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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 Libav.
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 *
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 * Libav 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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 * Libav 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 Libav; 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
/**
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 * @file
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 * The simplest AC-3 encoder.
27
 */
28

    
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//#define DEBUG
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//#define ASSERT_LEVEL 2
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#include "libavutil/audioconvert.h"
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#include "libavutil/avassert.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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42

    
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#ifndef CONFIG_AC3ENC_FLOAT
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#define CONFIG_AC3ENC_FLOAT 0
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#endif
46

    
47

    
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/** Maximum number of exponent groups. +1 for separate DC exponent. */
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#define AC3_MAX_EXP_GROUPS 85
50

    
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/* 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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/** 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)))
59

    
60

    
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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
66

    
67

    
68
/**
69
 * Data for a single audio block.
70
 */
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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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    uint8_t  coeff_shift[AC3_MAX_CHANNELS];     ///< fixed-point coefficient 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
84
} AC3Block;
85

    
86
/**
87
 * AC-3 encoder private context.
88
 */
89
typedef struct AC3EncodeContext {
90
    PutBitContext pb;                       ///< bitstream writer context
91
    DSPContext dsp;
92
    AC3DSPContext ac3dsp;                   ///< AC-3 optimized functions
93
    AC3MDCTContext mdct;                    ///< MDCT context
94

    
95
    AC3Block blocks[AC3_MAX_BLOCKS];        ///< per-block info
96

    
97
    int bitstream_id;                       ///< bitstream id                           (bsid)
98
    int bitstream_mode;                     ///< bitstream mode                         (bsmod)
99

    
100
    int bit_rate;                           ///< target bit rate, in bits-per-second
101
    int sample_rate;                        ///< sampling frequency, in Hz
102

    
103
    int frame_size_min;                     ///< minimum frame size in case rounding is necessary
104
    int frame_size;                         ///< current frame size in bytes
105
    int frame_size_code;                    ///< frame size code                        (frmsizecod)
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    uint16_t crc_inv[2];
107
    int bits_written;                       ///< bit count    (used to avg. bitrate)
108
    int samples_written;                    ///< sample count (used to avg. bitrate)
109

    
110
    int fbw_channels;                       ///< number of full-bandwidth channels      (nfchans)
111
    int channels;                           ///< total number of channels               (nchans)
112
    int lfe_on;                             ///< indicates if there is an LFE channel   (lfeon)
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    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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    int cutoff;                             ///< user-specified cutoff frequency, in Hz
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    int bandwidth_code[AC3_MAX_CHANNELS];   ///< bandwidth code (0 to 60)               (chbwcod)
119
    int nb_coefs[AC3_MAX_CHANNELS];
120

    
121
    int rematrixing;                        ///< determines how rematrixing strategy is calculated
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    int num_rematrixing_bands;              ///< number of rematrixing bands
123

    
124
    /* bitrate allocation control */
125
    int slow_gain_code;                     ///< slow gain code                         (sgaincod)
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    int slow_decay_code;                    ///< slow decay code                        (sdcycod)
127
    int fast_decay_code;                    ///< fast decay code                        (fdcycod)
128
    int db_per_bit_code;                    ///< dB/bit code                            (dbpbcod)
129
    int floor_code;                         ///< floor code                             (floorcod)
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    AC3BitAllocParameters bit_alloc;        ///< bit allocation parameters
131
    int coarse_snr_offset;                  ///< coarse SNR offsets                     (csnroffst)
132
    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
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    int frame_bits;                         ///< all frame bits except exponents and mantissas
136
    int exponent_bits;                      ///< number of bits used for exponents
137

    
138
    /* mantissa encoding */
139
    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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142
    SampleType **planar_samples;
143
    uint8_t *bap_buffer;
144
    uint8_t *bap1_buffer;
145
    CoefType *mdct_coef_buffer;
146
    int32_t *fixed_coef_buffer;
147
    uint8_t *exp_buffer;
148
    uint8_t *grouped_exp_buffer;
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    int16_t *psd_buffer;
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    int16_t *band_psd_buffer;
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    int16_t *mask_buffer;
152
    uint16_t *qmant_buffer;
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154
    uint8_t exp_strategy[AC3_MAX_CHANNELS][AC3_MAX_BLOCKS]; ///< exponent strategies
155

    
156
    DECLARE_ALIGNED(16, SampleType, windowed_samples)[AC3_WINDOW_SIZE];
157
} AC3EncodeContext;
158

    
159

    
160
/* prototypes for functions in ac3enc_fixed.c and ac3enc_float.c */
161

    
162
static av_cold void mdct_end(AC3MDCTContext *mdct);
163

    
164
static av_cold int mdct_init(AVCodecContext *avctx, AC3MDCTContext *mdct,
165
                             int nbits);
166

    
167
static void mdct512(AC3MDCTContext *mdct, CoefType *out, SampleType *in);
168

    
169
static void apply_window(DSPContext *dsp, SampleType *output, const SampleType *input,
170
                         const SampleType *window, unsigned int len);
171

    
172
static int normalize_samples(AC3EncodeContext *s);
173

    
174
static void scale_coefficients(AC3EncodeContext *s);
175

    
176

    
177
/**
178
 * LUT for number of exponent groups.
179
 * exponent_group_tab[exponent strategy-1][number of coefficients]
180
 */
181
static uint8_t exponent_group_tab[3][256];
182

    
183

    
184
/**
185
 * List of supported channel layouts.
186
 */
187
static const int64_t ac3_channel_layouts[] = {
188
     AV_CH_LAYOUT_MONO,
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     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,
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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),
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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,
206
     0
207
};
208

    
209

    
210
/**
211
 * Adjust the frame size to make the average bit rate match the target bit rate.
212
 * This is only needed for 11025, 22050, and 44100 sample rates.
213
 */
214
static void adjust_frame_size(AC3EncodeContext *s)
215
{
216
    while (s->bits_written >= s->bit_rate && s->samples_written >= s->sample_rate) {
217
        s->bits_written    -= s->bit_rate;
218
        s->samples_written -= s->sample_rate;
219
    }
220
    s->frame_size = s->frame_size_min +
221
                    2 * (s->bits_written * s->sample_rate < s->samples_written * s->bit_rate);
222
    s->bits_written    += s->frame_size * 8;
223
    s->samples_written += AC3_FRAME_SIZE;
224
}
225

