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/*
2
 * The simplest AC-3 encoder
3
 * Copyright (c) 2000 Fabrice Bellard
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 * Copyright (c) 2006-2010 Justin Ruggles <justin.ruggles@gmail.com>
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 * Copyright (c) 2006-2010 Prakash Punnoor <prakash@punnoor.de>
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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 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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 * 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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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
23

    
24
/**
25
 * @file
26
 * The simplest AC-3 encoder.
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 */
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//#define DEBUG
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#include "libavcore/audioconvert.h"
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#include "libavutil/crc.h"
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#include "avcodec.h"
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#include "put_bits.h"
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#include "dsputil.h"
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#include "ac3.h"
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#include "audioconvert.h"
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39

    
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#ifndef CONFIG_AC3ENC_FLOAT
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#define CONFIG_AC3ENC_FLOAT 0
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#endif
43

    
44

    
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/** Maximum number of exponent groups. +1 for separate DC exponent. */
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#define AC3_MAX_EXP_GROUPS 85
47

    
48
/** Scale a float value by 2^bits and convert to an integer. */
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#define SCALE_FLOAT(a, bits) lrintf((a) * (float)(1 << (bits)))
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51

    
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#if CONFIG_AC3ENC_FLOAT
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#include "ac3enc_float.h"
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#else
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#include "ac3enc_fixed.h"
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#endif
57

    
58

    
59
/**
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 * Data for a single audio block.
61
 */
62
typedef struct AC3Block {
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    uint8_t  **bap;                             ///< bit allocation pointers (bap)
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    CoefType **mdct_coef;                       ///< MDCT coefficients
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    uint8_t  **exp;                             ///< original exponents
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    uint8_t  **grouped_exp;                     ///< grouped exponents
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    int16_t  **psd;                             ///< psd per frequency bin
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    int16_t  **band_psd;                        ///< psd per critical band
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    int16_t  **mask;                            ///< masking curve
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    uint16_t **qmant;                           ///< quantized mantissas
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    uint8_t  exp_strategy[AC3_MAX_CHANNELS];    ///< exponent strategies
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    int8_t   exp_shift[AC3_MAX_CHANNELS];       ///< exponent shift values
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} AC3Block;
74

    
75
/**
76
 * AC-3 encoder private context.
77
 */
78
typedef struct AC3EncodeContext {
79
    PutBitContext pb;                       ///< bitstream writer context
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    DSPContext dsp;
81
    AC3MDCTContext mdct;                    ///< MDCT context
82

    
83
    AC3Block blocks[AC3_MAX_BLOCKS];        ///< per-block info
84

    
85
    int bitstream_id;                       ///< bitstream id                           (bsid)
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    int bitstream_mode;                     ///< bitstream mode                         (bsmod)
87

    
88
    int bit_rate;                           ///< target bit rate, in bits-per-second
89
    int sample_rate;                        ///< sampling frequency, in Hz
90

    
91
    int frame_size_min;                     ///< minimum frame size in case rounding is necessary
92
    int frame_size;                         ///< current frame size in bytes
93
    int frame_size_code;                    ///< frame size code                        (frmsizecod)
94
    uint16_t crc_inv[2];
95
    int bits_written;                       ///< bit count    (used to avg. bitrate)
96
    int samples_written;                    ///< sample count (used to avg. bitrate)
97

    
98
    int fbw_channels;                       ///< number of full-bandwidth channels      (nfchans)
99
    int channels;                           ///< total number of channels               (nchans)
100
    int lfe_on;                             ///< indicates if there is an LFE channel   (lfeon)
101
    int lfe_channel;                        ///< channel index of the LFE channel
102
    int channel_mode;                       ///< channel mode                           (acmod)
103
    const uint8_t *channel_map;             ///< channel map used to reorder channels
104

    
105
    int cutoff;                             ///< user-specified cutoff frequency, in Hz
106
    int bandwidth_code[AC3_MAX_CHANNELS];   ///< bandwidth code (0 to 60)               (chbwcod)
107
    int nb_coefs[AC3_MAX_CHANNELS];
108

    
109
    /* bitrate allocation control */
110
    int slow_gain_code;                     ///< slow gain code                         (sgaincod)
111
    int slow_decay_code;                    ///< slow decay code                        (sdcycod)
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    int fast_decay_code;                    ///< fast decay code                        (fdcycod)
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    int db_per_bit_code;                    ///< dB/bit code                            (dbpbcod)
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    int floor_code;                         ///< floor code                             (floorcod)
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    AC3BitAllocParameters bit_alloc;        ///< bit allocation parameters
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    int coarse_snr_offset;                  ///< coarse SNR offsets                     (csnroffst)
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    int fast_gain_code[AC3_MAX_CHANNELS];   ///< fast gain codes (signal-to-mask ratio) (fgaincod)
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    int fine_snr_offset[AC3_MAX_CHANNELS];  ///< fine SNR offsets                       (fsnroffst)
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    int frame_bits_fixed;                   ///< number of non-coefficient bits for fixed parameters
120
    int frame_bits;                         ///< all frame bits except exponents and mantissas
121
    int exponent_bits;                      ///< number of bits used for exponents
122

    
123
    /* mantissa encoding */
124
    int mant1_cnt, mant2_cnt, mant4_cnt;    ///< mantissa counts for bap=1,2,4
125
    uint16_t *qmant1_ptr, *qmant2_ptr, *qmant4_ptr; ///< mantissa pointers for bap=1,2,4
126

    
127
    SampleType **planar_samples;
128
    uint8_t *bap_buffer;
129
    uint8_t *bap1_buffer;
130
    CoefType *mdct_coef_buffer;
131
    uint8_t *exp_buffer;
132
    uint8_t *grouped_exp_buffer;
133
    int16_t *psd_buffer;
134
    int16_t *band_psd_buffer;
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    int16_t *mask_buffer;
136
    uint16_t *qmant_buffer;
137

    
138
    DECLARE_ALIGNED(16, SampleType, windowed_samples)[AC3_WINDOW_SIZE];
139
} AC3EncodeContext;
140

    
141

    
142
/* prototypes for functions in ac3enc_fixed.c and ac3enc_float.c */
143

    
144
static av_cold void mdct_end(AC3MDCTContext *mdct);
145

    
146
static av_cold int mdct_init(AVCodecContext *avctx, AC3MDCTContext *mdct,
147
                             int nbits);
148

    
149
static void mdct512(AC3MDCTContext *mdct, CoefType *out, SampleType *in);
150

    
151
static void apply_window(SampleType *output, const SampleType *input,
152
                         const SampleType *window, int n);
153

    
154
static int normalize_samples(AC3EncodeContext *s);
155

    
156

    
157
/**
158
 * LUT for number of exponent groups.
159
 * exponent_group_tab[exponent strategy-1][number of coefficients]
160
 */
161
static uint8_t exponent_group_tab[3][256];
162

    
163

    
164
/**
165
 * List of supported channel layouts.
166
 */
167
static const int64_t ac3_channel_layouts[] = {
168
     AV_CH_LAYOUT_MONO,
169
     AV_CH_LAYOUT_STEREO,
170
     AV_CH_LAYOUT_2_1,
171
     AV_CH_LAYOUT_SURROUND,
172
     AV_CH_LAYOUT_2_2,
173
     AV_CH_LAYOUT_QUAD,
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     AV_CH_LAYOUT_4POINT0,
175
     AV_CH_LAYOUT_5POINT0,
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     AV_CH_LAYOUT_5POINT0_BACK,
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    (AV_CH_LAYOUT_MONO     | AV_CH_LOW_FREQUENCY),
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    (AV_CH_LAYOUT_STEREO   | AV_CH_LOW_FREQUENCY),
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    (AV_CH_LAYOUT_2_1      | AV_CH_LOW_FREQUENCY),
180
    (AV_CH_LAYOUT_SURROUND | AV_CH_LOW_FREQUENCY),
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    (AV_CH_LAYOUT_2_2      | AV_CH_LOW_FREQUENCY),
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    (AV_CH_LAYOUT_QUAD     | AV_CH_LOW_FREQUENCY),
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    (AV_CH_LAYOUT_4POINT0  | AV_CH_LOW_FREQUENCY),
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     AV_CH_LAYOUT_5POINT1,
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     AV_CH_LAYOUT_5POINT1_BACK,
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     0
187
};
188

    
189

    
190
/**
191
 * Adjust the frame size to make the average bit rate match the target bit rate.
192
 * This is only needed for 11025, 22050, and 44100 sample rates.
193
 */
194
static void adjust_frame_size(AC3EncodeContext *s)
195
{
196
    while (s->bits_written >= s->bit_rate && s->samples_written >= s->sample_rate) {
197
        s->bits_written    -= s->bit_rate;
198
        s->samples_written -= s->sample_rate;
199
    }
200
    s->frame_size = s->frame_size_min +
201
                    2 * (s->bits_written * s->sample_rate < s->samples_written * s->bit_rate);
202
    s->bits_written    += s->frame_size * 8;
203
    s->samples_written += AC3_FRAME_SIZE;
204
}
205

