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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
26
 * The simplest AC-3 encoder.
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 */
28

    
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//#define DEBUG
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#include "libavutil/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 "ac3dsp.h"
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#include "ac3.h"
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#include "audioconvert.h"
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40

    
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#ifndef CONFIG_AC3ENC_FLOAT
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#define CONFIG_AC3ENC_FLOAT 0
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#endif
44

    
45

    
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/** Maximum number of exponent groups. +1 for separate DC exponent. */
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#define AC3_MAX_EXP_GROUPS 85
48

    
49
/* stereo rematrixing algorithms */
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#define AC3_REMATRIXING_IS_STATIC 0x1
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#define AC3_REMATRIXING_SUMS    0
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#define AC3_REMATRIXING_NONE    1
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#define AC3_REMATRIXING_ALWAYS  3
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55
/** 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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58

    
59
#if CONFIG_AC3ENC_FLOAT
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#include "ac3enc_float.h"
61
#else
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#include "ac3enc_fixed.h"
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#endif
64

    
65

    
66
/**
67
 * Data for a single audio block.
68
 */
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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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    int32_t  **fixed_coef;                      ///< fixed-point 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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    int8_t   exp_shift[AC3_MAX_CHANNELS];       ///< exponent shift values
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    uint8_t  new_rematrixing_strategy;          ///< send new rematrixing flags in this block
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    uint8_t  rematrixing_flags[4];              ///< rematrixing flags
82
} AC3Block;
83

    
84
/**
85
 * AC-3 encoder private context.
86
 */
87
typedef struct AC3EncodeContext {
88
    PutBitContext pb;                       ///< bitstream writer context
89
    DSPContext dsp;
90
    AC3DSPContext ac3dsp;                   ///< AC-3 optimized functions
91
    AC3MDCTContext mdct;                    ///< MDCT context
92

    
93
    AC3Block blocks[AC3_MAX_BLOCKS];        ///< per-block info
94

    
95
    int bitstream_id;                       ///< bitstream id                           (bsid)
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    int bitstream_mode;                     ///< bitstream mode                         (bsmod)
97

    
98
    int bit_rate;                           ///< target bit rate, in bits-per-second
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    int sample_rate;                        ///< sampling frequency, in Hz
100

    
101
    int frame_size_min;                     ///< minimum frame size in case rounding is necessary
102
    int frame_size;                         ///< current frame size in bytes
103
    int frame_size_code;                    ///< frame size code                        (frmsizecod)
104
    uint16_t crc_inv[2];
105
    int bits_written;                       ///< bit count    (used to avg. bitrate)
106
    int samples_written;                    ///< sample count (used to avg. bitrate)
107

    
108
    int fbw_channels;                       ///< number of full-bandwidth channels      (nfchans)
109
    int channels;                           ///< total number of channels               (nchans)
110
    int lfe_on;                             ///< indicates if there is an LFE channel   (lfeon)
111
    int lfe_channel;                        ///< channel index of the LFE channel
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    int channel_mode;                       ///< channel mode                           (acmod)
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    const uint8_t *channel_map;             ///< channel map used to reorder channels
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115
    int cutoff;                             ///< user-specified cutoff frequency, in Hz
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    int bandwidth_code[AC3_MAX_CHANNELS];   ///< bandwidth code (0 to 60)               (chbwcod)
117
    int nb_coefs[AC3_MAX_CHANNELS];
118

    
119
    int rematrixing;                        ///< determines how rematrixing strategy is calculated
120

    
121
    /* bitrate allocation control */
122
    int slow_gain_code;                     ///< slow gain code                         (sgaincod)
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    int slow_decay_code;                    ///< slow decay code                        (sdcycod)
124
    int fast_decay_code;                    ///< fast decay code                        (fdcycod)
125
    int db_per_bit_code;                    ///< dB/bit code                            (dbpbcod)
126
    int floor_code;                         ///< floor code                             (floorcod)
127
    AC3BitAllocParameters bit_alloc;        ///< bit allocation parameters
128
    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)
130
    int fine_snr_offset[AC3_MAX_CHANNELS];  ///< fine SNR offsets                       (fsnroffst)
131
    int frame_bits_fixed;                   ///< number of non-coefficient bits for fixed parameters
132
    int frame_bits;                         ///< all frame bits except exponents and mantissas
133
    int exponent_bits;                      ///< number of bits used for exponents
134

    
135
    /* mantissa encoding */
136
    int mant1_cnt, mant2_cnt, mant4_cnt;    ///< mantissa counts for bap=1,2,4
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    uint16_t *qmant1_ptr, *qmant2_ptr, *qmant4_ptr; ///< mantissa pointers for bap=1,2,4
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139
    SampleType **planar_samples;
140
    uint8_t *bap_buffer;
141
    uint8_t *bap1_buffer;
142
    CoefType *mdct_coef_buffer;
143
    int32_t *fixed_coef_buffer;
144
    uint8_t *exp_buffer;
145
    uint8_t *grouped_exp_buffer;
146
    int16_t *psd_buffer;
147
    int16_t *band_psd_buffer;
148
    int16_t *mask_buffer;
149
    uint16_t *qmant_buffer;
150

    
151
    uint8_t exp_strategy[AC3_MAX_CHANNELS][AC3_MAX_BLOCKS]; ///< exponent strategies
152

    
153
    DECLARE_ALIGNED(16, SampleType, windowed_samples)[AC3_WINDOW_SIZE];
154
} AC3EncodeContext;
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156

    
157
/* prototypes for functions in ac3enc_fixed.c and ac3enc_float.c */
158

    
159
static av_cold void mdct_end(AC3MDCTContext *mdct);
160

    
161
static av_cold int mdct_init(AVCodecContext *avctx, AC3MDCTContext *mdct,
162
                             int nbits);
163

    
164
static void mdct512(AC3MDCTContext *mdct, CoefType *out, SampleType *in);
165

    
166
static void apply_window(DSPContext *dsp, SampleType *output, const SampleType *input,
167
                         const SampleType *window, int n);
168

    
169
static int normalize_samples(AC3EncodeContext *s);
170

    
171
static void scale_coefficients(AC3EncodeContext *s);
172

    
173

    
174
/**
175
 * LUT for number of exponent groups.
176
 * exponent_group_tab[exponent strategy-1][number of coefficients]
177
 */
178
static uint8_t exponent_group_tab[3][256];
179

    
180

    
181
/**
182
 * List of supported channel layouts.
183
 */
184
static const int64_t ac3_channel_layouts[] = {
185
     AV_CH_LAYOUT_MONO,
186
     AV_CH_LAYOUT_STEREO,
187
     AV_CH_LAYOUT_2_1,
188
     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,
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     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),
198
    (AV_CH_LAYOUT_2_2      | AV_CH_LOW_FREQUENCY),
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    (AV_CH_LAYOUT_QUAD     | AV_CH_LOW_FREQUENCY),
200
    (AV_CH_LAYOUT_4POINT0  | AV_CH_LOW_FREQUENCY),
201
     AV_CH_LAYOUT_5POINT1,
202
     AV_CH_LAYOUT_5POINT1_BACK,
203
     0
204
};
205

    
206

    
207
/**
208
 * Adjust the frame size to make the average bit rate match the target bit rate.
209
 * This is only needed for 11025, 22050, and 44100 sample rates.
210
 */
211
static void adjust_frame_size(AC3EncodeContext *s)
212
{
213
    while (s->bits_written >= s->bit_rate && s->samples_written >= s->sample_rate) {
214
        s->bits_written    -= s->bit_rate;
215
        s->samples_written -= s->sample_rate;
216
    }
217
    s->frame_size = s->frame_size_min +
218
                    2 * (s->bits_written * s->sample_rate < s->samples_written * s->bit_rate);
219
    s->bits_written    += s->frame_size * 8;
220
    s->samples_written += AC3_FRAME_SIZE;
221
}
222

    
223

    
224
/**
225
 * Deinterleave input samples.
226
 * Channels are reordered from FFmpeg's default order to AC-3 order.
227
 */
228
static void deinterleave_input_samples(AC3EncodeContext *s,
229
                                       const SampleType *samples)
230
{
231
    int ch, i;
232

    
233
    /* deinterleave and remap input samples */
234
    for (ch = 0; ch < s->channels; ch++) {
235
        const SampleType *sptr;
236
        int sinc;
237

    
238
        /* copy last 256 samples of previous frame to the start of the current frame */
239
        memcpy(&s->planar_samples[ch][0], &s->planar_samples[ch][AC3_FRAME_SIZE],
240
               AC3_BLOCK_SIZE * sizeof(s->planar_samples[0][0]));
241

    
242
        /* deinterleave */
243
        sinc = s->channels;
244
        sptr = samples + s->channel_map[ch];
245
        for (i = AC3_BLOCK_SIZE; i < AC3_FRAME_SIZE+AC3_BLOCK_SIZE; i++) {
246
            s->planar_samples[ch][i] = *sptr;
247
            sptr += sinc;
248
        }
249
    }
250
}
251

    
252

    
253
/**
254
 * Apply the MDCT to input samples to generate frequency coefficients.
255
 * This applies the KBD window and normalizes the input to reduce precision
256
 * loss due to fixed-point calculations.
257
 */
258
static void apply_mdct(AC3EncodeContext *s)
259
{
260
    int blk, ch;
261