    
226

    
227
/**
228
 * Deinterleave input samples.
229
 * Channels are reordered from Libav's default order to AC-3 order.
230
 */
231
static void deinterleave_input_samples(AC3EncodeContext *s,
232
                                       const SampleType *samples)
233
{
234
    int ch, i;
235

    
236
    /* deinterleave and remap input samples */
237
    for (ch = 0; ch < s->channels; ch++) {
238
        const SampleType *sptr;
239
        int sinc;
240

    
241
        /* copy last 256 samples of previous frame to the start of the current frame */
242
        memcpy(&s->planar_samples[ch][0], &s->planar_samples[ch][AC3_FRAME_SIZE],
243
               AC3_BLOCK_SIZE * sizeof(s->planar_samples[0][0]));
244

    
245
        /* deinterleave */
246
        sinc = s->channels;
247
        sptr = samples + s->channel_map[ch];
248
        for (i = AC3_BLOCK_SIZE; i < AC3_FRAME_SIZE+AC3_BLOCK_SIZE; i++) {
249
            s->planar_samples[ch][i] = *sptr;
250
            sptr += sinc;
251
        }
252
    }
253
}
254

    
255

    
256
/**
257
 * Apply the MDCT to input samples to generate frequency coefficients.
258
 * This applies the KBD window and normalizes the input to reduce precision
259
 * loss due to fixed-point calculations.
260
 */
261
static void apply_mdct(AC3EncodeContext *s)
262
{
263
    int blk, ch;
264

    
265
    for (ch = 0; ch < s->channels; ch++) {
266
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
267
            AC3Block *block = &s->blocks[blk];
268
            const SampleType *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE];
269

    
270
            apply_window(&s->dsp, s->windowed_samples, input_samples, s->mdct.window, AC3_WINDOW_SIZE);
271

    
272
            block->coeff_shift[ch] = normalize_samples(s);
273

    
274
            mdct512(&s->mdct, block->mdct_coef[ch], s->windowed_samples);
275
        }
276
    }
277
}
278

    
279

    
280
/**
281
 * Initialize stereo rematrixing.
282
 * If the strategy does not change for each frame, set the rematrixing flags.
283
 */
284
static void rematrixing_init(AC3EncodeContext *s)
285
{
286
    if (s->channel_mode == AC3_CHMODE_STEREO)
287
        s->rematrixing = AC3_REMATRIXING_SUMS;
288
    else
289
        s->rematrixing = AC3_REMATRIXING_NONE;
290
    /* NOTE: AC3_REMATRIXING_ALWAYS might be used in
291
             the future in conjunction with channel coupling. */
292

    
293
    if (s->rematrixing & AC3_REMATRIXING_IS_STATIC) {
294
        int flag = (s->rematrixing == AC3_REMATRIXING_ALWAYS);
295
        s->blocks[0].new_rematrixing_strategy = 1;
296
        memset(s->blocks[0].rematrixing_flags, flag,
297
               sizeof(s->blocks[0].rematrixing_flags));
298
    }
299
}
300

    
301

    
302
/**
303
 * Determine rematrixing flags for each block and band.
304
 */
305
static void compute_rematrixing_strategy(AC3EncodeContext *s)
306
{
307
    int nb_coefs;
308
    int blk, bnd, i;
309
    AC3Block *block, *block0;
310

    
311
    s->num_rematrixing_bands = 4;
312

    
313
    if (s->rematrixing & AC3_REMATRIXING_IS_STATIC)
314
        return;
315

    
316
    nb_coefs = FFMIN(s->nb_coefs[0], s->nb_coefs[1]);
317

    
318
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
319
        block = &s->blocks[blk];
320
        block->new_rematrixing_strategy = !blk;
321
        for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++) {
322
            /* calculate calculate sum of squared coeffs for one band in one block */
323
            int start = ff_ac3_rematrix_band_tab[bnd];
324
            int end   = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
325
            CoefSumType sum[4] = {0,};
326
            for (i = start; i < end; i++) {
327
                CoefType lt = block->mdct_coef[0][i];
328
                CoefType rt = block->mdct_coef[1][i];
329
                CoefType md = lt + rt;
330
                CoefType sd = lt - rt;
331
                MAC_COEF(sum[0], lt, lt);
332
                MAC_COEF(sum[1], rt, rt);
333
                MAC_COEF(sum[2], md, md);
334
                MAC_COEF(sum[3], sd, sd);
335
            }
336

    
337
            /* compare sums to determine if rematrixing will be used for this band */
338
            if (FFMIN(sum[2], sum[3]) < FFMIN(sum[0], sum[1]))
339
                block->rematrixing_flags[bnd] = 1;
340
            else
341
                block->rematrixing_flags[bnd] = 0;
342

    
343
            /* determine if new rematrixing flags will be sent */
344
            if (blk &&
345
                block->rematrixing_flags[bnd] != block0->rematrixing_flags[bnd]) {
346
                block->new_rematrixing_strategy = 1;
347
            }
348
        }
349
        block0 = block;
350
    }
351
}
352

    
353

    
354
/**
355
 * Apply stereo rematrixing to coefficients based on rematrixing flags.
356
 */
357
static void apply_rematrixing(AC3EncodeContext *s)
358
{
359
    int nb_coefs;
360
    int blk, bnd, i;
361
    int start, end;
362
    uint8_t *flags;
363