    
206

    
207
/**
208
 * Deinterleave input samples.
209
 * Channels are reordered from FFmpeg's default order to AC-3 order.
210
 */
211
static void deinterleave_input_samples(AC3EncodeContext *s,
212
                                       const SampleType *samples)
213
{
214
    int ch, i;
215

    
216
    /* deinterleave and remap input samples */
217
    for (ch = 0; ch < s->channels; ch++) {
218
        const SampleType *sptr;
219
        int sinc;
220

    
221
        /* copy last 256 samples of previous frame to the start of the current frame */
222
        memcpy(&s->planar_samples[ch][0], &s->planar_samples[ch][AC3_FRAME_SIZE],
223
               AC3_BLOCK_SIZE * sizeof(s->planar_samples[0][0]));
224

    
225
        /* deinterleave */
226
        sinc = s->channels;
227
        sptr = samples + s->channel_map[ch];
228
        for (i = AC3_BLOCK_SIZE; i < AC3_FRAME_SIZE+AC3_BLOCK_SIZE; i++) {
229
            s->planar_samples[ch][i] = *sptr;
230
            sptr += sinc;
231
        }
232
    }
233
}
234

    
235

    
236
/**
237
 * Apply the MDCT to input samples to generate frequency coefficients.
238
 * This applies the KBD window and normalizes the input to reduce precision
239
 * loss due to fixed-point calculations.
240
 */
241
static void apply_mdct(AC3EncodeContext *s)
242
{
243
    int blk, ch;
244

    
245
    for (ch = 0; ch < s->channels; ch++) {
246
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
247
            AC3Block *block = &s->blocks[blk];
248
            const SampleType *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE];
249

    
250
            apply_window(s->windowed_samples, input_samples, s->mdct.window, AC3_WINDOW_SIZE);
251

    
252
            block->exp_shift[ch] = normalize_samples(s);
253

    
254
            mdct512(&s->mdct, block->mdct_coef[ch], s->windowed_samples);
255
        }
256
    }
257
}
258

    
259

    
260
/**
261
 * Initialize exponent tables.
262
 */
263
static av_cold void exponent_init(AC3EncodeContext *s)
264
{
265
    int i;
266
    for (i = 73; i < 256; i++) {
267
        exponent_group_tab[0][i] = (i - 1) /  3;
268
        exponent_group_tab[1][i] = (i + 2) /  6;
269
        exponent_group_tab[2][i] = (i + 8) / 12;
270
    }
271
    /* LFE */
272
    exponent_group_tab[0][7] = 2;
273
}
274

    
275

    
276
/**
277
 * Extract exponents from the MDCT coefficients.
278
 * This takes into account the normalization that was done to the input samples
279
 * by adjusting the exponents by the exponent shift values.
280
 */
281
static void extract_exponents(AC3EncodeContext *s)
282
{
283
    int blk, ch, i;
284

    
285
    for (ch = 0; ch < s->channels; ch++) {
286
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
287
            AC3Block *block = &s->blocks[blk];
288
            uint8_t *exp   = block->exp[ch];
289
            CoefType *coef = block->mdct_coef[ch];
290
            int exp_shift  = block->exp_shift[ch];
291
            for (i = 0; i < AC3_MAX_COEFS; i++) {
292
                int e;
293
                int v = abs(SCALE_COEF(coef[i]));
294
                if (v == 0)
295
                    e = 24;
296
                else {
297
                    e = 23 - av_log2(v) + exp_shift;
298
                    if (e >= 24) {
299
                        e = 24;
300
                        coef[i] = 0;
301
                    }
302
                }
303
                exp[i] = e;
304
            }
305
        }
306
    }
307
}
308

    
309

    
310
/**
311
 * Exponent Difference Threshold.
312
 * New exponents are sent if their SAD exceed this number.
313
 */
314
#define EXP_DIFF_THRESHOLD 1000
315

    
316

    
317
/**
318
 * Calculate exponent strategies for all blocks in a single channel.
319
 */
320
static void compute_exp_strategy_ch(AC3EncodeContext *s, uint8_t *exp_strategy,
321
                                    uint8_t **exp)
322
{
323
    int blk, blk1;
324
    int exp_diff;
325

    
326
    /* estimate if the exponent variation & decide if they should be
327
       reused in the next frame */
328
    exp_strategy[0] = EXP_NEW;
329
    for (blk = 1; blk < AC3_MAX_BLOCKS; blk++) {
330
        exp_diff = s->dsp.sad[0](NULL, exp[blk], exp[blk-1], 16, 16);
331
        if (exp_diff > EXP_DIFF_THRESHOLD)
332
            exp_strategy[blk] = EXP_NEW;
333
        else
334
            exp_strategy[blk] = EXP_REUSE;
335
    }
336
    emms_c();
337

    
338
    /* now select the encoding strategy type : if exponents are often
339
       recoded, we use a coarse encoding */
340
    blk = 0;
341
    while (blk < AC3_MAX_BLOCKS) {
342
        blk1 = blk + 1;
343
        while (blk1 < AC3_MAX_BLOCKS && exp_strategy[blk1] == EXP_REUSE)
344
            blk1++;
345
        switch (blk1 - blk) {
346
        case 1:  exp_strategy[blk] = EXP_D45; break;
347
        case 2:
348
        case 3:  exp_strategy[blk] = EXP_D25; break;
349
        default: exp_strategy[blk] = EXP_D15; break;
350
        }
351
        blk = blk1;
352
    }
353
}
354

    
355

    
356
/**
357
 * Calculate exponent strategies for all channels.
358
 * Array arrangement is reversed to simplify the per-channel calculation.
359
 */
360
static void compute_exp_strategy(AC3EncodeContext *s)
361
{
362
    uint8_t *exp1[AC3_MAX_CHANNELS][AC3_MAX_BLOCKS];
363
    uint8_t exp_str1[AC3_MAX_CHANNELS][AC3_MAX_BLOCKS];
364
    int ch, blk;
365

    
366
    for (ch = 0; ch < s->fbw_channels; ch++) {
367
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
368
            exp1[ch][blk]     = s->blocks[blk].exp[ch];
369
            exp_str1[ch][blk] = s->blocks[blk].exp_strategy[ch];
370
        }
371

    
372
        compute_exp_strategy_ch(s, exp_str1[ch], exp1[ch]);
373

    
374
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++)
375
            s->blocks[blk].exp_strategy[ch] = exp_str1[ch][blk];
376
    }
377
    if (s->lfe_on) {
378
        ch = s->lfe_channel;
379
        s->blocks[0].exp_strategy[ch] = EXP_D15;
380
        for (blk = 1; blk < AC3_MAX_BLOCKS; blk++)
381
            s->blocks[blk].exp_strategy[ch] = EXP_REUSE;
382
    }
383
}
384

    
385

    
386
/**
387
 * Set each encoded exponent in a block to the minimum of itself and the
388
 * exponent in the same frequency bin of a following block.
389
 * exp[i] = min(exp[i], exp1[i]
390
 */
391
static void exponent_min(uint8_t *exp, uint8_t *exp1, int n)
392
{
393
    int i;
394
    for (i = 0; i < n; i++) {
395
        if (exp1[i] < exp[i])
396
            exp[i] = exp1[i];
397
    }
398
}
399

    
400

    
401
/**
402
 * Update the exponents so that they are the ones the decoder will decode.
403
 */
404
static void encode_exponents_blk_ch(uint8_t *exp, int nb_exps, int exp_strategy)
405
{
406
    int nb_groups, i, k;
407

    
408
    nb_groups = exponent_group_tab[exp_strategy-1][nb_exps] * 3;
409

    
410
    /* for each group, compute the minimum exponent */
411
    switch(exp_strategy) {
412
    case EXP_D25:
413
        for (i = 1, k = 1; i <= nb_groups; i++) {
414
            uint8_t exp_min = exp[k];
415
            if (exp[k+1] < exp_min)
416
                exp_min = exp[k+1];
417
            exp[i] = exp_min;
418
            k += 2;
419
        }
420
        break;
421
    case EXP_D45:
422
        for (i = 1, k = 1; i <= nb_groups; i++) {
423
            uint8_t exp_min = exp[k];
424
            if (exp[k+1] < exp_min)
425
                exp_min = exp[k+1];
426
            if (exp[k+2] < exp_min)
427
                exp_min = exp[k+2];
428
            if (exp[k+3] < exp_min)
429
                exp_min = exp[k+3];
430
            exp[i] = exp_min;
431
            k += 4;
432
        }
433
        break;
434
    }
435

