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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,
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 * 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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 *
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 * 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"
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#include "ac3_parser.h"
37
#include "bitstream.h"
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#include "dsputil.h"
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#include "random.h"
40

    
41
/**
42
 * Table of bin locations for rematrixing bands
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 * 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

    
56
/** tables for ungrouping mantissas */
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static float b1_mantissas[32][3];
58
static float b2_mantissas[128][3];
59
static float b3_mantissas[8];
60
static float b4_mantissas[128][2];
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static float b5_mantissas[16];
62

    
63
/**
64
 * Quantization table: levels for symmetric. bits for asymmetric.
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 * reference: Table 7.18 Mapping of bap to Quantizer
66
 */
67
static const uint8_t qntztab[16] = {
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    0, 3, 5, 7, 11, 15,
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    5, 6, 7, 8, 9, 10, 11, 12, 14, 16
70
};
71

    
72
/** dynamic range table. converts codes to scale factors. */
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static float dynrng_tbl[256];
74

    
75
/** dialogue normalization table */
76
static float dialnorm_tbl[32];
77

    
78
/* Adjustmens in dB gain */
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#define LEVEL_MINUS_3DB         0.7071067811865476
80
#define LEVEL_MINUS_4POINT5DB   0.5946035575013605
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#define LEVEL_MINUS_6DB         0.5000000000000000
82
#define LEVEL_MINUS_9DB         0.3535533905932738
83
#define LEVEL_ZERO              0.0000000000000000
84
#define LEVEL_ONE               1.0000000000000000
85

    
86
static const float gain_levels[6] = {
87
    LEVEL_ZERO,
88
    LEVEL_ONE,
89
    LEVEL_MINUS_3DB,
90
    LEVEL_MINUS_4POINT5DB,
91
    LEVEL_MINUS_6DB,
92
    LEVEL_MINUS_9DB
93
};
94

    
95
/**
96
 * Table for center mix levels
97
 * reference: Section 5.4.2.4 cmixlev
98
 */
99
static const uint8_t clevs[4] = { 2, 3, 4, 3 };
100

    
101
/**
102
 * Table for surround mix levels
103
 * reference: Section 5.4.2.5 surmixlev
104
 */
105
static const uint8_t slevs[4] = { 2, 4, 0, 4 };
106

    
107
/**
108
 * Table for default stereo downmixing coefficients
109
 * reference: Section 7.8.2 Downmixing Into Two Channels
110
 */
111
static const uint8_t ac3_default_coeffs[8][5][2] = {
112
    { { 1, 0 }, { 0, 1 },                               },
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    { { 2, 2 },                                         },
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    { { 1, 0 }, { 0, 1 },                               },
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    { { 1, 0 }, { 3, 3 }, { 0, 1 },                     },
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    { { 1, 0 }, { 0, 1 }, { 4, 4 },                     },
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    { { 1, 0 }, { 3, 3 }, { 0, 1 }, { 5, 5 },           },
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    { { 1, 0 }, { 0, 1 }, { 4, 0 }, { 0, 4 },           },
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    { { 1, 0 }, { 3, 3 }, { 0, 1 }, { 4, 0 }, { 0, 4 }, },
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};
121

    
122
/* override ac3.h to include coupling channel */
123
#undef AC3_MAX_CHANNELS
124
#define AC3_MAX_CHANNELS 7
125
#define CPL_CH 0
126

    
127
#define AC3_OUTPUT_LFEON  8
128

    
129
typedef struct {
130
    int acmod;
131
    int dsurmod;
132

    
133
    int blksw[AC3_MAX_CHANNELS];
134
    int dithflag[AC3_MAX_CHANNELS];
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    int dither_all;
136
    int cplinu;
137
    int chincpl[AC3_MAX_CHANNELS];
138
    int phsflginu;
139
    int cplbndstrc[18];
140
    int rematstr;
141
    int nrematbnd;
142
    int rematflg[4];
143
    int expstr[AC3_MAX_CHANNELS];
144
    int snroffst[AC3_MAX_CHANNELS];
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    int fgain[AC3_MAX_CHANNELS];
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    int deltbae[AC3_MAX_CHANNELS];
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    int deltnseg[AC3_MAX_CHANNELS];
148
    uint8_t  deltoffst[AC3_MAX_CHANNELS][8];
149
    uint8_t  deltlen[AC3_MAX_CHANNELS][8];
150
    uint8_t  deltba[AC3_MAX_CHANNELS][8];
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152
    /* Derived Attributes. */
153
    int      sampling_rate;
154
    int      bit_rate;
155
    int      frame_size;
156

    
157
    int      nchans;            //number of total channels
158
    int      nfchans;           //number of full-bandwidth channels
159
    int      lfeon;             //lfe channel in use
160
    int      lfe_ch;            ///< index of LFE channel
161
    int      output_mode;       ///< output channel configuration
162
    int      out_channels;      ///< number of output channels
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164
    float    downmix_coeffs[AC3_MAX_CHANNELS][2];   ///< stereo downmix coefficients
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    float    dialnorm[2];                       ///< dialogue normalization
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    float    dynrng;            //dynamic range gain
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    float    dynrng2;           //dynamic range gain for 1+1 mode
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    float    cplco[AC3_MAX_CHANNELS][18];   //coupling coordinates
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    int      ncplbnd;           //number of coupling bands
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    int      ncplsubnd;         //number of coupling sub bands
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    int      startmant[AC3_MAX_CHANNELS];   ///< start frequency bin
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    int      endmant[AC3_MAX_CHANNELS];     //channel end mantissas
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    AC3BitAllocParameters bit_alloc_params; ///< bit allocation parameters
174

    
175
    int8_t   dexps[AC3_MAX_CHANNELS][256];  ///< decoded exponents
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    uint8_t  bap[AC3_MAX_CHANNELS][256];    ///< bit allocation pointers
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    int16_t  psd[AC3_MAX_CHANNELS][256];    ///< scaled exponents
178
    int16_t  bndpsd[AC3_MAX_CHANNELS][50];  ///< interpolated exponents
179
    int16_t  mask[AC3_MAX_CHANNELS][50];    ///< masking curve values
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181
    DECLARE_ALIGNED_16(float, transform_coeffs[AC3_MAX_CHANNELS][256]);  //transform coefficients
182

