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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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 */
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24
/**
25
 * @file
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 * 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;
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    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)
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    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)
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    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
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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;
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    int16_t *band_psd_buffer;
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    int16_t *mask_buffer;
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    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 ac3_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,
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     AV_CH_LAYOUT_2_1,
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     AV_CH_LAYOUT_SURROUND,
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     AV_CH_LAYOUT_2_2,
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     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),
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    (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],
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               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
            for (i = 0; i < AC3_MAX_COEFS; i++) {
289
                int e;
290
                int v = abs(SCALE_COEF(block->mdct_coef[ch][i]));
291
                if (v == 0)
292
                    e = 24;
293
                else {
294
                    e = 23 - av_log2(v) + block->exp_shift[ch];
295
                    if (e >= 24) {
296
                        e = 24;
297
                        block->mdct_coef[ch][i] = 0;
298
                    }
299
                }
300
                block->exp[ch][i] = e;
301
            }
302
        }
303
    }
304
}
305

    
306

    
307
/**
308
 * Exponent Difference Threshold.
309
 * New exponents are sent if their SAD exceed this number.
310
 */
311
#define EXP_DIFF_THRESHOLD 1000
312

    
313

    
314
/**
315
 * Calculate exponent strategies for all blocks in a single channel.
316
 */
317
static void compute_exp_strategy_ch(AC3EncodeContext *s, uint8_t *exp_strategy,
318
                                    uint8_t **exp)
319
{
320
    int blk, blk1;
321
    int exp_diff;
322

    
323
    /* estimate if the exponent variation & decide if they should be
324
       reused in the next frame */
325
    exp_strategy[0] = EXP_NEW;
326
    for (blk = 1; blk < AC3_MAX_BLOCKS; blk++) {
327
        exp_diff = s->dsp.sad[0](NULL, exp[blk], exp[blk-1], 16, 16);
328
        if (exp_diff > EXP_DIFF_THRESHOLD)
329
            exp_strategy[blk] = EXP_NEW;
330
        else
331
            exp_strategy[blk] = EXP_REUSE;
332
    }
333
    emms_c();
334

    
335
    /* now select the encoding strategy type : if exponents are often
336
       recoded, we use a coarse encoding */
337
    blk = 0;
338
    while (blk < AC3_MAX_BLOCKS) {
339
        blk1 = blk + 1;
340
        while (blk1 < AC3_MAX_BLOCKS && exp_strategy[blk1] == EXP_REUSE)
341
            blk1++;
342
        switch (blk1 - blk) {
343
        case 1:  exp_strategy[blk] = EXP_D45; break;
344
        case 2:
345
        case 3:  exp_strategy[blk] = EXP_D25; break;
346
        default: exp_strategy[blk] = EXP_D15; break;
347
        }
348
        blk = blk1;
349
    }
350
}
351

    
352

    
353
/**
354
 * Calculate exponent strategies for all channels.
355
 * Array arrangement is reversed to simplify the per-channel calculation.
356
 */
357
static void compute_exp_strategy(AC3EncodeContext *s)
358
{
359
    uint8_t *exp1[AC3_MAX_CHANNELS][AC3_MAX_BLOCKS];
360
    uint8_t exp_str1[AC3_MAX_CHANNELS][AC3_MAX_BLOCKS];
361
    int ch, blk;
362

    
363
    for (ch = 0; ch < s->fbw_channels; ch++) {
364
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
365
            exp1[ch][blk]     = s->blocks[blk].exp[ch];
366
            exp_str1[ch][blk] = s->blocks[blk].exp_strategy[ch];
367
        }
368

    
369
        compute_exp_strategy_ch(s, exp_str1[ch], exp1[ch]);
370

    
371
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++)
372
            s->blocks[blk].exp_strategy[ch] = exp_str1[ch][blk];
373
    }
374
    if (s->lfe_on) {
375
        ch = s->lfe_channel;
376
        s->blocks[0].exp_strategy[ch] = EXP_D15;
377
        for (blk = 1; blk < AC3_MAX_BLOCKS; blk++)
378
            s->blocks[blk].exp_strategy[ch] = EXP_REUSE;
379
    }
380
}
381

    
382

    
383
/**
384
 * Set each encoded exponent in a block to the minimum of itself and the
385
 * exponent in the same frequency bin of a following block.
386
 * exp[i] = min(exp[i], exp1[i]
387
 */
388
static void exponent_min(uint8_t *exp, uint8_t *exp1, int n)
389
{
390
    int i;
391
    for (i = 0; i < n; i++) {
392
        if (exp1[i] < exp[i])
393
            exp[i] = exp1[i];
394
    }
395
}
396

    
397

    
398
/**
399
 * Update the exponents so that they are the ones the decoder will decode.
400
 */
401
static void encode_exponents_blk_ch(uint8_t *exp, int nb_exps, int exp_strategy)
402
{
403
    int nb_groups, i, k;
404

    
405
    nb_groups = exponent_group_tab[exp_strategy-1][nb_exps] * 3;
406

    
407
    /* for each group, compute the minimum exponent */
408
    switch(exp_strategy) {
409
    case EXP_D25:
410
        for (i = 1, k = 1; i <= nb_groups; i++) {
411
            uint8_t exp_min = exp[k];
412
            if (exp[k+1] < exp_min)
413
                exp_min = exp[k+1];
414
            exp[i] = exp_min;
415
            k += 2;
416
        }
417
        break;
418
    case EXP_D45:
419
        for (i = 1, k = 1; i <= nb_groups; i++) {
420
            uint8_t exp_min = exp[k];
421
            if (exp[k+1] < exp_min)
422
                exp_min = exp[k+1];
423
            if (exp[k+2] < exp_min)
424
                exp_min = exp[k+2];
425
            if (exp[k+3] < exp_min)
426
                exp_min = exp[k+3];
427
            exp[i] = exp_min;
428
            k += 4;
429
        }
430
        break;
431
    }
432

    
433
    /* constraint for DC exponent */
434
    if (exp[0] > 15)
435
        exp[0] = 15;
436

    
437
    /* decrease the delta between each groups to within 2 so that they can be
438
       differentially encoded */
439
    for (i = 1; i <= nb_groups; i++)
440
        exp[i] = FFMIN(exp[i], exp[i-1] + 2);
441
    i--;
442
    while (--i >= 0)
443
        exp[i] = FFMIN(exp[i], exp[i+1] + 2);
444

    
445
    /* now we have the exponent values the decoder will see */
446
    switch (exp_strategy) {
447
    case EXP_D25:
448
        for (i = nb_groups, k = nb_groups * 2; i > 0; i--) {
449
            uint8_t exp1 = exp[i];
450
            exp[k--] = exp1;
451
            exp[k--] = exp1;
452
        }
453
        break;
454
    case EXP_D45:
455
        for (i = nb_groups, k = nb_groups * 4; i > 0; i--) {
456
            exp[k] = exp[k-1] = exp[k-2] = exp[k-3] = exp[i];
457
            k -= 4;
458
        }
459
        break;
460
    }
461
}
462

    
463

    
464
/**
465
 * Encode exponents from original extracted form to what the decoder will see.
466
 * This copies and groups exponents based on exponent strategy and reduces
467
 * deltas between adjacent exponent groups so that they can be differentially
468
 * encoded.
469
 */
470
static void encode_exponents(AC3EncodeContext *s)
471
{
472
    int blk, blk1, blk2, ch;
473
    AC3Block *block, *block1, *block2;
474