    
262
    for (ch = 0; ch < s->channels; ch++) {
263
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
264
            AC3Block *block = &s->blocks[blk];
265
            const SampleType *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE];
266

    
267
            apply_window(&s->dsp, s->windowed_samples, input_samples, s->mdct.window, AC3_WINDOW_SIZE);
268

    
269
            block->exp_shift[ch] = normalize_samples(s);
270

    
271
            mdct512(&s->mdct, block->mdct_coef[ch], s->windowed_samples);
272
        }
273
    }
274
}
275

    
276

    
277
/**
278
 * Initialize stereo rematrixing.
279
 * If the strategy does not change for each frame, set the rematrixing flags.
280
 */
281
static void rematrixing_init(AC3EncodeContext *s)
282
{
283
    if (s->channel_mode == AC3_CHMODE_STEREO)
284
        s->rematrixing = AC3_REMATRIXING_SUMS;
285
    else
286
        s->rematrixing = AC3_REMATRIXING_NONE;
287
    /* NOTE: AC3_REMATRIXING_ALWAYS might be used in
288
             the future in conjunction with channel coupling. */
289

    
290
    if (s->rematrixing & AC3_REMATRIXING_IS_STATIC) {
291
        int flag = (s->rematrixing == AC3_REMATRIXING_ALWAYS);
292
        s->blocks[0].new_rematrixing_strategy = 1;
293
        memset(s->blocks[0].rematrixing_flags, flag,
294
               sizeof(s->blocks[0].rematrixing_flags));
295
    }
296
}
297

    
298

    
299
/**
300
 * Determine rematrixing flags for each block and band.
301
 */
302
static void compute_rematrixing_strategy(AC3EncodeContext *s)
303
{
304
    int nb_coefs;
305
    int blk, bnd, i;
306
    AC3Block *block, *block0;
307

    
308
    if (s->rematrixing & AC3_REMATRIXING_IS_STATIC)
309
        return;
310

    
311
    nb_coefs = FFMIN(s->nb_coefs[0], s->nb_coefs[1]);
312

    
313
    s->blocks[0].new_rematrixing_strategy = 1;
314
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
315
        block = &s->blocks[blk];
316
        for (bnd = 0; bnd < 4; bnd++) {
317
            /* calculate calculate sum of squared coeffs for one band in one block */
318
            int start = ff_ac3_rematrix_band_tab[bnd];
319
            int end   = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
320
            CoefSumType sum[4] = {0,};
321
            for (i = start; i < end; i++) {
322
                CoefType lt = block->mdct_coef[0][i];
323
                CoefType rt = block->mdct_coef[1][i];
324
                CoefType md = lt + rt;
325
                CoefType sd = lt - rt;
326
                sum[0] += lt * lt;
327
                sum[1] += rt * rt;
328
                sum[2] += md * md;
329
                sum[3] += sd * sd;
330
            }
331

    
332
            /* compare sums to determine if rematrixing will be used for this band */
333
            if (FFMIN(sum[2], sum[3]) < FFMIN(sum[0], sum[1]))
334
                block->rematrixing_flags[bnd] = 1;
335
            else
336
                block->rematrixing_flags[bnd] = 0;
337

    
338
            /* determine if new rematrixing flags will be sent */
339
            if (blk &&
340
                !block->new_rematrixing_strategy &&
341
                block->rematrixing_flags[bnd] != block0->rematrixing_flags[bnd]) {
342
                block->new_rematrixing_strategy = 1;
343
            }
344
        }
345
        block0 = block;
346
    }
347
}
348

    
349

    
350
/**
351
 * Apply stereo rematrixing to coefficients based on rematrixing flags.
352
 */
353
static void apply_rematrixing(AC3EncodeContext *s)
354
{
355
    int nb_coefs;
356
    int blk, bnd, i;
357
    int start, end;
358
    uint8_t *flags;
359

    
360
    if (s->rematrixing == AC3_REMATRIXING_NONE)
361
        return;
362

    
363
    nb_coefs = FFMIN(s->nb_coefs[0], s->nb_coefs[1]);
364

    
365
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
366
        AC3Block *block = &s->blocks[blk];
367
        if (block->new_rematrixing_strategy)
368
            flags = block->rematrixing_flags;
369
        for (bnd = 0; bnd < 4; bnd++) {
370
            if (flags[bnd]) {
371
                start = ff_ac3_rematrix_band_tab[bnd];
372
                end   = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
373
                for (i = start; i < end; i++) {
374
                    int32_t lt = block->fixed_coef[0][i];
375
                    int32_t rt = block->fixed_coef[1][i];
376
                    block->fixed_coef[0][i] = (lt + rt) >> 1;
377
                    block->fixed_coef[1][i] = (lt - rt) >> 1;
378
                }
379
            }
380
        }
381
    }
382
}
383

    
384

    
385
/**
386
 * Initialize exponent tables.
387
 */
388
static av_cold void exponent_init(AC3EncodeContext *s)
389
{
390
    int i;
391
    for (i = 73; i < 256; i++) {
392
        exponent_group_tab[0][i] = (i - 1) /  3;
393
        exponent_group_tab[1][i] = (i + 2) /  6;
394
        exponent_group_tab[2][i] = (i + 8) / 12;
395
    }
396
    /* LFE */
397
    exponent_group_tab[0][7] = 2;
398
}
399

    
400

    
401
/**
402
 * Extract exponents from the MDCT coefficients.
403
 * This takes into account the normalization that was done to the input samples
404
 * by adjusting the exponents by the exponent shift values.
405
 */
406
static void extract_exponents(AC3EncodeContext *s)
407
{
408
    int blk, ch, i;
409

    
410
    for (ch = 0; ch < s->channels; ch++) {
411
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
412
            AC3Block *block = &s->blocks[blk];
413
            uint8_t *exp   = block->exp[ch];
414
            int32_t *coef = block->fixed_coef[ch];
415
            int exp_shift  = block->exp_shift[ch];
416
            for (i = 0; i < AC3_MAX_COEFS; i++) {
417
                int e;
418
                int v = abs(coef[i]);
419
                if (v == 0)
420
                    e = 24;
421
                else {
422
                    e = 23 - av_log2(v) + exp_shift;
423
                    if (e >= 24) {
424
                        e = 24;
425
                        coef[i] = 0;
426
                    }
427
                }
428
                exp[i] = e;
429
            }
430
        }
431
    }
432
}
433

    
434

    
435
/**
436
 * Exponent Difference Threshold.
437
 * New exponents are sent if their SAD exceed this number.
438
 */
439
#define EXP_DIFF_THRESHOLD 500
440

    
441

    
442
/**
443
 * Calculate exponent strategies for all blocks in a single channel.
444
 */
445
static void compute_exp_strategy_ch(AC3EncodeContext *s, uint8_t *exp_strategy,
446
                                    uint8_t *exp)
447
{
448
    int blk, blk1;
449
    int exp_diff;
450

    
451
    /* estimate if the exponent variation & decide if they should be
452
       reused in the next frame */
453
    exp_strategy[0] = EXP_NEW;
454
    exp += AC3_MAX_COEFS;
455
    for (blk = 1; blk < AC3_MAX_BLOCKS; blk++) {
456
        exp_diff = s->dsp.sad[0](NULL, exp, exp - AC3_MAX_COEFS, 16, 16);
457
        if (exp_diff > EXP_DIFF_THRESHOLD)
458
            exp_strategy[blk] = EXP_NEW;
459
        else
460
            exp_strategy[blk] = EXP_REUSE;
461
        exp += AC3_MAX_COEFS;
462
    }
463

    
464
    /* now select the encoding strategy type : if exponents are often
465
       recoded, we use a coarse encoding */
466
    blk = 0;
467
    while (blk < AC3_MAX_BLOCKS) {
468
        blk1 = blk + 1;
469
        while (blk1 < AC3_MAX_BLOCKS && exp_strategy[blk1] == EXP_REUSE)
470
            blk1++;
471
        switch (blk1 - blk) {
472
        case 1:  exp_strategy[blk] = EXP_D45; break;
473
        case 2:
474
        case 3:  exp_strategy[blk] = EXP_D25; break;
475
        default: exp_strategy[blk] = EXP_D15; break;
476
        }
477
        blk = blk1;
478
    }
479
}
480

    
481

    
482
/**
483
 * Calculate exponent strategies for all channels.
484
 * Array arrangement is reversed to simplify the per-channel calculation.
485
 */
486
static void compute_exp_strategy(AC3EncodeContext *s)
487
{
488
    int ch, blk;
489

    
490
    for (ch = 0; ch < s->fbw_channels; ch++) {
491
        compute_exp_strategy_ch(s, s->exp_strategy[ch], s->blocks[0].exp[ch]);
492
    }
493
    if (s->lfe_on) {
494
        ch = s->lfe_channel;
495
        s->exp_strategy[ch][0] = EXP_D15;
496
        for (blk = 1; blk < AC3_MAX_BLOCKS; blk++)
497
            s->exp_strategy[ch][blk] = EXP_REUSE;
498
    }
499
}
500

    
501

    
502
/**
503
 * Update the exponents so that they are the ones the decoder will decode.
504
 */
505
static void encode_exponents_blk_ch(uint8_t *exp, int nb_exps, int exp_strategy)
506
{
507
    int nb_groups, i, k;
508