    
183
    /* For IMDCT. */
184
    MDCTContext imdct_512;  //for 512 sample imdct transform
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    MDCTContext imdct_256;  //for 256 sample imdct transform
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    DSPContext  dsp;        //for optimization
187
    float       add_bias;   ///< offset for float_to_int16 conversion
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    float       mul_bias;   ///< scaling for float_to_int16 conversion
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    DECLARE_ALIGNED_16(float, output[AC3_MAX_CHANNELS-1][256]); //output after imdct transform and windowing
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    DECLARE_ALIGNED_16(short, int_output[AC3_MAX_CHANNELS-1][256]); ///< final 16-bit integer output
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    DECLARE_ALIGNED_16(float, delay[AC3_MAX_CHANNELS-1][256]);  //delay - added to the next block
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    DECLARE_ALIGNED_16(float, tmp_imdct[256]);                  //temporary storage for imdct transform
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    DECLARE_ALIGNED_16(float, tmp_output[512]);                 //temporary storage for output before windowing
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    DECLARE_ALIGNED_16(float, window[256]);                     //window coefficients
196

    
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    /* Miscellaneous. */
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    GetBitContext gb;
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    AVRandomState dith_state;   //for dither generation
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} AC3DecodeContext;
201

    
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/*********** BEGIN INIT HELPER FUNCTIONS ***********/
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/**
204
 * Generate a Kaiser-Bessel Derived Window.
205
 */
206
static void ac3_window_init(float *window)
207
{
208
   int i, j;
209
   double sum = 0.0, bessel, tmp;
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   double local_window[256];
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   double alpha2 = (5.0 * M_PI / 256.0) * (5.0 * M_PI / 256.0);
212

    
213
   for (i = 0; i < 256; i++) {
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       tmp = i * (256 - i) * alpha2;
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       bessel = 1.0;
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       for (j = 100; j > 0; j--) /* defaul to 100 iterations */
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           bessel = bessel * tmp / (j * j) + 1;
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       sum += bessel;
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       local_window[i] = sum;
220
   }
221

    
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   sum++;
223
   for (i = 0; i < 256; i++)
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       window[i] = sqrt(local_window[i] / sum);
225
}
226

    
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static inline float
228
symmetric_dequant(int code, int levels)
229
{
230
    return (code - (levels >> 1)) * (2.0f / levels);
231
}
232

    
233
/*
234
 * Initialize tables at runtime.
235
 */
236
static void ac3_tables_init(void)
237
{
238
    int i;
239

    
240
    /* generate grouped mantissa tables
241
       reference: Section 7.3.5 Ungrouping of Mantissas */
242
    for(i=0; i<32; i++) {
243
        /* bap=1 mantissas */
244
        b1_mantissas[i][0] = symmetric_dequant( i / 9     , 3);
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        b1_mantissas[i][1] = symmetric_dequant((i % 9) / 3, 3);
246
        b1_mantissas[i][2] = symmetric_dequant((i % 9) % 3, 3);
247
    }
248
    for(i=0; i<128; i++) {
249
        /* bap=2 mantissas */
250
        b2_mantissas[i][0] = symmetric_dequant( i / 25     , 5);
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        b2_mantissas[i][1] = symmetric_dequant((i % 25) / 5, 5);
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        b2_mantissas[i][2] = symmetric_dequant((i % 25) % 5, 5);
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254
        /* bap=4 mantissas */
255
        b4_mantissas[i][0] = symmetric_dequant(i / 11, 11);
256
        b4_mantissas[i][1] = symmetric_dequant(i % 11, 11);
257
    }
258
    /* generate ungrouped mantissa tables
259
       reference: Tables 7.21 and 7.23 */
260
    for(i=0; i<7; i++) {
261
        /* bap=3 mantissas */
262
        b3_mantissas[i] = symmetric_dequant(i, 7);
263
    }
264
    for(i=0; i<15; i++) {
265
        /* bap=5 mantissas */
266
        b5_mantissas[i] = symmetric_dequant(i, 15);
267
    }
268

    
269
    /* generate dynamic range table
270
       reference: Section 7.7.1 Dynamic Range Control */
271
    for(i=0; i<256; i++) {
272
        int v = (i >> 5) - ((i >> 7) << 3) - 5;
273
        dynrng_tbl[i] = powf(2.0f, v) * ((i & 0x1F) | 0x20);
274
    }
275

    
276
    /* generate dialogue normalization table
277
       references: Section 5.4.2.8 dialnorm
278
                   Section 7.6 Dialogue Normalization */
279
    for(i=1; i<32; i++) {
280
        dialnorm_tbl[i] = expf((i-31) * M_LN10 / 20.0f);
281
    }
282
    dialnorm_tbl[0] = dialnorm_tbl[31];
283

    
284
    //generate scale factors
285
    for (i = 0; i < 25; i++)
286
        scale_factors[i] = pow(2.0, -i);
287

    
288
    /* generate exponent tables
289
       reference: Section 7.1.3 Exponent Decoding */
290
    for(i=0; i<128; i++) {
291
        exp_ungroup_tbl[i][0] =  i / 25;
292
        exp_ungroup_tbl[i][1] = (i % 25) / 5;
293
        exp_ungroup_tbl[i][2] = (i % 25) % 5;
294
    }
295
}
296

    
297

    
298
static int ac3_decode_init(AVCodecContext *avctx)
299
{
300
    AC3DecodeContext *ctx = avctx->priv_data;
301

    
302
    ac3_common_init();
303
    ac3_tables_init();
304
    ff_mdct_init(&ctx->imdct_256, 8, 1);
305
    ff_mdct_init(&ctx->imdct_512, 9, 1);
306
    ac3_window_init(ctx->window);
307
    dsputil_init(&ctx->dsp, avctx);
308
    av_init_random(0, &ctx->dith_state);
309