    
436
    /* constraint for DC exponent */
437
    if (exp[0] > 15)
438
        exp[0] = 15;
439

    
440
    /* decrease the delta between each groups to within 2 so that they can be
441
       differentially encoded */
442
    for (i = 1; i <= nb_groups; i++)
443
        exp[i] = FFMIN(exp[i], exp[i-1] + 2);
444
    i--;
445
    while (--i >= 0)
446
        exp[i] = FFMIN(exp[i], exp[i+1] + 2);
447

    
448
    /* now we have the exponent values the decoder will see */
449
    switch (exp_strategy) {
450
    case EXP_D25:
451
        for (i = nb_groups, k = nb_groups * 2; i > 0; i--) {
452
            uint8_t exp1 = exp[i];
453
            exp[k--] = exp1;
454
            exp[k--] = exp1;
455
        }
456
        break;
457
    case EXP_D45:
458
        for (i = nb_groups, k = nb_groups * 4; i > 0; i--) {
459
            exp[k] = exp[k-1] = exp[k-2] = exp[k-3] = exp[i];
460
            k -= 4;
461
        }
462
        break;
463
    }
464
}
465

    
466

    
467
/**
468
 * Encode exponents from original extracted form to what the decoder will see.
469
 * This copies and groups exponents based on exponent strategy and reduces
470
 * deltas between adjacent exponent groups so that they can be differentially
471
 * encoded.
472
 */
473
static void encode_exponents(AC3EncodeContext *s)
474
{
475
    int blk, blk1, blk2, ch;
476
    AC3Block *block, *block1, *block2;
477

    
478
    for (ch = 0; ch < s->channels; ch++) {
479
        blk = 0;
480
        block = &s->blocks[0];
481
        while (blk < AC3_MAX_BLOCKS) {
482
            blk1 = blk + 1;
483
            block1 = block + 1;
484
            /* for the EXP_REUSE case we select the min of the exponents */
485
            while (blk1 < AC3_MAX_BLOCKS && block1->exp_strategy[ch] == EXP_REUSE) {
486
                exponent_min(block->exp[ch], block1->exp[ch], s->nb_coefs[ch]);
487
                blk1++;
488
                block1++;
489
            }
490
            encode_exponents_blk_ch(block->exp[ch], s->nb_coefs[ch],
491
                                    block->exp_strategy[ch]);
492
            /* copy encoded exponents for reuse case */
493
            block2 = block + 1;
494
            for (blk2 = blk+1; blk2 < blk1; blk2++, block2++) {
495
                memcpy(block2->exp[ch], block->exp[ch],
496
                       s->nb_coefs[ch] * sizeof(uint8_t));
497
            }
498
            blk = blk1;
499
            block = block1;
500
        }
501
    }
502
}
503

    
504

    
505
/**
506
 * Group exponents.
507
 * 3 delta-encoded exponents are in each 7-bit group. The number of groups
508
 * varies depending on exponent strategy and bandwidth.
509
 */
510
static void group_exponents(AC3EncodeContext *s)
511
{
512
    int blk, ch, i;
513
    int group_size, nb_groups, bit_count;
514
    uint8_t *p;
515
    int delta0, delta1, delta2;
516
    int exp0, exp1;
517

    
518
    bit_count = 0;
519
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
520
        AC3Block *block = &s->blocks[blk];
521
        for (ch = 0; ch < s->channels; ch++) {
522
            if (block->exp_strategy[ch] == EXP_REUSE) {
523
                continue;
524
            }
525
            group_size = block->exp_strategy[ch] + (block->exp_strategy[ch] == EXP_D45);
526
            nb_groups = exponent_group_tab[block->exp_strategy[ch]-1][s->nb_coefs[ch]];
527
            bit_count += 4 + (nb_groups * 7);
528
            p = block->exp[ch];
529

    
530
            /* DC exponent */
531
            exp1 = *p++;
532
            block->grouped_exp[ch][0] = exp1;
533

    
534
            /* remaining exponents are delta encoded */
535
            for (i = 1; i <= nb_groups; i++) {
536
                /* merge three delta in one code */
537
                exp0   = exp1;
538
                exp1   = p[0];
539
                p     += group_size;
540
                delta0 = exp1 - exp0 + 2;
541

    
542
                exp0   = exp1;
543
                exp1   = p[0];
544
                p     += group_size;
545
                delta1 = exp1 - exp0 + 2;
546

    
547
                exp0   = exp1;
548
                exp1   = p[0];
549
                p     += group_size;
550
                delta2 = exp1 - exp0 + 2;
551

    
552
                block->grouped_exp[ch][i] = ((delta0 * 5 + delta1) * 5) + delta2;
553
            }
554
        }
555
    }
556

    
557
    s->exponent_bits = bit_count;
558
}
559

    
560

    
561
/**
562
 * Calculate final exponents from the supplied MDCT coefficients and exponent shift.
563
 * Extract exponents from MDCT coefficients, calculate exponent strategies,
564
 * and encode final exponents.
565
 */
566
static void process_exponents(AC3EncodeContext *s)
567
{
568
    extract_exponents(s);
569

    
570
    compute_exp_strategy(s);
571

    
572
    encode_exponents(s);
573

    
574
    group_exponents(s);
575
}
576

    
577

    
578
/**
579
 * Count frame bits that are based solely on fixed parameters.
580
 * This only has to be run once when the encoder is initialized.
581
 */
582
static void count_frame_bits_fixed(AC3EncodeContext *s)
583
{
584
    static const int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
585
    int blk;
586
    int frame_bits;
587

    
588
    /* assumptions:
589
     *   no dynamic range codes
590
     *   no channel coupling
591
     *   no rematrixing
592
     *   bit allocation parameters do not change between blocks
593
     *   SNR offsets do not change between blocks
594
     *   no delta bit allocation
595
     *   no skipped data
596
     *   no auxilliary data
597
     */
598

    
599
    /* header size */
600
    frame_bits = 65;
601
    frame_bits += frame_bits_inc[s->channel_mode];
602

    
603
    /* audio blocks */
604
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
605
        frame_bits += s->fbw_channels * 2 + 2; /* blksw * c, dithflag * c, dynrnge, cplstre */
606
        if (s->channel_mode == AC3_CHMODE_STEREO) {
607
            frame_bits++; /* rematstr */
608
            if (!blk)
609
                frame_bits += 4;
610
        }
611
        frame_bits += 2 * s->fbw_channels; /* chexpstr[2] * c */
612
        if (s->lfe_on)
613
            frame_bits++; /* lfeexpstr */
614
        frame_bits++; /* baie */
615
        frame_bits++; /* snr */
616
        frame_bits += 2; /* delta / skip */
617
    }
618
    frame_bits++; /* cplinu for block 0 */
619
    /* bit alloc info */
620
    /* sdcycod[2], fdcycod[2], sgaincod[2], dbpbcod[2], floorcod[3] */
621
    /* csnroffset[6] */
622
    /* (fsnoffset[4] + fgaincod[4]) * c */
623
    frame_bits += 2*4 + 3 + 6 + s->channels * (4 + 3);
624

    
625
    /* auxdatae, crcrsv */
626
    frame_bits += 2;
627

    
628
    /* CRC */
629
    frame_bits += 16;
630

    
631
    s->frame_bits_fixed = frame_bits;
632
}
633

    
634

    
635
/**
636
 * Initialize bit allocation.
637
 * Set default parameter codes and calculate parameter values.
638
 */
639
static void bit_alloc_init(AC3EncodeContext *s)
640
{
641
    int ch;
642

    
643
    /* init default parameters */
644
    s->slow_decay_code = 2;
645
    s->fast_decay_code = 1;
646
    s->slow_gain_code  = 1;
647
    s->db_per_bit_code = 3;
648
    s->floor_code      = 4;
649
    for (ch = 0; ch < s->channels; ch++)
650
        s->fast_gain_code[ch] = 4;
651

    
652
    /* initial snr offset */
653
    s->coarse_snr_offset = 40;
654

    
655
    /* compute real values */
656
    /* currently none of these values change during encoding, so we can just
657
       set them once at initialization */
658
    s->bit_alloc.slow_decay = ff_ac3_slow_decay_tab[s->slow_decay_code] >> s->bit_alloc.sr_shift;
659
    s->bit_alloc.fast_decay = ff_ac3_fast_decay_tab[s->fast_decay_code] >> s->bit_alloc.sr_shift;
660
    s->bit_alloc.slow_gain  = ff_ac3_slow_gain_tab[s->slow_gain_code];
661
    s->bit_alloc.db_per_bit = ff_ac3_db_per_bit_tab[s->db_per_bit_code];
662
    s->bit_alloc.floor      = ff_ac3_floor_tab[s->floor_code];
663