    
509
    nb_groups = exponent_group_tab[exp_strategy-1][nb_exps] * 3;
510

    
511
    /* for each group, compute the minimum exponent */
512
    switch(exp_strategy) {
513
    case EXP_D25:
514
        for (i = 1, k = 1; i <= nb_groups; i++) {
515
            uint8_t exp_min = exp[k];
516
            if (exp[k+1] < exp_min)
517
                exp_min = exp[k+1];
518
            exp[i] = exp_min;
519
            k += 2;
520
        }
521
        break;
522
    case EXP_D45:
523
        for (i = 1, k = 1; i <= nb_groups; i++) {
524
            uint8_t exp_min = exp[k];
525
            if (exp[k+1] < exp_min)
526
                exp_min = exp[k+1];
527
            if (exp[k+2] < exp_min)
528
                exp_min = exp[k+2];
529
            if (exp[k+3] < exp_min)
530
                exp_min = exp[k+3];
531
            exp[i] = exp_min;
532
            k += 4;
533
        }
534
        break;
535
    }
536

    
537
    /* constraint for DC exponent */
538
    if (exp[0] > 15)
539
        exp[0] = 15;
540

    
541
    /* decrease the delta between each groups to within 2 so that they can be
542
       differentially encoded */
543
    for (i = 1; i <= nb_groups; i++)
544
        exp[i] = FFMIN(exp[i], exp[i-1] + 2);
545
    i--;
546
    while (--i >= 0)
547
        exp[i] = FFMIN(exp[i], exp[i+1] + 2);
548

    
549
    /* now we have the exponent values the decoder will see */
550
    switch (exp_strategy) {
551
    case EXP_D25:
552
        for (i = nb_groups, k = nb_groups * 2; i > 0; i--) {
553
            uint8_t exp1 = exp[i];
554
            exp[k--] = exp1;
555
            exp[k--] = exp1;
556
        }
557
        break;
558
    case EXP_D45:
559
        for (i = nb_groups, k = nb_groups * 4; i > 0; i--) {
560
            exp[k] = exp[k-1] = exp[k-2] = exp[k-3] = exp[i];
561
            k -= 4;
562
        }
563
        break;
564
    }
565
}
566

    
567

    
568
/**
569
 * Encode exponents from original extracted form to what the decoder will see.
570
 * This copies and groups exponents based on exponent strategy and reduces
571
 * deltas between adjacent exponent groups so that they can be differentially
572
 * encoded.
573
 */
574
static void encode_exponents(AC3EncodeContext *s)
575
{
576
    int blk, blk1, ch;
577
    uint8_t *exp, *exp1, *exp_strategy;
578
    int nb_coefs, num_reuse_blocks;
579

    
580
    for (ch = 0; ch < s->channels; ch++) {
581
        exp          = s->blocks[0].exp[ch];
582
        exp_strategy = s->exp_strategy[ch];
583
        nb_coefs     = s->nb_coefs[ch];
584

    
585
        blk = 0;
586
        while (blk < AC3_MAX_BLOCKS) {
587
            blk1 = blk + 1;
588

    
589
            /* count the number of EXP_REUSE blocks after the current block */
590
            while (blk1 < AC3_MAX_BLOCKS && exp_strategy[blk1] == EXP_REUSE)
591
                blk1++;
592
            num_reuse_blocks = blk1 - blk - 1;
593

    
594
            /* for the EXP_REUSE case we select the min of the exponents */
595
            s->ac3dsp.ac3_exponent_min(exp, num_reuse_blocks, nb_coefs);
596

    
597
            encode_exponents_blk_ch(exp, nb_coefs, exp_strategy[blk]);
598

    
599
            /* copy encoded exponents for reuse case */
600
            exp1 = exp + AC3_MAX_COEFS;
601
            while (blk < blk1-1) {
602
                memcpy(exp1, exp, nb_coefs * sizeof(*exp));
603
                exp1 += AC3_MAX_COEFS;
604
                blk++;
605
            }
606
            blk = blk1;
607
            exp = exp1;
608
        }
609
    }
610
}
611

    
612

    
613
/**
614
 * Group exponents.
615
 * 3 delta-encoded exponents are in each 7-bit group. The number of groups
616
 * varies depending on exponent strategy and bandwidth.
617
 */
618
static void group_exponents(AC3EncodeContext *s)
619
{
620
    int blk, ch, i;
621
    int group_size, nb_groups, bit_count;
622
    uint8_t *p;
623
    int delta0, delta1, delta2;
624
    int exp0, exp1;
625

    
626
    bit_count = 0;
627
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
628
        AC3Block *block = &s->blocks[blk];
629
        for (ch = 0; ch < s->channels; ch++) {
630
            int exp_strategy = s->exp_strategy[ch][blk];
631
            if (exp_strategy == EXP_REUSE)
632
                continue;
633
            group_size = exp_strategy + (exp_strategy == EXP_D45);
634
            nb_groups = exponent_group_tab[exp_strategy-1][s->nb_coefs[ch]];
635
            bit_count += 4 + (nb_groups * 7);
636
            p = block->exp[ch];
637

    
638
            /* DC exponent */
639
            exp1 = *p++;
640
            block->grouped_exp[ch][0] = exp1;
641

    
642
            /* remaining exponents are delta encoded */
643
            for (i = 1; i <= nb_groups; i++) {
644
                /* merge three delta in one code */
645
                exp0   = exp1;
646
                exp1   = p[0];
647
                p     += group_size;
648
                delta0 = exp1 - exp0 + 2;
649

    
650
                exp0   = exp1;
651
                exp1   = p[0];
652
                p     += group_size;
653
                delta1 = exp1 - exp0 + 2;
654

    
655
                exp0   = exp1;
656
                exp1   = p[0];
657
                p     += group_size;
658
                delta2 = exp1 - exp0 + 2;
659

    
660
                block->grouped_exp[ch][i] = ((delta0 * 5 + delta1) * 5) + delta2;
661
            }
662
        }
663
    }
664

    
665
    s->exponent_bits = bit_count;
666
}
667

    
668

    
669
/**
670
 * Calculate final exponents from the supplied MDCT coefficients and exponent shift.
671
 * Extract exponents from MDCT coefficients, calculate exponent strategies,
672
 * and encode final exponents.
673
 */
674
static void process_exponents(AC3EncodeContext *s)
675
{
676
    extract_exponents(s);
677

    
678
    compute_exp_strategy(s);
679

    
680
    encode_exponents(s);
681

    
682
    group_exponents(s);
683

    
684
    emms_c();
685
}
686

    
687

    
688
/**
689
 * Count frame bits that are based solely on fixed parameters.
690
 * This only has to be run once when the encoder is initialized.
691
 */
692
static void count_frame_bits_fixed(AC3EncodeContext *s)
693
{
694
    static const int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
695
    int blk;
696
    int frame_bits;
697

    
698
    /* assumptions:
699
     *   no dynamic range codes
700
     *   no channel coupling
701
     *   bit allocation parameters do not change between blocks
702
     *   SNR offsets do not change between blocks
703
     *   no delta bit allocation
704
     *   no skipped data
705
     *   no auxilliary data
706
     */
707

    
708
    /* header size */
709
    frame_bits = 65;
710
    frame_bits += frame_bits_inc[s->channel_mode];
711

    
712
    /* audio blocks */
713
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
714
        frame_bits += s->fbw_channels * 2 + 2; /* blksw * c, dithflag * c, dynrnge, cplstre */
715
        if (s->channel_mode == AC3_CHMODE_STEREO) {
716
            frame_bits++; /* rematstr */
717
        }
718
        frame_bits += 2 * s->fbw_channels; /* chexpstr[2] * c */
719
        if (s->lfe_on)
720
            frame_bits++; /* lfeexpstr */
721
        frame_bits++; /* baie */
722
        frame_bits++; /* snr */
723
        frame_bits += 2; /* delta / skip */
724
    }
725
    frame_bits++; /* cplinu for block 0 */
726
    /* bit alloc info */
727
    /* sdcycod[2], fdcycod[2], sgaincod[2], dbpbcod[2], floorcod[3] */
728
    /* csnroffset[6] */
729
    /* (fsnoffset[4] + fgaincod[4]) * c */
730
    frame_bits += 2*4 + 3 + 6 + s->channels * (4 + 3);
731

    
732
    /* auxdatae, crcrsv */
733
    frame_bits += 2;
734

    
735
    /* CRC */
736
    frame_bits += 16;
737

    
738
    s->frame_bits_fixed = frame_bits;
739
}
740

    
741

    
742
/**
743
 * Initialize bit allocation.
744
 * Set default parameter codes and calculate parameter values.
745
 */
746
static void bit_alloc_init(AC3EncodeContext *s)
747
{
748
    int ch;
749

    
750
    /* init default parameters */
751
    s->slow_decay_code = 2;
752
    s->fast_decay_code = 1;
753
    s->slow_gain_code  = 1;
754
    s->db_per_bit_code = 3;
755
    s->floor_code      = 7;
756
    for (ch = 0; ch < s->channels; ch++)
757
        s->fast_gain_code[ch] = 4;
758