    
310
    if(ctx->dsp.float_to_int16 == ff_float_to_int16_c) {
311
        ctx->add_bias = 385.0f;
312
        ctx->mul_bias = 1.0f;
313
    } else {
314
        ctx->add_bias = 0.0f;
315
        ctx->mul_bias = 32767.0f;
316
    }
317

    
318
    return 0;
319
}
320
/*********** END INIT FUNCTIONS ***********/
321

    
322
/**
323
 * Parses the 'sync info' and 'bit stream info' from the AC-3 bitstream.
324
 * GetBitContext within AC3DecodeContext must point to
325
 * start of the synchronized ac3 bitstream.
326
 */
327
static int ac3_parse_header(AC3DecodeContext *ctx)
328
{
329
    AC3HeaderInfo hdr;
330
    GetBitContext *gb = &ctx->gb;
331
    float cmixlev, surmixlev;
332
    int err, i;
333

    
334
    err = ff_ac3_parse_header(gb->buffer, &hdr);
335
    if(err)
336
        return err;
337

    
338
    /* get decoding parameters from header info */
339
    ctx->bit_alloc_params.fscod       = hdr.fscod;
340
    ctx->acmod                        = hdr.acmod;
341
    cmixlev                           = gain_levels[clevs[hdr.cmixlev]];
342
    surmixlev                         = gain_levels[slevs[hdr.surmixlev]];
343
    ctx->dsurmod                      = hdr.dsurmod;
344
    ctx->lfeon                        = hdr.lfeon;
345
    ctx->bit_alloc_params.halfratecod = hdr.halfratecod;
346
    ctx->sampling_rate                = hdr.sample_rate;
347
    ctx->bit_rate                     = hdr.bit_rate;
348
    ctx->nchans                       = hdr.channels;
349
    ctx->nfchans                      = ctx->nchans - ctx->lfeon;
350
    ctx->lfe_ch                       = ctx->nfchans + 1;
351
    ctx->frame_size                   = hdr.frame_size;
352

    
353
    /* set default output to all source channels */
354
    ctx->out_channels = ctx->nchans;
355
    ctx->output_mode = ctx->acmod;
356
    if(ctx->lfeon)
357
        ctx->output_mode |= AC3_OUTPUT_LFEON;
358

    
359
    /* skip over portion of header which has already been read */
360
    skip_bits(gb, 16); //skip the sync_word, sync_info->sync_word = get_bits(gb, 16);
361
    skip_bits(gb, 16); // skip crc1
362
    skip_bits(gb, 8);  // skip fscod and frmsizecod
363
    skip_bits(gb, 11); // skip bsid, bsmod, and acmod
364
    if(ctx->acmod == AC3_ACMOD_STEREO) {
365
        skip_bits(gb, 2); // skip dsurmod
366
    } else {
367
        if((ctx->acmod & 1) && ctx->acmod != AC3_ACMOD_MONO)
368
            skip_bits(gb, 2); // skip cmixlev
369
        if(ctx->acmod & 4)
370
            skip_bits(gb, 2); // skip surmixlev
371
    }
372
    skip_bits1(gb); // skip lfeon
373

    
374
    /* read the rest of the bsi. read twice for dual mono mode. */
375
    i = !(ctx->acmod);
376
    do {
377
        ctx->dialnorm[i] = dialnorm_tbl[get_bits(gb, 5)]; // dialogue normalization
378
        if (get_bits1(gb))
379
            skip_bits(gb, 8); //skip compression
380
        if (get_bits1(gb))
381
            skip_bits(gb, 8); //skip language code
382
        if (get_bits1(gb))
383
            skip_bits(gb, 7); //skip audio production information
384
    } while (i--);
385

    
386
    skip_bits(gb, 2); //skip copyright bit and original bitstream bit
387

    
388
    /* FIXME: read & use the xbsi1 downmix levels */
389
    if (get_bits1(gb))
390
        skip_bits(gb, 14); //skip timecode1
391
    if (get_bits1(gb))
392
        skip_bits(gb, 14); //skip timecode2
393

    
394
    if (get_bits1(gb)) {
395
        i = get_bits(gb, 6); //additional bsi length
396
        do {
397
            skip_bits(gb, 8);
398
        } while(i--);
399
    }
400

    
401
    /* set stereo downmixing coefficients
402
       reference: Section 7.8.2 Downmixing Into Two Channels */
403
    for(i=0; i<ctx->nfchans; i++) {
404
        ctx->downmix_coeffs[i][0] = gain_levels[ac3_default_coeffs[ctx->acmod][i][0]];
405
        ctx->downmix_coeffs[i][1] = gain_levels[ac3_default_coeffs[ctx->acmod][i][1]];
406
    }
407
    if(ctx->acmod > 1 && ctx->acmod & 1) {
408
        ctx->downmix_coeffs[1][0] = ctx->downmix_coeffs[1][1] = cmixlev;
409
    }
410
    if(ctx->acmod == AC3_ACMOD_2F1R || ctx->acmod == AC3_ACMOD_3F1R) {
411
        int nf = ctx->acmod - 2;
412
        ctx->downmix_coeffs[nf][0] = ctx->downmix_coeffs[nf][1] = surmixlev * LEVEL_MINUS_3DB;
413
    }
414
    if(ctx->acmod == AC3_ACMOD_2F2R || ctx->acmod == AC3_ACMOD_3F2R) {
415
        int nf = ctx->acmod - 4;
416
        ctx->downmix_coeffs[nf][0] = ctx->downmix_coeffs[nf+1][1] = surmixlev;
417
    }
418

    
419
    return 0;
420
}
421

    
422
/**
423
 * Decodes the grouped exponents.
424
 * This function decodes the coded exponents according to exponent strategy
425
 * and stores them in the decoded exponents buffer.
426
 *
427
 * @param[in]  gb      GetBitContext which points to start of coded exponents
428
 * @param[in]  expstr  Exponent coding strategy
429
 * @param[in]  ngrps   Number of grouped exponents
430
 * @param[in]  absexp  Absolute exponent or DC exponent
431
 * @param[out] dexps   Decoded exponents are stored in dexps
432
 */
433
static void decode_exponents(GetBitContext *gb, int expstr, int ngrps,
434
                             uint8_t absexp, int8_t *dexps)
435
{
436
    int i, j, grp, grpsize;
437
    int dexp[256];
438
    int expacc, prevexp;
439

