
    { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
117
};
118

    
119
/**
120
 * Symmetrical Dequantization
121
 * reference: Section 7.3.3 Expansion of Mantissas for Symmetrical Quantization
122
 *            Tables 7.19 to 7.23
123
 */
124
static inline int
125
symmetric_dequant(int code, int levels)
126
{
127
    return ((code - (levels >> 1)) << 24) / levels;
128
}
129

    
130
/*
131
 * Initialize tables at runtime.
132
 */
133
static av_cold void ac3_tables_init(void)
134
{
135
    int i;
136

    
137
    /* generate table for ungrouping 3 values in 7 bits
138
       reference: Section 7.1.3 Exponent Decoding */
139
    for(i=0; i<128; i++) {
140
        ungroup_3_in_7_bits_tab[i][0] =  i / 25;
141
        ungroup_3_in_7_bits_tab[i][1] = (i % 25) / 5;
142
        ungroup_3_in_7_bits_tab[i][2] = (i % 25) % 5;
143
    }
144

    
145
    /* generate grouped mantissa tables
146
       reference: Section 7.3.5 Ungrouping of Mantissas */
147
    for(i=0; i<32; i++) {
148
        /* bap=1 mantissas */
149
        b1_mantissas[i][0] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][0], 3);
150
        b1_mantissas[i][1] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][1], 3);
151
        b1_mantissas[i][2] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][2], 3);
152
    }
153
    for(i=0; i<128; i++) {
154
        /* bap=2 mantissas */
155
        b2_mantissas[i][0] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][0], 5);
156
        b2_mantissas[i][1] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][1], 5);
157
        b2_mantissas[i][2] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][2], 5);
158

    
159
        /* bap=4 mantissas */
160
        b4_mantissas[i][0] = symmetric_dequant(i / 11, 11);
161
        b4_mantissas[i][1] = symmetric_dequant(i % 11, 11);
162
    }
163
    /* generate ungrouped mantissa tables
164
       reference: Tables 7.21 and 7.23 */
165
    for(i=0; i<7; i++) {
166
        /* bap=3 mantissas */
167
        b3_mantissas[i] = symmetric_dequant(i, 7);
168
    }
169
    for(i=0; i<15; i++) {
170
        /* bap=5 mantissas */
171
        b5_mantissas[i] = symmetric_dequant(i, 15);
172
    }
173

    
174
    /* generate dynamic range table
175
       reference: Section 7.7.1 Dynamic Range Control */
176
    for(i=0; i<256; i++) {
177
        int v = (i >> 5) - ((i >> 7) << 3) - 5;
178
        dynamic_range_tab[i] = powf(2.0f, v) * ((i & 0x1F) | 0x20);
179
    }
180
}
181

    
182

    
183
/**
184
 * AVCodec initialization
185
 */
186
static av_cold int ac3_decode_init(AVCodecContext *avctx)
187
{
188
    AC3DecodeContext *s = avctx->priv_data;
189
    s->avctx = avctx;
190

    
191
    ff_ac3_common_init();
192
    ac3_tables_init();
193
    ff_mdct_init(&s->imdct_256, 8, 1, 1.0);
194
    ff_mdct_init(&s->imdct_512, 9, 1, 1.0);
195
    ff_kbd_window_init(s->window, 5.0, 256);
196
    dsputil_init(&s->dsp, avctx);
197
    ff_fmt_convert_init(&s->fmt_conv, avctx);
198
    av_lfg_init(&s->dith_state, 0);
199

    
200
    /* set scale value for float to int16 conversion */
201
    s->mul_bias = 32767.0f;
202

    
203
    /* allow downmixing to stereo or mono */
204
    if (avctx->channels > 0 && avctx->request_channels > 0 &&
205
            avctx->request_channels < avctx->channels &&
206
            avctx->request_channels <= 2) {
207
        avctx->channels = avctx->request_channels;
208
    }
209
    s->downmixed = 1;
210

    
211
    /* allocate context input buffer */
212
        s->input_buffer = av_mallocz(AC3_FRAME_BUFFER_SIZE + FF_INPUT_BUFFER_PADDING_SIZE);
213
        if (!s->input_buffer)
214
            return AVERROR(ENOMEM);
215

    
216
    avctx->sample_fmt = AV_SAMPLE_FMT_S16;
217
    return 0;
218
}
219

    
220
/**
221
 * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
222
 * GetBitContext within AC3DecodeContext must point to
223
 * the start of the synchronized AC-3 bitstream.
224
 */
225
static int ac3_parse_header(AC3DecodeContext *s)
226
{
227
    GetBitContext *gbc = &s->gbc;
228
    int i;
229

    
230
    /* read the rest of the bsi. read twice for dual mono mode. */
231
    i = !(s->channel_mode);
232
    do {
233
        skip_bits(gbc, 5); // skip dialog normalization
234
        if (get_bits1(gbc))
235
            skip_bits(gbc, 8); //skip compression
236
        if (get_bits1(gbc))
237
            skip_bits(gbc, 8); //skip language code
238
        if (get_bits1(gbc))
239
            skip_bits(gbc, 7); //skip audio production information
240
    } while (i--);
241

    
242
    skip_bits(gbc, 2); //skip copyright bit and original bitstream bit
243

    
244
    /* skip the timecodes (or extra bitstream information for Alternate Syntax)
245
       TODO: read & use the xbsi1 downmix levels */
246
    if (get_bits1(gbc))
247
        skip_bits(gbc, 14); //skip timecode1 / xbsi1
248
    if (get_bits1(gbc))
249
        skip_bits(gbc, 14); //skip timecode2 / xbsi2
250

    
251
    /* skip additional bitstream info */
252
    if (get_bits1(gbc)) {
253
        i = get_bits(gbc, 6);
254
        do {
255
            skip_bits(gbc, 8);
256
        } while(i--);
257
    }
258

    
259
    return 0;
260
}
261

    
262
/**
263
 * Common function to parse AC-3 or E-AC-3 frame header
264
 */
265
static int parse_frame_header(AC3DecodeContext *s)
266
{
267
    AC3HeaderInfo hdr;
268
    int err;
269

    
270
    err = ff_ac3_parse_header(&s->gbc, &hdr);
271
    if(err)
272
        return err;
273

    
274
    /* get decoding parameters from header info */
275
    s->bit_alloc_params.sr_code     = hdr.sr_code;
276
    s->bitstream_mode               = hdr.bitstream_mode;
277
    s->channel_mode                 = hdr.channel_mode;
278
    s->channel_layout               = hdr.channel_layout;
279
    s->lfe_on                       = hdr.lfe_on;
280
    s->bit_alloc_params.sr_shift    = hdr.sr_shift;
281
    s->sample_rate                  = hdr.sample_rate;
282
    s->bit_rate                     = hdr.bit_rate;
283
    s->channels                     = hdr.channels;
284
    s->fbw_channels                 = s->channels - s->lfe_on;
285
    s->lfe_ch                       = s->fbw_channels + 1;
286
    s->frame_size                   = hdr.frame_size;
287
    s->center_mix_level             = hdr.center_mix_level;
288
    s->surround_mix_level           = hdr.surround_mix_level;
289
    s->num_blocks                   = hdr.num_blocks;
290
    s->frame_type                   = hdr.frame_type;
291
    s->substreamid                  = hdr.substreamid;
292