    
475
    for (ch = 0; ch < s->channels; ch++) {
476
        blk = 0;
477
        block = &s->blocks[0];
478
        while (blk < AC3_MAX_BLOCKS) {
479
            blk1 = blk + 1;
480
            block1 = block + 1;
481
            /* for the EXP_REUSE case we select the min of the exponents */
482
            while (blk1 < AC3_MAX_BLOCKS && block1->exp_strategy[ch] == EXP_REUSE) {
483
                exponent_min(block->exp[ch], block1->exp[ch], s->nb_coefs[ch]);
484
                blk1++;
485
                block1++;
486
            }
487
            encode_exponents_blk_ch(block->exp[ch], s->nb_coefs[ch],
488
                                    block->exp_strategy[ch]);
489
            /* copy encoded exponents for reuse case */
490
            block2 = block + 1;
491
            for (blk2 = blk+1; blk2 < blk1; blk2++, block2++) {
492
                memcpy(block2->exp[ch], block->exp[ch],
493
                       s->nb_coefs[ch] * sizeof(uint8_t));
494
            }
495
            blk = blk1;
496
            block = block1;
497
        }
498
    }
499
}
500

    
501

    
502
/**
503
 * Group exponents.
504
 * 3 delta-encoded exponents are in each 7-bit group. The number of groups
505
 * varies depending on exponent strategy and bandwidth.
506
 */
507
static void group_exponents(AC3EncodeContext *s)
508
{
509
    int blk, ch, i;
510
    int group_size, nb_groups, bit_count;
511
    uint8_t *p;
512
    int delta0, delta1, delta2;
513
    int exp0, exp1;
514

    
515
    bit_count = 0;
516
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
517
        AC3Block *block = &s->blocks[blk];
518
        for (ch = 0; ch < s->channels; ch++) {
519
            if (block->exp_strategy[ch] == EXP_REUSE) {
520
                continue;
521
            }
522
            group_size = block->exp_strategy[ch] + (block->exp_strategy[ch] == EXP_D45);
523
            nb_groups = exponent_group_tab[block->exp_strategy[ch]-1][s->nb_coefs[ch]];
524
            bit_count += 4 + (nb_groups * 7);
525
            p = block->exp[ch];
526

    
527
            /* DC exponent */
528
            exp1 = *p++;
529
            block->grouped_exp[ch][0] = exp1;
530

    
531
            /* remaining exponents are delta encoded */
532
            for (i = 1; i <= nb_groups; i++) {
533
                /* merge three delta in one code */
534
                exp0   = exp1;
535
                exp1   = p[0];
536
                p     += group_size;
537
                delta0 = exp1 - exp0 + 2;
538

    
539
                exp0   = exp1;
540
                exp1   = p[0];
541
                p     += group_size;
542
                delta1 = exp1 - exp0 + 2;
543

    
544
                exp0   = exp1;
545
                exp1   = p[0];
546
                p     += group_size;
547
                delta2 = exp1 - exp0 + 2;
548

    
549
                block->grouped_exp[ch][i] = ((delta0 * 5 + delta1) * 5) + delta2;
550
            }
551
        }
552
    }
553

    
554
    s->exponent_bits = bit_count;
555
}
556

    
557

    
558
/**
559
 * Calculate final exponents from the supplied MDCT coefficients and exponent shift.
560
 * Extract exponents from MDCT coefficients, calculate exponent strategies,
561
 * and encode final exponents.
562
 */
563
static void process_exponents(AC3EncodeContext *s)
564
{
565
    extract_exponents(s);
566

    
567
    compute_exp_strategy(s);
568

    
569
    encode_exponents(s);
570

    
571
    group_exponents(s);
572
}
573

    
574

    
575
/**
576
 * Count frame bits that are based solely on fixed parameters.
577
 * This only has to be run once when the encoder is initialized.
578
 */
579
static void count_frame_bits_fixed(AC3EncodeContext *s)
580
{
581
    static const int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
582
    int blk;
583
    int frame_bits;
584

    
585
    /* assumptions:
586
     *   no dynamic range codes
587
     *   no channel coupling
588
     *   no rematrixing
589
     *   bit allocation parameters do not change between blocks
590
     *   SNR offsets do not change between blocks
591
     *   no delta bit allocation
592
     *   no skipped data
593
     *   no auxilliary data
594
     */
595

    
596
    /* header size */
597
    frame_bits = 65;
598
    frame_bits += frame_bits_inc[s->channel_mode];
599

    
600
    /* audio blocks */
601
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
602
        frame_bits += s->fbw_channels * 2 + 2; /* blksw * c, dithflag * c, dynrnge, cplstre */
603
        if (s->channel_mode == AC3_CHMODE_STEREO) {
604
            frame_bits++; /* rematstr */
605
            if (!blk)
606
                frame_bits += 4;
607
        }
608
        frame_bits += 2 * s->fbw_channels; /* chexpstr[2] * c */
609
        if (s->lfe_on)
610
            frame_bits++; /* lfeexpstr */
611
        frame_bits++; /* baie */
612
        frame_bits++; /* snr */
613
        frame_bits += 2; /* delta / skip */
614
    }
615
    frame_bits++; /* cplinu for block 0 */
616
    /* bit alloc info */
617
    /* sdcycod[2], fdcycod[2], sgaincod[2], dbpbcod[2], floorcod[3] */
618
    /* csnroffset[6] */
619
    /* (fsnoffset[4] + fgaincod[4]) * c */
620
    frame_bits += 2*4 + 3 + 6 + s->channels * (4 + 3);
621

    
622
    /* auxdatae, crcrsv */
623
    frame_bits += 2;
624

    
625
    /* CRC */
626
    frame_bits += 16;
627

    
628
    s->frame_bits_fixed = frame_bits;
629
}
630

    
631

    
632
/**
633
 * Initialize bit allocation.
634
 * Set default parameter codes and calculate parameter values.
635
 */
636
static void bit_alloc_init(AC3EncodeContext *s)
637
{
638
    int ch;
639

    
640
    /* init default parameters */
641
    s->slow_decay_code = 2;
642
    s->fast_decay_code = 1;
643
    s->slow_gain_code  = 1;
644
    s->db_per_bit_code = 3;
645
    s->floor_code      = 4;
646
    for (ch = 0; ch < s->channels; ch++)
647
        s->fast_gain_code[ch] = 4;
648

    
649
    /* initial snr offset */
650
    s->coarse_snr_offset = 40;
651

    
652
    /* compute real values */
653
    /* currently none of these values change during encoding, so we can just
654
       set them once at initialization */
655
    s->bit_alloc.slow_decay = ff_ac3_slow_decay_tab[s->slow_decay_code] >> s->bit_alloc.sr_shift;
656
    s->bit_alloc.fast_decay = ff_ac3_fast_decay_tab[s->fast_decay_code] >> s->bit_alloc.sr_shift;
657
    s->bit_alloc.slow_gain  = ff_ac3_slow_gain_tab[s->slow_gain_code];
658
    s->bit_alloc.db_per_bit = ff_ac3_db_per_bit_tab[s->db_per_bit_code];
659
    s->bit_alloc.floor      = ff_ac3_floor_tab[s->floor_code];
660