    
364
    if (s->rematrixing == AC3_REMATRIXING_NONE)
365
        return;
366

    
367
    nb_coefs = FFMIN(s->nb_coefs[0], s->nb_coefs[1]);
368

    
369
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
370
        AC3Block *block = &s->blocks[blk];
371
        if (block->new_rematrixing_strategy)
372
            flags = block->rematrixing_flags;
373
        for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++) {
374
            if (flags[bnd]) {
375
                start = ff_ac3_rematrix_band_tab[bnd];
376
                end   = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
377
                for (i = start; i < end; i++) {
378
                    int32_t lt = block->fixed_coef[0][i];
379
                    int32_t rt = block->fixed_coef[1][i];
380
                    block->fixed_coef[0][i] = (lt + rt) >> 1;
381
                    block->fixed_coef[1][i] = (lt - rt) >> 1;
382
                }
383
            }
384
        }
385
    }
386
}
387

    
388

    
389
/**
390
 * Initialize exponent tables.
391
 */
392
static av_cold void exponent_init(AC3EncodeContext *s)
393
{
394
    int i;
395
    for (i = 73; i < 256; i++) {
396
        exponent_group_tab[0][i] = (i - 1) /  3;
397
        exponent_group_tab[1][i] = (i + 2) /  6;
398
        exponent_group_tab[2][i] = (i + 8) / 12;
399
    }
400
    /* LFE */
401
    exponent_group_tab[0][7] = 2;
402
}
403

    
404

    
405
/**
406
 * Extract exponents from the MDCT coefficients.
407
 * This takes into account the normalization that was done to the input samples
408
 * by adjusting the exponents by the exponent shift values.
409
 */
410
static void extract_exponents(AC3EncodeContext *s)
411
{
412
    int blk, ch, i;
413

    
414
    for (ch = 0; ch < s->channels; ch++) {
415
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
416
            AC3Block *block = &s->blocks[blk];
417
            uint8_t *exp   = block->exp[ch];
418
            int32_t *coef = block->fixed_coef[ch];
419
            for (i = 0; i < AC3_MAX_COEFS; i++) {
420
                int e;
421
                int v = abs(coef[i]);
422
                if (v == 0)
423
                    e = 24;
424
                else {
425
                    e = 23 - av_log2(v);
426
                    if (e >= 24) {
427
                        e = 24;
428
                        coef[i] = 0;
429
                    }
430
                    av_assert2(e >= 0);
431
                }
432
                exp[i] = e;
433
            }
434
        }
435
    }
436
}
437

    
438

    
439
/**
440
 * Exponent Difference Threshold.
441
 * New exponents are sent if their SAD exceed this number.
442
 */
443
#define EXP_DIFF_THRESHOLD 500
444

    
445

    
446
/**
447
 * Calculate exponent strategies for all blocks in a single channel.
448
 */
449
static void compute_exp_strategy_ch(AC3EncodeContext *s, uint8_t *exp_strategy,
450
                                    uint8_t *exp)
451
{
452
    int blk, blk1;
453
    int exp_diff;
454

    
455
    /* estimate if the exponent variation & decide if they should be
456
       reused in the next frame */
457
    exp_strategy[0] = EXP_NEW;
458
    exp += AC3_MAX_COEFS;
459
    for (blk = 1; blk < AC3_MAX_BLOCKS; blk++) {
460
        exp_diff = s->dsp.sad[0](NULL, exp, exp - AC3_MAX_COEFS, 16, 16);
461
        if (exp_diff > EXP_DIFF_THRESHOLD)
462
            exp_strategy[blk] = EXP_NEW;
463
        else
464
            exp_strategy[blk] = EXP_REUSE;
465
        exp += AC3_MAX_COEFS;
466
    }
467

    
468
    /* now select the encoding strategy type : if exponents are often
469
       recoded, we use a coarse encoding */
470
    blk = 0;
471
    while (blk < AC3_MAX_BLOCKS) {
472
        blk1 = blk + 1;
473
        while (blk1 < AC3_MAX_BLOCKS && exp_strategy[blk1] == EXP_REUSE)
474
            blk1++;
475
        switch (blk1 - blk) {
476
        case 1:  exp_strategy[blk] = EXP_D45; break;
477
        case 2:
478
        case 3:  exp_strategy[blk] = EXP_D25; break;
479
        default: exp_strategy[blk] = EXP_D15; break;
480
        }
481
        blk = blk1;
482
    }
483
}
484

    
485

    
486
/**
487
 * Calculate exponent strategies for all channels.
488
 * Array arrangement is reversed to simplify the per-channel calculation.
489
 */
490
static void compute_exp_strategy(AC3EncodeContext *s)
491
{
492
    int ch, blk;
493

    
494
    for (ch = 0; ch < s->fbw_channels; ch++) {
495
        compute_exp_strategy_ch(s, s->exp_strategy[ch], s->blocks[0].exp[ch]);
496
    }
497
    if (s->lfe_on) {
498
        ch = s->lfe_channel;
499
        s->exp_strategy[ch][0] = EXP_D15;
500
        for (blk = 1; blk < AC3_MAX_BLOCKS; blk++)
501
            s->exp_strategy[ch][blk] = EXP_REUSE;
502
    }
503
}
504

    
505

    
506
/**
507
 * Update the exponents so that they are the ones the decoder will decode.
508
 */
509
static void encode_exponents_blk_ch(uint8_t *exp, int nb_exps, int exp_strategy)
510
{
511
    int nb_groups, i, k;
512

    
513
    nb_groups = exponent_group_tab[exp_strategy-1][nb_exps] * 3;
514

    
515
    /* for each group, compute the minimum exponent */
516
    switch(exp_strategy) {
517
    case EXP_D25:
518
        for (i = 1, k = 1; i <= nb_groups; i++) {
519
            uint8_t exp_min = exp[k];
520
            if (exp[k+1] < exp_min)
521
                exp_min = exp[k+1];
522
            exp[i] = exp_min;
523
            k += 2;
524
        }
525
        break;
526
    case EXP_D45:
527
        for (i = 1, k = 1; i <= nb_groups; i++) {
528
            uint8_t exp_min = exp[k];
529
            if (exp[k+1] < exp_min)
530
                exp_min = exp[k+1];
531
            if (exp[k+2] < exp_min)
532
                exp_min = exp[k+2];
533
            if (exp[k+3] < exp_min)
534
                exp_min = exp[k+3];
535
            exp[i] = exp_min;
536
            k += 4;
537
        }
538
        break;
539
    }
540