    
440
    /* unpack groups */
441
    grpsize = expstr + (expstr == EXP_D45);
442
    for(grp=0,i=0; grp<ngrps; grp++) {
443
        expacc = get_bits(gb, 7);
444
        dexp[i++] = exp_ungroup_tbl[expacc][0];
445
        dexp[i++] = exp_ungroup_tbl[expacc][1];
446
        dexp[i++] = exp_ungroup_tbl[expacc][2];
447
    }
448

    
449
    /* convert to absolute exps and expand groups */
450
    prevexp = absexp;
451
    for(i=0; i<ngrps*3; i++) {
452
        prevexp = av_clip(prevexp + dexp[i]-2, 0, 24);
453
        for(j=0; j<grpsize; j++) {
454
            dexps[(i*grpsize)+j] = prevexp;
455
        }
456
    }
457
}
458

    
459
/**
460
 * Generates transform coefficients for each coupled channel in the coupling
461
 * range using the coupling coefficients and coupling coordinates.
462
 * reference: Section 7.4.3 Coupling Coordinate Format
463
 */
464
static void uncouple_channels(AC3DecodeContext *ctx)
465
{
466
    int i, j, ch, bnd, subbnd;
467

    
468
    subbnd = -1;
469
    i = ctx->startmant[CPL_CH];
470
    for(bnd=0; bnd<ctx->ncplbnd; bnd++) {
471
        do {
472
            subbnd++;
473
            for(j=0; j<12; j++) {
474
                for(ch=1; ch<=ctx->nfchans; ch++) {
475
                    if(ctx->chincpl[ch])
476
                        ctx->transform_coeffs[ch][i] = ctx->transform_coeffs[CPL_CH][i] * ctx->cplco[ch][bnd] * 8.0f;
477
                }
478
                i++;
479
            }
480
        } while(ctx->cplbndstrc[subbnd]);
481
    }
482
}
483

    
484
typedef struct { /* grouped mantissas for 3-level 5-leve and 11-level quantization */
485
    float b1_mant[3];
486
    float b2_mant[3];
487
    float b4_mant[2];
488
    int b1ptr;
489
    int b2ptr;
490
    int b4ptr;
491
} mant_groups;
492

    
493
/* Get the transform coefficients for particular channel */
494
static int get_transform_coeffs_ch(AC3DecodeContext *ctx, int ch_index, mant_groups *m)
495
{
496
    GetBitContext *gb = &ctx->gb;
497
    int i, gcode, tbap, start, end;
498
    uint8_t *exps;
499
    uint8_t *bap;
500
    float *coeffs;
501

    
502
    exps = ctx->dexps[ch_index];
503
    bap = ctx->bap[ch_index];
504
    coeffs = ctx->transform_coeffs[ch_index];
505
    start = ctx->startmant[ch_index];
506
    end = ctx->endmant[ch_index];
507

    
508

    
509
    for (i = start; i < end; i++) {
510
        tbap = bap[i];
511
        switch (tbap) {
512
            case 0:
513
                coeffs[i] = ((av_random(&ctx->dith_state) & 0xFFFF) * LEVEL_MINUS_3DB) / 32768.0f;
514
                break;
515

    
516
            case 1:
517
                if(m->b1ptr > 2) {
518
                    gcode = get_bits(gb, 5);
519
                    m->b1_mant[0] = b1_mantissas[gcode][0];
520
                    m->b1_mant[1] = b1_mantissas[gcode][1];
521
                    m->b1_mant[2] = b1_mantissas[gcode][2];
522
                    m->b1ptr = 0;
523
                }
524
                coeffs[i] = m->b1_mant[m->b1ptr++];
525
                break;
526

    
527
            case 2:
528
                if(m->b2ptr > 2) {
529
                    gcode = get_bits(gb, 7);
530
                    m->b2_mant[0] = b2_mantissas[gcode][0];
531
                    m->b2_mant[1] = b2_mantissas[gcode][1];
532
                    m->b2_mant[2] = b2_mantissas[gcode][2];
533
                    m->b2ptr = 0;
534
                }
535
                coeffs[i] = m->b2_mant[m->b2ptr++];
536
                break;
537

    
538
            case 3:
539
                coeffs[i] = b3_mantissas[get_bits(gb, 3)];
540
                break;
541

    
542
            case 4:
543
                if(m->b4ptr > 1) {
544
                    gcode = get_bits(gb, 7);
545
                    m->b4_mant[0] = b4_mantissas[gcode][0];
546
                    m->b4_mant[1] = b4_mantissas[gcode][1];
547
                    m->b4ptr = 0;
548
                }
549
                coeffs[i] = m->b4_mant[m->b4ptr++];
550
                break;
551

    
552
            case 5:
553
                coeffs[i] = b5_mantissas[get_bits(gb, 4)];
554
                break;
555

    
556
            default:
557
                coeffs[i] = get_sbits(gb, qntztab[tbap]) * scale_factors[qntztab[tbap]-1];
558
                break;
559
        }
560
        coeffs[i] *= scale_factors[exps[i]];
561
    }
562

    
563
    return 0;
564
}
565

    
566
/**
567
 * Removes random dithering from coefficients with zero-bit mantissas
568
 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
569
 */
570
static void remove_dithering(AC3DecodeContext *ctx) {
571
    int ch, i;
572
    int end=0;
573
    float *coeffs;
574
    uint8_t *bap;
575

    
576
    for(ch=1; ch<=ctx->nfchans; ch++) {
577
        if(!ctx->dithflag[ch]) {
578
            coeffs = ctx->transform_coeffs[ch];
579
            bap = ctx->bap[ch];
580
            if(ctx->chincpl[ch])
581
                end = ctx->startmant[CPL_CH];
582
            else
583
                end = ctx->endmant[ch];
584
            for(i=0; i<end; i++) {
585
                if(bap[i] == 0)
586
                    coeffs[i] = 0.0f;
587
            }
588
            if(ctx->chincpl[ch]) {
589
                bap = ctx->bap[CPL_CH];
590
                for(; i<ctx->endmant[CPL_CH]; i++) {
591
                    if(bap[i] == 0)
592
                        coeffs[i] = 0.0f;
593
                }
594
            }
595
        }
596
    }
597
}
598