    
293
    if(s->lfe_on) {
294
        s->start_freq[s->lfe_ch] = 0;
295
        s->end_freq[s->lfe_ch] = 7;
296
        s->num_exp_groups[s->lfe_ch] = 2;
297
        s->channel_in_cpl[s->lfe_ch] = 0;
298
    }
299

    
300
    if (hdr.bitstream_id <= 10) {
301
        s->eac3                  = 0;
302
        s->snr_offset_strategy   = 2;
303
        s->block_switch_syntax   = 1;
304
        s->dither_flag_syntax    = 1;
305
        s->bit_allocation_syntax = 1;
306
        s->fast_gain_syntax      = 0;
307
        s->first_cpl_leak        = 0;
308
        s->dba_syntax            = 1;
309
        s->skip_syntax           = 1;
310
        memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht));
311
        return ac3_parse_header(s);
312
    } else if (CONFIG_EAC3_DECODER) {
313
        s->eac3 = 1;
314
        return ff_eac3_parse_header(s);
315
    } else {
316
        av_log(s->avctx, AV_LOG_ERROR, "E-AC-3 support not compiled in\n");
317
        return -1;
318
    }
319
}
320

    
321
/**
322
 * Set stereo downmixing coefficients based on frame header info.
323
 * reference: Section 7.8.2 Downmixing Into Two Channels
324
 */
325
static void set_downmix_coeffs(AC3DecodeContext *s)
326
{
327
    int i;
328
    float cmix = gain_levels[center_levels[s->center_mix_level]];
329
    float smix = gain_levels[surround_levels[s->surround_mix_level]];
330
    float norm0, norm1;
331

    
332
    for(i=0; i<s->fbw_channels; i++) {
333
        s->downmix_coeffs[i][0] = gain_levels[ac3_default_coeffs[s->channel_mode][i][0]];
334
        s->downmix_coeffs[i][1] = gain_levels[ac3_default_coeffs[s->channel_mode][i][1]];
335
    }
336
    if(s->channel_mode > 1 && s->channel_mode & 1) {
337
        s->downmix_coeffs[1][0] = s->downmix_coeffs[1][1] = cmix;
338
    }
339
    if(s->channel_mode == AC3_CHMODE_2F1R || s->channel_mode == AC3_CHMODE_3F1R) {
340
        int nf = s->channel_mode - 2;
341
        s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf][1] = smix * LEVEL_MINUS_3DB;
342
    }
343
    if(s->channel_mode == AC3_CHMODE_2F2R || s->channel_mode == AC3_CHMODE_3F2R) {
344
        int nf = s->channel_mode - 4;
345
        s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf+1][1] = smix;
346
    }
347

    
348
    /* renormalize */
349
    norm0 = norm1 = 0.0;
350
    for(i=0; i<s->fbw_channels; i++) {
351
        norm0 += s->downmix_coeffs[i][0];
352
        norm1 += s->downmix_coeffs[i][1];
353
    }
354
    norm0 = 1.0f / norm0;
355
    norm1 = 1.0f / norm1;
356
    for(i=0; i<s->fbw_channels; i++) {
357
        s->downmix_coeffs[i][0] *= norm0;
358
        s->downmix_coeffs[i][1] *= norm1;
359
    }
360

    
361
    if(s->output_mode == AC3_CHMODE_MONO) {
362
        for(i=0; i<s->fbw_channels; i++)
363
            s->downmix_coeffs[i][0] = (s->downmix_coeffs[i][0] + s->downmix_coeffs[i][1]) * LEVEL_MINUS_3DB;
364
    }
365
}
366

    
367
/**
368
 * Decode the grouped exponents according to exponent strategy.
369
 * reference: Section 7.1.3 Exponent Decoding
370
 */
371
static int decode_exponents(GetBitContext *gbc, int exp_strategy, int ngrps,
372
                            uint8_t absexp, int8_t *dexps)
373
{
374
    int i, j, grp, group_size;
375
    int dexp[256];
376
    int expacc, prevexp;
377

    
378
    /* unpack groups */
379
    group_size = exp_strategy + (exp_strategy == EXP_D45);
380
    for(grp=0,i=0; grp<ngrps; grp++) {
381
        expacc = get_bits(gbc, 7);
382
        dexp[i++] = ungroup_3_in_7_bits_tab[expacc][0];
383
        dexp[i++] = ungroup_3_in_7_bits_tab[expacc][1];
384
        dexp[i++] = ungroup_3_in_7_bits_tab[expacc][2];
385
    }
386

    
387
    /* convert to absolute exps and expand groups */
388
    prevexp = absexp;
389
    for(i=0,j=0; i<ngrps*3; i++) {
390
        prevexp += dexp[i] - 2;
391
        if (prevexp > 24U)
392
            return -1;
393
        switch (group_size) {
394
            case 4: dexps[j++] = prevexp;
395
                    dexps[j++] = prevexp;
396
            case 2: dexps[j++] = prevexp;
397
            case 1: dexps[j++] = prevexp;
398
        }
399
    }
400
    return 0;
401
}
402

    
403
/**
404
 * Generate transform coefficients for each coupled channel in the coupling
405
 * range using the coupling coefficients and coupling coordinates.
406
 * reference: Section 7.4.3 Coupling Coordinate Format
407
 */
408
static void calc_transform_coeffs_cpl(AC3DecodeContext *s)
409
{
410
    int bin, band, ch;
411

    
412
    bin = s->start_freq[CPL_CH];
413
    for (band = 0; band < s->num_cpl_bands; band++) {
414
        int band_start = bin;
415
        int band_end = bin + s->cpl_band_sizes[band];
416
        for (ch = 1; ch <= s->fbw_channels; ch++) {
417
            if (s->channel_in_cpl[ch]) {
418
                int cpl_coord = s->cpl_coords[ch][band] << 5;
419
                for (bin = band_start; bin < band_end; bin++) {
420
                    s->fixed_coeffs[ch][bin] = MULH(s->fixed_coeffs[CPL_CH][bin] << 4, cpl_coord);
421
                }
422
                if (ch == 2 && s->phase_flags[band]) {
423
                    for (bin = band_start; bin < band_end; bin++)
424
                        s->fixed_coeffs[2][bin] = -s->fixed_coeffs[2][bin];
425
                }
426
            }
427
        }
428
        bin = band_end;
429
    }
430
}
431