    
541
    /* constraint for DC exponent */
542
    if (exp[0] > 15)
543
        exp[0] = 15;
544

    
545
    /* decrease the delta between each groups to within 2 so that they can be
546
       differentially encoded */
547
    for (i = 1; i <= nb_groups; i++)
548
        exp[i] = FFMIN(exp[i], exp[i-1] + 2);
549
    i--;
550
    while (--i >= 0)
551
        exp[i] = FFMIN(exp[i], exp[i+1] + 2);
552

    
553
    /* now we have the exponent values the decoder will see */
554
    switch (exp_strategy) {
555
    case EXP_D25:
556
        for (i = nb_groups, k = nb_groups * 2; i > 0; i--) {
557
            uint8_t exp1 = exp[i];
558
            exp[k--] = exp1;
559
            exp[k--] = exp1;
560
        }
561
        break;
562
    case EXP_D45:
563
        for (i = nb_groups, k = nb_groups * 4; i > 0; i--) {
564
            exp[k] = exp[k-1] = exp[k-2] = exp[k-3] = exp[i];
565
            k -= 4;
566
        }
567
        break;
568
    }
569
}
570

    
571

    
572
/**
573
 * Encode exponents from original extracted form to what the decoder will see.
574
 * This copies and groups exponents based on exponent strategy and reduces
575
 * deltas between adjacent exponent groups so that they can be differentially
576
 * encoded.
577
 */
578
static void encode_exponents(AC3EncodeContext *s)
579
{
580
    int blk, blk1, ch;
581
    uint8_t *exp, *exp1, *exp_strategy;
582
    int nb_coefs, num_reuse_blocks;
583

    
584
    for (ch = 0; ch < s->channels; ch++) {
585
        exp          = s->blocks[0].exp[ch];
586
        exp_strategy = s->exp_strategy[ch];
587
        nb_coefs     = s->nb_coefs[ch];
588

    
589
        blk = 0;
590
        while (blk < AC3_MAX_BLOCKS) {
591
            blk1 = blk + 1;
592

    
593
            /* count the number of EXP_REUSE blocks after the current block */
594
            while (blk1 < AC3_MAX_BLOCKS && exp_strategy[blk1] == EXP_REUSE)
595
                blk1++;
596
            num_reuse_blocks = blk1 - blk - 1;
597

    
598
            /* for the EXP_REUSE case we select the min of the exponents */
599
            s->ac3dsp.ac3_exponent_min(exp, num_reuse_blocks, nb_coefs);
600

    
601
            encode_exponents_blk_ch(exp, nb_coefs, exp_strategy[blk]);
602

    
603
            /* copy encoded exponents for reuse case */
604
            exp1 = exp + AC3_MAX_COEFS;
605
            while (blk < blk1-1) {
606
                memcpy(exp1, exp, nb_coefs * sizeof(*exp));
607
                exp1 += AC3_MAX_COEFS;
608
                blk++;
609
            }
610
            blk = blk1;
611
            exp = exp1;
612
        }
613
    }
614
}
615

    
616

    
617
/**
618
 * Group exponents.
619
 * 3 delta-encoded exponents are in each 7-bit group. The number of groups
620
 * varies depending on exponent strategy and bandwidth.
621
 */
622
static void group_exponents(AC3EncodeContext *s)
623
{
624
    int blk, ch, i;
625
    int group_size, nb_groups, bit_count;
626
    uint8_t *p;
627
    int delta0, delta1, delta2;
628
    int exp0, exp1;
629

    
630
    bit_count = 0;
631
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
632
        AC3Block *block = &s->blocks[blk];
633
        for (ch = 0; ch < s->channels; ch++) {
634
            int exp_strategy = s->exp_strategy[ch][blk];
635
            if (exp_strategy == EXP_REUSE)
636
                continue;
637
            group_size = exp_strategy + (exp_strategy == EXP_D45);
638
            nb_groups = exponent_group_tab[exp_strategy-1][s->nb_coefs[ch]];
639
            bit_count += 4 + (nb_groups * 7);
640
            p = block->exp[ch];
641

    
642
            /* DC exponent */
643
            exp1 = *p++;
644
            block->grouped_exp[ch][0] = exp1;
645

    
646
            /* remaining exponents are delta encoded */
647
            for (i = 1; i <= nb_groups; i++) {
648
                /* merge three delta in one code */
649
                exp0   = exp1;
650
                exp1   = p[0];
651
                p     += group_size;
652
                delta0 = exp1 - exp0 + 2;
653
                av_assert2(delta0 >= 0 && delta0 <= 4);
654

    
655
                exp0   = exp1;
656
                exp1   = p[0];
657
                p     += group_size;
658
                delta1 = exp1 - exp0 + 2;
659
                av_assert2(delta1 >= 0 && delta1 <= 4);
660

    
661
                exp0   = exp1;
662
                exp1   = p[0];
663
                p     += group_size;
664
                delta2 = exp1 - exp0 + 2;
665
                av_assert2(delta2 >= 0 && delta2 <= 4);
666

    
667
                block->grouped_exp[ch][i] = ((delta0 * 5 + delta1) * 5) + delta2;
668
            }
669
        }
670
    }
671

    
672
    s->exponent_bits = bit_count;
673
}
674

    
675

    
676
/**
677
 * Calculate final exponents from the supplied MDCT coefficients and exponent shift.
678
 * Extract exponents from MDCT coefficients, calculate exponent strategies,
679
 * and encode final exponents.
680
 */
681
static void process_exponents(AC3EncodeContext *s)
682
{
683
    extract_exponents(s);
684