    
759
    /* initial snr offset */
760
    s->coarse_snr_offset = 40;
761

    
762
    /* compute real values */
763
    /* currently none of these values change during encoding, so we can just
764
       set them once at initialization */
765
    s->bit_alloc.slow_decay = ff_ac3_slow_decay_tab[s->slow_decay_code] >> s->bit_alloc.sr_shift;
766
    s->bit_alloc.fast_decay = ff_ac3_fast_decay_tab[s->fast_decay_code] >> s->bit_alloc.sr_shift;
767
    s->bit_alloc.slow_gain  = ff_ac3_slow_gain_tab[s->slow_gain_code];
768
    s->bit_alloc.db_per_bit = ff_ac3_db_per_bit_tab[s->db_per_bit_code];
769
    s->bit_alloc.floor      = ff_ac3_floor_tab[s->floor_code];
770

    
771
    count_frame_bits_fixed(s);
772
}
773

    
774

    
775
/**
776
 * Count the bits used to encode the frame, minus exponents and mantissas.
777
 * Bits based on fixed parameters have already been counted, so now we just
778
 * have to add the bits based on parameters that change during encoding.
779
 */
780
static void count_frame_bits(AC3EncodeContext *s)
781
{
782
    int blk, ch;
783
    int frame_bits = 0;
784

    
785
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
786
        /* stereo rematrixing */
787
        if (s->channel_mode == AC3_CHMODE_STEREO &&
788
            s->blocks[blk].new_rematrixing_strategy) {
789
            frame_bits += 4;
790
        }
791

    
792
        for (ch = 0; ch < s->fbw_channels; ch++) {
793
            if (s->exp_strategy[ch][blk] != EXP_REUSE)
794
                frame_bits += 6 + 2; /* chbwcod[6], gainrng[2] */
795
        }
796
    }
797
    s->frame_bits = s->frame_bits_fixed + frame_bits;
798
}
799

    
800

    
801
/**
802
 * Calculate the number of bits needed to encode a set of mantissas.
803
 */
804
static int compute_mantissa_size(int mant_cnt[5], uint8_t *bap, int nb_coefs)
805
{
806
    int bits, b, i;
807

    
808
    bits = 0;
809
    for (i = 0; i < nb_coefs; i++) {
810
        b = bap[i];
811
        if (b <= 4) {
812
            // bap=1 to bap=4 will be counted in compute_mantissa_size_final
813
            mant_cnt[b]++;
814
        } else if (b <= 13) {
815
            // bap=5 to bap=13 use (bap-1) bits
816
            bits += b - 1;
817
        } else {
818
            // bap=14 uses 14 bits and bap=15 uses 16 bits
819
            bits += (b == 14) ? 14 : 16;
820
        }
821
    }
822
    return bits;
823
}
824

    
825

    
826
/**
827
 * Finalize the mantissa bit count by adding in the grouped mantissas.
828
 */
829
static int compute_mantissa_size_final(int mant_cnt[5])
830
{
831
    // bap=1 : 3 mantissas in 5 bits
832
    int bits = (mant_cnt[1] / 3) * 5;
833
    // bap=2 : 3 mantissas in 7 bits
834
    // bap=4 : 2 mantissas in 7 bits
835
    bits += ((mant_cnt[2] / 3) + (mant_cnt[4] >> 1)) * 7;
836
    // bap=3 : each mantissa is 3 bits
837
    bits += mant_cnt[3] * 3;
838
    return bits;
839
}
840

    
841

    
842
/**
843
 * Calculate masking curve based on the final exponents.
844
 * Also calculate the power spectral densities to use in future calculations.
845
 */
846
static void bit_alloc_masking(AC3EncodeContext *s)
847
{
848
    int blk, ch;
849

    
850
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
851
        AC3Block *block = &s->blocks[blk];
852
        for (ch = 0; ch < s->channels; ch++) {
853
            /* We only need psd and mask for calculating bap.
854
               Since we currently do not calculate bap when exponent
855
               strategy is EXP_REUSE we do not need to calculate psd or mask. */
856
            if (s->exp_strategy[ch][blk] != EXP_REUSE) {
857
                ff_ac3_bit_alloc_calc_psd(block->exp[ch], 0,
858
                                          s->nb_coefs[ch],
859
                                          block->psd[ch], block->band_psd[ch]);
860
                ff_ac3_bit_alloc_calc_mask(&s->bit_alloc, block->band_psd[ch],
861
                                           0, s->nb_coefs[ch],
862
                                           ff_ac3_fast_gain_tab[s->fast_gain_code[ch]],
863
                                           ch == s->lfe_channel,
864
                                           DBA_NONE, 0, NULL, NULL, NULL,
865
                                           block->mask[ch]);
866
            }
867
        }
868
    }
869
}
870

    
871

    
872
/**
873
 * Ensure that bap for each block and channel point to the current bap_buffer.
874
 * They may have been switched during the bit allocation search.
875
 */
876
static void reset_block_bap(AC3EncodeContext *s)
877
{
878
    int blk, ch;
879
    if (s->blocks[0].bap[0] == s->bap_buffer)
880
        return;
881
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
882
        for (ch = 0; ch < s->channels; ch++) {
883
            s->blocks[blk].bap[ch] = &s->bap_buffer[AC3_MAX_COEFS * (blk * s->channels + ch)];
884
        }
885
    }
886
}
887

    
888

    
889
/**
890
 * Run the bit allocation with a given SNR offset.
891
 * This calculates the bit allocation pointers that will be used to determine
892
 * the quantization of each mantissa.
893
 * @return the number of bits needed for mantissas if the given SNR offset is
894
 *         is used.
895
 */
896
static int bit_alloc(AC3EncodeContext *s, int snr_offset)
897
{
898
    int blk, ch;
899
    int mantissa_bits;
900
    int mant_cnt[5];
901

    
902
    snr_offset = (snr_offset - 240) << 2;
903

    
904
    reset_block_bap(s);
905
    mantissa_bits = 0;
906
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
907
        AC3Block *block = &s->blocks[blk];
908
        // initialize grouped mantissa counts. these are set so that they are
909
        // padded to the next whole group size when bits are counted in
910
        // compute_mantissa_size_final
911
        mant_cnt[0] = mant_cnt[3] = 0;
912
        mant_cnt[1] = mant_cnt[2] = 2;
913
        mant_cnt[4] = 1;
914
        for (ch = 0; ch < s->channels; ch++) {
915
            /* Currently the only bit allocation parameters which vary across
916
               blocks within a frame are the exponent values.  We can take
917
               advantage of that by reusing the bit allocation pointers
918
               whenever we reuse exponents. */
919
            if (s->exp_strategy[ch][blk] == EXP_REUSE) {
920
                memcpy(block->bap[ch], s->blocks[blk-1].bap[ch], AC3_MAX_COEFS);
921
            } else {
922
                ff_ac3_bit_alloc_calc_bap(block->mask[ch], block->psd[ch], 0,
923
                                          s->nb_coefs[ch], snr_offset,
924
                                          s->bit_alloc.floor, ff_ac3_bap_tab,
925
                                          block->bap[ch]);
926
            }
927
            mantissa_bits += compute_mantissa_size(mant_cnt, block->bap[ch], s->nb_coefs[ch]);
928
        }
929
        mantissa_bits += compute_mantissa_size_final(mant_cnt);
930
    }
931
    return mantissa_bits;
932
}
933

    
934

    
935
/**
936
 * Constant bitrate bit allocation search.
937
 * Find the largest SNR offset that will allow data to fit in the frame.
938
 */
939
static int cbr_bit_allocation(AC3EncodeContext *s)
940
{
941
    int ch;
942
    int bits_left;
943
    int snr_offset, snr_incr;
944

    
945
    bits_left = 8 * s->frame_size - (s->frame_bits + s->exponent_bits);
946

    
947
    snr_offset = s->coarse_snr_offset << 4;
948

    
949
    /* if previous frame SNR offset was 1023, check if current frame can also
950
       use SNR offset of 1023. if so, skip the search. */
951
    if ((snr_offset | s->fine_snr_offset[0]) == 1023) {
952
        if (bit_alloc(s, 1023) <= bits_left)
953
            return 0;
954
    }
955

    
956
    while (snr_offset >= 0 &&
957
           bit_alloc(s, snr_offset) > bits_left) {
958
        snr_offset -= 64;
959
    }
960
    if (snr_offset < 0)
961
        return AVERROR(EINVAL);
962

    
963
    FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
964
    for (snr_incr = 64; snr_incr > 0; snr_incr >>= 2) {
965
        while (snr_offset + snr_incr <= 1023 &&
966
               bit_alloc(s, snr_offset + snr_incr) <= bits_left) {
967
            snr_offset += snr_incr;
968
            FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
969
        }
970
    }
971
    FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
972
    reset_block_bap(s);
973

    
974
    s->coarse_snr_offset = snr_offset >> 4;
975
    for (ch = 0; ch < s->channels; ch++)
976
        s->fine_snr_offset[ch] = snr_offset & 0xF;
977

    
978
    return 0;
979
}
980

    
981

    
982
/**
983
 * Downgrade exponent strategies to reduce the bits used by the exponents.
984
 * This is a fallback for when bit allocation fails with the normal exponent
985
 * strategies.  Each time this function is run it only downgrades the
986
 * strategy in 1 channel of 1 block.
987
 * @return non-zero if downgrade was unsuccessful
988
 */
989
static int downgrade_exponents(AC3EncodeContext *s)
990
{
991
    int ch, blk;
992