    
432
/**
433
 * Grouped mantissas for 3-level 5-level and 11-level quantization
434
 */
435
typedef struct {
436
    int b1_mant[2];
437
    int b2_mant[2];
438
    int b4_mant;
439
    int b1;
440
    int b2;
441
    int b4;
442
} mant_groups;
443

    
444
/**
445
 * Decode the transform coefficients for a particular channel
446
 * reference: Section 7.3 Quantization and Decoding of Mantissas
447
 */
448
static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m)
449
{
450
    int start_freq = s->start_freq[ch_index];
451
    int end_freq = s->end_freq[ch_index];
452
    uint8_t *baps = s->bap[ch_index];
453
    int8_t *exps = s->dexps[ch_index];
454
    int *coeffs = s->fixed_coeffs[ch_index];
455
    int dither = (ch_index == CPL_CH) || s->dither_flag[ch_index];
456
    GetBitContext *gbc = &s->gbc;
457
    int freq;
458

    
459
    for(freq = start_freq; freq < end_freq; freq++){
460
        int bap = baps[freq];
461
        int mantissa;
462
        switch(bap){
463
            case 0:
464
                if (dither)
465
                    mantissa = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
466
                else
467
                    mantissa = 0;
468
                break;
469
            case 1:
470
                if(m->b1){
471
                    m->b1--;
472
                    mantissa = m->b1_mant[m->b1];
473
                }
474
                else{
475
                    int bits      = get_bits(gbc, 5);
476
                    mantissa      = b1_mantissas[bits][0];
477
                    m->b1_mant[1] = b1_mantissas[bits][1];
478
                    m->b1_mant[0] = b1_mantissas[bits][2];
479
                    m->b1         = 2;
480
                }
481
                break;
482
            case 2:
483
                if(m->b2){
484
                    m->b2--;
485
                    mantissa = m->b2_mant[m->b2];
486
                }
487
                else{
488
                    int bits      = get_bits(gbc, 7);
489
                    mantissa      = b2_mantissas[bits][0];
490
                    m->b2_mant[1] = b2_mantissas[bits][1];
491
                    m->b2_mant[0] = b2_mantissas[bits][2];
492
                    m->b2         = 2;
493
                }
494
                break;
495
            case 3:
496
                mantissa = b3_mantissas[get_bits(gbc, 3)];
497
                break;
498
            case 4:
499
                if(m->b4){
500
                    m->b4 = 0;
501
                    mantissa = m->b4_mant;
502
                }
503
                else{
504
                    int bits   = get_bits(gbc, 7);
505
                    mantissa   = b4_mantissas[bits][0];
506
                    m->b4_mant = b4_mantissas[bits][1];
507
                    m->b4      = 1;
508
                }
509
                break;
510
            case 5:
511
                mantissa = b5_mantissas[get_bits(gbc, 4)];
512
                break;
513
            default: /* 6 to 15 */
514
                mantissa = get_bits(gbc, quantization_tab[bap]);
515
                /* Shift mantissa and sign-extend it. */
516
                mantissa = (mantissa << (32-quantization_tab[bap]))>>8;
517
                break;
518
        }
519
        coeffs[freq] = mantissa >> exps[freq];
520
    }
521
}
522

    
523
/**
524
 * Remove random dithering from coupling range coefficients with zero-bit
525
 * mantissas for coupled channels which do not use dithering.
526
 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
527
 */
528
static void remove_dithering(AC3DecodeContext *s) {
529
    int ch, i;
530

    
531
    for(ch=1; ch<=s->fbw_channels; ch++) {
532
        if(!s->dither_flag[ch] && s->channel_in_cpl[ch]) {
533
            for(i = s->start_freq[CPL_CH]; i<s->end_freq[CPL_CH]; i++) {
534
                if(!s->bap[CPL_CH][i])
535
                    s->fixed_coeffs[ch][i] = 0;
536
            }
537
        }
538
    }
539
}
540

    
541
static void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk, int ch,
542
                                    mant_groups *m)
543
{
544
    if (!s->channel_uses_aht[ch]) {
545
        ac3_decode_transform_coeffs_ch(s, ch, m);
546
    } else {
547
        /* if AHT is used, mantissas for all blocks are encoded in the first
548
           block of the frame. */
549
        int bin;
550
        if (!blk && CONFIG_EAC3_DECODER)
551
            ff_eac3_decode_transform_coeffs_aht_ch(s, ch);
552
        for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
553
            s->fixed_coeffs[ch][bin] = s->pre_mantissa[ch][bin][blk] >> s->dexps[ch][bin];
554
        }
555
    }
556
}
557

    
558
/**
559
 * Decode the transform coefficients.
560
 */
561
static void decode_transform_coeffs(AC3DecodeContext *s, int blk)
562
{
563
    int ch, end;
564
    int got_cplchan = 0;
565
    mant_groups m;
566

    
567
    m.b1 = m.b2 = m.b4 = 0;
568

    
569
    for (ch = 1; ch <= s->channels; ch++) {
570
        /* transform coefficients for full-bandwidth channel */
571
        decode_transform_coeffs_ch(s, blk, ch, &m);
572
        /* tranform coefficients for coupling channel come right after the
573
           coefficients for the first coupled channel*/
574
        if (s->channel_in_cpl[ch])  {
575
            if (!got_cplchan) {
576
                decode_transform_coeffs_ch(s, blk, CPL_CH, &m);
577
                calc_transform_coeffs_cpl(s);
578
                got_cplchan = 1;
579
            }
580
            end = s->end_freq[CPL_CH];
581
        } else {
582
            end = s->end_freq[ch];
583
        }
584
        do
585
            s->fixed_coeffs[ch][end] = 0;
586
        while(++end < 256);
587
    }
588

    
589
    /* zero the dithered coefficients for appropriate channels */
590
    remove_dithering(s);
591
}
592

    
593
/**
594
 * Stereo rematrixing.
595
 * reference: Section 7.5.4 Rematrixing : Decoding Technique
596
 */
597
static void do_rematrixing(AC3DecodeContext *s)
598
{
599
    int bnd, i;
600
    int end, bndend;
601

    
602
    end = FFMIN(s->end_freq[1], s->end_freq[2]);
603

    
604
    for(bnd=0; bnd<s->num_rematrixing_bands; bnd++) {
605
        if(s->rematrixing_flags[bnd]) {
606
            bndend = FFMIN(end, ff_ac3_rematrix_band_tab[bnd+1]);
607
            for(i=ff_ac3_rematrix_band_tab[bnd]; i<bndend; i++) {
608
                int tmp0 = s->fixed_coeffs[1][i];
609
                s->fixed_coeffs[1][i] += s->fixed_coeffs[2][i];
610
                s->fixed_coeffs[2][i]  = tmp0 - s->fixed_coeffs[2][i];
611
            }
612
        }
613
    }
614
}
615