    
599
/* Get the transform coefficients.
600
 * This function extracts the tranform coefficients form the ac3 bitstream.
601
 * This function is called after bit allocation is performed.
602
 */
603
static int get_transform_coeffs(AC3DecodeContext * ctx)
604
{
605
    int ch, end;
606
    int got_cplchan = 0;
607
    mant_groups m;
608

    
609
    m.b1ptr = m.b2ptr = m.b4ptr = 3;
610

    
611
    for (ch = 1; ch <= ctx->nchans; ch++) {
612
        /* transform coefficients for individual channel */
613
        if (get_transform_coeffs_ch(ctx, ch, &m))
614
            return -1;
615
        /* tranform coefficients for coupling channels */
616
        if (ctx->chincpl[ch])  {
617
            if (!got_cplchan) {
618
                if (get_transform_coeffs_ch(ctx, CPL_CH, &m)) {
619
                    av_log(NULL, AV_LOG_ERROR, "error in decoupling channels\n");
620
                    return -1;
621
                }
622
                uncouple_channels(ctx);
623
                got_cplchan = 1;
624
            }
625
            end = ctx->endmant[CPL_CH];
626
        } else {
627
            end = ctx->endmant[ch];
628
        }
629
        do
630
            ctx->transform_coeffs[ch][end] = 0;
631
        while(++end < 256);
632
    }
633

    
634
    /* if any channel doesn't use dithering, zero appropriate coefficients */
635
    if(!ctx->dither_all)
636
        remove_dithering(ctx);
637

    
638
    return 0;
639
}
640

    
641
/**
642
 * Performs stereo rematrixing.
643
 * reference: Section 7.5.4 Rematrixing : Decoding Technique
644
 */
645
static void do_rematrixing(AC3DecodeContext *ctx)
646
{
647
    int bnd, i;
648
    int end, bndend;
649
    float tmp0, tmp1;
650

    
651
    end = FFMIN(ctx->endmant[1], ctx->endmant[2]);
652

    
653
    for(bnd=0; bnd<ctx->nrematbnd; bnd++) {
654
        if(ctx->rematflg[bnd]) {
655
            bndend = FFMIN(end, rematrix_band_tbl[bnd+1]);
656
            for(i=rematrix_band_tbl[bnd]; i<bndend; i++) {
657
                tmp0 = ctx->transform_coeffs[1][i];
658
                tmp1 = ctx->transform_coeffs[2][i];
659
                ctx->transform_coeffs[1][i] = tmp0 + tmp1;
660
                ctx->transform_coeffs[2][i] = tmp0 - tmp1;
661
            }
662
        }
663
    }
664
}
665

    
666
/* This function performs the imdct on 256 sample transform
667
 * coefficients.
668
 */
669
static void do_imdct_256(AC3DecodeContext *ctx, int chindex)
670
{
671
    int i, k;
672
    DECLARE_ALIGNED_16(float, x[128]);
673
    FFTComplex z[2][64];
674
    float *o_ptr = ctx->tmp_output;
675

    
676
    for(i=0; i<2; i++) {
677
        /* de-interleave coefficients */
678
        for(k=0; k<128; k++) {
679
            x[k] = ctx->transform_coeffs[chindex][2*k+i];
680
        }
681

    
682
        /* run standard IMDCT */
683
        ctx->imdct_256.fft.imdct_calc(&ctx->imdct_256, o_ptr, x, ctx->tmp_imdct);
684

    
685
        /* reverse the post-rotation & reordering from standard IMDCT */
686
        for(k=0; k<32; k++) {
687
            z[i][32+k].re = -o_ptr[128+2*k];
688
            z[i][32+k].im = -o_ptr[2*k];
689
            z[i][31-k].re =  o_ptr[2*k+1];
690
            z[i][31-k].im =  o_ptr[128+2*k+1];
691
        }
692
    }
693

    
694
    /* apply AC-3 post-rotation & reordering */
695
    for(k=0; k<64; k++) {
696
        o_ptr[    2*k  ] = -z[0][   k].im;
697
        o_ptr[    2*k+1] =  z[0][63-k].re;
698
        o_ptr[128+2*k  ] = -z[0][   k].re;
699
        o_ptr[128+2*k+1] =  z[0][63-k].im;
700
        o_ptr[256+2*k  ] = -z[1][   k].re;
701
        o_ptr[256+2*k+1] =  z[1][63-k].im;
702
        o_ptr[384+2*k  ] =  z[1][   k].im;
703
        o_ptr[384+2*k+1] = -z[1][63-k].re;
704
    }
705
}
706

    
707
/* IMDCT Transform. */
708
static inline void do_imdct(AC3DecodeContext *ctx)
709
{
710
    int ch;
711
    int nchans;
712

    
713
    nchans = ctx->nfchans;
714
    if(ctx->output_mode & AC3_OUTPUT_LFEON)
715
        nchans++;
716

    
717
    for (ch=1; ch<=nchans; ch++) {
718
        if (ctx->blksw[ch]) {
719
            do_imdct_256(ctx, ch);
720
        } else {
721
            ctx->imdct_512.fft.imdct_calc(&ctx->imdct_512, ctx->tmp_output,
722
                                          ctx->transform_coeffs[ch],
723
                                          ctx->tmp_imdct);
724
        }
725
        ctx->dsp.vector_fmul_add_add(ctx->output[ch-1], ctx->tmp_output,
726
                                     ctx->window, ctx->delay[ch-1], 0, 256, 1);
727
        ctx->dsp.vector_fmul_reverse(ctx->delay[ch-1], ctx->tmp_output+256,
728
                                     ctx->window, 256);
729
    }
730
}
731

    
732
/**
733
 * Downmixes the output to stereo.
734
 */
735
static void ac3_downmix(float samples[AC3_MAX_CHANNELS][256], int nfchans,
736
                        int output_mode, float coef[AC3_MAX_CHANNELS][2])
737
{
738
    int i, j;
739
    float v0, v1, s0, s1;
740