    
993
    for (ch = 0; ch < s->fbw_channels; ch++) {
994
        for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
995
            if (s->exp_strategy[ch][blk] == EXP_D15) {
996
                s->exp_strategy[ch][blk] = EXP_D25;
997
                return 0;
998
            }
999
        }
1000
    }
1001
    for (ch = 0; ch < s->fbw_channels; ch++) {
1002
        for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
1003
            if (s->exp_strategy[ch][blk] == EXP_D25) {
1004
                s->exp_strategy[ch][blk] = EXP_D45;
1005
                return 0;
1006
            }
1007
        }
1008
    }
1009
    for (ch = 0; ch < s->fbw_channels; ch++) {
1010
        /* block 0 cannot reuse exponents, so only downgrade D45 to REUSE if
1011
           the block number > 0 */
1012
        for (blk = AC3_MAX_BLOCKS-1; blk > 0; blk--) {
1013
            if (s->exp_strategy[ch][blk] > EXP_REUSE) {
1014
                s->exp_strategy[ch][blk] = EXP_REUSE;
1015
                return 0;
1016
            }
1017
        }
1018
    }
1019
    return -1;
1020
}
1021

    
1022

    
1023
/**
1024
 * Reduce the bandwidth to reduce the number of bits used for a given SNR offset.
1025
 * This is a second fallback for when bit allocation still fails after exponents
1026
 * have been downgraded.
1027
 * @return non-zero if bandwidth reduction was unsuccessful
1028
 */
1029
static int reduce_bandwidth(AC3EncodeContext *s, int min_bw_code)
1030
{
1031
    int ch;
1032

    
1033
    if (s->bandwidth_code[0] > min_bw_code) {
1034
        for (ch = 0; ch < s->fbw_channels; ch++) {
1035
            s->bandwidth_code[ch]--;
1036
            s->nb_coefs[ch] = s->bandwidth_code[ch] * 3 + 73;
1037
        }
1038
        return 0;
1039
    }
1040
    return -1;
1041
}
1042

    
1043

    
1044
/**
1045
 * Perform bit allocation search.
1046
 * Finds the SNR offset value that maximizes quality and fits in the specified
1047
 * frame size.  Output is the SNR offset and a set of bit allocation pointers
1048
 * used to quantize the mantissas.
1049
 */
1050
static int compute_bit_allocation(AC3EncodeContext *s)
1051
{
1052
    int ret;
1053

    
1054
    count_frame_bits(s);
1055

    
1056
    bit_alloc_masking(s);
1057

    
1058
    ret = cbr_bit_allocation(s);
1059
    while (ret) {
1060
        /* fallback 1: downgrade exponents */
1061
        if (!downgrade_exponents(s)) {
1062
            extract_exponents(s);
1063
            encode_exponents(s);
1064
            group_exponents(s);
1065
            ret = compute_bit_allocation(s);
1066
            continue;
1067
        }
1068

    
1069
        /* fallback 2: reduce bandwidth */
1070
        /* only do this if the user has not specified a specific cutoff
1071
           frequency */
1072
        if (!s->cutoff && !reduce_bandwidth(s, 0)) {
1073
            process_exponents(s);
1074
            ret = compute_bit_allocation(s);
1075
            continue;
1076
        }
1077

    
1078
        /* fallbacks were not enough... */
1079
        break;
1080
    }
1081

    
1082
    return ret;
1083
}
1084

    
1085

    
1086
/**
1087
 * Symmetric quantization on 'levels' levels.
1088
 */
1089
static inline int sym_quant(int c, int e, int levels)
1090
{
1091
    int v;
1092

    
1093
    if (c >= 0) {
1094
        v = (levels * (c << e)) >> 24;
1095
        v = (v + 1) >> 1;
1096
        v = (levels >> 1) + v;
1097
    } else {
1098
        v = (levels * ((-c) << e)) >> 24;
1099
        v = (v + 1) >> 1;
1100
        v = (levels >> 1) - v;
1101
    }
1102
    assert(v >= 0 && v < levels);
1103
    return v;
1104
}
1105

    
1106

    
1107
/**
1108
 * Asymmetric quantization on 2^qbits levels.
1109
 */
1110
static inline int asym_quant(int c, int e, int qbits)
1111
{
1112
    int lshift, m, v;
1113

    
1114
    lshift = e + qbits - 24;
1115
    if (lshift >= 0)
1116
        v = c << lshift;
1117
    else
1118
        v = c >> (-lshift);
1119
    /* rounding */
1120
    v = (v + 1) >> 1;
1121
    m = (1 << (qbits-1));
1122
    if (v >= m)
1123
        v = m - 1;
1124
    assert(v >= -m);
1125
    return v & ((1 << qbits)-1);
1126
}
1127

    
1128

    
1129
/**
1130
 * Quantize a set of mantissas for a single channel in a single block.
1131
 */
1132
static void quantize_mantissas_blk_ch(AC3EncodeContext *s, int32_t *fixed_coef,
1133
                                      int8_t exp_shift, uint8_t *exp,
1134
                                      uint8_t *bap, uint16_t *qmant, int n)
1135
{
1136
    int i;
1137

    
1138
    for (i = 0; i < n; i++) {
1139
        int v;
1140
        int c = fixed_coef[i];
1141
        int e = exp[i] - exp_shift;
1142
        int b = bap[i];
1143
        switch (b) {
1144
        case 0:
1145
            v = 0;
1146
            break;
1147
        case 1:
1148
            v = sym_quant(c, e, 3);
1149
            switch (s->mant1_cnt) {
1150
            case 0:
1151
                s->qmant1_ptr = &qmant[i];
1152
                v = 9 * v;
1153
                s->mant1_cnt = 1;
1154
                break;
1155
            case 1:
1156
                *s->qmant1_ptr += 3 * v;
1157
                s->mant1_cnt = 2;
1158
                v = 128;
1159
                break;
1160
            default:
1161
                *s->qmant1_ptr += v;
1162
                s->mant1_cnt = 0;
1163
                v = 128;
1164
                break;
1165
            }
1166
            break;
1167
        case 2:
1168
            v = sym_quant(c, e, 5);
1169
            switch (s->mant2_cnt) {
1170
            case 0:
1171
                s->qmant2_ptr = &qmant[i];
1172
                v = 25 * v;
1173
                s->mant2_cnt = 1;
1174
                break;
1175
            case 1:
1176
                *s->qmant2_ptr += 5 * v;
1177
                s->mant2_cnt = 2;
1178
                v = 128;
1179
                break;
1180
            default:
1181
                *s->qmant2_ptr += v;
1182
                s->mant2_cnt = 0;
1183
                v = 128;
1184
                break;
1185
            }
1186
            break;
1187
        case 3:
1188
            v = sym_quant(c, e, 7);
1189
            break;
1190
        case 4:
1191
            v = sym_quant(c, e, 11);
1192
            switch (s->mant4_cnt) {
1193
            case 0:
1194
                s->qmant4_ptr = &qmant[i];
1195
                v = 11 * v;
1196
                s->mant4_cnt = 1;
1197
                break;
1198
            default:
1199
                *s->qmant4_ptr += v;
1200
                s->mant4_cnt = 0;
1201
                v = 128;
1202
                break;
1203
            }
1204
            break;
1205
        case 5:
1206
            v = sym_quant(c, e, 15);
1207
            break;
1208
        case 14:
1209
            v = asym_quant(c, e, 14);
1210
            break;
1211
        case 15:
1212
            v = asym_quant(c, e, 16);
1213
            break;
1214
        default:
1215
            v = asym_quant(c, e, b - 1);
1216
            break;
1217
        }
1218
        qmant[i] = v;
1219
    }
1220
}
1221

    
1222

    
1223
/**
1224
 * Quantize mantissas using coefficients, exponents, and bit allocation pointers.
1225
 */
1226
static void quantize_mantissas(AC3EncodeContext *s)
1227
{
1228
    int blk, ch;
1229

    
1230

    
1231
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1232
        AC3Block *block = &s->blocks[blk];
1233
        s->mant1_cnt  = s->mant2_cnt  = s->mant4_cnt  = 0;
1234
        s->qmant1_ptr = s->qmant2_ptr = s->qmant4_ptr = NULL;
1235

    
1236
        for (ch = 0; ch < s->channels; ch++) {
1237
            quantize_mantissas_blk_ch(s, block->fixed_coef[ch], block->exp_shift[ch],
1238
                                      block->exp[ch], block->bap[ch],
1239
                                      block->qmant[ch], s->nb_coefs[ch]);
1240
        }
1241
    }
1242
}
1243