    
616
/**
617
 * Inverse MDCT Transform.
618
 * Convert frequency domain coefficients to time-domain audio samples.
619
 * reference: Section 7.9.4 Transformation Equations
620
 */
621
static inline void do_imdct(AC3DecodeContext *s, int channels)
622
{
623
    int ch;
624

    
625
    for (ch=1; ch<=channels; ch++) {
626
        if (s->block_switch[ch]) {
627
            int i;
628
            float *x = s->tmp_output+128;
629
            for(i=0; i<128; i++)
630
                x[i] = s->transform_coeffs[ch][2*i];
631
            s->imdct_256.imdct_half(&s->imdct_256, s->tmp_output, x);
632
            s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, 128);
633
            for(i=0; i<128; i++)
634
                x[i] = s->transform_coeffs[ch][2*i+1];
635
            s->imdct_256.imdct_half(&s->imdct_256, s->delay[ch-1], x);
636
        } else {
637
            s->imdct_512.imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]);
638
            s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, 128);
639
            memcpy(s->delay[ch-1], s->tmp_output+128, 128*sizeof(float));
640
        }
641
    }
642
}
643

    
644
/**
645
 * Downmix the output to mono or stereo.
646
 */
647
void ff_ac3_downmix_c(float (*samples)[256], float (*matrix)[2], int out_ch, int in_ch, int len)
648
{
649
    int i, j;
650
    float v0, v1;
651
    if(out_ch == 2) {
652
        for(i=0; i<len; i++) {
653
            v0 = v1 = 0.0f;
654
            for(j=0; j<in_ch; j++) {
655
                v0 += samples[j][i] * matrix[j][0];
656
                v1 += samples[j][i] * matrix[j][1];
657
            }
658
            samples[0][i] = v0;
659
            samples[1][i] = v1;
660
        }
661
    } else if(out_ch == 1) {
662
        for(i=0; i<len; i++) {
663
            v0 = 0.0f;
664
            for(j=0; j<in_ch; j++)
665
                v0 += samples[j][i] * matrix[j][0];
666
            samples[0][i] = v0;
667
        }
668
    }
669
}
670

    
671
/**
672
 * Upmix delay samples from stereo to original channel layout.
673
 */
674
static void ac3_upmix_delay(AC3DecodeContext *s)
675
{
676
    int channel_data_size = sizeof(s->delay[0]);
677
    switch(s->channel_mode) {
678
        case AC3_CHMODE_DUALMONO:
679
        case AC3_CHMODE_STEREO:
680
            /* upmix mono to stereo */
681
            memcpy(s->delay[1], s->delay[0], channel_data_size);
682
            break;
683
        case AC3_CHMODE_2F2R:
684
            memset(s->delay[3], 0, channel_data_size);
685
        case AC3_CHMODE_2F1R:
686
            memset(s->delay[2], 0, channel_data_size);
687
            break;
688
        case AC3_CHMODE_3F2R:
689
            memset(s->delay[4], 0, channel_data_size);
690
        case AC3_CHMODE_3F1R:
691
            memset(s->delay[3], 0, channel_data_size);
692
        case AC3_CHMODE_3F:
693
            memcpy(s->delay[2], s->delay[1], channel_data_size);
694
            memset(s->delay[1], 0, channel_data_size);
695
            break;
696
    }
697
}
698

    
699
/**
700
 * Decode band structure for coupling, spectral extension, or enhanced coupling.
701
 * The band structure defines how many subbands are in each band.  For each
702
 * subband in the range, 1 means it is combined with the previous band, and 0
703
 * means that it starts a new band.
704
 *
705
 * @param[in] gbc bit reader context
706
 * @param[in] blk block number
707
 * @param[in] eac3 flag to indicate E-AC-3
708
 * @param[in] ecpl flag to indicate enhanced coupling
709
 * @param[in] start_subband subband number for start of range
710
 * @param[in] end_subband subband number for end of range
711
 * @param[in] default_band_struct default band structure table
712
 * @param[out] num_bands number of bands (optionally NULL)
713
 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
714
 */
715
static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
716
                                  int ecpl, int start_subband, int end_subband,
717
                                  const uint8_t *default_band_struct,
718
                                  int *num_bands, uint8_t *band_sizes)
719
{
720
    int subbnd, bnd, n_subbands, n_bands=0;
721
    uint8_t bnd_sz[22];
722
    uint8_t coded_band_struct[22];
723
    const uint8_t *band_struct;
724

    
725
    n_subbands = end_subband - start_subband;
726

    
727
    /* decode band structure from bitstream or use default */
728
    if (!eac3 || get_bits1(gbc)) {
729
        for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) {
730
            coded_band_struct[subbnd] = get_bits1(gbc);
731
        }
732
        band_struct = coded_band_struct;
733
    } else if (!blk) {
734
        band_struct = &default_band_struct[start_subband+1];
735
    } else {
736
        /* no change in band structure */
737
        return;
738
    }
739

    
740
    /* calculate number of bands and band sizes based on band structure.
741
       note that the first 4 subbands in enhanced coupling span only 6 bins
742
       instead of 12. */
743
    if (num_bands || band_sizes ) {
744
        n_bands = n_subbands;
745
        bnd_sz[0] = ecpl ? 6 : 12;
746
        for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) {
747
            int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12;
748
            if (band_struct[subbnd-1]) {
749
                n_bands--;
750
                bnd_sz[bnd] += subbnd_size;
751
            } else {
752
                bnd_sz[++bnd] = subbnd_size;
753
            }
754
        }
755
    }
756

    
757
    /* set optional output params */
758
    if (num_bands)
759
        *num_bands = n_bands;
760
    if (band_sizes)
761
        memcpy(band_sizes, bnd_sz, n_bands);
762
}
763

    
764
/**
765
 * Decode a single audio block from the AC-3 bitstream.
766
 */
767
static int decode_audio_block(AC3DecodeContext *s, int blk)
768
{
769
    int fbw_channels = s->fbw_channels;
770
    int channel_mode = s->channel_mode;
771
    int i, bnd, seg, ch;
772
    int different_transforms;
773
    int downmix_output;
774
    int cpl_in_use;
775
    GetBitContext *gbc = &s->gbc;
776
    uint8_t bit_alloc_stages[AC3_MAX_CHANNELS];
777

    
778
    memset(bit_alloc_stages, 0, AC3_MAX_CHANNELS);
779

    
780
    /* block switch flags */
781
    different_transforms = 0;
782
    if (s->block_switch_syntax) {
783
        for (ch = 1; ch <= fbw_channels; ch++) {
784
            s->block_switch[ch] = get_bits1(gbc);
785
            if(ch > 1 && s->block_switch[ch] != s->block_switch[1])
786
                different_transforms = 1;
787
        }
788
    }
789

    
790
    /* dithering flags */
791
    if (s->dither_flag_syntax) {
792
        for (ch = 1; ch <= fbw_channels; ch++) {
793
            s->dither_flag[ch] = get_bits1(gbc);
794
        }
795
    }
796