    
664
    count_frame_bits_fixed(s);
665
}
666

    
667

    
668
/**
669
 * Count the bits used to encode the frame, minus exponents and mantissas.
670
 * Bits based on fixed parameters have already been counted, so now we just
671
 * have to add the bits based on parameters that change during encoding.
672
 */
673
static void count_frame_bits(AC3EncodeContext *s)
674
{
675
    int blk, ch;
676
    int frame_bits = 0;
677

    
678
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
679
        uint8_t *exp_strategy = s->blocks[blk].exp_strategy;
680
        for (ch = 0; ch < s->fbw_channels; ch++) {
681
            if (exp_strategy[ch] != EXP_REUSE)
682
                frame_bits += 6 + 2; /* chbwcod[6], gainrng[2] */
683
        }
684
    }
685
    s->frame_bits = s->frame_bits_fixed + frame_bits;
686
}
687

    
688

    
689
/**
690
 * Calculate the number of bits needed to encode a set of mantissas.
691
 */
692
static int compute_mantissa_size(int mant_cnt[5], uint8_t *bap, int nb_coefs)
693
{
694
    int bits, b, i;
695

    
696
    bits = 0;
697
    for (i = 0; i < nb_coefs; i++) {
698
        b = bap[i];
699
        if (b <= 4) {
700
            // bap=1 to bap=4 will be counted in compute_mantissa_size_final
701
            mant_cnt[b]++;
702
        } else if (b <= 13) {
703
            // bap=5 to bap=13 use (bap-1) bits
704
            bits += b - 1;
705
        } else {
706
            // bap=14 uses 14 bits and bap=15 uses 16 bits
707
            bits += (b == 14) ? 14 : 16;
708
        }
709
    }
710
    return bits;
711
}
712

    
713

    
714
/**
715
 * Finalize the mantissa bit count by adding in the grouped mantissas.
716
 */
717
static int compute_mantissa_size_final(int mant_cnt[5])
718
{
719
    // bap=1 : 3 mantissas in 5 bits
720
    int bits = (mant_cnt[1] / 3) * 5;
721
    // bap=2 : 3 mantissas in 7 bits
722
    // bap=4 : 2 mantissas in 7 bits
723
    bits += ((mant_cnt[2] / 3) + (mant_cnt[4] >> 1)) * 7;
724
    // bap=3 : each mantissa is 3 bits
725
    bits += mant_cnt[3] * 3;
726
    return bits;
727
}
728

    
729

    
730
/**
731
 * Calculate masking curve based on the final exponents.
732
 * Also calculate the power spectral densities to use in future calculations.
733
 */
734
static void bit_alloc_masking(AC3EncodeContext *s)
735
{
736
    int blk, ch;
737

    
738
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
739
        AC3Block *block = &s->blocks[blk];
740
        for (ch = 0; ch < s->channels; ch++) {
741
            /* We only need psd and mask for calculating bap.
742
               Since we currently do not calculate bap when exponent
743
               strategy is EXP_REUSE we do not need to calculate psd or mask. */
744
            if (block->exp_strategy[ch] != EXP_REUSE) {
745
                ff_ac3_bit_alloc_calc_psd(block->exp[ch], 0,
746
                                          s->nb_coefs[ch],
747
                                          block->psd[ch], block->band_psd[ch]);
748
                ff_ac3_bit_alloc_calc_mask(&s->bit_alloc, block->band_psd[ch],
749
                                           0, s->nb_coefs[ch],
750
                                           ff_ac3_fast_gain_tab[s->fast_gain_code[ch]],
751
                                           ch == s->lfe_channel,
752
                                           DBA_NONE, 0, NULL, NULL, NULL,
753
                                           block->mask[ch]);
754
            }
755
        }
756
    }
757
}
758

    
759

    
760
/**
761
 * Ensure that bap for each block and channel point to the current bap_buffer.
762
 * They may have been switched during the bit allocation search.
763
 */
764
static void reset_block_bap(AC3EncodeContext *s)
765
{
766
    int blk, ch;
767
    if (s->blocks[0].bap[0] == s->bap_buffer)
768
        return;
769
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
770
        for (ch = 0; ch < s->channels; ch++) {
771
            s->blocks[blk].bap[ch] = &s->bap_buffer[AC3_MAX_COEFS * (blk * s->channels + ch)];
772
        }
773
    }
774
}
775

    
776

    
777
/**
778
 * Run the bit allocation with a given SNR offset.
779
 * This calculates the bit allocation pointers that will be used to determine
780
 * the quantization of each mantissa.
781
 * @return the number of bits needed for mantissas if the given SNR offset is
782
 *         is used.
783
 */
784
static int bit_alloc(AC3EncodeContext *s, int snr_offset)
785
{
786
    int blk, ch;
787
    int mantissa_bits;
788
    int mant_cnt[5];
789

    
790
    snr_offset = (snr_offset - 240) << 2;
791

    
792
    reset_block_bap(s);
793
    mantissa_bits = 0;
794
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
795
        AC3Block *block = &s->blocks[blk];
796
        // initialize grouped mantissa counts. these are set so that they are
797
        // padded to the next whole group size when bits are counted in
798
        // compute_mantissa_size_final
799
        mant_cnt[0] = mant_cnt[3] = 0;
800
        mant_cnt[1] = mant_cnt[2] = 2;
801
        mant_cnt[4] = 1;
802
        for (ch = 0; ch < s->channels; ch++) {
803
            /* Currently the only bit allocation parameters which vary across
804
               blocks within a frame are the exponent values.  We can take
805
               advantage of that by reusing the bit allocation pointers
806
               whenever we reuse exponents. */
807
            if (block->exp_strategy[ch] == EXP_REUSE) {
808
                memcpy(block->bap[ch], s->blocks[blk-1].bap[ch], AC3_MAX_COEFS);
809
            } else {
810
                ff_ac3_bit_alloc_calc_bap(block->mask[ch], block->psd[ch], 0,
811
                                          s->nb_coefs[ch], snr_offset,
812
                                          s->bit_alloc.floor, ff_ac3_bap_tab,
813
                                          block->bap[ch]);
814
            }
815
            mantissa_bits += compute_mantissa_size(mant_cnt, block->bap[ch], s->nb_coefs[ch]);
816
        }
817
        mantissa_bits += compute_mantissa_size_final(mant_cnt);
818
    }
819
    return mantissa_bits;
820
}
821

    
822

    
823
/**
824
 * Constant bitrate bit allocation search.
825
 * Find the largest SNR offset that will allow data to fit in the frame.
826
 */
827
static int cbr_bit_allocation(AC3EncodeContext *s)
828
{
829
    int ch;
830
    int bits_left;
831
    int snr_offset, snr_incr;
832

    
833
    bits_left = 8 * s->frame_size - (s->frame_bits + s->exponent_bits);
834

    
835
    snr_offset = s->coarse_snr_offset << 4;
836

    
837
    /* if previous frame SNR offset was 1023, check if current frame can also
838
       use SNR offset of 1023. if so, skip the search. */
839
    if ((snr_offset | s->fine_snr_offset[0]) == 1023) {
840
        if (bit_alloc(s, 1023) <= bits_left)
841
            return 0;
842
    }
843

    
844
    while (snr_offset >= 0 &&
845
           bit_alloc(s, snr_offset) > bits_left) {
846
        snr_offset -= 64;
847
    }
848
    if (snr_offset < 0)
849
        return AVERROR(EINVAL);
850

    
851
    FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
852
    for (snr_incr = 64; snr_incr > 0; snr_incr >>= 2) {
853
        while (snr_offset + snr_incr <= 1023 &&
854
               bit_alloc(s, snr_offset + snr_incr) <= bits_left) {
855
            snr_offset += snr_incr;
856
            FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
857
        }
858
    }
859
    FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
860
    reset_block_bap(s);
861

    
862
    s->coarse_snr_offset = snr_offset >> 4;
863
    for (ch = 0; ch < s->channels; ch++)
864
        s->fine_snr_offset[ch] = snr_offset & 0xF;
865

    
866
    return 0;
867
}
868

    
869

    
870
/**
871
 * Downgrade exponent strategies to reduce the bits used by the exponents.
872
 * This is a fallback for when bit allocation fails with the normal exponent
873
 * strategies.  Each time this function is run it only downgrades the
874
 * strategy in 1 channel of 1 block.
875
 * @return non-zero if downgrade was unsuccessful
876
 */
877
static int downgrade_exponents(AC3EncodeContext *s)
878
{
879
    int ch, blk;
880