    
741
    for(i=0; i<256; i++) {
742
        v0 = v1 = s0 = s1 = 0.0f;
743
        for(j=0; j<nfchans; j++) {
744
            v0 += samples[j][i] * coef[j][0];
745
            v1 += samples[j][i] * coef[j][1];
746
            s0 += coef[j][0];
747
            s1 += coef[j][1];
748
        }
749
        v0 /= s0;
750
        v1 /= s1;
751
        if(output_mode == AC3_ACMOD_MONO) {
752
            samples[0][i] = (v0 + v1) * LEVEL_MINUS_3DB;
753
        } else if(output_mode == AC3_ACMOD_STEREO) {
754
            samples[0][i] = v0;
755
            samples[1][i] = v1;
756
        }
757
    }
758
}
759

    
760
/* Parse the audio block from ac3 bitstream.
761
 * This function extract the audio block from the ac3 bitstream
762
 * and produces the output for the block. This function must
763
 * be called for each of the six audio block in the ac3 bitstream.
764
 */
765
static int ac3_parse_audio_block(AC3DecodeContext *ctx, int blk)
766
{
767
    int nfchans = ctx->nfchans;
768
    int acmod = ctx->acmod;
769
    int i, bnd, seg, ch;
770
    GetBitContext *gb = &ctx->gb;
771
    uint8_t bit_alloc_stages[AC3_MAX_CHANNELS];
772

    
773
    memset(bit_alloc_stages, 0, AC3_MAX_CHANNELS);
774

    
775
    for (ch = 1; ch <= nfchans; ch++) /*block switch flag */
776
        ctx->blksw[ch] = get_bits1(gb);
777

    
778
    ctx->dither_all = 1;
779
    for (ch = 1; ch <= nfchans; ch++) { /* dithering flag */
780
        ctx->dithflag[ch] = get_bits1(gb);
781
        if(!ctx->dithflag[ch])
782
            ctx->dither_all = 0;
783
    }
784

    
785
    if (get_bits1(gb)) { /* dynamic range */
786
        ctx->dynrng = dynrng_tbl[get_bits(gb, 8)];
787
    } else if(blk == 0) {
788
        ctx->dynrng = 1.0;
789
    }
790

    
791
    if(acmod == AC3_ACMOD_DUALMONO) { /* dynamic range 1+1 mode */
792
        if(get_bits1(gb)) {
793
            ctx->dynrng2 = dynrng_tbl[get_bits(gb, 8)];
794
        } else if(blk == 0) {
795
            ctx->dynrng2 = 1.0;
796
        }
797
    }
798

    
799
    if (get_bits1(gb)) { /* coupling strategy */
800
        memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
801
        ctx->cplinu = get_bits1(gb);
802
        if (ctx->cplinu) { /* coupling in use */
803
            int cplbegf, cplendf;
804

    
805
            for (ch = 1; ch <= nfchans; ch++)
806
                ctx->chincpl[ch] = get_bits1(gb);
807

    
808
            if (acmod == AC3_ACMOD_STEREO)
809
                ctx->phsflginu = get_bits1(gb); //phase flag in use
810

    
811
            cplbegf = get_bits(gb, 4);
812
            cplendf = get_bits(gb, 4);
813

    
814
            if (3 + cplendf - cplbegf < 0) {
815
                av_log(NULL, AV_LOG_ERROR, "cplendf = %d < cplbegf = %d\n", cplendf, cplbegf);
816
                return -1;
817
            }
818

    
819
            ctx->ncplbnd = ctx->ncplsubnd = 3 + cplendf - cplbegf;
820
            ctx->startmant[CPL_CH] = cplbegf * 12 + 37;
821
            ctx->endmant[CPL_CH] = cplendf * 12 + 73;
822
            for (bnd = 0; bnd < ctx->ncplsubnd - 1; bnd++) { /* coupling band structure */
823
                if (get_bits1(gb)) {
824
                    ctx->cplbndstrc[bnd] = 1;
825
                    ctx->ncplbnd--;
826
                }
827
            }
828
        } else {
829
            for (ch = 1; ch <= nfchans; ch++)
830
                ctx->chincpl[ch] = 0;
831
        }
832
    }
833

    
834
    if (ctx->cplinu) {
835
        int cplcoe = 0;
836

    
837
        for (ch = 1; ch <= nfchans; ch++) {
838
            if (ctx->chincpl[ch]) {
839
                if (get_bits1(gb)) { /* coupling co-ordinates */
840
                    int mstrcplco, cplcoexp, cplcomant;
841
                    cplcoe = 1;
842
                    mstrcplco = 3 * get_bits(gb, 2);
843
                    for (bnd = 0; bnd < ctx->ncplbnd; bnd++) {
844
                        cplcoexp = get_bits(gb, 4);
845
                        cplcomant = get_bits(gb, 4);
846
                        if (cplcoexp == 15)
847
                            ctx->cplco[ch][bnd] = cplcomant / 16.0f;
848
                        else
849
                            ctx->cplco[ch][bnd] = (cplcomant + 16.0f) / 32.0f;
850
                        ctx->cplco[ch][bnd] *= scale_factors[cplcoexp + mstrcplco];
851
                    }
852
                }
853
            }
854
        }
855

    
856
        if (acmod == AC3_ACMOD_STEREO && ctx->phsflginu && cplcoe) {
857
            for (bnd = 0; bnd < ctx->ncplbnd; bnd++) {
858
                if (get_bits1(gb))
859
                    ctx->cplco[2][bnd] = -ctx->cplco[2][bnd];
860
            }
861
        }
862
    }
863

    
864
    if (acmod == AC3_ACMOD_STEREO) {/* rematrixing */
865
        ctx->rematstr = get_bits1(gb);
866
        if (ctx->rematstr) {
867
            ctx->nrematbnd = 4;
868
            if(ctx->cplinu && ctx->startmant[CPL_CH] <= 61)
869
                ctx->nrematbnd -= 1 + (ctx->startmant[CPL_CH] == 37);
870
            for(bnd=0; bnd<ctx->nrematbnd; bnd++)
871
                ctx->rematflg[bnd] = get_bits1(gb);
872
        }
873
    }
874