    
661
    count_frame_bits_fixed(s);
662
}
663

    
664

    
665
/**
666
 * Count the bits used to encode the frame, minus exponents and mantissas.
667
 * Bits based on fixed parameters have already been counted, so now we just
668
 * have to add the bits based on parameters that change during encoding.
669
 */
670
static void count_frame_bits(AC3EncodeContext *s)
671
{
672
    int blk, ch;
673
    int frame_bits = 0;
674

    
675
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
676
        uint8_t *exp_strategy = s->blocks[blk].exp_strategy;
677
        for (ch = 0; ch < s->fbw_channels; ch++) {
678
            if (exp_strategy[ch] != EXP_REUSE)
679
                frame_bits += 6 + 2; /* chbwcod[6], gainrng[2] */
680
        }
681
    }
682
    s->frame_bits = s->frame_bits_fixed + frame_bits;
683
}
684

    
685

    
686
/**
687
 * Calculate the number of bits needed to encode a set of mantissas.
688
 */
689
static int compute_mantissa_size(int mant_cnt[5], uint8_t *bap, int nb_coefs)
690
{
691
    int bits, b, i;
692

    
693
    bits = 0;
694
    for (i = 0; i < nb_coefs; i++) {
695
        b = bap[i];
696
        if (b <= 4) {
697
            // bap=1 to bap=4 will be counted in compute_mantissa_size_final
698
            mant_cnt[b]++;
699
        } else if (b <= 13) {
700
            // bap=5 to bap=13 use (bap-1) bits
701
            bits += b - 1;
702
        } else {
703
            // bap=14 uses 14 bits and bap=15 uses 16 bits
704
            bits += (b == 14) ? 14 : 16;
705
        }
706
    }
707
    return bits;
708
}
709

    
710

    
711
/**
712
 * Finalize the mantissa bit count by adding in the grouped mantissas.
713
 */
714
static int compute_mantissa_size_final(int mant_cnt[5])
715
{
716
    // bap=1 : 3 mantissas in 5 bits
717
    int bits = (mant_cnt[1] / 3) * 5;
718
    // bap=2 : 3 mantissas in 7 bits
719
    // bap=4 : 2 mantissas in 7 bits
720
    bits += ((mant_cnt[2] / 3) + (mant_cnt[4] >> 1)) * 7;
721
    // bap=3 : each mantissa is 3 bits
722
    bits += mant_cnt[3] * 3;
723
    return bits;
724
}
725

    
726

    
727
/**
728
 * Calculate masking curve based on the final exponents.
729
 * Also calculate the power spectral densities to use in future calculations.
730
 */
731
static void bit_alloc_masking(AC3EncodeContext *s)
732
{
733
    int blk, ch;
734

    
735
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
736
        AC3Block *block = &s->blocks[blk];
737
        for (ch = 0; ch < s->channels; ch++) {
738
            /* We only need psd and mask for calculating bap.
739
               Since we currently do not calculate bap when exponent
740
               strategy is EXP_REUSE we do not need to calculate psd or mask. */
741
            if (block->exp_strategy[ch] != EXP_REUSE) {
742
                ff_ac3_bit_alloc_calc_psd(block->exp[ch], 0,
743
                                          s->nb_coefs[ch],
744
                                          block->psd[ch], block->band_psd[ch]);
745
                ff_ac3_bit_alloc_calc_mask(&s->bit_alloc, block->band_psd[ch],
746
                                           0, s->nb_coefs[ch],
747
                                           ff_ac3_fast_gain_tab[s->fast_gain_code[ch]],
748
                                           ch == s->lfe_channel,
749
                                           DBA_NONE, 0, NULL, NULL, NULL,
750
                                           block->mask[ch]);
751
            }
752
        }
753
    }
754
}
755

    
756

    
757
/**
758
 * Ensure that bap for each block and channel point to the current bap_buffer.
759
 * They may have been switched during the bit allocation search.
760
 */
761
static void reset_block_bap(AC3EncodeContext *s)
762
{
763
    int blk, ch;
764
    if (s->blocks[0].bap[0] == s->bap_buffer)
765
        return;
766
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
767
        for (ch = 0; ch < s->channels; ch++) {
768
            s->blocks[blk].bap[ch] = &s->bap_buffer[AC3_MAX_COEFS * (blk * s->channels + ch)];
769
        }
770
    }
771
}
772

    
773

    
774
/**
775
 * Run the bit allocation with a given SNR offset.
776
 * This calculates the bit allocation pointers that will be used to determine
777
 * the quantization of each mantissa.
778
 * @return the number of bits needed for mantissas if the given SNR offset is
779
 *         is used.
780
 */
781
static int bit_alloc(AC3EncodeContext *s, int snr_offset)
782
{
783
    int blk, ch;
784
    int mantissa_bits;
785
    int mant_cnt[5];
786

    
787
    snr_offset = (snr_offset - 240) << 2;
788

    
789
    reset_block_bap(s);
790
    mantissa_bits = 0;
791
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
792
        AC3Block *block = &s->blocks[blk];
793
        // initialize grouped mantissa counts. these are set so that they are
794
        // padded to the next whole group size when bits are counted in
795
        // compute_mantissa_size_final
796
        mant_cnt[0] = mant_cnt[3] = 0;
797
        mant_cnt[1] = mant_cnt[2] = 2;
798
        mant_cnt[4] = 1;
799
        for (ch = 0; ch < s->channels; ch++) {
800
            /* Currently the only bit allocation parameters which vary across
801
               blocks within a frame are the exponent values.  We can take
802
               advantage of that by reusing the bit allocation pointers
803
               whenever we reuse exponents. */
804
            if (block->exp_strategy[ch] == EXP_REUSE) {
805
                memcpy(block->bap[ch], s->blocks[blk-1].bap[ch], AC3_MAX_COEFS);
806
            } else {
807
                ff_ac3_bit_alloc_calc_bap(block->mask[ch], block->psd[ch], 0,
808
                                          s->nb_coefs[ch], snr_offset,
809
                                          s->bit_alloc.floor, ff_ac3_bap_tab,
810
                                          block->bap[ch]);
811
            }
812
            mantissa_bits += compute_mantissa_size(mant_cnt, block->bap[ch], s->nb_coefs[ch]);
813
        }
814
        mantissa_bits += compute_mantissa_size_final(mant_cnt);
815
    }
816
    return mantissa_bits;
817
}
818

    
819

    
820
/**
821
 * Constant bitrate bit allocation search.
822
 * Find the largest SNR offset that will allow data to fit in the frame.
823
 */
824
static int cbr_bit_allocation(AC3EncodeContext *s)
825
{
826
    int ch;
827
    int bits_left;
828
    int snr_offset, snr_incr;
829

    
830
    bits_left = 8 * s->frame_size - (s->frame_bits + s->exponent_bits);
831

    
832
    snr_offset = s->coarse_snr_offset << 4;
833

    
834
    /* if previous frame SNR offset was 1023, check if current frame can also
835
       use SNR offset of 1023. if so, skip the search. */
836
    if ((snr_offset | s->fine_snr_offset[0]) == 1023) {
837
        if (bit_alloc(s, 1023) <= bits_left)
838
            return 0;
839
    }
840

    
841
    while (snr_offset >= 0 &&
842
           bit_alloc(s, snr_offset) > bits_left) {
843
        snr_offset -= 64;
844
    }
845
    if (snr_offset < 0)
846
        return AVERROR(EINVAL);
847