    
797
    /* dynamic range */
798
    i = !(s->channel_mode);
799
    do {
800
        if(get_bits1(gbc)) {
801
            s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)]-1.0) *
802
                                  s->avctx->drc_scale)+1.0;
803
        } else if(blk == 0) {
804
            s->dynamic_range[i] = 1.0f;
805
        }
806
    } while(i--);
807

    
808
    /* spectral extension strategy */
809
    if (s->eac3 && (!blk || get_bits1(gbc))) {
810
        s->spx_in_use = get_bits1(gbc);
811
        if (s->spx_in_use) {
812
            int dst_start_freq, dst_end_freq, src_start_freq,
813
                start_subband, end_subband;
814

    
815
            /* determine which channels use spx */
816
            if (s->channel_mode == AC3_CHMODE_MONO) {
817
                s->channel_uses_spx[1] = 1;
818
            } else {
819
                for (ch = 1; ch <= fbw_channels; ch++)
820
                    s->channel_uses_spx[ch] = get_bits1(gbc);
821
            }
822

    
823
            /* get the frequency bins of the spx copy region and the spx start
824
               and end subbands */
825
            dst_start_freq = get_bits(gbc, 2);
826
            start_subband  = get_bits(gbc, 3) + 2;
827
            if (start_subband > 7)
828
                start_subband += start_subband - 7;
829
            end_subband    = get_bits(gbc, 3) + 5;
830
            if (end_subband   > 7)
831
                end_subband   += end_subband   - 7;
832
            dst_start_freq = dst_start_freq * 12 + 25;
833
            src_start_freq = start_subband  * 12 + 25;
834
            dst_end_freq   = end_subband    * 12 + 25;
835

    
836
            /* check validity of spx ranges */
837
            if (start_subband >= end_subband) {
838
                av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
839
                       "range (%d >= %d)\n", start_subband, end_subband);
840
                return -1;
841
            }
842
            if (dst_start_freq >= src_start_freq) {
843
                av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
844
                       "copy start bin (%d >= %d)\n", dst_start_freq, src_start_freq);
845
                return -1;
846
            }
847

    
848
            s->spx_dst_start_freq = dst_start_freq;
849
            s->spx_src_start_freq = src_start_freq;
850
            s->spx_dst_end_freq   = dst_end_freq;
851

    
852
            decode_band_structure(gbc, blk, s->eac3, 0,
853
                                  start_subband, end_subband,
854
                                  ff_eac3_default_spx_band_struct,
855
                                  &s->num_spx_bands,
856
                                  s->spx_band_sizes);
857
        } else {
858
            for (ch = 1; ch <= fbw_channels; ch++) {
859
                s->channel_uses_spx[ch] = 0;
860
                s->first_spx_coords[ch] = 1;
861
            }
862
        }
863
    }
864

    
865
    /* spectral extension coordinates */
866
    if (s->spx_in_use) {
867
        for (ch = 1; ch <= fbw_channels; ch++) {
868
            if (s->channel_uses_spx[ch]) {
869
                if (s->first_spx_coords[ch] || get_bits1(gbc)) {
870
                    float spx_blend;
871
                    int bin, master_spx_coord;
872

    
873
                    s->first_spx_coords[ch] = 0;
874
                    spx_blend = get_bits(gbc, 5) * (1.0f/32);
875
                    master_spx_coord = get_bits(gbc, 2) * 3;
876

    
877
                    bin = s->spx_src_start_freq;
878
                    for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
879
                        int bandsize;
880
                        int spx_coord_exp, spx_coord_mant;
881
                        float nratio, sblend, nblend, spx_coord;
882

    
883
                        /* calculate blending factors */
884
                        bandsize = s->spx_band_sizes[bnd];
885
                        nratio = ((float)((bin + (bandsize >> 1))) / s->spx_dst_end_freq) - spx_blend;
886
                        nratio = av_clipf(nratio, 0.0f, 1.0f);
887
                        nblend = sqrtf(3.0f * nratio); // noise is scaled by sqrt(3) to give unity variance
888
                        sblend = sqrtf(1.0f - nratio);
889
                        bin += bandsize;
890

    
891
                        /* decode spx coordinates */
892
                        spx_coord_exp  = get_bits(gbc, 4);
893
                        spx_coord_mant = get_bits(gbc, 2);
894
                        if (spx_coord_exp == 15) spx_coord_mant <<= 1;
895
                        else                     spx_coord_mant += 4;
896
                        spx_coord_mant <<= (25 - spx_coord_exp - master_spx_coord);
897
                        spx_coord = spx_coord_mant * (1.0f/(1<<23));
898

    
899
                        /* multiply noise and signal blending factors by spx coordinate */
900
                        s->spx_noise_blend [ch][bnd] = nblend * spx_coord;
901
                        s->spx_signal_blend[ch][bnd] = sblend * spx_coord;
902
                    }
903
                }
904
            } else {
905
                s->first_spx_coords[ch] = 1;
906
            }
907
        }
908
    }
909

    
910
    /* coupling strategy */
911
    if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
912
        memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
913
        if (!s->eac3)
914
            s->cpl_in_use[blk] = get_bits1(gbc);
915
        if (s->cpl_in_use[blk]) {
916
            /* coupling in use */
917
            int cpl_start_subband, cpl_end_subband;
918

    
919
            if (channel_mode < AC3_CHMODE_STEREO) {
920
                av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n");
921
                return -1;
922
            }
923

    
924
            /* check for enhanced coupling */
925
            if (s->eac3 && get_bits1(gbc)) {
926
                /* TODO: parse enhanced coupling strategy info */
927
                av_log_missing_feature(s->avctx, "Enhanced coupling", 1);
928
                return -1;
929
            }
930

    
931
            /* determine which channels are coupled */
932
            if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
933
                s->channel_in_cpl[1] = 1;
934
                s->channel_in_cpl[2] = 1;
935
            } else {
936
                for (ch = 1; ch <= fbw_channels; ch++)
937
                    s->channel_in_cpl[ch] = get_bits1(gbc);
938
            }
939

    
940
            /* phase flags in use */
941
            if (channel_mode == AC3_CHMODE_STEREO)
942
                s->phase_flags_in_use = get_bits1(gbc);
943

    
944
            /* coupling frequency range */
945
            cpl_start_subband = get_bits(gbc, 4);
946
            cpl_end_subband = s->spx_in_use ? (s->spx_src_start_freq - 37) / 12 :
947
                                              get_bits(gbc, 4) + 3;
948
            if (cpl_start_subband >= cpl_end_subband) {
949
                av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n",
950
                       cpl_start_subband, cpl_end_subband);
951
                return -1;
952
            }
953
            s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
954
            s->end_freq[CPL_CH]   = cpl_end_subband   * 12 + 37;
955