    
685
    compute_exp_strategy(s);
686

    
687
    encode_exponents(s);
688

    
689
    group_exponents(s);
690

    
691
    emms_c();
692
}
693

    
694

    
695
/**
696
 * Count frame bits that are based solely on fixed parameters.
697
 * This only has to be run once when the encoder is initialized.
698
 */
699
static void count_frame_bits_fixed(AC3EncodeContext *s)
700
{
701
    static const int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
702
    int blk;
703
    int frame_bits;
704

    
705
    /* assumptions:
706
     *   no dynamic range codes
707
     *   no channel coupling
708
     *   bit allocation parameters do not change between blocks
709
     *   SNR offsets do not change between blocks
710
     *   no delta bit allocation
711
     *   no skipped data
712
     *   no auxilliary data
713
     */
714

    
715
    /* header size */
716
    frame_bits = 65;
717
    frame_bits += frame_bits_inc[s->channel_mode];
718

    
719
    /* audio blocks */
720
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
721
        frame_bits += s->fbw_channels * 2 + 2; /* blksw * c, dithflag * c, dynrnge, cplstre */
722
        if (s->channel_mode == AC3_CHMODE_STEREO) {
723
            frame_bits++; /* rematstr */
724
        }
725
        frame_bits += 2 * s->fbw_channels; /* chexpstr[2] * c */
726
        if (s->lfe_on)
727
            frame_bits++; /* lfeexpstr */
728
        frame_bits++; /* baie */
729
        frame_bits++; /* snr */
730
        frame_bits += 2; /* delta / skip */
731
    }
732
    frame_bits++; /* cplinu for block 0 */
733
    /* bit alloc info */
734
    /* sdcycod[2], fdcycod[2], sgaincod[2], dbpbcod[2], floorcod[3] */
735
    /* csnroffset[6] */
736
    /* (fsnoffset[4] + fgaincod[4]) * c */
737
    frame_bits += 2*4 + 3 + 6 + s->channels * (4 + 3);
738

    
739
    /* auxdatae, crcrsv */
740
    frame_bits += 2;
741

    
742
    /* CRC */
743
    frame_bits += 16;
744

    
745
    s->frame_bits_fixed = frame_bits;
746
}
747

    
748

    
749
/**
750
 * Initialize bit allocation.
751
 * Set default parameter codes and calculate parameter values.
752
 */
753
static void bit_alloc_init(AC3EncodeContext *s)
754
{
755
    int ch;
756

    
757
    /* init default parameters */
758
    s->slow_decay_code = 2;
759
    s->fast_decay_code = 1;
760
    s->slow_gain_code  = 1;
761
    s->db_per_bit_code = 3;
762
    s->floor_code      = 7;
763
    for (ch = 0; ch < s->channels; ch++)
764
        s->fast_gain_code[ch] = 4;
765

    
766
    /* initial snr offset */
767
    s->coarse_snr_offset = 40;
768

    
769
    /* compute real values */
770
    /* currently none of these values change during encoding, so we can just
771
       set them once at initialization */
772
    s->bit_alloc.slow_decay = ff_ac3_slow_decay_tab[s->slow_decay_code] >> s->bit_alloc.sr_shift;
773
    s->bit_alloc.fast_decay = ff_ac3_fast_decay_tab[s->fast_decay_code] >> s->bit_alloc.sr_shift;
774
    s->bit_alloc.slow_gain  = ff_ac3_slow_gain_tab[s->slow_gain_code];
775
    s->bit_alloc.db_per_bit = ff_ac3_db_per_bit_tab[s->db_per_bit_code];
776
    s->bit_alloc.floor      = ff_ac3_floor_tab[s->floor_code];
777

    
778
    count_frame_bits_fixed(s);
779
}
780

    
781

    
782
/**
783
 * Count the bits used to encode the frame, minus exponents and mantissas.
784
 * Bits based on fixed parameters have already been counted, so now we just
785
 * have to add the bits based on parameters that change during encoding.
786
 */
787
static void count_frame_bits(AC3EncodeContext *s)
788
{
789
    int blk, ch;
790
    int frame_bits = 0;
791

    
792
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
793
        /* stereo rematrixing */
794
        if (s->channel_mode == AC3_CHMODE_STEREO &&
795
            s->blocks[blk].new_rematrixing_strategy) {
796
            frame_bits += s->num_rematrixing_bands;
797
        }
798

    
799
        for (ch = 0; ch < s->fbw_channels; ch++) {
800
            if (s->exp_strategy[ch][blk] != EXP_REUSE)
801
                frame_bits += 6 + 2; /* chbwcod[6], gainrng[2] */
802
        }
803
    }
804
    s->frame_bits = s->frame_bits_fixed + frame_bits;
805
}
806

    
807

    
808
/**
809
 * Calculate the number of bits needed to encode a set of mantissas.
810
 */
811
static int compute_mantissa_size(int mant_cnt[5], uint8_t *bap, int nb_coefs)
812
{
813
    int bits, b, i;
814

    
815
    bits = 0;
816
    for (i = 0; i < nb_coefs; i++) {
817
        b = bap[i];
818
        if (b <= 4) {
819
            // bap=1 to bap=4 will be counted in compute_mantissa_size_final
820
            mant_cnt[b]++;
821
        } else if (b <= 13) {
822
            // bap=5 to bap=13 use (bap-1) bits
823
            bits += b - 1;
824
        } else {
825
            // bap=14 uses 14 bits and bap=15 uses 16 bits
826
            bits += (b == 14) ? 14 : 16;
827
        }
828
    }
829
    return bits;
830
}
831

    
832

    
833
/**
834
 * Finalize the mantissa bit count by adding in the grouped mantissas.
835
 */
836
static int compute_mantissa_size_final(int mant_cnt[5])
837
{
838
    // bap=1 : 3 mantissas in 5 bits
839
    int bits = (mant_cnt[1] / 3) * 5;
840
    // bap=2 : 3 mantissas in 7 bits
841
    // bap=4 : 2 mantissas in 7 bits
842
    bits += ((mant_cnt[2] / 3) + (mant_cnt[4] >> 1)) * 7;
843
    // bap=3 : each mantissa is 3 bits
844
    bits += mant_cnt[3] * 3;
845
    return bits;
846
}
847