    
848
    FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
849
    for (snr_incr = 64; snr_incr > 0; snr_incr >>= 2) {
850
        while (snr_offset + snr_incr <= 1023 &&
851
               bit_alloc(s, snr_offset + snr_incr) <= bits_left) {
852
            snr_offset += snr_incr;
853
            FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
854
        }
855
    }
856
    FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
857
    reset_block_bap(s);
858

    
859
    s->coarse_snr_offset = snr_offset >> 4;
860
    for (ch = 0; ch < s->channels; ch++)
861
        s->fine_snr_offset[ch] = snr_offset & 0xF;
862

    
863
    return 0;
864
}
865

    
866

    
867
/**
868
 * Downgrade exponent strategies to reduce the bits used by the exponents.
869
 * This is a fallback for when bit allocation fails with the normal exponent
870
 * strategies.  Each time this function is run it only downgrades the
871
 * strategy in 1 channel of 1 block.
872
 * @return non-zero if downgrade was unsuccessful
873
 */
874
static int downgrade_exponents(AC3EncodeContext *s)
875
{
876
    int ch, blk;
877

    
878
    for (ch = 0; ch < s->fbw_channels; ch++) {
879
        for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
880
            if (s->blocks[blk].exp_strategy[ch] == EXP_D15) {
881
                s->blocks[blk].exp_strategy[ch] = EXP_D25;
882
                return 0;
883
            }
884
        }
885
    }
886
    for (ch = 0; ch < s->fbw_channels; ch++) {
887
        for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
888
            if (s->blocks[blk].exp_strategy[ch] == EXP_D25) {
889
                s->blocks[blk].exp_strategy[ch] = EXP_D45;
890
                return 0;
891
            }
892
        }
893
    }
894
    for (ch = 0; ch < s->fbw_channels; ch++) {
895
        /* block 0 cannot reuse exponents, so only downgrade D45 to REUSE if
896
           the block number > 0 */
897
        for (blk = AC3_MAX_BLOCKS-1; blk > 0; blk--) {
898
            if (s->blocks[blk].exp_strategy[ch] > EXP_REUSE) {
899
                s->blocks[blk].exp_strategy[ch] = EXP_REUSE;
900
                return 0;
901
            }
902
        }
903
    }
904
    return -1;
905
}
906

    
907

    
908
/**
909
 * Reduce the bandwidth to reduce the number of bits used for a given SNR offset.
910
 * This is a second fallback for when bit allocation still fails after exponents
911
 * have been downgraded.
912
 * @return non-zero if bandwidth reduction was unsuccessful
913
 */
914
static int reduce_bandwidth(AC3EncodeContext *s, int min_bw_code)
915
{
916
    int ch;
917

    
918
    if (s->bandwidth_code[0] > min_bw_code) {
919
        for (ch = 0; ch < s->fbw_channels; ch++) {
920
            s->bandwidth_code[ch]--;
921
            s->nb_coefs[ch] = s->bandwidth_code[ch] * 3 + 73;
922
        }
923
        return 0;
924
    }
925
    return -1;
926
}
927

    
928

    
929
/**
930
 * Perform bit allocation search.
931
 * Finds the SNR offset value that maximizes quality and fits in the specified
932
 * frame size.  Output is the SNR offset and a set of bit allocation pointers
933
 * used to quantize the mantissas.
934
 */
935
static int compute_bit_allocation(AC3EncodeContext *s)
936
{
937
    int ret;
938

    
939
    count_frame_bits(s);
940

    
941
    bit_alloc_masking(s);
942

    
943
    ret = cbr_bit_allocation(s);
944
    while (ret) {
945
        /* fallback 1: downgrade exponents */
946
        if (!downgrade_exponents(s)) {
947
            extract_exponents(s);
948
            encode_exponents(s);
949
            group_exponents(s);
950
            ret = compute_bit_allocation(s);
951
            continue;
952
        }
953

    
954
        /* fallback 2: reduce bandwidth */
955
        /* only do this if the user has not specified a specific cutoff
956
           frequency */
957
        if (!s->cutoff && !reduce_bandwidth(s, 0)) {
958
            process_exponents(s);
959
            ret = compute_bit_allocation(s);
960
            continue;
961
        }
962

    
963
        /* fallbacks were not enough... */
964
        break;
965
    }
966

    
967
    return ret;
968
}
969

    
970

    
971
/**
972
 * Symmetric quantization on 'levels' levels.
973
 */
974
static inline int sym_quant(int c, int e, int levels)
975
{
976
    int v;
977

    
978
    if (c >= 0) {
979
        v = (levels * (c << e)) >> 24;
980
        v = (v + 1) >> 1;
981
        v = (levels >> 1) + v;
982
    } else {
983
        v = (levels * ((-c) << e)) >> 24;
984
        v = (v + 1) >> 1;
985
        v = (levels >> 1) - v;
986
    }
987
    assert(v >= 0 && v < levels);
988
    return v;
989
}
990

    
991

    
992
/**
993
 * Asymmetric quantization on 2^qbits levels.
994
 */
995
static inline int asym_quant(int c, int e, int qbits)
996
{
997
    int lshift, m, v;
998

    
999
    lshift = e + qbits - 24;
1000
    if (lshift >= 0)
1001
        v = c << lshift;
1002
    else
1003
        v = c >> (-lshift);
1004
    /* rounding */
1005
    v = (v + 1) >> 1;
1006
    m = (1 << (qbits-1));
1007
    if (v >= m)
1008
        v = m - 1;
1009
    assert(v >= -m);
1010
    return v & ((1 << qbits)-1);
1011
}
1012

    
1013

    
1014
/**
1015
 * Quantize a set of mantissas for a single channel in a single block.
1016
 */
1017
static void quantize_mantissas_blk_ch(AC3EncodeContext *s, CoefType *mdct_coef,
1018
                                      int8_t exp_shift, uint8_t *exp,
1019
                                      uint8_t *bap, uint16_t *qmant, int n)
1020
{
1021
    int i;
1022

    
1023
    for (i = 0; i < n; i++) {
1024
        int v;
1025
        int c = SCALE_COEF(mdct_coef[i]);
1026
        int e = exp[i] - exp_shift;
1027
        int b = bap[i];
1028
        switch (b) {
1029
        case 0:
1030
            v = 0;
1031
            break;
1032
        case 1:
1033
            v = sym_quant(c, e, 3);
1034
            switch (s->mant1_cnt) {
1035
            case 0:
1036
                s->qmant1_ptr = &qmant[i];
1037
                v = 9 * v;
1038
                s->mant1_cnt = 1;
1039
                break;
1040
            case 1:
1041
                *s->qmant1_ptr += 3 * v;
1042
                s->mant1_cnt = 2;
1043
                v = 128;
1044
                break;
1045
            default:
1046
                *s->qmant1_ptr += v;
1047
                s->mant1_cnt = 0;
1048
                v = 128;
1049
                break;
1050
            }
1051
            break;
1052
        case 2:
1053
            v = sym_quant(c, e, 5);
1054
            switch (s->mant2_cnt) {
1055
            case 0:
1056
                s->qmant2_ptr = &qmant[i];
1057
                v = 25 * v;
1058
                s->mant2_cnt = 1;
1059
                break;
1060
            case 1:
1061
                *s->qmant2_ptr += 5 * v;
1062
                s->mant2_cnt = 2;
1063
                v = 128;
1064
                break;
1065
            default:
1066
                *s->qmant2_ptr += v;
1067
                s->mant2_cnt = 0;
1068
                v = 128;
1069
                break;
1070
            }
1071
            break;
1072
        case 3:
1073
            v = sym_quant(c, e, 7);
1074
            break;
1075
        case 4:
1076
            v = sym_quant(c, e, 11);
1077
            switch (s->mant4_cnt) {
1078
            case 0:
1079
                s->qmant4_ptr = &qmant[i];
1080
                v = 11 * v;
1081
                s->mant4_cnt = 1;
1082
                break;
1083
            default:
1084
                *s->qmant4_ptr += v;
1085
                s->mant4_cnt = 0;
1086
                v = 128;
1087
                break;
1088
            }
1089
            break;
1090
        case 5:
1091
            v = sym_quant(c, e, 15);
1092
            break;
1093
        case 14:
1094
            v = asym_quant(c, e, 14);
1095
            break;
1096
        case 15:
1097
            v = asym_quant(c, e, 16);
1098
            break;
1099
        default:
1100
            v = asym_quant(c, e, b - 1);
1101
            break;
1102
        }
1103
        qmant[i] = v;
1104
    }
1105
}
1106