    
1244

    
1245
/**
1246
 * Write the AC-3 frame header to the output bitstream.
1247
 */
1248
static void output_frame_header(AC3EncodeContext *s)
1249
{
1250
    put_bits(&s->pb, 16, 0x0b77);   /* frame header */
1251
    put_bits(&s->pb, 16, 0);        /* crc1: will be filled later */
1252
    put_bits(&s->pb, 2,  s->bit_alloc.sr_code);
1253
    put_bits(&s->pb, 6,  s->frame_size_code + (s->frame_size - s->frame_size_min) / 2);
1254
    put_bits(&s->pb, 5,  s->bitstream_id);
1255
    put_bits(&s->pb, 3,  s->bitstream_mode);
1256
    put_bits(&s->pb, 3,  s->channel_mode);
1257
    if ((s->channel_mode & 0x01) && s->channel_mode != AC3_CHMODE_MONO)
1258
        put_bits(&s->pb, 2, 1);     /* XXX -4.5 dB */
1259
    if (s->channel_mode & 0x04)
1260
        put_bits(&s->pb, 2, 1);     /* XXX -6 dB */
1261
    if (s->channel_mode == AC3_CHMODE_STEREO)
1262
        put_bits(&s->pb, 2, 0);     /* surround not indicated */
1263
    put_bits(&s->pb, 1, s->lfe_on); /* LFE */
1264
    put_bits(&s->pb, 5, 31);        /* dialog norm: -31 db */
1265
    put_bits(&s->pb, 1, 0);         /* no compression control word */
1266
    put_bits(&s->pb, 1, 0);         /* no lang code */
1267
    put_bits(&s->pb, 1, 0);         /* no audio production info */
1268
    put_bits(&s->pb, 1, 0);         /* no copyright */
1269
    put_bits(&s->pb, 1, 1);         /* original bitstream */
1270
    put_bits(&s->pb, 1, 0);         /* no time code 1 */
1271
    put_bits(&s->pb, 1, 0);         /* no time code 2 */
1272
    put_bits(&s->pb, 1, 0);         /* no additional bit stream info */
1273
}
1274

    
1275

    
1276
/**
1277
 * Write one audio block to the output bitstream.
1278
 */
1279
static void output_audio_block(AC3EncodeContext *s, int blk)
1280
{
1281
    int ch, i, baie, rbnd;
1282
    AC3Block *block = &s->blocks[blk];
1283

    
1284
    /* block switching */
1285
    for (ch = 0; ch < s->fbw_channels; ch++)
1286
        put_bits(&s->pb, 1, 0);
1287

    
1288
    /* dither flags */
1289
    for (ch = 0; ch < s->fbw_channels; ch++)
1290
        put_bits(&s->pb, 1, 1);
1291

    
1292
    /* dynamic range codes */
1293
    put_bits(&s->pb, 1, 0);
1294

    
1295
    /* channel coupling */
1296
    if (!blk) {
1297
        put_bits(&s->pb, 1, 1); /* coupling strategy present */
1298
        put_bits(&s->pb, 1, 0); /* no coupling strategy */
1299
    } else {
1300
        put_bits(&s->pb, 1, 0); /* no new coupling strategy */
1301
    }
1302

    
1303
    /* stereo rematrixing */
1304
    if (s->channel_mode == AC3_CHMODE_STEREO) {
1305
        put_bits(&s->pb, 1, block->new_rematrixing_strategy);
1306
        if (block->new_rematrixing_strategy) {
1307
            /* rematrixing flags */
1308
            for (rbnd = 0; rbnd < 4; rbnd++)
1309
                put_bits(&s->pb, 1, block->rematrixing_flags[rbnd]);
1310
        }
1311
    }
1312

    
1313
    /* exponent strategy */
1314
    for (ch = 0; ch < s->fbw_channels; ch++)
1315
        put_bits(&s->pb, 2, s->exp_strategy[ch][blk]);
1316
    if (s->lfe_on)
1317
        put_bits(&s->pb, 1, s->exp_strategy[s->lfe_channel][blk]);
1318

    
1319
    /* bandwidth */
1320
    for (ch = 0; ch < s->fbw_channels; ch++) {
1321
        if (s->exp_strategy[ch][blk] != EXP_REUSE)
1322
            put_bits(&s->pb, 6, s->bandwidth_code[ch]);
1323
    }
1324

    
1325
    /* exponents */
1326
    for (ch = 0; ch < s->channels; ch++) {
1327
        int nb_groups;
1328

    
1329
        if (s->exp_strategy[ch][blk] == EXP_REUSE)
1330
            continue;
1331

    
1332
        /* DC exponent */
1333
        put_bits(&s->pb, 4, block->grouped_exp[ch][0]);
1334

    
1335
        /* exponent groups */
1336
        nb_groups = exponent_group_tab[s->exp_strategy[ch][blk]-1][s->nb_coefs[ch]];
1337
        for (i = 1; i <= nb_groups; i++)
1338
            put_bits(&s->pb, 7, block->grouped_exp[ch][i]);
1339

    
1340
        /* gain range info */
1341
        if (ch != s->lfe_channel)
1342
            put_bits(&s->pb, 2, 0);
1343
    }
1344

    
1345
    /* bit allocation info */
1346
    baie = (blk == 0);
1347
    put_bits(&s->pb, 1, baie);
1348
    if (baie) {
1349
        put_bits(&s->pb, 2, s->slow_decay_code);
1350
        put_bits(&s->pb, 2, s->fast_decay_code);
1351
        put_bits(&s->pb, 2, s->slow_gain_code);
1352
        put_bits(&s->pb, 2, s->db_per_bit_code);
1353
        put_bits(&s->pb, 3, s->floor_code);
1354
    }
1355

    
1356
    /* snr offset */
1357
    put_bits(&s->pb, 1, baie);
1358
    if (baie) {
1359
        put_bits(&s->pb, 6, s->coarse_snr_offset);
1360
        for (ch = 0; ch < s->channels; ch++) {
1361
            put_bits(&s->pb, 4, s->fine_snr_offset[ch]);
1362
            put_bits(&s->pb, 3, s->fast_gain_code[ch]);
1363
        }
1364
    }
1365

    
1366
    put_bits(&s->pb, 1, 0); /* no delta bit allocation */
1367
    put_bits(&s->pb, 1, 0); /* no data to skip */
1368

    
1369
    /* mantissas */
1370
    for (ch = 0; ch < s->channels; ch++) {
1371
        int b, q;
1372
        for (i = 0; i < s->nb_coefs[ch]; i++) {
1373
            q = block->qmant[ch][i];
1374
            b = block->bap[ch][i];
1375
            switch (b) {
1376
            case 0:                                         break;
1377
            case 1: if (q != 128) put_bits(&s->pb,   5, q); break;
1378
            case 2: if (q != 128) put_bits(&s->pb,   7, q); break;
1379
            case 3:               put_bits(&s->pb,   3, q); break;
1380
            case 4: if (q != 128) put_bits(&s->pb,   7, q); break;
1381
            case 14:              put_bits(&s->pb,  14, q); break;
1382
            case 15:              put_bits(&s->pb,  16, q); break;
1383
            default:              put_bits(&s->pb, b-1, q); break;
1384
            }
1385
        }
1386
    }
1387
}
1388

    
1389

    
1390
/** CRC-16 Polynomial */
1391
#define CRC16_POLY ((1 << 0) | (1 << 2) | (1 << 15) | (1 << 16))
1392

    
1393

    
1394
static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly)
1395
{
1396
    unsigned int c;
1397

    
1398
    c = 0;
1399
    while (a) {
1400
        if (a & 1)
1401
            c ^= b;
1402
        a = a >> 1;
1403
        b = b << 1;
1404
        if (b & (1 << 16))
1405
            b ^= poly;
1406
    }
1407
    return c;
1408
}
1409

    
1410

    
1411
static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly)
1412
{
1413
    unsigned int r;
1414
    r = 1;
1415
    while (n) {
1416
        if (n & 1)
1417
            r = mul_poly(r, a, poly);
1418
        a = mul_poly(a, a, poly);
1419
        n >>= 1;
1420
    }
1421
    return r;
1422
}
1423

    
1424

    
1425
/**
1426
 * Fill the end of the frame with 0's and compute the two CRCs.
1427
 */
1428
static void output_frame_end(AC3EncodeContext *s)
1429
{
1430
    const AVCRC *crc_ctx = av_crc_get_table(AV_CRC_16_ANSI);
1431
    int frame_size_58, pad_bytes, crc1, crc2_partial, crc2, crc_inv;
1432
    uint8_t *frame;
1433

    
1434
    frame_size_58 = ((s->frame_size >> 2) + (s->frame_size >> 4)) << 1;
1435

    
1436
    /* pad the remainder of the frame with zeros */
1437
    flush_put_bits(&s->pb);
1438
    frame = s->pb.buf;
1439
    pad_bytes = s->frame_size - (put_bits_ptr(&s->pb) - frame) - 2;
1440
    assert(pad_bytes >= 0);
1441
    if (pad_bytes > 0)
1442
        memset(put_bits_ptr(&s->pb), 0, pad_bytes);
1443

    
1444
    /* compute crc1 */
1445
    /* this is not so easy because it is at the beginning of the data... */
1446
    crc1    = av_bswap16(av_crc(crc_ctx, 0, frame + 4, frame_size_58 - 4));
1447
    crc_inv = s->crc_inv[s->frame_size > s->frame_size_min];
1448
    crc1    = mul_poly(crc_inv, crc1, CRC16_POLY);
1449
    AV_WB16(frame + 2, crc1);
1450

    
1451
    /* compute crc2 */
1452
    crc2_partial = av_crc(crc_ctx, 0, frame + frame_size_58,
1453
                          s->frame_size - frame_size_58 - 3);
1454
    crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
1455
    /* ensure crc2 does not match sync word by flipping crcrsv bit if needed */
1456
    if (crc2 == 0x770B) {
1457
        frame[s->frame_size - 3] ^= 0x1;
1458
        crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
1459
    }
1460
    crc2 = av_bswap16(crc2);
1461
    AV_WB16(frame + s->frame_size - 2, crc2);
1462
}
1463