    
848

    
849
/**
850
 * Calculate masking curve based on the final exponents.
851
 * Also calculate the power spectral densities to use in future calculations.
852
 */
853
static void bit_alloc_masking(AC3EncodeContext *s)
854
{
855
    int blk, ch;
856

    
857
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
858
        AC3Block *block = &s->blocks[blk];
859
        for (ch = 0; ch < s->channels; ch++) {
860
            /* We only need psd and mask for calculating bap.
861
               Since we currently do not calculate bap when exponent
862
               strategy is EXP_REUSE we do not need to calculate psd or mask. */
863
            if (s->exp_strategy[ch][blk] != EXP_REUSE) {
864
                ff_ac3_bit_alloc_calc_psd(block->exp[ch], 0,
865
                                          s->nb_coefs[ch],
866
                                          block->psd[ch], block->band_psd[ch]);
867
                ff_ac3_bit_alloc_calc_mask(&s->bit_alloc, block->band_psd[ch],
868
                                           0, s->nb_coefs[ch],
869
                                           ff_ac3_fast_gain_tab[s->fast_gain_code[ch]],
870
                                           ch == s->lfe_channel,
871
                                           DBA_NONE, 0, NULL, NULL, NULL,
872
                                           block->mask[ch]);
873
            }
874
        }
875
    }
876
}
877

    
878

    
879
/**
880
 * Ensure that bap for each block and channel point to the current bap_buffer.
881
 * They may have been switched during the bit allocation search.
882
 */
883
static void reset_block_bap(AC3EncodeContext *s)
884
{
885
    int blk, ch;
886
    if (s->blocks[0].bap[0] == s->bap_buffer)
887
        return;
888
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
889
        for (ch = 0; ch < s->channels; ch++) {
890
            s->blocks[blk].bap[ch] = &s->bap_buffer[AC3_MAX_COEFS * (blk * s->channels + ch)];
891
        }
892
    }
893
}
894

    
895

    
896
/**
897
 * Run the bit allocation with a given SNR offset.
898
 * This calculates the bit allocation pointers that will be used to determine
899
 * the quantization of each mantissa.
900
 * @return the number of bits needed for mantissas if the given SNR offset is
901
 *         is used.
902
 */
903
static int bit_alloc(AC3EncodeContext *s, int snr_offset)
904
{
905
    int blk, ch;
906
    int mantissa_bits;
907
    int mant_cnt[5];
908

    
909
    snr_offset = (snr_offset - 240) << 2;
910

    
911
    reset_block_bap(s);
912
    mantissa_bits = 0;
913
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
914
        AC3Block *block = &s->blocks[blk];
915
        // initialize grouped mantissa counts. these are set so that they are
916
        // padded to the next whole group size when bits are counted in
917
        // compute_mantissa_size_final
918
        mant_cnt[0] = mant_cnt[3] = 0;
919
        mant_cnt[1] = mant_cnt[2] = 2;
920
        mant_cnt[4] = 1;
921
        for (ch = 0; ch < s->channels; ch++) {
922
            /* Currently the only bit allocation parameters which vary across
923
               blocks within a frame are the exponent values.  We can take
924
               advantage of that by reusing the bit allocation pointers
925
               whenever we reuse exponents. */
926
            if (s->exp_strategy[ch][blk] == EXP_REUSE) {
927
                memcpy(block->bap[ch], s->blocks[blk-1].bap[ch], AC3_MAX_COEFS);
928
            } else {
929
                ff_ac3_bit_alloc_calc_bap(block->mask[ch], block->psd[ch], 0,
930
                                          s->nb_coefs[ch], snr_offset,
931
                                          s->bit_alloc.floor, ff_ac3_bap_tab,
932
                                          block->bap[ch]);
933
            }
934
            mantissa_bits += compute_mantissa_size(mant_cnt, block->bap[ch], s->nb_coefs[ch]);
935
        }
936
        mantissa_bits += compute_mantissa_size_final(mant_cnt);
937
    }
938
    return mantissa_bits;
939
}
940

    
941

    
942
/**
943
 * Constant bitrate bit allocation search.
944
 * Find the largest SNR offset that will allow data to fit in the frame.
945
 */
946
static int cbr_bit_allocation(AC3EncodeContext *s)
947
{
948
    int ch;
949
    int bits_left;
950
    int snr_offset, snr_incr;
951

    
952
    bits_left = 8 * s->frame_size - (s->frame_bits + s->exponent_bits);
953
    av_assert2(bits_left >= 0);
954

    
955
    snr_offset = s->coarse_snr_offset << 4;
956

    
957
    /* if previous frame SNR offset was 1023, check if current frame can also
958
       use SNR offset of 1023. if so, skip the search. */
959
    if ((snr_offset | s->fine_snr_offset[0]) == 1023) {
960
        if (bit_alloc(s, 1023) <= bits_left)
961
            return 0;
962
    }
963

    
964
    while (snr_offset >= 0 &&
965
           bit_alloc(s, snr_offset) > bits_left) {
966
        snr_offset -= 64;
967
    }
968
    if (snr_offset < 0)
969
        return AVERROR(EINVAL);
970

    
971
    FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
972
    for (snr_incr = 64; snr_incr > 0; snr_incr >>= 2) {
973
        while (snr_offset + snr_incr <= 1023 &&
974
               bit_alloc(s, snr_offset + snr_incr) <= bits_left) {
975
            snr_offset += snr_incr;
976
            FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
977
        }
978
    }
979
    FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
980
    reset_block_bap(s);
981

    
982
    s->coarse_snr_offset = snr_offset >> 4;
983
    for (ch = 0; ch < s->channels; ch++)
984
        s->fine_snr_offset[ch] = snr_offset & 0xF;
985