    
956
            decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband,
957
                                  cpl_end_subband,
958
                                  ff_eac3_default_cpl_band_struct,
959
                                  &s->num_cpl_bands, s->cpl_band_sizes);
960
        } else {
961
            /* coupling not in use */
962
            for (ch = 1; ch <= fbw_channels; ch++) {
963
                s->channel_in_cpl[ch] = 0;
964
                s->first_cpl_coords[ch] = 1;
965
            }
966
            s->first_cpl_leak = s->eac3;
967
            s->phase_flags_in_use = 0;
968
        }
969
    } else if (!s->eac3) {
970
        if(!blk) {
971
            av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must be present in block 0\n");
972
            return -1;
973
        } else {
974
            s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
975
        }
976
    }
977
    cpl_in_use = s->cpl_in_use[blk];
978

    
979
    /* coupling coordinates */
980
    if (cpl_in_use) {
981
        int cpl_coords_exist = 0;
982

    
983
        for (ch = 1; ch <= fbw_channels; ch++) {
984
            if (s->channel_in_cpl[ch]) {
985
                if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) {
986
                    int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
987
                    s->first_cpl_coords[ch] = 0;
988
                    cpl_coords_exist = 1;
989
                    master_cpl_coord = 3 * get_bits(gbc, 2);
990
                    for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
991
                        cpl_coord_exp = get_bits(gbc, 4);
992
                        cpl_coord_mant = get_bits(gbc, 4);
993
                        if (cpl_coord_exp == 15)
994
                            s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
995
                        else
996
                            s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
997
                        s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
998
                    }
999
                } else if (!blk) {
1000
                    av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must be present in block 0\n");
1001
                    return -1;
1002
                }
1003
            } else {
1004
                /* channel not in coupling */
1005
                s->first_cpl_coords[ch] = 1;
1006
            }
1007
        }
1008
        /* phase flags */
1009
        if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
1010
            for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
1011
                s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
1012
            }
1013
        }
1014
    }
1015

    
1016
    /* stereo rematrixing strategy and band structure */
1017
    if (channel_mode == AC3_CHMODE_STEREO) {
1018
        if ((s->eac3 && !blk) || get_bits1(gbc)) {
1019
            s->num_rematrixing_bands = 4;
1020
            if (cpl_in_use && s->start_freq[CPL_CH] <= 61) {
1021
                s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
1022
            } else if (s->spx_in_use && s->spx_src_start_freq <= 61) {
1023
                s->num_rematrixing_bands--;
1024
            }
1025
            for(bnd=0; bnd<s->num_rematrixing_bands; bnd++)
1026
                s->rematrixing_flags[bnd] = get_bits1(gbc);
1027
        } else if (!blk) {
1028
            av_log(s->avctx, AV_LOG_WARNING, "Warning: new rematrixing strategy not present in block 0\n");
1029
            s->num_rematrixing_bands = 0;
1030
        }
1031
    }
1032

    
1033
    /* exponent strategies for each channel */
1034
    for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1035
        if (!s->eac3)
1036
            s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch));
1037
        if(s->exp_strategy[blk][ch] != EXP_REUSE)
1038
            bit_alloc_stages[ch] = 3;
1039
    }
1040

    
1041
    /* channel bandwidth */
1042
    for (ch = 1; ch <= fbw_channels; ch++) {
1043
        s->start_freq[ch] = 0;
1044
        if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1045
            int group_size;
1046
            int prev = s->end_freq[ch];
1047
            if (s->channel_in_cpl[ch])
1048
                s->end_freq[ch] = s->start_freq[CPL_CH];
1049
            else if (s->channel_uses_spx[ch])
1050
                s->end_freq[ch] = s->spx_src_start_freq;
1051
            else {
1052
                int bandwidth_code = get_bits(gbc, 6);
1053
                if (bandwidth_code > 60) {
1054
                    av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code);
1055
                    return -1;
1056
                }
1057
                s->end_freq[ch] = bandwidth_code * 3 + 73;
1058
            }
1059
            group_size = 3 << (s->exp_strategy[blk][ch] - 1);
1060
            s->num_exp_groups[ch] = (s->end_freq[ch]+group_size-4) / group_size;
1061
            if(blk > 0 && s->end_freq[ch] != prev)
1062
                memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
1063
        }
1064
    }
1065
    if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) {
1066
        s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) /
1067
                                    (3 << (s->exp_strategy[blk][CPL_CH] - 1));
1068
    }
1069

    
1070
    /* decode exponents for each channel */
1071
    for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1072
        if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1073
            s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
1074
            if (decode_exponents(gbc, s->exp_strategy[blk][ch],
1075
                                 s->num_exp_groups[ch], s->dexps[ch][0],
1076
                                 &s->dexps[ch][s->start_freq[ch]+!!ch])) {
1077
                av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n");
1078
                return -1;
1079
            }
1080
            if(ch != CPL_CH && ch != s->lfe_ch)
1081
                skip_bits(gbc, 2); /* skip gainrng */
1082
        }
1083
    }
1084

    
1085
    /* bit allocation information */
1086
    if (s->bit_allocation_syntax) {
1087
        if (get_bits1(gbc)) {
1088
            s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1089
            s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1090
            s->bit_alloc_params.slow_gain  = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
1091
            s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
1092
            s->bit_alloc_params.floor  = ff_ac3_floor_tab[get_bits(gbc, 3)];
1093
            for(ch=!cpl_in_use; ch<=s->channels; ch++)
1094
                bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1095
        } else if (!blk) {
1096
            av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must be present in block 0\n");
1097
            return -1;
1098
        }
1099
    }
1100

    
1101
    /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1102
    if(!s->eac3 || !blk){
1103
        if(s->snr_offset_strategy && get_bits1(gbc)) {
1104
            int snr = 0;
1105
            int csnr;
1106
            csnr = (get_bits(gbc, 6) - 15) << 4;
1107
            for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
1108
                /* snr offset */
1109
                if (ch == i || s->snr_offset_strategy == 2)
1110
                    snr = (csnr + get_bits(gbc, 4)) << 2;
1111
                /* run at least last bit allocation stage if snr offset changes */
1112
                if(blk && s->snr_offset[ch] != snr) {
1113
                    bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
1114
                }
1115
                s->snr_offset[ch] = snr;
1116

    
1117
                /* fast gain (normal AC-3 only) */
1118
                if (!s->eac3) {
1119
                    int prev = s->fast_gain[ch];
1120
                    s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1121
                    /* run last 2 bit allocation stages if fast gain changes */
1122
                    if(blk && prev != s->fast_gain[ch])
1123
                        bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1124
                }
1125
            }
1126
        } else if (!s->eac3 && !blk) {
1127
            av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
1128
            return -1;
1129
        }
1130
    }
1131