    
881
    for (ch = 0; ch < s->fbw_channels; ch++) {
882
        for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
883
            if (s->blocks[blk].exp_strategy[ch] == EXP_D15) {
884
                s->blocks[blk].exp_strategy[ch] = EXP_D25;
885
                return 0;
886
            }
887
        }
888
    }
889
    for (ch = 0; ch < s->fbw_channels; ch++) {
890
        for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
891
            if (s->blocks[blk].exp_strategy[ch] == EXP_D25) {
892
                s->blocks[blk].exp_strategy[ch] = EXP_D45;
893
                return 0;
894
            }
895
        }
896
    }
897
    for (ch = 0; ch < s->fbw_channels; ch++) {
898
        /* block 0 cannot reuse exponents, so only downgrade D45 to REUSE if
899
           the block number > 0 */
900
        for (blk = AC3_MAX_BLOCKS-1; blk > 0; blk--) {
901
            if (s->blocks[blk].exp_strategy[ch] > EXP_REUSE) {
902
                s->blocks[blk].exp_strategy[ch] = EXP_REUSE;
903
                return 0;
904
            }
905
        }
906
    }
907
    return -1;
908
}
909

    
910

    
911
/**
912
 * Reduce the bandwidth to reduce the number of bits used for a given SNR offset.
913
 * This is a second fallback for when bit allocation still fails after exponents
914
 * have been downgraded.
915
 * @return non-zero if bandwidth reduction was unsuccessful
916
 */
917
static int reduce_bandwidth(AC3EncodeContext *s, int min_bw_code)
918
{
919
    int ch;
920

    
921
    if (s->bandwidth_code[0] > min_bw_code) {
922
        for (ch = 0; ch < s->fbw_channels; ch++) {
923
            s->bandwidth_code[ch]--;
924
            s->nb_coefs[ch] = s->bandwidth_code[ch] * 3 + 73;
925
        }
926
        return 0;
927
    }
928
    return -1;
929
}
930

    
931

    
932
/**
933
 * Perform bit allocation search.
934
 * Finds the SNR offset value that maximizes quality and fits in the specified
935
 * frame size.  Output is the SNR offset and a set of bit allocation pointers
936
 * used to quantize the mantissas.
937
 */
938
static int compute_bit_allocation(AC3EncodeContext *s)
939
{
940
    int ret;
941

    
942
    count_frame_bits(s);
943

    
944
    bit_alloc_masking(s);
945

    
946
    ret = cbr_bit_allocation(s);
947
    while (ret) {
948
        /* fallback 1: downgrade exponents */
949
        if (!downgrade_exponents(s)) {
950
            extract_exponents(s);
951
            encode_exponents(s);
952
            group_exponents(s);
953
            ret = compute_bit_allocation(s);
954
            continue;
955
        }
956

    
957
        /* fallback 2: reduce bandwidth */
958
        /* only do this if the user has not specified a specific cutoff
959
           frequency */
960
        if (!s->cutoff && !reduce_bandwidth(s, 0)) {
961
            process_exponents(s);
962
            ret = compute_bit_allocation(s);
963
            continue;
964
        }
965

    
966
        /* fallbacks were not enough... */
967
        break;
968
    }
969

    
970
    return ret;
971
}
972

    
973

    
974
/**
975
 * Symmetric quantization on 'levels' levels.
976
 */
977
static inline int sym_quant(int c, int e, int levels)
978
{
979
    int v;
980

    
981
    if (c >= 0) {
982
        v = (levels * (c << e)) >> 24;
983
        v = (v + 1) >> 1;
984
        v = (levels >> 1) + v;
985
    } else {
986
        v = (levels * ((-c) << e)) >> 24;
987
        v = (v + 1) >> 1;
988
        v = (levels >> 1) - v;
989
    }
990
    assert(v >= 0 && v < levels);
991
    return v;
992
}
993

    
994

    
995
/**
996
 * Asymmetric quantization on 2^qbits levels.
997
 */
998
static inline int asym_quant(int c, int e, int qbits)
999
{
1000
    int lshift, m, v;
1001

    
1002
    lshift = e + qbits - 24;
1003
    if (lshift >= 0)
1004
        v = c << lshift;
1005
    else
1006
        v = c >> (-lshift);
1007
    /* rounding */
1008
    v = (v + 1) >> 1;
1009
    m = (1 << (qbits-1));
1010
    if (v >= m)
1011
        v = m - 1;
1012
    assert(v >= -m);
1013
    return v & ((1 << qbits)-1);
1014
}
1015

    
1016

    
1017
/**
1018
 * Quantize a set of mantissas for a single channel in a single block.
1019
 */
1020
static void quantize_mantissas_blk_ch(AC3EncodeContext *s, CoefType *mdct_coef,
1021
                                      int8_t exp_shift, uint8_t *exp,
1022
                                      uint8_t *bap, uint16_t *qmant, int n)
1023
{
1024
    int i;
1025

    
1026
    for (i = 0; i < n; i++) {
1027
        int v;
1028
        int c = SCALE_COEF(mdct_coef[i]);
1029
        int e = exp[i] - exp_shift;
1030
        int b = bap[i];
1031
        switch (b) {
1032
        case 0:
1033
            v = 0;
1034
            break;
1035
        case 1:
1036
            v = sym_quant(c, e, 3);
1037
            switch (s->mant1_cnt) {
1038
            case 0:
1039
                s->qmant1_ptr = &qmant[i];
1040
                v = 9 * v;
1041
                s->mant1_cnt = 1;
1042
                break;
1043
            case 1:
1044
                *s->qmant1_ptr += 3 * v;
1045
                s->mant1_cnt = 2;
1046
                v = 128;
1047
                break;
1048
            default:
1049
                *s->qmant1_ptr += v;
1050
                s->mant1_cnt = 0;
1051
                v = 128;
1052
                break;
1053
            }
1054
            break;
1055
        case 2:
1056
            v = sym_quant(c, e, 5);
1057
            switch (s->mant2_cnt) {
1058
            case 0:
1059
                s->qmant2_ptr = &qmant[i];
1060
                v = 25 * v;
1061
                s->mant2_cnt = 1;
1062
                break;
1063
            case 1:
1064
                *s->qmant2_ptr += 5 * v;
1065
                s->mant2_cnt = 2;
1066
                v = 128;
1067
                break;
1068
            default:
1069
                *s->qmant2_ptr += v;
1070
                s->mant2_cnt = 0;
1071
                v = 128;
1072
                break;
1073
            }
1074
            break;
1075
        case 3:
1076
            v = sym_quant(c, e, 7);
1077
            break;
1078
        case 4:
1079
            v = sym_quant(c, e, 11);
1080
            switch (s->mant4_cnt) {
1081
            case 0:
1082
                s->qmant4_ptr = &qmant[i];
1083
                v = 11 * v;
1084
                s->mant4_cnt = 1;
1085
                break;
1086
            default:
1087
                *s->qmant4_ptr += v;
1088
                s->mant4_cnt = 0;
1089
                v = 128;
1090
                break;
1091
            }
1092
            break;
1093
        case 5:
1094
            v = sym_quant(c, e, 15);
1095
            break;
1096
        case 14:
1097
            v = asym_quant(c, e, 14);
1098
            break;
1099
        case 15:
1100
            v = asym_quant(c, e, 16);
1101
            break;
1102
        default:
1103
            v = asym_quant(c, e, b - 1);
1104
            break;
1105
        }
1106
        qmant[i] = v;
1107
    }
1108
}
1109

    
1110

    
1111
/**
1112
 * Quantize mantissas using coefficients, exponents, and bit allocation pointers.
1113
 */
1114
static void quantize_mantissas(AC3EncodeContext *s)
1115
{
1116
    int blk, ch;
1117

    
1118

    
1119
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1120
        AC3Block *block = &s->blocks[blk];
1121
        s->mant1_cnt  = s->mant2_cnt  = s->mant4_cnt  = 0;
1122
        s->qmant1_ptr = s->qmant2_ptr = s->qmant4_ptr = NULL;
1123

    
1124
        for (ch = 0; ch < s->channels; ch++) {
1125
            quantize_mantissas_blk_ch(s, block->mdct_coef[ch], block->exp_shift[ch],
1126
                                      block->exp[ch], block->bap[ch],
1127
                                      block->qmant[ch], s->nb_coefs[ch]);
1128
        }
1129
    }
1130
}
1131