    
1464

    
1465
/**
1466
 * Write the frame to the output bitstream.
1467
 */
1468
static void output_frame(AC3EncodeContext *s, unsigned char *frame)
1469
{
1470
    int blk;
1471

    
1472
    init_put_bits(&s->pb, frame, AC3_MAX_CODED_FRAME_SIZE);
1473

    
1474
    output_frame_header(s);
1475

    
1476
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++)
1477
        output_audio_block(s, blk);
1478

    
1479
    output_frame_end(s);
1480
}
1481

    
1482

    
1483
/**
1484
 * Encode a single AC-3 frame.
1485
 */
1486
static int ac3_encode_frame(AVCodecContext *avctx, unsigned char *frame,
1487
                            int buf_size, void *data)
1488
{
1489
    AC3EncodeContext *s = avctx->priv_data;
1490
    const SampleType *samples = data;
1491
    int ret;
1492

    
1493
    if (s->bit_alloc.sr_code == 1)
1494
        adjust_frame_size(s);
1495

    
1496
    deinterleave_input_samples(s, samples);
1497

    
1498
    apply_mdct(s);
1499

    
1500
    compute_rematrixing_strategy(s);
1501

    
1502
    scale_coefficients(s);
1503

    
1504
    apply_rematrixing(s);
1505

    
1506
    process_exponents(s);
1507

    
1508
    ret = compute_bit_allocation(s);
1509
    if (ret) {
1510
        av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
1511
        return ret;
1512
    }
1513

    
1514
    quantize_mantissas(s);
1515

    
1516
    output_frame(s, frame);
1517

    
1518
    return s->frame_size;
1519
}
1520

    
1521

    
1522
/**
1523
 * Finalize encoding and free any memory allocated by the encoder.
1524
 */
1525
static av_cold int ac3_encode_close(AVCodecContext *avctx)
1526
{
1527
    int blk, ch;
1528
    AC3EncodeContext *s = avctx->priv_data;
1529

    
1530
    for (ch = 0; ch < s->channels; ch++)
1531
        av_freep(&s->planar_samples[ch]);
1532
    av_freep(&s->planar_samples);
1533
    av_freep(&s->bap_buffer);
1534
    av_freep(&s->bap1_buffer);
1535
    av_freep(&s->mdct_coef_buffer);
1536
    av_freep(&s->fixed_coef_buffer);
1537
    av_freep(&s->exp_buffer);
1538
    av_freep(&s->grouped_exp_buffer);
1539
    av_freep(&s->psd_buffer);
1540
    av_freep(&s->band_psd_buffer);
1541
    av_freep(&s->mask_buffer);
1542
    av_freep(&s->qmant_buffer);
1543
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1544
        AC3Block *block = &s->blocks[blk];
1545
        av_freep(&block->bap);
1546
        av_freep(&block->mdct_coef);
1547
        av_freep(&block->fixed_coef);
1548
        av_freep(&block->exp);
1549
        av_freep(&block->grouped_exp);
1550
        av_freep(&block->psd);
1551
        av_freep(&block->band_psd);
1552
        av_freep(&block->mask);
1553
        av_freep(&block->qmant);
1554
    }
1555

    
1556
    mdct_end(&s->mdct);
1557

    
1558
    av_freep(&avctx->coded_frame);
1559
    return 0;
1560
}
1561

    
1562

    
1563
/**
1564
 * Set channel information during initialization.
1565
 */
1566
static av_cold int set_channel_info(AC3EncodeContext *s, int channels,
1567
                                    int64_t *channel_layout)
1568
{
1569
    int ch_layout;
1570

    
1571
    if (channels < 1 || channels > AC3_MAX_CHANNELS)
1572
        return AVERROR(EINVAL);
1573
    if ((uint64_t)*channel_layout > 0x7FF)
1574
        return AVERROR(EINVAL);
1575
    ch_layout = *channel_layout;
1576
    if (!ch_layout)
1577
        ch_layout = avcodec_guess_channel_layout(channels, CODEC_ID_AC3, NULL);
1578
    if (av_get_channel_layout_nb_channels(ch_layout) != channels)
1579
        return AVERROR(EINVAL);
1580

    
1581
    s->lfe_on       = !!(ch_layout & AV_CH_LOW_FREQUENCY);
1582
    s->channels     = channels;
1583
    s->fbw_channels = channels - s->lfe_on;
1584
    s->lfe_channel  = s->lfe_on ? s->fbw_channels : -1;
1585
    if (s->lfe_on)
1586
        ch_layout -= AV_CH_LOW_FREQUENCY;
1587

    
1588
    switch (ch_layout) {
1589
    case AV_CH_LAYOUT_MONO:           s->channel_mode = AC3_CHMODE_MONO;   break;
1590
    case AV_CH_LAYOUT_STEREO:         s->channel_mode = AC3_CHMODE_STEREO; break;
1591
    case AV_CH_LAYOUT_SURROUND:       s->channel_mode = AC3_CHMODE_3F;     break;
1592
    case AV_CH_LAYOUT_2_1:            s->channel_mode = AC3_CHMODE_2F1R;   break;
1593
    case AV_CH_LAYOUT_4POINT0:        s->channel_mode = AC3_CHMODE_3F1R;   break;
1594
    case AV_CH_LAYOUT_QUAD:
1595
    case AV_CH_LAYOUT_2_2:            s->channel_mode = AC3_CHMODE_2F2R;   break;
1596
    case AV_CH_LAYOUT_5POINT0:
1597
    case AV_CH_LAYOUT_5POINT0_BACK:   s->channel_mode = AC3_CHMODE_3F2R;   break;
1598
    default:
1599
        return AVERROR(EINVAL);
1600
    }
1601

    
1602
    s->channel_map  = ff_ac3_enc_channel_map[s->channel_mode][s->lfe_on];
1603
    *channel_layout = ch_layout;
1604
    if (s->lfe_on)
1605
        *channel_layout |= AV_CH_LOW_FREQUENCY;
1606

    
1607
    return 0;
1608
}
1609

    
1610

    
1611
static av_cold int validate_options(AVCodecContext *avctx, AC3EncodeContext *s)
1612
{
1613
    int i, ret;
1614

    
1615
    /* validate channel layout */
1616
    if (!avctx->channel_layout) {
1617
        av_log(avctx, AV_LOG_WARNING, "No channel layout specified. The "
1618
                                      "encoder will guess the layout, but it "
1619
                                      "might be incorrect.\n");
1620
    }
1621
    ret = set_channel_info(s, avctx->channels, &avctx->channel_layout);
1622
    if (ret) {
1623
        av_log(avctx, AV_LOG_ERROR, "invalid channel layout\n");
1624
        return ret;
1625
    }
1626

    
1627
    /* validate sample rate */
1628
    for (i = 0; i < 9; i++) {
1629
        if ((ff_ac3_sample_rate_tab[i / 3] >> (i % 3)) == avctx->sample_rate)
1630
            break;
1631
    }
1632
    if (i == 9) {
1633
        av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1634
        return AVERROR(EINVAL);
1635
    }
1636
    s->sample_rate        = avctx->sample_rate;
1637
    s->bit_alloc.sr_shift = i % 3;
1638
    s->bit_alloc.sr_code  = i / 3;
1639

    
1640
    /* validate bit rate */
1641
    for (i = 0; i < 19; i++) {
1642
        if ((ff_ac3_bitrate_tab[i] >> s->bit_alloc.sr_shift)*1000 == avctx->bit_rate)
1643
            break;
1644
    }
1645
    if (i == 19) {
1646
        av_log(avctx, AV_LOG_ERROR, "invalid bit rate\n");
1647
        return AVERROR(EINVAL);
1648
    }
1649
    s->bit_rate        = avctx->bit_rate;
1650
    s->frame_size_code = i << 1;
1651

    
1652
    /* validate cutoff */
1653
    if (avctx->cutoff < 0) {
1654
        av_log(avctx, AV_LOG_ERROR, "invalid cutoff frequency\n");
1655
        return AVERROR(EINVAL);
1656
    }
1657
    s->cutoff = avctx->cutoff;
1658
    if (s->cutoff > (s->sample_rate >> 1))
1659
        s->cutoff = s->sample_rate >> 1;
1660

    
1661
    return 0;
1662
}
1663

    
1664

    
1665
/**
1666
 * Set bandwidth for all channels.
1667
 * The user can optionally supply a cutoff frequency. Otherwise an appropriate
1668
 * default value will be used.
1669
 */
1670
static av_cold void set_bandwidth(AC3EncodeContext *s)
1671
{
1672
    int ch, bw_code;
1673

    
1674
    if (s->cutoff) {
1675
        /* calculate bandwidth based on user-specified cutoff frequency */
1676
        int fbw_coeffs;
1677
        fbw_coeffs     = s->cutoff * 2 * AC3_MAX_COEFS / s->sample_rate;
1678
        bw_code        = av_clip((fbw_coeffs - 73) / 3, 0, 60);
1679
    } else {
1680
        /* use default bandwidth setting */
1681
        /* XXX: should compute the bandwidth according to the frame
1682
           size, so that we avoid annoying high frequency artifacts */
1683
        bw_code = 50;
1684
    }
1685