    
1132
    /* fast gain (E-AC-3 only) */
1133
    if (s->fast_gain_syntax && get_bits1(gbc)) {
1134
        for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1135
            int prev = s->fast_gain[ch];
1136
            s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1137
            /* run last 2 bit allocation stages if fast gain changes */
1138
            if(blk && prev != s->fast_gain[ch])
1139
                bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1140
        }
1141
    } else if (s->eac3 && !blk) {
1142
        for (ch = !cpl_in_use; ch <= s->channels; ch++)
1143
            s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
1144
    }
1145

    
1146
    /* E-AC-3 to AC-3 converter SNR offset */
1147
    if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
1148
        skip_bits(gbc, 10); // skip converter snr offset
1149
    }
1150

    
1151
    /* coupling leak information */
1152
    if (cpl_in_use) {
1153
        if (s->first_cpl_leak || get_bits1(gbc)) {
1154
            int fl = get_bits(gbc, 3);
1155
            int sl = get_bits(gbc, 3);
1156
            /* run last 2 bit allocation stages for coupling channel if
1157
               coupling leak changes */
1158
            if(blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
1159
                       sl != s->bit_alloc_params.cpl_slow_leak)) {
1160
                bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
1161
            }
1162
            s->bit_alloc_params.cpl_fast_leak = fl;
1163
            s->bit_alloc_params.cpl_slow_leak = sl;
1164
        } else if (!s->eac3 && !blk) {
1165
            av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must be present in block 0\n");
1166
            return -1;
1167
        }
1168
        s->first_cpl_leak = 0;
1169
    }
1170

    
1171
    /* delta bit allocation information */
1172
    if (s->dba_syntax && get_bits1(gbc)) {
1173
        /* delta bit allocation exists (strategy) */
1174
        for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1175
            s->dba_mode[ch] = get_bits(gbc, 2);
1176
            if (s->dba_mode[ch] == DBA_RESERVED) {
1177
                av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
1178
                return -1;
1179
            }
1180
            bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1181
        }
1182
        /* channel delta offset, len and bit allocation */
1183
        for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1184
            if (s->dba_mode[ch] == DBA_NEW) {
1185
                s->dba_nsegs[ch] = get_bits(gbc, 3);
1186
                for (seg = 0; seg <= s->dba_nsegs[ch]; seg++) {
1187
                    s->dba_offsets[ch][seg] = get_bits(gbc, 5);
1188
                    s->dba_lengths[ch][seg] = get_bits(gbc, 4);
1189
                    s->dba_values[ch][seg] = get_bits(gbc, 3);
1190
                }
1191
                /* run last 2 bit allocation stages if new dba values */
1192
                bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1193
            }
1194
        }
1195
    } else if(blk == 0) {
1196
        for(ch=0; ch<=s->channels; ch++) {
1197
            s->dba_mode[ch] = DBA_NONE;
1198
        }
1199
    }
1200

    
1201
    /* Bit allocation */
1202
    for(ch=!cpl_in_use; ch<=s->channels; ch++) {
1203
        if(bit_alloc_stages[ch] > 2) {
1204
            /* Exponent mapping into PSD and PSD integration */
1205
            ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
1206
                                      s->start_freq[ch], s->end_freq[ch],
1207
                                      s->psd[ch], s->band_psd[ch]);
1208
        }
1209
        if(bit_alloc_stages[ch] > 1) {
1210
            /* Compute excitation function, Compute masking curve, and
1211
               Apply delta bit allocation */
1212
            if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1213
                                           s->start_freq[ch], s->end_freq[ch],
1214
                                           s->fast_gain[ch], (ch == s->lfe_ch),
1215
                                           s->dba_mode[ch], s->dba_nsegs[ch],
1216
                                           s->dba_offsets[ch], s->dba_lengths[ch],
1217
                                           s->dba_values[ch], s->mask[ch])) {
1218
                av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n");
1219
                return -1;
1220
            }
1221
        }
1222
        if(bit_alloc_stages[ch] > 0) {
1223
            /* Compute bit allocation */
1224
            const uint8_t *bap_tab = s->channel_uses_aht[ch] ?
1225
                                     ff_eac3_hebap_tab : ff_ac3_bap_tab;
1226
            ff_ac3_bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1227
                                      s->start_freq[ch], s->end_freq[ch],
1228
                                      s->snr_offset[ch],
1229
                                      s->bit_alloc_params.floor,
1230
                                      bap_tab, s->bap[ch]);
1231
        }
1232
    }
1233

    
1234
    /* unused dummy data */
1235
    if (s->skip_syntax && get_bits1(gbc)) {
1236
        int skipl = get_bits(gbc, 9);
1237
        while(skipl--)
1238
            skip_bits(gbc, 8);
1239
    }
1240

    
1241
    /* unpack the transform coefficients
1242
       this also uncouples channels if coupling is in use. */
1243
    decode_transform_coeffs(s, blk);
1244

    
1245
    /* TODO: generate enhanced coupling coordinates and uncouple */
1246

    
1247
    /* recover coefficients if rematrixing is in use */
1248
    if(s->channel_mode == AC3_CHMODE_STEREO)
1249
        do_rematrixing(s);
1250

    
1251
    /* apply scaling to coefficients (headroom, dynrng) */
1252
    for(ch=1; ch<=s->channels; ch++) {
1253
        float gain = s->mul_bias / 4194304.0f;
1254
        if(s->channel_mode == AC3_CHMODE_DUALMONO) {
1255
            gain *= s->dynamic_range[2-ch];
1256
        } else {
1257
            gain *= s->dynamic_range[0];
1258
        }
1259
        s->fmt_conv.int32_to_float_fmul_scalar(s->transform_coeffs[ch], s->fixed_coeffs[ch], gain, 256);
1260
    }
1261

    
1262
    /* apply spectral extension to high frequency bins */
1263
    if (s->spx_in_use && CONFIG_EAC3_DECODER) {
1264
        ff_eac3_apply_spectral_extension(s);
1265
    }
1266

    
1267
    /* downmix and MDCT. order depends on whether block switching is used for
1268
       any channel in this block. this is because coefficients for the long
1269
       and short transforms cannot be mixed. */
1270
    downmix_output = s->channels != s->out_channels &&
1271
                     !((s->output_mode & AC3_OUTPUT_LFEON) &&
1272
                     s->fbw_channels == s->out_channels);
1273
    if(different_transforms) {
1274
        /* the delay samples have already been downmixed, so we upmix the delay
1275
           samples in order to reconstruct all channels before downmixing. */
1276
        if(s->downmixed) {
1277
            s->downmixed = 0;
1278
            ac3_upmix_delay(s);
1279
        }
1280

    
1281
        do_imdct(s, s->channels);
1282

    
1283
        if(downmix_output) {
1284
            s->dsp.ac3_downmix(s->output, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1285
        }
1286
    } else {
1287
        if(downmix_output) {
1288
            s->dsp.ac3_downmix(s->transform_coeffs+1, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1289
        }
1290