    
1107

    
1108
/**
1109
 * Quantize mantissas using coefficients, exponents, and bit allocation pointers.
1110
 */
1111
static void quantize_mantissas(AC3EncodeContext *s)
1112
{
1113
    int blk, ch;
1114

    
1115

    
1116
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1117
        AC3Block *block = &s->blocks[blk];
1118
        s->mant1_cnt  = s->mant2_cnt  = s->mant4_cnt  = 0;
1119
        s->qmant1_ptr = s->qmant2_ptr = s->qmant4_ptr = NULL;
1120

    
1121
        for (ch = 0; ch < s->channels; ch++) {
1122
            quantize_mantissas_blk_ch(s, block->mdct_coef[ch], block->exp_shift[ch],
1123
                                      block->exp[ch], block->bap[ch],
1124
                                      block->qmant[ch], s->nb_coefs[ch]);
1125
        }
1126
    }
1127
}
1128

    
1129

    
1130
/**
1131
 * Write the AC-3 frame header to the output bitstream.
1132
 */
1133
static void output_frame_header(AC3EncodeContext *s)
1134
{
1135
    put_bits(&s->pb, 16, 0x0b77);   /* frame header */
1136
    put_bits(&s->pb, 16, 0);        /* crc1: will be filled later */
1137
    put_bits(&s->pb, 2,  s->bit_alloc.sr_code);
1138
    put_bits(&s->pb, 6,  s->frame_size_code + (s->frame_size - s->frame_size_min) / 2);
1139
    put_bits(&s->pb, 5,  s->bitstream_id);
1140
    put_bits(&s->pb, 3,  s->bitstream_mode);
1141
    put_bits(&s->pb, 3,  s->channel_mode);
1142
    if ((s->channel_mode & 0x01) && s->channel_mode != AC3_CHMODE_MONO)
1143
        put_bits(&s->pb, 2, 1);     /* XXX -4.5 dB */
1144
    if (s->channel_mode & 0x04)
1145
        put_bits(&s->pb, 2, 1);     /* XXX -6 dB */
1146
    if (s->channel_mode == AC3_CHMODE_STEREO)
1147
        put_bits(&s->pb, 2, 0);     /* surround not indicated */
1148
    put_bits(&s->pb, 1, s->lfe_on); /* LFE */
1149
    put_bits(&s->pb, 5, 31);        /* dialog norm: -31 db */
1150
    put_bits(&s->pb, 1, 0);         /* no compression control word */
1151
    put_bits(&s->pb, 1, 0);         /* no lang code */
1152
    put_bits(&s->pb, 1, 0);         /* no audio production info */
1153
    put_bits(&s->pb, 1, 0);         /* no copyright */
1154
    put_bits(&s->pb, 1, 1);         /* original bitstream */
1155
    put_bits(&s->pb, 1, 0);         /* no time code 1 */
1156
    put_bits(&s->pb, 1, 0);         /* no time code 2 */
1157
    put_bits(&s->pb, 1, 0);         /* no additional bit stream info */
1158
}
1159

    
1160

    
1161
/**
1162
 * Write one audio block to the output bitstream.
1163
 */
1164
static void output_audio_block(AC3EncodeContext *s, int block_num)
1165
{
1166
    int ch, i, baie, rbnd;
1167
    AC3Block *block = &s->blocks[block_num];
1168

    
1169
    /* block switching */
1170
    for (ch = 0; ch < s->fbw_channels; ch++)
1171
        put_bits(&s->pb, 1, 0);
1172

    
1173
    /* dither flags */
1174
    for (ch = 0; ch < s->fbw_channels; ch++)
1175
        put_bits(&s->pb, 1, 1);
1176

    
1177
    /* dynamic range codes */
1178
    put_bits(&s->pb, 1, 0);
1179

    
1180
    /* channel coupling */
1181
    if (!block_num) {
1182
        put_bits(&s->pb, 1, 1); /* coupling strategy present */
1183
        put_bits(&s->pb, 1, 0); /* no coupling strategy */
1184
    } else {
1185
        put_bits(&s->pb, 1, 0); /* no new coupling strategy */
1186
    }
1187

    
1188
    /* stereo rematrixing */
1189
    if (s->channel_mode == AC3_CHMODE_STEREO) {
1190
        if (!block_num) {
1191
            /* first block must define rematrixing (rematstr) */
1192
            put_bits(&s->pb, 1, 1);
1193

    
1194
            /* dummy rematrixing rematflg(1:4)=0 */
1195
            for (rbnd = 0; rbnd < 4; rbnd++)
1196
                put_bits(&s->pb, 1, 0);
1197
        } else {
1198
            /* no matrixing (but should be used in the future) */
1199
            put_bits(&s->pb, 1, 0);
1200
        }
1201
    }
1202

    
1203
    /* exponent strategy */
1204
    for (ch = 0; ch < s->fbw_channels; ch++)
1205
        put_bits(&s->pb, 2, block->exp_strategy[ch]);
1206
    if (s->lfe_on)
1207
        put_bits(&s->pb, 1, block->exp_strategy[s->lfe_channel]);
1208

    
1209
    /* bandwidth */
1210
    for (ch = 0; ch < s->fbw_channels; ch++) {
1211
        if (block->exp_strategy[ch] != EXP_REUSE)
1212
            put_bits(&s->pb, 6, s->bandwidth_code[ch]);
1213
    }
1214

    
1215
    /* exponents */
1216
    for (ch = 0; ch < s->channels; ch++) {
1217
        int nb_groups;
1218

    
1219
        if (block->exp_strategy[ch] == EXP_REUSE)
1220
            continue;
1221

    
1222
        /* DC exponent */
1223
        put_bits(&s->pb, 4, block->grouped_exp[ch][0]);
1224

    
1225
        /* exponent groups */
1226
        nb_groups = exponent_group_tab[block->exp_strategy[ch]-1][s->nb_coefs[ch]];
1227
        for (i = 1; i <= nb_groups; i++)
1228
            put_bits(&s->pb, 7, block->grouped_exp[ch][i]);
1229