    
875
    ctx->expstr[CPL_CH] = EXP_REUSE;
876
    ctx->expstr[ctx->lfe_ch] = EXP_REUSE;
877
    for (ch = !ctx->cplinu; ch <= ctx->nchans; ch++) {
878
        if(ch == ctx->lfe_ch)
879
            ctx->expstr[ch] = get_bits(gb, 1);
880
        else
881
            ctx->expstr[ch] = get_bits(gb, 2);
882
        if(ctx->expstr[ch] != EXP_REUSE)
883
            bit_alloc_stages[ch] = 3;
884
    }
885

    
886
    for (ch = 1; ch <= nfchans; ch++) { /* channel bandwidth code */
887
        ctx->startmant[ch] = 0;
888
        if (ctx->expstr[ch] != EXP_REUSE) {
889
            int prev = ctx->endmant[ch];
890
            if (ctx->chincpl[ch])
891
                ctx->endmant[ch] = ctx->startmant[CPL_CH];
892
            else {
893
                int chbwcod = get_bits(gb, 6);
894
                if (chbwcod > 60) {
895
                    av_log(NULL, AV_LOG_ERROR, "chbwcod = %d > 60", chbwcod);
896
                    return -1;
897
                }
898
                ctx->endmant[ch] = chbwcod * 3 + 73;
899
            }
900
            if(blk > 0 && ctx->endmant[ch] != prev)
901
                memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
902
        }
903
    }
904
    ctx->startmant[ctx->lfe_ch] = 0;
905
    ctx->endmant[ctx->lfe_ch] = 7;
906

    
907
    for (ch = !ctx->cplinu; ch <= ctx->nchans; ch++) {
908
        if (ctx->expstr[ch] != EXP_REUSE) {
909
            int grpsize, ngrps;
910
            grpsize = 3 << (ctx->expstr[ch] - 1);
911
            if(ch == CPL_CH)
912
                ngrps = (ctx->endmant[ch] - ctx->startmant[ch]) / grpsize;
913
            else if(ch == ctx->lfe_ch)
914
                ngrps = 2;
915
            else
916
                ngrps = (ctx->endmant[ch] + grpsize - 4) / grpsize;
917
            ctx->dexps[ch][0] = get_bits(gb, 4) << !ch;
918
            decode_exponents(gb, ctx->expstr[ch], ngrps, ctx->dexps[ch][0],
919
                             &ctx->dexps[ch][ctx->startmant[ch]+!!ch]);
920
            if(ch != CPL_CH && ch != ctx->lfe_ch)
921
                skip_bits(gb, 2); /* skip gainrng */
922
        }
923
    }
924

    
925
    if (get_bits1(gb)) { /* bit allocation information */
926
        ctx->bit_alloc_params.sdecay = ff_sdecaytab[get_bits(gb, 2)];
927
        ctx->bit_alloc_params.fdecay = ff_fdecaytab[get_bits(gb, 2)];
928
        ctx->bit_alloc_params.sgain  = ff_sgaintab[get_bits(gb, 2)];
929
        ctx->bit_alloc_params.dbknee = ff_dbkneetab[get_bits(gb, 2)];
930
        ctx->bit_alloc_params.floor  = ff_floortab[get_bits(gb, 3)];
931
        for(ch=!ctx->cplinu; ch<=ctx->nchans; ch++) {
932
            bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
933
        }
934
    }
935

    
936
    if (get_bits1(gb)) { /* snroffset */
937
        int csnr;
938
        csnr = (get_bits(gb, 6) - 15) << 4;
939
        for (ch = !ctx->cplinu; ch <= ctx->nchans; ch++) { /* snr offset and fast gain */
940
            ctx->snroffst[ch] = (csnr + get_bits(gb, 4)) << 2;
941
            ctx->fgain[ch] = ff_fgaintab[get_bits(gb, 3)];
942
        }
943
        memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
944
    }
945

    
946
    if (ctx->cplinu && get_bits1(gb)) { /* coupling leak information */
947
        ctx->bit_alloc_params.cplfleak = get_bits(gb, 3);
948
        ctx->bit_alloc_params.cplsleak = get_bits(gb, 3);
949
        bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
950
    }
951

    
952
    if (get_bits1(gb)) { /* delta bit allocation information */
953
        for (ch = !ctx->cplinu; ch <= nfchans; ch++) {
954
            ctx->deltbae[ch] = get_bits(gb, 2);
955
            if (ctx->deltbae[ch] == DBA_RESERVED) {
956
                av_log(NULL, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
957
                return -1;
958
            }
959
            bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
960
        }
961

    
962
        for (ch = !ctx->cplinu; ch <= nfchans; ch++) {
963
            if (ctx->deltbae[ch] == DBA_NEW) {/*channel delta offset, len and bit allocation */
964
                ctx->deltnseg[ch] = get_bits(gb, 3);
965
                for (seg = 0; seg <= ctx->deltnseg[ch]; seg++) {
966
                    ctx->deltoffst[ch][seg] = get_bits(gb, 5);
967
                    ctx->deltlen[ch][seg] = get_bits(gb, 4);
968
                    ctx->deltba[ch][seg] = get_bits(gb, 3);
969
                }
970
            }
971
        }
972
    } else if(blk == 0) {
973
        for(ch=0; ch<=ctx->nchans; ch++) {
974
            ctx->deltbae[ch] = DBA_NONE;
975
        }
976
    }
977