    
1132

    
1133
/**
1134
 * Write the AC-3 frame header to the output bitstream.
1135
 */
1136
static void output_frame_header(AC3EncodeContext *s)
1137
{
1138
    put_bits(&s->pb, 16, 0x0b77);   /* frame header */
1139
    put_bits(&s->pb, 16, 0);        /* crc1: will be filled later */
1140
    put_bits(&s->pb, 2,  s->bit_alloc.sr_code);
1141
    put_bits(&s->pb, 6,  s->frame_size_code + (s->frame_size - s->frame_size_min) / 2);
1142
    put_bits(&s->pb, 5,  s->bitstream_id);
1143
    put_bits(&s->pb, 3,  s->bitstream_mode);
1144
    put_bits(&s->pb, 3,  s->channel_mode);
1145
    if ((s->channel_mode & 0x01) && s->channel_mode != AC3_CHMODE_MONO)
1146
        put_bits(&s->pb, 2, 1);     /* XXX -4.5 dB */
1147
    if (s->channel_mode & 0x04)
1148
        put_bits(&s->pb, 2, 1);     /* XXX -6 dB */
1149
    if (s->channel_mode == AC3_CHMODE_STEREO)
1150
        put_bits(&s->pb, 2, 0);     /* surround not indicated */
1151
    put_bits(&s->pb, 1, s->lfe_on); /* LFE */
1152
    put_bits(&s->pb, 5, 31);        /* dialog norm: -31 db */
1153
    put_bits(&s->pb, 1, 0);         /* no compression control word */
1154
    put_bits(&s->pb, 1, 0);         /* no lang code */
1155
    put_bits(&s->pb, 1, 0);         /* no audio production info */
1156
    put_bits(&s->pb, 1, 0);         /* no copyright */
1157
    put_bits(&s->pb, 1, 1);         /* original bitstream */
1158
    put_bits(&s->pb, 1, 0);         /* no time code 1 */
1159
    put_bits(&s->pb, 1, 0);         /* no time code 2 */
1160
    put_bits(&s->pb, 1, 0);         /* no additional bit stream info */
1161
}
1162

    
1163

    
1164
/**
1165
 * Write one audio block to the output bitstream.
1166
 */
1167
static void output_audio_block(AC3EncodeContext *s, int block_num)
1168
{
1169
    int ch, i, baie, rbnd;
1170
    AC3Block *block = &s->blocks[block_num];
1171

    
1172
    /* block switching */
1173
    for (ch = 0; ch < s->fbw_channels; ch++)
1174
        put_bits(&s->pb, 1, 0);
1175

    
1176
    /* dither flags */
1177
    for (ch = 0; ch < s->fbw_channels; ch++)
1178
        put_bits(&s->pb, 1, 1);
1179

    
1180
    /* dynamic range codes */
1181
    put_bits(&s->pb, 1, 0);
1182

    
1183
    /* channel coupling */
1184
    if (!block_num) {
1185
        put_bits(&s->pb, 1, 1); /* coupling strategy present */
1186
        put_bits(&s->pb, 1, 0); /* no coupling strategy */
1187
    } else {
1188
        put_bits(&s->pb, 1, 0); /* no new coupling strategy */
1189
    }
1190

    
1191
    /* stereo rematrixing */
1192
    if (s->channel_mode == AC3_CHMODE_STEREO) {
1193
        if (!block_num) {
1194
            /* first block must define rematrixing (rematstr) */
1195
            put_bits(&s->pb, 1, 1);
1196

    
1197
            /* dummy rematrixing rematflg(1:4)=0 */
1198
            for (rbnd = 0; rbnd < 4; rbnd++)
1199
                put_bits(&s->pb, 1, 0);
1200
        } else {
1201
            /* no matrixing (but should be used in the future) */
1202
            put_bits(&s->pb, 1, 0);
1203
        }
1204
    }
1205

    
1206
    /* exponent strategy */
1207
    for (ch = 0; ch < s->fbw_channels; ch++)
1208
        put_bits(&s->pb, 2, block->exp_strategy[ch]);
1209
    if (s->lfe_on)
1210
        put_bits(&s->pb, 1, block->exp_strategy[s->lfe_channel]);
1211

    
1212
    /* bandwidth */
1213
    for (ch = 0; ch < s->fbw_channels; ch++) {
1214
        if (block->exp_strategy[ch] != EXP_REUSE)
1215
            put_bits(&s->pb, 6, s->bandwidth_code[ch]);
1216
    }
1217

    
1218
    /* exponents */
1219
    for (ch = 0; ch < s->channels; ch++) {
1220
        int nb_groups;
1221

    
1222
        if (block->exp_strategy[ch] == EXP_REUSE)
1223
            continue;
1224

    
1225
        /* DC exponent */
1226
        put_bits(&s->pb, 4, block->grouped_exp[ch][0]);
1227

    
1228
        /* exponent groups */
1229
        nb_groups = exponent_group_tab[block->exp_strategy[ch]-1][s->nb_coefs[ch]];
1230
        for (i = 1; i <= nb_groups; i++)
1231
            put_bits(&s->pb, 7, block->grouped_exp[ch][i]);
1232

    
1233
        /* gain range info */
1234
        if (ch != s->lfe_channel)
1235
            put_bits(&s->pb, 2, 0);
1236
    }
1237

    
1238
    /* bit allocation info */
1239
    baie = (block_num == 0);
1240
    put_bits(&s->pb, 1, baie);
1241
    if (baie) {
1242
        put_bits(&s->pb, 2, s->slow_decay_code);
1243
        put_bits(&s->pb, 2, s->fast_decay_code);
1244
        put_bits(&s->pb, 2, s->slow_gain_code);
1245
        put_bits(&s->pb, 2, s->db_per_bit_code);
1246
        put_bits(&s->pb, 3, s->floor_code);
1247
    }
1248

    
1249
    /* snr offset */
1250
    put_bits(&s->pb, 1, baie);
1251
    if (baie) {
1252
        put_bits(&s->pb, 6, s->coarse_snr_offset);
1253
        for (ch = 0; ch < s->channels; ch++) {
1254
            put_bits(&s->pb, 4, s->fine_snr_offset[ch]);
1255
            put_bits(&s->pb, 3, s->fast_gain_code[ch]);
1256
        }
1257
    }
1258

    
1259
    put_bits(&s->pb, 1, 0); /* no delta bit allocation */
1260
    put_bits(&s->pb, 1, 0); /* no data to skip */
1261

    
1262
    /* mantissas */
1263
    for (ch = 0; ch < s->channels; ch++) {
1264
        int b, q;
1265
        for (i = 0; i < s->nb_coefs[ch]; i++) {
1266
            q = block->qmant[ch][i];
1267
            b = block->bap[ch][i];
1268
            switch (b) {
1269
            case 0:                                         break;
1270
            case 1: if (q != 128) put_bits(&s->pb,   5, q); break;
1271
            case 2: if (q != 128) put_bits(&s->pb,   7, q); break;
1272
            case 3:               put_bits(&s->pb,   3, q); break;
1273
            case 4: if (q != 128) put_bits(&s->pb,   7, q); break;
1274
            case 14:              put_bits(&s->pb,  14, q); break;
1275
            case 15:              put_bits(&s->pb,  16, q); break;
1276
            default:              put_bits(&s->pb, b-1, q); break;
1277
            }
1278
        }
1279
    }
1280
}
1281

    
1282

    
1283
/** CRC-16 Polynomial */
1284
#define CRC16_POLY ((1 << 0) | (1 << 2) | (1 << 15) | (1 << 16))
1285

    
1286

    
1287
static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly)
1288
{
1289
    unsigned int c;
1290

    
1291
    c = 0;
1292
    while (a) {
1293
        if (a & 1)
1294
            c ^= b;
1295
        a = a >> 1;
1296
        b = b << 1;
1297
        if (b & (1 << 16))
1298
            b ^= poly;
1299
    }
1300
    return c;
1301
}
1302

    
1303

    
1304
static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly)
1305
{
1306
    unsigned int r;
1307
    r = 1;
1308
    while (n) {
1309
        if (n & 1)
1310
            r = mul_poly(r, a, poly);
1311
        a = mul_poly(a, a, poly);
1312
        n >>= 1;
1313
    }
1314
    return r;
1315
}
1316

    
1317

    
1318
/**
1319
 * Fill the end of the frame with 0's and compute the two CRCs.
1320
 */
1321
static void output_frame_end(AC3EncodeContext *s)
1322
{
1323
    const AVCRC *crc_ctx = av_crc_get_table(AV_CRC_16_ANSI);
1324
    int frame_size_58, pad_bytes, crc1, crc2_partial, crc2, crc_inv;
1325
    uint8_t *frame;
1326

    
1327
    frame_size_58 = ((s->frame_size >> 2) + (s->frame_size >> 4)) << 1;
1328

    
1329
    /* pad the remainder of the frame with zeros */
1330
    flush_put_bits(&s->pb);
1331
    frame = s->pb.buf;
1332
    pad_bytes = s->frame_size - (put_bits_ptr(&s->pb) - frame) - 2;
1333
    assert(pad_bytes >= 0);
1334
    if (pad_bytes > 0)
1335
        memset(put_bits_ptr(&s->pb), 0, pad_bytes);
1336

    
1337
    /* compute crc1 */
1338
    /* this is not so easy because it is at the beginning of the data... */
1339
    crc1    = av_bswap16(av_crc(crc_ctx, 0, frame + 4, frame_size_58 - 4));
1340
    crc_inv = s->crc_inv[s->frame_size > s->frame_size_min];
1341
    crc1    = mul_poly(crc_inv, crc1, CRC16_POLY);
1342
    AV_WB16(frame + 2, crc1);
1343