    
1230
        /* gain range info */
1231
        if (ch != s->lfe_channel)
1232
            put_bits(&s->pb, 2, 0);
1233
    }
1234

    
1235
    /* bit allocation info */
1236
    baie = (block_num == 0);
1237
    put_bits(&s->pb, 1, baie);
1238
    if (baie) {
1239
        put_bits(&s->pb, 2, s->slow_decay_code);
1240
        put_bits(&s->pb, 2, s->fast_decay_code);
1241
        put_bits(&s->pb, 2, s->slow_gain_code);
1242
        put_bits(&s->pb, 2, s->db_per_bit_code);
1243
        put_bits(&s->pb, 3, s->floor_code);
1244
    }
1245

    
1246
    /* snr offset */
1247
    put_bits(&s->pb, 1, baie);
1248
    if (baie) {
1249
        put_bits(&s->pb, 6, s->coarse_snr_offset);
1250
        for (ch = 0; ch < s->channels; ch++) {
1251
            put_bits(&s->pb, 4, s->fine_snr_offset[ch]);
1252
            put_bits(&s->pb, 3, s->fast_gain_code[ch]);
1253
        }
1254
    }
1255

    
1256
    put_bits(&s->pb, 1, 0); /* no delta bit allocation */
1257
    put_bits(&s->pb, 1, 0); /* no data to skip */
1258

    
1259
    /* mantissas */
1260
    for (ch = 0; ch < s->channels; ch++) {
1261
        int b, q;
1262
        for (i = 0; i < s->nb_coefs[ch]; i++) {
1263
            q = block->qmant[ch][i];
1264
            b = block->bap[ch][i];
1265
            switch (b) {
1266
            case 0:                                         break;
1267
            case 1: if (q != 128) put_bits(&s->pb,   5, q); break;
1268
            case 2: if (q != 128) put_bits(&s->pb,   7, q); break;
1269
            case 3:               put_bits(&s->pb,   3, q); break;
1270
            case 4: if (q != 128) put_bits(&s->pb,   7, q); break;
1271
            case 14:              put_bits(&s->pb,  14, q); break;
1272
            case 15:              put_bits(&s->pb,  16, q); break;
1273
            default:              put_bits(&s->pb, b-1, q); break;
1274
            }
1275
        }
1276
    }
1277
}
1278

    
1279

    
1280
/** CRC-16 Polynomial */
1281
#define CRC16_POLY ((1 << 0) | (1 << 2) | (1 << 15) | (1 << 16))
1282

    
1283

    
1284
static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly)
1285
{
1286
    unsigned int c;
1287

    
1288
    c = 0;
1289
    while (a) {
1290
        if (a & 1)
1291
            c ^= b;
1292
        a = a >> 1;
1293
        b = b << 1;
1294
        if (b & (1 << 16))
1295
            b ^= poly;
1296
    }
1297
    return c;
1298
}
1299

    
1300

    
1301
static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly)
1302
{
1303
    unsigned int r;
1304
    r = 1;
1305
    while (n) {
1306
        if (n & 1)
1307
            r = mul_poly(r, a, poly);
1308
        a = mul_poly(a, a, poly);
1309
        n >>= 1;
1310
    }
1311
    return r;
1312
}
1313

    
1314

    
1315
/**
1316
 * Fill the end of the frame with 0's and compute the two CRCs.
1317
 */
1318
static void output_frame_end(AC3EncodeContext *s)
1319
{
1320
    const AVCRC *crc_ctx = av_crc_get_table(AV_CRC_16_ANSI);
1321
    int frame_size_58, pad_bytes, crc1, crc2_partial, crc2, crc_inv;
1322
    uint8_t *frame;
1323

    
1324
    frame_size_58 = ((s->frame_size >> 2) + (s->frame_size >> 4)) << 1;
1325

    
1326
    /* pad the remainder of the frame with zeros */
1327
    flush_put_bits(&s->pb);
1328
    frame = s->pb.buf;
1329
    pad_bytes = s->frame_size - (put_bits_ptr(&s->pb) - frame) - 2;
1330
    assert(pad_bytes >= 0);
1331
    if (pad_bytes > 0)
1332
        memset(put_bits_ptr(&s->pb), 0, pad_bytes);
1333

    
1334
    /* compute crc1 */
1335
    /* this is not so easy because it is at the beginning of the data... */
1336
    crc1    = av_bswap16(av_crc(crc_ctx, 0, frame + 4, frame_size_58 - 4));
1337
    crc_inv = s->crc_inv[s->frame_size > s->frame_size_min];
1338
    crc1    = mul_poly(crc_inv, crc1, CRC16_POLY);
1339
    AV_WB16(frame + 2, crc1);
1340

    
1341
    /* compute crc2 */
1342
    crc2_partial = av_crc(crc_ctx, 0, frame + frame_size_58,
1343
                          s->frame_size - frame_size_58 - 3);
1344
    crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
1345
    /* ensure crc2 does not match sync word by flipping crcrsv bit if needed */
1346
    if (crc2 == 0x770B) {
1347
        frame[s->frame_size - 3] ^= 0x1;
1348
        crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
1349
    }
1350
    crc2 = av_bswap16(crc2);
1351
    AV_WB16(frame + s->frame_size - 2, crc2);
1352
}
1353

    
1354

    
1355
/**
1356
 * Write the frame to the output bitstream.
1357
 */
1358
static void output_frame(AC3EncodeContext *s, unsigned char *frame)
1359
{
1360
    int blk;
1361

    
1362
    init_put_bits(&s->pb, frame, AC3_MAX_CODED_FRAME_SIZE);
1363

    
1364
    output_frame_header(s);
1365

    
1366
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++)
1367
        output_audio_block(s, blk);
1368

    
1369
    output_frame_end(s);
1370
}
1371

    
1372

    
1373
/**
1374
 * Encode a single AC-3 frame.
1375
 */
1376
static int ac3_encode_frame(AVCodecContext *avctx, unsigned char *frame,
1377
                            int buf_size, void *data)
1378
{
1379
    AC3EncodeContext *s = avctx->priv_data;
1380
    const SampleType *samples = data;
1381
    int ret;
1382

    
1383
    if (s->bit_alloc.sr_code == 1)
1384
        adjust_frame_size(s);
1385

    
1386
    deinterleave_input_samples(s, samples);
1387

    
1388
    apply_mdct(s);
1389

    
1390
    process_exponents(s);
1391

    
1392
    ret = compute_bit_allocation(s);
1393
    if (ret) {
1394
        av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
1395
        return ret;
1396
    }
1397

    
1398
    quantize_mantissas(s);
1399

    
1400
    output_frame(s, frame);
1401

    
1402
    return s->frame_size;
1403
}
1404

    
1405

    
1406
/**
1407
 * Finalize encoding and free any memory allocated by the encoder.
1408
 */
1409
static av_cold int ac3_encode_close(AVCodecContext *avctx)
1410
{
1411
    int blk, ch;
1412
    AC3EncodeContext *s = avctx->priv_data;
1413