    
986
    return 0;
987
}
988

    
989

    
990
/**
991
 * Downgrade exponent strategies to reduce the bits used by the exponents.
992
 * This is a fallback for when bit allocation fails with the normal exponent
993
 * strategies.  Each time this function is run it only downgrades the
994
 * strategy in 1 channel of 1 block.
995
 * @return non-zero if downgrade was unsuccessful
996
 */
997
static int downgrade_exponents(AC3EncodeContext *s)
998
{
999
    int ch, blk;
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_D15) {
1004
                s->exp_strategy[ch][blk] = EXP_D25;
1005
                return 0;
1006
            }
1007
        }
1008
    }
1009
    for (ch = 0; ch < s->fbw_channels; ch++) {
1010
        for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
1011
            if (s->exp_strategy[ch][blk] == EXP_D25) {
1012
                s->exp_strategy[ch][blk] = EXP_D45;
1013
                return 0;
1014
            }
1015
        }
1016
    }
1017
    for (ch = 0; ch < s->fbw_channels; ch++) {
1018
        /* block 0 cannot reuse exponents, so only downgrade D45 to REUSE if
1019
           the block number > 0 */
1020
        for (blk = AC3_MAX_BLOCKS-1; blk > 0; blk--) {
1021
            if (s->exp_strategy[ch][blk] > EXP_REUSE) {
1022
                s->exp_strategy[ch][blk] = EXP_REUSE;
1023
                return 0;
1024
            }
1025
        }
1026
    }
1027
    return -1;
1028
}
1029

    
1030

    
1031
/**
1032
 * Reduce the bandwidth to reduce the number of bits used for a given SNR offset.
1033
 * This is a second fallback for when bit allocation still fails after exponents
1034
 * have been downgraded.
1035
 * @return non-zero if bandwidth reduction was unsuccessful
1036
 */
1037
static int reduce_bandwidth(AC3EncodeContext *s, int min_bw_code)
1038
{
1039
    int ch;
1040

    
1041
    if (s->bandwidth_code[0] > min_bw_code) {
1042
        for (ch = 0; ch < s->fbw_channels; ch++) {
1043
            s->bandwidth_code[ch]--;
1044
            s->nb_coefs[ch] = s->bandwidth_code[ch] * 3 + 73;
1045
        }
1046
        return 0;
1047
    }
1048
    return -1;
1049
}
1050

    
1051

    
1052
/**
1053
 * Perform bit allocation search.
1054
 * Finds the SNR offset value that maximizes quality and fits in the specified
1055
 * frame size.  Output is the SNR offset and a set of bit allocation pointers
1056
 * used to quantize the mantissas.
1057
 */
1058
static int compute_bit_allocation(AC3EncodeContext *s)
1059
{
1060
    int ret;
1061

    
1062
    count_frame_bits(s);
1063

    
1064
    bit_alloc_masking(s);
1065

    
1066
    ret = cbr_bit_allocation(s);
1067
    while (ret) {
1068
        /* fallback 1: downgrade exponents */
1069
        if (!downgrade_exponents(s)) {
1070
            extract_exponents(s);
1071
            encode_exponents(s);
1072
            group_exponents(s);
1073
            ret = compute_bit_allocation(s);
1074
            continue;
1075
        }
1076

    
1077
        /* fallback 2: reduce bandwidth */
1078
        /* only do this if the user has not specified a specific cutoff
1079
           frequency */
1080
        if (!s->cutoff && !reduce_bandwidth(s, 0)) {
1081
            process_exponents(s);
1082
            ret = compute_bit_allocation(s);
1083
            continue;
1084
        }
1085

    
1086
        /* fallbacks were not enough... */
1087
        break;
1088
    }
1089

    
1090
    return ret;
1091
}
1092

    
1093

    
1094
/**
1095
 * Symmetric quantization on 'levels' levels.
1096
 */
1097
static inline int sym_quant(int c, int e, int levels)
1098
{
1099
    int v = ((((levels * c) >> (24 - e)) + 1) >> 1) + (levels >> 1);
1100
    av_assert2(v >= 0 && v < levels);
1101
    return v;
1102
}
1103

    
1104

    
1105
/**
1106
 * Asymmetric quantization on 2^qbits levels.
1107
 */
1108
static inline int asym_quant(int c, int e, int qbits)
1109
{
1110
    int lshift, m, v;
1111

    
1112
    lshift = e + qbits - 24;
1113
    if (lshift >= 0)
1114
        v = c << lshift;
1115
    else
1116
        v = c >> (-lshift);
1117
    /* rounding */
1118
    v = (v + 1) >> 1;
1119
    m = (1 << (qbits-1));
1120
    if (v >= m)
1121
        v = m - 1;
1122
    av_assert2(v >= -m);
1123
    return v & ((1 << qbits)-1);
1124
}
1125

    
1126

    
1127
/**
1128
 * Quantize a set of mantissas for a single channel in a single block.
1129
 */
1130
static void quantize_mantissas_blk_ch(AC3EncodeContext *s, int32_t *fixed_coef,
1131
                                      uint8_t *exp,
1132
                                      uint8_t *bap, uint16_t *qmant, int n)
1133
{
1134
    int i;
1135