    
1344
    /* compute crc2 */
1345
    crc2_partial = av_crc(crc_ctx, 0, frame + frame_size_58,
1346
                          s->frame_size - frame_size_58 - 3);
1347
    crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
1348
    /* ensure crc2 does not match sync word by flipping crcrsv bit if needed */
1349
    if (crc2 == 0x770B) {
1350
        frame[s->frame_size - 3] ^= 0x1;
1351
        crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
1352
    }
1353
    crc2 = av_bswap16(crc2);
1354
    AV_WB16(frame + s->frame_size - 2, crc2);
1355
}
1356

    
1357

    
1358
/**
1359
 * Write the frame to the output bitstream.
1360
 */
1361
static void output_frame(AC3EncodeContext *s, unsigned char *frame)
1362
{
1363
    int blk;
1364

    
1365
    init_put_bits(&s->pb, frame, AC3_MAX_CODED_FRAME_SIZE);
1366

    
1367
    output_frame_header(s);
1368

    
1369
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++)
1370
        output_audio_block(s, blk);
1371

    
1372
    output_frame_end(s);
1373
}
1374

    
1375

    
1376
/**
1377
 * Encode a single AC-3 frame.
1378
 */
1379
static int ac3_encode_frame(AVCodecContext *avctx, unsigned char *frame,
1380
                            int buf_size, void *data)
1381
{
1382
    AC3EncodeContext *s = avctx->priv_data;
1383
    const SampleType *samples = data;
1384
    int ret;
1385

    
1386
    if (s->bit_alloc.sr_code == 1)
1387
        adjust_frame_size(s);
1388

    
1389
    deinterleave_input_samples(s, samples);
1390

    
1391
    apply_mdct(s);
1392

    
1393
    process_exponents(s);
1394

    
1395
    ret = compute_bit_allocation(s);
1396
    if (ret) {
1397
        av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
1398
        return ret;
1399
    }
1400

    
1401
    quantize_mantissas(s);
1402

    
1403
    output_frame(s, frame);
1404

    
1405
    return s->frame_size;
1406
}
1407

    
1408

    
1409
/**
1410
 * Finalize encoding and free any memory allocated by the encoder.
1411
 */
1412
static av_cold int ac3_encode_close(AVCodecContext *avctx)
1413
{
1414
    int blk, ch;
1415
    AC3EncodeContext *s = avctx->priv_data;
1416

    
1417
    for (ch = 0; ch < s->channels; ch++)
1418
        av_freep(&s->planar_samples[ch]);
1419
    av_freep(&s->planar_samples);
1420
    av_freep(&s->bap_buffer);
1421
    av_freep(&s->bap1_buffer);
1422
    av_freep(&s->mdct_coef_buffer);
1423
    av_freep(&s->exp_buffer);
1424
    av_freep(&s->grouped_exp_buffer);
1425
    av_freep(&s->psd_buffer);
1426
    av_freep(&s->band_psd_buffer);
1427
    av_freep(&s->mask_buffer);
1428
    av_freep(&s->qmant_buffer);
1429
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1430
        AC3Block *block = &s->blocks[blk];
1431
        av_freep(&block->bap);
1432
        av_freep(&block->mdct_coef);
1433
        av_freep(&block->exp);
1434
        av_freep(&block->grouped_exp);
1435
        av_freep(&block->psd);
1436
        av_freep(&block->band_psd);
1437
        av_freep(&block->mask);
1438
        av_freep(&block->qmant);
1439
    }
1440

    
1441
    mdct_end(&s->mdct);
1442

    
1443
    av_freep(&avctx->coded_frame);
1444
    return 0;
1445
}
1446

    
1447

    
1448
/**
1449
 * Set channel information during initialization.
1450
 */
1451
static av_cold int set_channel_info(AC3EncodeContext *s, int channels,
1452
                                    int64_t *channel_layout)
1453
{
1454
    int ch_layout;
1455

    
1456
    if (channels < 1 || channels > AC3_MAX_CHANNELS)
1457
        return AVERROR(EINVAL);
1458
    if ((uint64_t)*channel_layout > 0x7FF)
1459
        return AVERROR(EINVAL);
1460
    ch_layout = *channel_layout;
1461
    if (!ch_layout)
1462
        ch_layout = avcodec_guess_channel_layout(channels, CODEC_ID_AC3, NULL);
1463
    if (av_get_channel_layout_nb_channels(ch_layout) != channels)
1464
        return AVERROR(EINVAL);
1465

    
1466
    s->lfe_on       = !!(ch_layout & AV_CH_LOW_FREQUENCY);
1467
    s->channels     = channels;
1468
    s->fbw_channels = channels - s->lfe_on;
1469
    s->lfe_channel  = s->lfe_on ? s->fbw_channels : -1;
1470
    if (s->lfe_on)
1471
        ch_layout -= AV_CH_LOW_FREQUENCY;
1472

    
1473
    switch (ch_layout) {
1474
    case AV_CH_LAYOUT_MONO:           s->channel_mode = AC3_CHMODE_MONO;   break;
1475
    case AV_CH_LAYOUT_STEREO:         s->channel_mode = AC3_CHMODE_STEREO; break;
1476
    case AV_CH_LAYOUT_SURROUND:       s->channel_mode = AC3_CHMODE_3F;     break;
1477
    case AV_CH_LAYOUT_2_1:            s->channel_mode = AC3_CHMODE_2F1R;   break;
1478
    case AV_CH_LAYOUT_4POINT0:        s->channel_mode = AC3_CHMODE_3F1R;   break;
1479
    case AV_CH_LAYOUT_QUAD:
1480
    case AV_CH_LAYOUT_2_2:            s->channel_mode = AC3_CHMODE_2F2R;   break;
1481
    case AV_CH_LAYOUT_5POINT0:
1482
    case AV_CH_LAYOUT_5POINT0_BACK:   s->channel_mode = AC3_CHMODE_3F2R;   break;
1483
    default:
1484
        return AVERROR(EINVAL);
1485
    }
1486

    
1487
    s->channel_map  = ff_ac3_enc_channel_map[s->channel_mode][s->lfe_on];
1488
    *channel_layout = ch_layout;
1489
    if (s->lfe_on)
1490
        *channel_layout |= AV_CH_LOW_FREQUENCY;
1491

    
1492
    return 0;
1493
}
1494

    
1495

    
1496
static av_cold int validate_options(AVCodecContext *avctx, AC3EncodeContext *s)
1497
{
1498
    int i, ret;
1499

    
1500
    /* validate channel layout */
1501
    if (!avctx->channel_layout) {
1502
        av_log(avctx, AV_LOG_WARNING, "No channel layout specified. The "
1503
                                      "encoder will guess the layout, but it "
1504
                                      "might be incorrect.\n");
1505
    }
1506
    ret = set_channel_info(s, avctx->channels, &avctx->channel_layout);
1507
    if (ret) {
1508
        av_log(avctx, AV_LOG_ERROR, "invalid channel layout\n");
1509
        return ret;
1510
    }
1511

    
1512
    /* validate sample rate */
1513
    for (i = 0; i < 9; i++) {
1514
        if ((ff_ac3_sample_rate_tab[i / 3] >> (i % 3)) == avctx->sample_rate)
1515
            break;
1516
    }
1517
    if (i == 9) {
1518
        av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1519
        return AVERROR(EINVAL);
1520
    }
1521
    s->sample_rate        = avctx->sample_rate;
1522
    s->bit_alloc.sr_shift = i % 3;
1523
    s->bit_alloc.sr_code  = i / 3;
1524

    
1525
    /* validate bit rate */
1526
    for (i = 0; i < 19; i++) {
1527
        if ((ff_ac3_bitrate_tab[i] >> s->bit_alloc.sr_shift)*1000 == avctx->bit_rate)
1528
            break;
1529
    }
1530
    if (i == 19) {
1531
        av_log(avctx, AV_LOG_ERROR, "invalid bit rate\n");
1532
        return AVERROR(EINVAL);
1533
    }
1534
    s->bit_rate        = avctx->bit_rate;
1535
    s->frame_size_code = i << 1;
1536

    
1537
    /* validate cutoff */
1538
    if (avctx->cutoff < 0) {
1539
        av_log(avctx, AV_LOG_ERROR, "invalid cutoff frequency\n");
1540
        return AVERROR(EINVAL);
1541
    }
1542
    s->cutoff = avctx->cutoff;
1543
    if (s->cutoff > (s->sample_rate >> 1))
1544
        s->cutoff = s->sample_rate >> 1;
1545