    
1414
    for (ch = 0; ch < s->channels; ch++)
1415
        av_freep(&s->planar_samples[ch]);
1416
    av_freep(&s->planar_samples);
1417
    av_freep(&s->bap_buffer);
1418
    av_freep(&s->bap1_buffer);
1419
    av_freep(&s->mdct_coef_buffer);
1420
    av_freep(&s->exp_buffer);
1421
    av_freep(&s->grouped_exp_buffer);
1422
    av_freep(&s->psd_buffer);
1423
    av_freep(&s->band_psd_buffer);
1424
    av_freep(&s->mask_buffer);
1425
    av_freep(&s->qmant_buffer);
1426
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1427
        AC3Block *block = &s->blocks[blk];
1428
        av_freep(&block->bap);
1429
        av_freep(&block->mdct_coef);
1430
        av_freep(&block->exp);
1431
        av_freep(&block->grouped_exp);
1432
        av_freep(&block->psd);
1433
        av_freep(&block->band_psd);
1434
        av_freep(&block->mask);
1435
        av_freep(&block->qmant);
1436
    }
1437

    
1438
    mdct_end(&s->mdct);
1439

    
1440
    av_freep(&avctx->coded_frame);
1441
    return 0;
1442
}
1443

    
1444

    
1445
/**
1446
 * Set channel information during initialization.
1447
 */
1448
static av_cold int set_channel_info(AC3EncodeContext *s, int channels,
1449
                                    int64_t *channel_layout)
1450
{
1451
    int ch_layout;
1452

    
1453
    if (channels < 1 || channels > AC3_MAX_CHANNELS)
1454
        return AVERROR(EINVAL);
1455
    if ((uint64_t)*channel_layout > 0x7FF)
1456
        return AVERROR(EINVAL);
1457
    ch_layout = *channel_layout;
1458
    if (!ch_layout)
1459
        ch_layout = avcodec_guess_channel_layout(channels, CODEC_ID_AC3, NULL);
1460
    if (av_get_channel_layout_nb_channels(ch_layout) != channels)
1461
        return AVERROR(EINVAL);
1462

    
1463
    s->lfe_on       = !!(ch_layout & AV_CH_LOW_FREQUENCY);
1464
    s->channels     = channels;
1465
    s->fbw_channels = channels - s->lfe_on;
1466
    s->lfe_channel  = s->lfe_on ? s->fbw_channels : -1;
1467
    if (s->lfe_on)
1468
        ch_layout -= AV_CH_LOW_FREQUENCY;
1469

    
1470
    switch (ch_layout) {
1471
    case AV_CH_LAYOUT_MONO:           s->channel_mode = AC3_CHMODE_MONO;   break;
1472
    case AV_CH_LAYOUT_STEREO:         s->channel_mode = AC3_CHMODE_STEREO; break;
1473
    case AV_CH_LAYOUT_SURROUND:       s->channel_mode = AC3_CHMODE_3F;     break;
1474
    case AV_CH_LAYOUT_2_1:            s->channel_mode = AC3_CHMODE_2F1R;   break;
1475
    case AV_CH_LAYOUT_4POINT0:        s->channel_mode = AC3_CHMODE_3F1R;   break;
1476
    case AV_CH_LAYOUT_QUAD:
1477
    case AV_CH_LAYOUT_2_2:            s->channel_mode = AC3_CHMODE_2F2R;   break;
1478
    case AV_CH_LAYOUT_5POINT0:
1479
    case AV_CH_LAYOUT_5POINT0_BACK:   s->channel_mode = AC3_CHMODE_3F2R;   break;
1480
    default:
1481
        return AVERROR(EINVAL);
1482
    }
1483

    
1484
    s->channel_map  = ff_ac3_enc_channel_map[s->channel_mode][s->lfe_on];
1485
    *channel_layout = ch_layout;
1486
    if (s->lfe_on)
1487
        *channel_layout |= AV_CH_LOW_FREQUENCY;
1488

    
1489
    return 0;
1490
}
1491

    
1492

    
1493
static av_cold int validate_options(AVCodecContext *avctx, AC3EncodeContext *s)
1494
{
1495
    int i, ret;
1496

    
1497
    /* validate channel layout */
1498
    if (!avctx->channel_layout) {
1499
        av_log(avctx, AV_LOG_WARNING, "No channel layout specified. The "
1500
                                      "encoder will guess the layout, but it "
1501
                                      "might be incorrect.\n");
1502
    }
1503
    ret = set_channel_info(s, avctx->channels, &avctx->channel_layout);
1504
    if (ret) {
1505
        av_log(avctx, AV_LOG_ERROR, "invalid channel layout\n");
1506
        return ret;
1507
    }
1508

    
1509
    /* validate sample rate */
1510
    for (i = 0; i < 9; i++) {
1511
        if ((ff_ac3_sample_rate_tab[i / 3] >> (i % 3)) == avctx->sample_rate)
1512
            break;
1513
    }
1514
    if (i == 9) {
1515
        av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1516
        return AVERROR(EINVAL);
1517
    }
1518
    s->sample_rate        = avctx->sample_rate;
1519
    s->bit_alloc.sr_shift = i % 3;
1520
    s->bit_alloc.sr_code  = i / 3;
1521

    
1522
    /* validate bit rate */
1523
    for (i = 0; i < 19; i++) {
1524
        if ((ff_ac3_bitrate_tab[i] >> s->bit_alloc.sr_shift)*1000 == avctx->bit_rate)
1525
            break;
1526
    }
1527
    if (i == 19) {
1528
        av_log(avctx, AV_LOG_ERROR, "invalid bit rate\n");
1529
        return AVERROR(EINVAL);
1530
    }
1531
    s->bit_rate        = avctx->bit_rate;
1532
    s->frame_size_code = i << 1;
1533

    
1534
    /* validate cutoff */
1535
    if (avctx->cutoff < 0) {
1536
        av_log(avctx, AV_LOG_ERROR, "invalid cutoff frequency\n");
1537
        return AVERROR(EINVAL);
1538
    }
1539
    s->cutoff = avctx->cutoff;
1540
    if (s->cutoff > (s->sample_rate >> 1))
1541
        s->cutoff = s->sample_rate >> 1;
1542

    
1543
    return 0;
1544
}
1545

    
1546

    
1547
/**
1548
 * Set bandwidth for all channels.
1549
 * The user can optionally supply a cutoff frequency. Otherwise an appropriate
1550
 * default value will be used.
1551
 */
1552
static av_cold void set_bandwidth(AC3EncodeContext *s)
1553
{
1554
    int ch, bw_code;
1555

    
1556
    if (s->cutoff) {
1557
        /* calculate bandwidth based on user-specified cutoff frequency */
1558
        int fbw_coeffs;
1559
        fbw_coeffs     = s->cutoff * 2 * AC3_MAX_COEFS / s->sample_rate;
1560
        bw_code        = av_clip((fbw_coeffs - 73) / 3, 0, 60);
1561
    } else {
1562
        /* use default bandwidth setting */
1563
        /* XXX: should compute the bandwidth according to the frame
1564
           size, so that we avoid annoying high frequency artifacts */
1565
        bw_code = 50;
1566
    }
1567

    
1568
    /* set number of coefficients for each channel */
1569
    for (ch = 0; ch < s->fbw_channels; ch++) {
1570
        s->bandwidth_code[ch] = bw_code;
1571
        s->nb_coefs[ch]       = bw_code * 3 + 73;
1572
    }
1573
    if (s->lfe_on)
1574
        s->nb_coefs[s->lfe_channel] = 7; /* LFE channel always has 7 coefs */
1575
}
1576

    
1577

    
1578
static av_cold int allocate_buffers(AVCodecContext *avctx)
1579
{
1580
    int blk, ch;
1581
    AC3EncodeContext *s = avctx->priv_data;
1582