    
978
    for(ch=!ctx->cplinu; ch<=ctx->nchans; ch++) {
979
        if(bit_alloc_stages[ch] > 2) {
980
            /* Exponent mapping into PSD and PSD integration */
981
            ff_ac3_bit_alloc_calc_psd(ctx->dexps[ch],
982
                                      ctx->startmant[ch], ctx->endmant[ch],
983
                                      ctx->psd[ch], ctx->bndpsd[ch]);
984
        }
985
        if(bit_alloc_stages[ch] > 1) {
986
            /* Compute excitation function, Compute masking curve, and
987
               Apply delta bit allocation */
988
            ff_ac3_bit_alloc_calc_mask(&ctx->bit_alloc_params, ctx->bndpsd[ch],
989
                                       ctx->startmant[ch], ctx->endmant[ch],
990
                                       ctx->fgain[ch], (ch == ctx->lfe_ch),
991
                                       ctx->deltbae[ch], ctx->deltnseg[ch],
992
                                       ctx->deltoffst[ch], ctx->deltlen[ch],
993
                                       ctx->deltba[ch], ctx->mask[ch]);
994
        }
995
        if(bit_alloc_stages[ch] > 0) {
996
            /* Compute bit allocation */
997
            ff_ac3_bit_alloc_calc_bap(ctx->mask[ch], ctx->psd[ch],
998
                                      ctx->startmant[ch], ctx->endmant[ch],
999
                                      ctx->snroffst[ch],
1000
                                      ctx->bit_alloc_params.floor,
1001
                                      ctx->bap[ch]);
1002
        }
1003
    }
1004

    
1005
    if (get_bits1(gb)) { /* unused dummy data */
1006
        int skipl = get_bits(gb, 9);
1007
        while(skipl--)
1008
            skip_bits(gb, 8);
1009
    }
1010
    /* unpack the transform coefficients
1011
     * * this also uncouples channels if coupling is in use.
1012
     */
1013
    if (get_transform_coeffs(ctx)) {
1014
        av_log(NULL, AV_LOG_ERROR, "Error in routine get_transform_coeffs\n");
1015
        return -1;
1016
    }
1017

    
1018
    /* recover coefficients if rematrixing is in use */
1019
    if(ctx->acmod == AC3_ACMOD_STEREO)
1020
        do_rematrixing(ctx);
1021

    
1022
    /* apply scaling to coefficients (headroom, dialnorm, dynrng) */
1023
    for(ch=1; ch<=ctx->nchans; ch++) {
1024
        float gain = 2.0f * ctx->mul_bias;
1025
        if(ctx->acmod == AC3_ACMOD_DUALMONO && ch == 2) {
1026
            gain *= ctx->dialnorm[ch-1] * ctx->dynrng2;
1027
        } else {
1028
            gain *= ctx->dialnorm[0] * ctx->dynrng;
1029
        }
1030
        for(i=0; i<ctx->endmant[ch]; i++) {
1031
            ctx->transform_coeffs[ch][i] *= gain;
1032
        }
1033
    }
1034

    
1035
    do_imdct(ctx);
1036

    
1037
    /* downmix output if needed */
1038
    if(ctx->nchans != ctx->out_channels && !((ctx->output_mode & AC3_OUTPUT_LFEON) &&
1039
            ctx->nfchans == ctx->out_channels)) {
1040
        ac3_downmix(ctx->output, ctx->nfchans, ctx->output_mode,
1041
                    ctx->downmix_coeffs);
1042
    }
1043

    
1044
    /* convert float to 16-bit integer */
1045
    for(ch=0; ch<ctx->out_channels; ch++) {
1046
        for(i=0; i<256; i++) {
1047
            ctx->output[ch][i] += ctx->add_bias;
1048
        }
1049
        ctx->dsp.float_to_int16(ctx->int_output[ch], ctx->output[ch], 256);
1050
    }
1051

    
1052
    return 0;
1053
}
1054

    
1055
/* Decode ac3 frame.
1056
 *
1057
 * @param avctx Pointer to AVCodecContext
1058
 * @param data Pointer to pcm smaples
1059
 * @param data_size Set to number of pcm samples produced by decoding
1060
 * @param buf Data to be decoded
1061
 * @param buf_size Size of the buffer
1062
 */
1063
static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size, uint8_t *buf, int buf_size)
1064
{
1065
    AC3DecodeContext *ctx = (AC3DecodeContext *)avctx->priv_data;
1066
    int16_t *out_samples = (int16_t *)data;
1067
    int i, blk, ch;
1068

    
1069
    //Initialize the GetBitContext with the start of valid AC3 Frame.
1070
    init_get_bits(&ctx->gb, buf, buf_size * 8);
1071

    
1072
    //Parse the syncinfo.
1073
    if (ac3_parse_header(ctx)) {
1074
        av_log(avctx, AV_LOG_ERROR, "\n");
1075
        *data_size = 0;
1076
        return buf_size;
1077
    }
1078

    
1079
    avctx->sample_rate = ctx->sampling_rate;
1080
    avctx->bit_rate = ctx->bit_rate;
1081

    
1082
    /* channel config */
1083
    ctx->out_channels = ctx->nchans;
1084
    if (avctx->channels == 0) {
1085
        avctx->channels = ctx->out_channels;
1086
    } else if(ctx->out_channels < avctx->channels) {
1087
        av_log(avctx, AV_LOG_ERROR, "Cannot upmix AC3 from %d to %d channels.\n",
1088
               ctx->out_channels, avctx->channels);
1089
        return -1;
1090
    }
1091
    if(avctx->channels == 2) {
1092
        ctx->output_mode = AC3_ACMOD_STEREO;
1093
    } else if(avctx->channels == 1) {
1094
        ctx->output_mode = AC3_ACMOD_MONO;
1095
    } else if(avctx->channels != ctx->out_channels) {
1096
        av_log(avctx, AV_LOG_ERROR, "Cannot downmix AC3 from %d to %d channels.\n",
1097
               ctx->out_channels, avctx->channels);
1098
        return -1;
1099
    }
1100
    ctx->out_channels = avctx->channels;
1101

    
1102
    //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);
1103

    
1104
    //Parse the Audio Blocks.
1105
    for (blk = 0; blk < NB_BLOCKS; blk++) {
1106
        if (ac3_parse_audio_block(ctx, blk)) {
1107
            av_log(avctx, AV_LOG_ERROR, "error parsing the audio block\n");
1108
            *data_size = 0;
1109
            return ctx->frame_size;
1110
        }
1111
        for (i = 0; i < 256; i++)
1112
            for (ch = 0; ch < ctx->out_channels; ch++)
1113
                *(out_samples++) = ctx->int_output[ch][i];
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