    
1546
    return 0;
1547
}
1548

    
1549

    
1550
/**
1551
 * Set bandwidth for all channels.
1552
 * The user can optionally supply a cutoff frequency. Otherwise an appropriate
1553
 * default value will be used.
1554
 */
1555
static av_cold void set_bandwidth(AC3EncodeContext *s)
1556
{
1557
    int ch, bw_code;
1558

    
1559
    if (s->cutoff) {
1560
        /* calculate bandwidth based on user-specified cutoff frequency */
1561
        int fbw_coeffs;
1562
        fbw_coeffs     = s->cutoff * 2 * AC3_MAX_COEFS / s->sample_rate;
1563
        bw_code        = av_clip((fbw_coeffs - 73) / 3, 0, 60);
1564
    } else {
1565
        /* use default bandwidth setting */
1566
        /* XXX: should compute the bandwidth according to the frame
1567
           size, so that we avoid annoying high frequency artifacts */
1568
        bw_code = 50;
1569
    }
1570

    
1571
    /* set number of coefficients for each channel */
1572
    for (ch = 0; ch < s->fbw_channels; ch++) {
1573
        s->bandwidth_code[ch] = bw_code;
1574
        s->nb_coefs[ch]       = bw_code * 3 + 73;
1575
    }
1576
    if (s->lfe_on)
1577
        s->nb_coefs[s->lfe_channel] = 7; /* LFE channel always has 7 coefs */
1578
}
1579

    
1580

    
1581
static av_cold int allocate_buffers(AVCodecContext *avctx)
1582
{
1583
    int blk, ch;
1584
    AC3EncodeContext *s = avctx->priv_data;
1585

    
1586
    FF_ALLOC_OR_GOTO(avctx, s->planar_samples, s->channels * sizeof(*s->planar_samples),
1587
                     alloc_fail);
1588
    for (ch = 0; ch < s->channels; ch++) {
1589
        FF_ALLOCZ_OR_GOTO(avctx, s->planar_samples[ch],
1590
                          (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),
1591
                          alloc_fail);
1592
    }
1593
    FF_ALLOC_OR_GOTO(avctx, s->bap_buffer,  AC3_MAX_BLOCKS * s->channels *
1594
                     AC3_MAX_COEFS * sizeof(*s->bap_buffer),  alloc_fail);
1595
    FF_ALLOC_OR_GOTO(avctx, s->bap1_buffer, AC3_MAX_BLOCKS * s->channels *
1596
                     AC3_MAX_COEFS * sizeof(*s->bap1_buffer), alloc_fail);
1597
    FF_ALLOC_OR_GOTO(avctx, s->mdct_coef_buffer, AC3_MAX_BLOCKS * s->channels *
1598
                     AC3_MAX_COEFS * sizeof(*s->mdct_coef_buffer), alloc_fail);
1599
    FF_ALLOC_OR_GOTO(avctx, s->exp_buffer, AC3_MAX_BLOCKS * s->channels *
1600
                     AC3_MAX_COEFS * sizeof(*s->exp_buffer), alloc_fail);
1601
    FF_ALLOC_OR_GOTO(avctx, s->grouped_exp_buffer, AC3_MAX_BLOCKS * s->channels *
1602
                     128 * sizeof(*s->grouped_exp_buffer), alloc_fail);
1603
    FF_ALLOC_OR_GOTO(avctx, s->psd_buffer, AC3_MAX_BLOCKS * s->channels *
1604
                     AC3_MAX_COEFS * sizeof(*s->psd_buffer), alloc_fail);
1605
    FF_ALLOC_OR_GOTO(avctx, s->band_psd_buffer, AC3_MAX_BLOCKS * s->channels *
1606
                     64 * sizeof(*s->band_psd_buffer), alloc_fail);
1607
    FF_ALLOC_OR_GOTO(avctx, s->mask_buffer, AC3_MAX_BLOCKS * s->channels *
1608
                     64 * sizeof(*s->mask_buffer), alloc_fail);
1609
    FF_ALLOC_OR_GOTO(avctx, s->qmant_buffer, AC3_MAX_BLOCKS * s->channels *
1610
                     AC3_MAX_COEFS * sizeof(*s->qmant_buffer), alloc_fail);
1611
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1612
        AC3Block *block = &s->blocks[blk];
1613
        FF_ALLOC_OR_GOTO(avctx, block->bap, s->channels * sizeof(*block->bap),
1614
                         alloc_fail);
1615
        FF_ALLOCZ_OR_GOTO(avctx, block->mdct_coef, s->channels * sizeof(*block->mdct_coef),
1616
                          alloc_fail);
1617
        FF_ALLOCZ_OR_GOTO(avctx, block->exp, s->channels * sizeof(*block->exp),
1618
                          alloc_fail);
1619
        FF_ALLOCZ_OR_GOTO(avctx, block->grouped_exp, s->channels * sizeof(*block->grouped_exp),
1620
                          alloc_fail);
1621
        FF_ALLOCZ_OR_GOTO(avctx, block->psd, s->channels * sizeof(*block->psd),
1622
                          alloc_fail);
1623
        FF_ALLOCZ_OR_GOTO(avctx, block->band_psd, s->channels * sizeof(*block->band_psd),
1624
                          alloc_fail);
1625
        FF_ALLOCZ_OR_GOTO(avctx, block->mask, s->channels * sizeof(*block->mask),
1626
                          alloc_fail);
1627
        FF_ALLOCZ_OR_GOTO(avctx, block->qmant, s->channels * sizeof(*block->qmant),
1628
                          alloc_fail);
1629

    
1630
        for (ch = 0; ch < s->channels; ch++) {
1631
            block->bap[ch]         = &s->bap_buffer        [AC3_MAX_COEFS * (blk * s->channels + ch)];
1632
            block->mdct_coef[ch]   = &s->mdct_coef_buffer  [AC3_MAX_COEFS * (blk * s->channels + ch)];
1633
            block->exp[ch]         = &s->exp_buffer        [AC3_MAX_COEFS * (blk * s->channels + ch)];
1634
            block->grouped_exp[ch] = &s->grouped_exp_buffer[128           * (blk * s->channels + ch)];
1635
            block->psd[ch]         = &s->psd_buffer        [AC3_MAX_COEFS * (blk * s->channels + ch)];
1636
            block->band_psd[ch]    = &s->band_psd_buffer   [64            * (blk * s->channels + ch)];
1637
            block->mask[ch]        = &s->mask_buffer       [64            * (blk * s->channels + ch)];
1638
            block->qmant[ch]       = &s->qmant_buffer      [AC3_MAX_COEFS * (blk * s->channels + ch)];
1639
        }
1640
    }
1641

    
1642
    return 0;
1643
alloc_fail:
1644
    return AVERROR(ENOMEM);
1645
}
1646

    
1647

    
1648
/**
1649
 * Initialize the encoder.
1650
 */
1651
static av_cold int ac3_encode_init(AVCodecContext *avctx)
1652
{
1653
    AC3EncodeContext *s = avctx->priv_data;
1654
    int ret, frame_size_58;
1655

    
1656
    avctx->frame_size = AC3_FRAME_SIZE;
1657

    
1658
    ac3_common_init();
1659

    
1660
    ret = validate_options(avctx, s);
1661
    if (ret)
1662
        return ret;
1663

    
1664
    s->bitstream_id   = 8 + s->bit_alloc.sr_shift;
1665
    s->bitstream_mode = 0; /* complete main audio service */
1666

    
1667
    s->frame_size_min  = 2 * ff_ac3_frame_size_tab[s->frame_size_code][s->bit_alloc.sr_code];
1668
    s->bits_written    = 0;
1669
    s->samples_written = 0;
1670
    s->frame_size      = s->frame_size_min;
1671

    
1672
    /* calculate crc_inv for both possible frame sizes */
1673
    frame_size_58 = (( s->frame_size    >> 2) + ( s->frame_size    >> 4)) << 1;
1674
    s->crc_inv[0] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
1675
    if (s->bit_alloc.sr_code == 1) {
1676
        frame_size_58 = (((s->frame_size+2) >> 2) + ((s->frame_size+2) >> 4)) << 1;
1677
        s->crc_inv[1] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
1678
    }
1679

    
1680
    set_bandwidth(s);
1681

    
1682
    exponent_init(s);
1683

    
1684
    bit_alloc_init(s);
1685

    
1686
    ret = mdct_init(avctx, &s->mdct, 9);
1687
    if (ret)
1688
        goto init_fail;
1689

    
1690
    ret = allocate_buffers(avctx);
1691
    if (ret)
1692
        goto init_fail;
1693

    
1694
    avctx->coded_frame= avcodec_alloc_frame();
1695

    
1696
    dsputil_init(&s->dsp, avctx);
1697

    
1698
    return 0;
1699
init_fail:
1700
    ac3_encode_close(avctx);
1701
    return ret;
1702
}