    
1583
    FF_ALLOC_OR_GOTO(avctx, s->planar_samples, s->channels * sizeof(*s->planar_samples),
1584
                     alloc_fail);
1585
    for (ch = 0; ch < s->channels; ch++) {
1586
        FF_ALLOCZ_OR_GOTO(avctx, s->planar_samples[ch],
1587
                          (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),
1588
                          alloc_fail);
1589
    }
1590
    FF_ALLOC_OR_GOTO(avctx, s->bap_buffer,  AC3_MAX_BLOCKS * s->channels *
1591
                     AC3_MAX_COEFS * sizeof(*s->bap_buffer),  alloc_fail);
1592
    FF_ALLOC_OR_GOTO(avctx, s->bap1_buffer, AC3_MAX_BLOCKS * s->channels *
1593
                     AC3_MAX_COEFS * sizeof(*s->bap1_buffer), alloc_fail);
1594
    FF_ALLOC_OR_GOTO(avctx, s->mdct_coef_buffer, AC3_MAX_BLOCKS * s->channels *
1595
                     AC3_MAX_COEFS * sizeof(*s->mdct_coef_buffer), alloc_fail);
1596
    FF_ALLOC_OR_GOTO(avctx, s->exp_buffer, AC3_MAX_BLOCKS * s->channels *
1597
                     AC3_MAX_COEFS * sizeof(*s->exp_buffer), alloc_fail);
1598
    FF_ALLOC_OR_GOTO(avctx, s->grouped_exp_buffer, AC3_MAX_BLOCKS * s->channels *
1599
                     128 * sizeof(*s->grouped_exp_buffer), alloc_fail);
1600
    FF_ALLOC_OR_GOTO(avctx, s->psd_buffer, AC3_MAX_BLOCKS * s->channels *
1601
                     AC3_MAX_COEFS * sizeof(*s->psd_buffer), alloc_fail);
1602
    FF_ALLOC_OR_GOTO(avctx, s->band_psd_buffer, AC3_MAX_BLOCKS * s->channels *
1603
                     64 * sizeof(*s->band_psd_buffer), alloc_fail);
1604
    FF_ALLOC_OR_GOTO(avctx, s->mask_buffer, AC3_MAX_BLOCKS * s->channels *
1605
                     64 * sizeof(*s->mask_buffer), alloc_fail);
1606
    FF_ALLOC_OR_GOTO(avctx, s->qmant_buffer, AC3_MAX_BLOCKS * s->channels *
1607
                     AC3_MAX_COEFS * sizeof(*s->qmant_buffer), alloc_fail);
1608
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1609
        AC3Block *block = &s->blocks[blk];
1610
        FF_ALLOC_OR_GOTO(avctx, block->bap, s->channels * sizeof(*block->bap),
1611
                         alloc_fail);
1612
        FF_ALLOCZ_OR_GOTO(avctx, block->mdct_coef, s->channels * sizeof(*block->mdct_coef),
1613
                          alloc_fail);
1614
        FF_ALLOCZ_OR_GOTO(avctx, block->exp, s->channels * sizeof(*block->exp),
1615
                          alloc_fail);
1616
        FF_ALLOCZ_OR_GOTO(avctx, block->grouped_exp, s->channels * sizeof(*block->grouped_exp),
1617
                          alloc_fail);
1618
        FF_ALLOCZ_OR_GOTO(avctx, block->psd, s->channels * sizeof(*block->psd),
1619
                          alloc_fail);
1620
        FF_ALLOCZ_OR_GOTO(avctx, block->band_psd, s->channels * sizeof(*block->band_psd),
1621
                          alloc_fail);
1622
        FF_ALLOCZ_OR_GOTO(avctx, block->mask, s->channels * sizeof(*block->mask),
1623
                          alloc_fail);
1624
        FF_ALLOCZ_OR_GOTO(avctx, block->qmant, s->channels * sizeof(*block->qmant),
1625
                          alloc_fail);
1626

    
1627
        for (ch = 0; ch < s->channels; ch++) {
1628
            block->bap[ch]         = &s->bap_buffer        [AC3_MAX_COEFS * (blk * s->channels + ch)];
1629
            block->mdct_coef[ch]   = &s->mdct_coef_buffer  [AC3_MAX_COEFS * (blk * s->channels + ch)];
1630
            block->exp[ch]         = &s->exp_buffer        [AC3_MAX_COEFS * (blk * s->channels + ch)];
1631
            block->grouped_exp[ch] = &s->grouped_exp_buffer[128           * (blk * s->channels + ch)];
1632
            block->psd[ch]         = &s->psd_buffer        [AC3_MAX_COEFS * (blk * s->channels + ch)];
1633
            block->band_psd[ch]    = &s->band_psd_buffer   [64            * (blk * s->channels + ch)];
1634
            block->mask[ch]        = &s->mask_buffer       [64            * (blk * s->channels + ch)];
1635
            block->qmant[ch]       = &s->qmant_buffer      [AC3_MAX_COEFS * (blk * s->channels + ch)];
1636
        }
1637
    }
1638

    
1639
    return 0;
1640
alloc_fail:
1641
    return AVERROR(ENOMEM);
1642
}
1643

    
1644

    
1645
/**
1646
 * Initialize the encoder.
1647
 */
1648
static av_cold int ac3_encode_init(AVCodecContext *avctx)
1649
{
1650
    AC3EncodeContext *s = avctx->priv_data;
1651
    int ret, frame_size_58;
1652

    
1653
    avctx->frame_size = AC3_FRAME_SIZE;
1654

    
1655
    ac3_common_init();
1656

    
1657
    ret = validate_options(avctx, s);
1658
    if (ret)
1659
        return ret;
1660

    
1661
    s->bitstream_id   = 8 + s->bit_alloc.sr_shift;
1662
    s->bitstream_mode = 0; /* complete main audio service */
1663

    
1664
    s->frame_size_min  = 2 * ff_ac3_frame_size_tab[s->frame_size_code][s->bit_alloc.sr_code];
1665
    s->bits_written    = 0;
1666
    s->samples_written = 0;
1667
    s->frame_size      = s->frame_size_min;
1668

    
1669
    /* calculate crc_inv for both possible frame sizes */
1670
    frame_size_58 = (( s->frame_size    >> 2) + ( s->frame_size    >> 4)) << 1;
1671
    s->crc_inv[0] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
1672
    if (s->bit_alloc.sr_code == 1) {
1673
        frame_size_58 = (((s->frame_size+2) >> 2) + ((s->frame_size+2) >> 4)) << 1;
1674
        s->crc_inv[1] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
1675
    }
1676

    
1677
    set_bandwidth(s);
1678

    
1679
    exponent_init(s);
1680

    
1681
    bit_alloc_init(s);
1682

    
1683
    ret = mdct_init(avctx, &s->mdct, 9);
1684
    if (ret)
1685
        goto init_fail;
1686

    
1687
    ret = allocate_buffers(avctx);
1688
    if (ret)
1689
        goto init_fail;
1690

    
1691
    avctx->coded_frame= avcodec_alloc_frame();
1692

    
1693
    dsputil_init(&s->dsp, avctx);
1694

    
1695
    return 0;
1696
init_fail:
1697
    ac3_encode_close(avctx);
1698
    return ret;
1699
}