    
1291
        if(downmix_output && !s->downmixed) {
1292
            s->downmixed = 1;
1293
            s->dsp.ac3_downmix(s->delay, s->downmix_coeffs, s->out_channels, s->fbw_channels, 128);
1294
        }
1295

    
1296
        do_imdct(s, s->out_channels);
1297
    }
1298

    
1299
    return 0;
1300
}
1301

    
1302
/**
1303
 * Decode a single AC-3 frame.
1304
 */
1305
static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
1306
                            AVPacket *avpkt)
1307
{
1308
    const uint8_t *buf = avpkt->data;
1309
    int buf_size = avpkt->size;
1310
    AC3DecodeContext *s = avctx->priv_data;
1311
    int16_t *out_samples = (int16_t *)data;
1312
    int blk, ch, err;
1313
    const uint8_t *channel_map;
1314
    const float *output[AC3_MAX_CHANNELS];
1315

    
1316
    /* copy input buffer to decoder context to avoid reading past the end
1317
       of the buffer, which can be caused by a damaged input stream. */
1318
    if (buf_size >= 2 && AV_RB16(buf) == 0x770B) {
1319
        // seems to be byte-swapped AC-3
1320
        int cnt = FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE) >> 1;
1321
        s->dsp.bswap16_buf((uint16_t *)s->input_buffer, (const uint16_t *)buf, cnt);
1322
    } else
1323
        memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1324
    buf = s->input_buffer;
1325
    /* initialize the GetBitContext with the start of valid AC-3 Frame */
1326
    init_get_bits(&s->gbc, buf, buf_size * 8);
1327

    
1328
    /* parse the syncinfo */
1329
    *data_size = 0;
1330
    err = parse_frame_header(s);
1331

    
1332
    if (err) {
1333
        switch(err) {
1334
            case AAC_AC3_PARSE_ERROR_SYNC:
1335
                av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1336
                return -1;
1337
            case AAC_AC3_PARSE_ERROR_BSID:
1338
                av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1339
                break;
1340
            case AAC_AC3_PARSE_ERROR_SAMPLE_RATE:
1341
                av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1342
                break;
1343
            case AAC_AC3_PARSE_ERROR_FRAME_SIZE:
1344
                av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1345
                break;
1346
            case AAC_AC3_PARSE_ERROR_FRAME_TYPE:
1347
                /* skip frame if CRC is ok. otherwise use error concealment. */
1348
                /* TODO: add support for substreams and dependent frames */
1349
                if(s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) {
1350
                    av_log(avctx, AV_LOG_ERROR, "unsupported frame type : skipping frame\n");
1351
                    return s->frame_size;
1352
                } else {
1353
                    av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
1354
                }
1355
                break;
1356
            default:
1357
                av_log(avctx, AV_LOG_ERROR, "invalid header\n");
1358
                break;
1359
        }
1360
    } else {
1361
        /* check that reported frame size fits in input buffer */
1362
        if (s->frame_size > buf_size) {
1363
            av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1364
            err = AAC_AC3_PARSE_ERROR_FRAME_SIZE;
1365
        } else if (avctx->error_recognition >= FF_ER_CAREFUL) {
1366
            /* check for crc mismatch */
1367
            if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2], s->frame_size-2)) {
1368
                av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1369
                err = AAC_AC3_PARSE_ERROR_CRC;
1370
            }
1371
        }
1372
    }
1373

    
1374
    /* if frame is ok, set audio parameters */
1375
    if (!err) {
1376
        avctx->sample_rate = s->sample_rate;
1377
        avctx->bit_rate = s->bit_rate;
1378

    
1379
        /* channel config */
1380
        s->out_channels = s->channels;
1381
        s->output_mode = s->channel_mode;
1382
        if(s->lfe_on)
1383
            s->output_mode |= AC3_OUTPUT_LFEON;
1384
        if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
1385
                avctx->request_channels < s->channels) {
1386
            s->out_channels = avctx->request_channels;
1387
            s->output_mode  = avctx->request_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1388
            s->channel_layout = ff_ac3_channel_layout_tab[s->output_mode];
1389
        }
1390
        avctx->channels = s->out_channels;
1391
        avctx->channel_layout = s->channel_layout;
1392

    
1393
        /* set downmixing coefficients if needed */
1394
        if(s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1395
                s->fbw_channels == s->out_channels)) {
1396
            set_downmix_coeffs(s);
1397
        }
1398
    } else if (!s->out_channels) {
1399
        s->out_channels = avctx->channels;
1400
        if(s->out_channels < s->channels)
1401
            s->output_mode  = s->out_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1402
    }
1403
    /* set audio service type based on bitstream mode for AC-3 */
1404
    avctx->audio_service_type = s->bitstream_mode;
1405
    if (s->bitstream_mode == 0x7 && s->channels > 1)
1406
        avctx->audio_service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE;
1407

    
1408
    /* decode the audio blocks */
1409
    channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on];
1410
    for (ch = 0; ch < s->out_channels; ch++)
1411
        output[ch] = s->output[channel_map[ch]];
1412
    for (blk = 0; blk < s->num_blocks; blk++) {
1413
        if (!err && decode_audio_block(s, blk)) {
1414
            av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n");
1415
            err = 1;
1416
        }
1417
        s->fmt_conv.float_to_int16_interleave(out_samples, output, 256, s->out_channels);
1418
        out_samples += 256 * s->out_channels;
1419
    }
1420
    *data_size = s->num_blocks * 256 * avctx->channels * sizeof (int16_t);
1421
    return FFMIN(buf_size, s->frame_size);
1422
}
1423

    
1424
/**
1425
 * Uninitialize the AC-3 decoder.
1426
 */
1427
static av_cold int ac3_decode_end(AVCodecContext *avctx)
1428
{
1429
    AC3DecodeContext *s = avctx->priv_data;
1430
    ff_mdct_end(&s->imdct_512);
1431
    ff_mdct_end(&s->imdct_256);
1432

    
1433
    av_freep(&s->input_buffer);
1434

    
1435
    return 0;
1436
}
1437

    
1438
AVCodec ff_ac3_decoder = {
1439
    .name = "ac3",
1440
    .type = AVMEDIA_TYPE_AUDIO,
1441
    .id = CODEC_ID_AC3,
1442
    .priv_data_size = sizeof (AC3DecodeContext),
1443
    .init = ac3_decode_init,
1444
    .close = ac3_decode_end,
1445
    .decode = ac3_decode_frame,
1446
    .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1447
};
1448

    
1449
#if CONFIG_EAC3_DECODER
1450
AVCodec ff_eac3_decoder = {
1451
    .name = "eac3",
1452
    .type = AVMEDIA_TYPE_AUDIO,
1453
    .id = CODEC_ID_EAC3,
1454
    .priv_data_size = sizeof (AC3DecodeContext),
1455
    .init = ac3_decode_init,
1456
    .close = ac3_decode_end,
1457
    .decode = ac3_decode_frame,
1458
    .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"),
1459
};
1460
#endif