    
1686
    /* set number of coefficients for each channel */
1687
    for (ch = 0; ch < s->fbw_channels; ch++) {
1688
        s->bandwidth_code[ch] = bw_code;
1689
        s->nb_coefs[ch]       = bw_code * 3 + 73;
1690
    }
1691
    if (s->lfe_on)
1692
        s->nb_coefs[s->lfe_channel] = 7; /* LFE channel always has 7 coefs */
1693
}
1694

    
1695

    
1696
static av_cold int allocate_buffers(AVCodecContext *avctx)
1697
{
1698
    int blk, ch;
1699
    AC3EncodeContext *s = avctx->priv_data;
1700

    
1701
    FF_ALLOC_OR_GOTO(avctx, s->planar_samples, s->channels * sizeof(*s->planar_samples),
1702
                     alloc_fail);
1703
    for (ch = 0; ch < s->channels; ch++) {
1704
        FF_ALLOCZ_OR_GOTO(avctx, s->planar_samples[ch],
1705
                          (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),
1706
                          alloc_fail);
1707
    }
1708
    FF_ALLOC_OR_GOTO(avctx, s->bap_buffer,  AC3_MAX_BLOCKS * s->channels *
1709
                     AC3_MAX_COEFS * sizeof(*s->bap_buffer),  alloc_fail);
1710
    FF_ALLOC_OR_GOTO(avctx, s->bap1_buffer, AC3_MAX_BLOCKS * s->channels *
1711
                     AC3_MAX_COEFS * sizeof(*s->bap1_buffer), alloc_fail);
1712
    FF_ALLOC_OR_GOTO(avctx, s->mdct_coef_buffer, AC3_MAX_BLOCKS * s->channels *
1713
                     AC3_MAX_COEFS * sizeof(*s->mdct_coef_buffer), alloc_fail);
1714
    FF_ALLOC_OR_GOTO(avctx, s->exp_buffer, AC3_MAX_BLOCKS * s->channels *
1715
                     AC3_MAX_COEFS * sizeof(*s->exp_buffer), alloc_fail);
1716
    FF_ALLOC_OR_GOTO(avctx, s->grouped_exp_buffer, AC3_MAX_BLOCKS * s->channels *
1717
                     128 * sizeof(*s->grouped_exp_buffer), alloc_fail);
1718
    FF_ALLOC_OR_GOTO(avctx, s->psd_buffer, AC3_MAX_BLOCKS * s->channels *
1719
                     AC3_MAX_COEFS * sizeof(*s->psd_buffer), alloc_fail);
1720
    FF_ALLOC_OR_GOTO(avctx, s->band_psd_buffer, AC3_MAX_BLOCKS * s->channels *
1721
                     64 * sizeof(*s->band_psd_buffer), alloc_fail);
1722
    FF_ALLOC_OR_GOTO(avctx, s->mask_buffer, AC3_MAX_BLOCKS * s->channels *
1723
                     64 * sizeof(*s->mask_buffer), alloc_fail);
1724
    FF_ALLOC_OR_GOTO(avctx, s->qmant_buffer, AC3_MAX_BLOCKS * s->channels *
1725
                     AC3_MAX_COEFS * sizeof(*s->qmant_buffer), alloc_fail);
1726
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1727
        AC3Block *block = &s->blocks[blk];
1728
        FF_ALLOC_OR_GOTO(avctx, block->bap, s->channels * sizeof(*block->bap),
1729
                         alloc_fail);
1730
        FF_ALLOCZ_OR_GOTO(avctx, block->mdct_coef, s->channels * sizeof(*block->mdct_coef),
1731
                          alloc_fail);
1732
        FF_ALLOCZ_OR_GOTO(avctx, block->exp, s->channels * sizeof(*block->exp),
1733
                          alloc_fail);
1734
        FF_ALLOCZ_OR_GOTO(avctx, block->grouped_exp, s->channels * sizeof(*block->grouped_exp),
1735
                          alloc_fail);
1736
        FF_ALLOCZ_OR_GOTO(avctx, block->psd, s->channels * sizeof(*block->psd),
1737
                          alloc_fail);
1738
        FF_ALLOCZ_OR_GOTO(avctx, block->band_psd, s->channels * sizeof(*block->band_psd),
1739
                          alloc_fail);
1740
        FF_ALLOCZ_OR_GOTO(avctx, block->mask, s->channels * sizeof(*block->mask),
1741
                          alloc_fail);
1742
        FF_ALLOCZ_OR_GOTO(avctx, block->qmant, s->channels * sizeof(*block->qmant),
1743
                          alloc_fail);
1744

    
1745
        for (ch = 0; ch < s->channels; ch++) {
1746
            /* arrangement: block, channel, coeff */
1747
            block->bap[ch]         = &s->bap_buffer        [AC3_MAX_COEFS * (blk * s->channels + ch)];
1748
            block->mdct_coef[ch]   = &s->mdct_coef_buffer  [AC3_MAX_COEFS * (blk * s->channels + ch)];
1749
            block->grouped_exp[ch] = &s->grouped_exp_buffer[128           * (blk * s->channels + ch)];
1750
            block->psd[ch]         = &s->psd_buffer        [AC3_MAX_COEFS * (blk * s->channels + ch)];
1751
            block->band_psd[ch]    = &s->band_psd_buffer   [64            * (blk * s->channels + ch)];
1752
            block->mask[ch]        = &s->mask_buffer       [64            * (blk * s->channels + ch)];
1753
            block->qmant[ch]       = &s->qmant_buffer      [AC3_MAX_COEFS * (blk * s->channels + ch)];
1754

    
1755
            /* arrangement: channel, block, coeff */
1756
            block->exp[ch]         = &s->exp_buffer        [AC3_MAX_COEFS * (AC3_MAX_BLOCKS * ch + blk)];
1757
        }
1758
    }
1759

    
1760
    if (CONFIG_AC3ENC_FLOAT) {
1761
        FF_ALLOC_OR_GOTO(avctx, s->fixed_coef_buffer, AC3_MAX_BLOCKS * s->channels *
1762
                         AC3_MAX_COEFS * sizeof(*s->fixed_coef_buffer), alloc_fail);
1763
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1764
            AC3Block *block = &s->blocks[blk];
1765
            FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, s->channels *
1766
                              sizeof(*block->fixed_coef), alloc_fail);
1767
            for (ch = 0; ch < s->channels; ch++)
1768
                block->fixed_coef[ch] = &s->fixed_coef_buffer[AC3_MAX_COEFS * (blk * s->channels + ch)];
1769
        }
1770
    } else {
1771
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1772
            AC3Block *block = &s->blocks[blk];
1773
            FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, s->channels *
1774
                              sizeof(*block->fixed_coef), alloc_fail);
1775
            for (ch = 0; ch < s->channels; ch++)
1776
                block->fixed_coef[ch] = (int32_t *)block->mdct_coef[ch];
1777
        }
1778
    }
1779

    
1780
    return 0;
1781
alloc_fail:
1782
    return AVERROR(ENOMEM);
1783
}
1784

    
1785

    
1786
/**
1787
 * Initialize the encoder.
1788
 */
1789
static av_cold int ac3_encode_init(AVCodecContext *avctx)
1790
{
1791
    AC3EncodeContext *s = avctx->priv_data;
1792
    int ret, frame_size_58;
1793

    
1794
    avctx->frame_size = AC3_FRAME_SIZE;
1795

    
1796
    ff_ac3_common_init();
1797

    
1798
    ret = validate_options(avctx, s);
1799
    if (ret)
1800
        return ret;
1801

    
1802
    s->bitstream_id   = 8 + s->bit_alloc.sr_shift;
1803
    s->bitstream_mode = 0; /* complete main audio service */
1804

    
1805
    s->frame_size_min  = 2 * ff_ac3_frame_size_tab[s->frame_size_code][s->bit_alloc.sr_code];
1806
    s->bits_written    = 0;
1807
    s->samples_written = 0;
1808
    s->frame_size      = s->frame_size_min;
1809

    
1810
    /* calculate crc_inv for both possible frame sizes */
1811
    frame_size_58 = (( s->frame_size    >> 2) + ( s->frame_size    >> 4)) << 1;
1812
    s->crc_inv[0] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
1813
    if (s->bit_alloc.sr_code == 1) {
1814
        frame_size_58 = (((s->frame_size+2) >> 2) + ((s->frame_size+2) >> 4)) << 1;
1815
        s->crc_inv[1] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
1816
    }
1817

    
1818
    set_bandwidth(s);
1819

    
1820
    rematrixing_init(s);
1821

    
1822
    exponent_init(s);
1823

    
1824
    bit_alloc_init(s);
1825

    
1826
    ret = mdct_init(avctx, &s->mdct, 9);
1827
    if (ret)
1828
        goto init_fail;
1829

    
1830
    ret = allocate_buffers(avctx);
1831
    if (ret)
1832
        goto init_fail;
1833

    
1834
    avctx->coded_frame= avcodec_alloc_frame();
1835

    
1836
    dsputil_init(&s->dsp, avctx);
1837
    ff_ac3dsp_init(&s->ac3dsp);
1838

    
1839
    return 0;
1840
init_fail:
1841
    ac3_encode_close(avctx);
1842
    return ret;
1843
}