    
1136
    for (i = 0; i < n; i++) {
1137
        int v;
1138
        int c = fixed_coef[i];
1139
        int e = exp[i];
1140
        int b = bap[i];
1141
        switch (b) {
1142
        case 0:
1143
            v = 0;
1144
            break;
1145
        case 1:
1146
            v = sym_quant(c, e, 3);
1147
            switch (s->mant1_cnt) {
1148
            case 0:
1149
                s->qmant1_ptr = &qmant[i];
1150
                v = 9 * v;
1151
                s->mant1_cnt = 1;
1152
                break;
1153
            case 1:
1154
                *s->qmant1_ptr += 3 * v;
1155
                s->mant1_cnt = 2;
1156
                v = 128;
1157
                break;
1158
            default:
1159
                *s->qmant1_ptr += v;
1160
                s->mant1_cnt = 0;
1161
                v = 128;
1162
                break;
1163
            }
1164
            break;
1165
        case 2:
1166
            v = sym_quant(c, e, 5);
1167
            switch (s->mant2_cnt) {
1168
            case 0:
1169
                s->qmant2_ptr = &qmant[i];
1170
                v = 25 * v;
1171
                s->mant2_cnt = 1;
1172
                break;
1173
            case 1:
1174
                *s->qmant2_ptr += 5 * v;
1175
                s->mant2_cnt = 2;
1176
                v = 128;
1177
                break;
1178
            default:
1179
                *s->qmant2_ptr += v;
1180
                s->mant2_cnt = 0;
1181
                v = 128;
1182
                break;
1183
            }
1184
            break;
1185
        case 3:
1186
            v = sym_quant(c, e, 7);
1187
            break;
1188
        case 4:
1189
            v = sym_quant(c, e, 11);
1190
            switch (s->mant4_cnt) {
1191
            case 0:
1192
                s->qmant4_ptr = &qmant[i];
1193
                v = 11 * v;
1194
                s->mant4_cnt = 1;
1195
                break;
1196
            default:
1197
                *s->qmant4_ptr += v;
1198
                s->mant4_cnt = 0;
1199
                v = 128;
1200
                break;
1201
            }
1202
            break;
1203
        case 5:
1204
            v = sym_quant(c, e, 15);
1205
            break;
1206
        case 14:
1207
            v = asym_quant(c, e, 14);
1208
            break;
1209
        case 15:
1210
            v = asym_quant(c, e, 16);
1211
            break;
1212
        default:
1213
            v = asym_quant(c, e, b - 1);
1214
            break;
1215
        }
1216
        qmant[i] = v;
1217
    }
1218
}
1219

    
1220

    
1221
/**
1222
 * Quantize mantissas using coefficients, exponents, and bit allocation pointers.
1223
 */
1224
static void quantize_mantissas(AC3EncodeContext *s)
1225
{
1226
    int blk, ch;
1227

    
1228

    
1229
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1230
        AC3Block *block = &s->blocks[blk];
1231
        s->mant1_cnt  = s->mant2_cnt  = s->mant4_cnt  = 0;
1232
        s->qmant1_ptr = s->qmant2_ptr = s->qmant4_ptr = NULL;
1233

    
1234
        for (ch = 0; ch < s->channels; ch++) {
1235
            quantize_mantissas_blk_ch(s, block->fixed_coef[ch],
1236
                                      block->exp[ch], block->bap[ch],
1237
                                      block->qmant[ch], s->nb_coefs[ch]);
1238
        }
1239
    }
1240
}
1241

    
1242

    
1243
/**
1244
 * Write the AC-3 frame header to the output bitstream.
1245
 */
1246
static void output_frame_header(AC3EncodeContext *s)
1247
{
1248
    put_bits(&s->pb, 16, 0x0b77);   /* frame header */
1249
    put_bits(&s->pb, 16, 0);        /* crc1: will be filled later */
1250
    put_bits(&s->pb, 2,  s->bit_alloc.sr_code);
1251
    put_bits(&s->pb, 6,  s->frame_size_code + (s->frame_size - s->frame_size_min) / 2);
1252
    put_bits(&s->pb, 5,  s->bitstream_id);
1253
    put_bits(&s->pb, 3,  s->bitstream_mode);
1254
    put_bits(&s->pb, 3,  s->channel_mode);
1255
    if ((s->channel_mode & 0x01) && s->channel_mode != AC3_CHMODE_MONO)
1256
        put_bits(&s->pb, 2, 1);     /* XXX -4.5 dB */
1257
    if (s->channel_mode & 0x04)
1258
        put_bits(&s->pb, 2, 1);     /* XXX -6 dB */
1259
    if (s->channel_mode == AC3_CHMODE_STEREO)
1260
        put_bits(&s->pb, 2, 0);     /* surround not indicated */
1261
    put_bits(&s->pb, 1, s->lfe_on); /* LFE */
1262
    put_bits(&s->pb, 5, 31);        /* dialog norm: -31 db */
1263
    put_bits(&s->pb, 1, 0);         /* no compression control word */
1264
    put_bits(&s->pb, 1, 0);         /* no lang code */
1265
    put_bits(&s->pb, 1, 0);         /* no audio production info */
1266
    put_bits(&s->pb, 1, 0);         /* no copyright */
1267
    put_bits(&s->pb, 1, 1);         /* original bitstream */
1268
    put_bits(&s->pb, 1, 0);         /* no time code 1 */
1269
    put_bits(&s->pb, 1, 0);         /* no time code 2 */
1270
    put_bits(&s->pb, 1, 0);         /* no additional bit stream info */
1271
}
1272

    
1273

    
1274
/**
1275
 * Write one audio block to the output bitstream.
1276
 */
1277
static void output_audio_block(AC3EncodeContext *s, int blk)
1278
{
1279
    int ch, i, baie, rbnd;
1280
    AC3Block *block = &s->blocks[blk];
1281

    
1282
    /* block switching */
1283
    for (ch = 0; ch < s->fbw_channels; ch++)
1284
        put_bits(&s->pb, 1, 0);
1285

    
1286
    /* dither flags */
1287
    for (ch = 0; ch < s->fbw_channels; ch++)
1288
        put_bits(&s->pb, 1, 1);
1289

    
1290
    /* dynamic range codes */
1291
    put_bits(&s->pb, 1, 0);
1292

    
1293
    /* channel coupling */
1294
    if (!blk) {
1295
        put_bits(&s->pb, 1, 1); /* coupling strategy present */
1296
        put_bits(&s->pb, 1, 0); /* no coupling strategy */
1297
    } else {
1298
        put_bits(&s->pb, 1, 0); /* no new coupling strategy */
1299
    }
1300

    
1301
    /* stereo rematrixing */
1302
    if (s->channel_mode == AC3_CHMODE_STEREO) {
1303
        put_bits(&s->pb, 1, block->new_rematrixing_strategy);
1304
        if (block->new_rematrixing_strategy) {
1305
            /* rematrixing flags */
1306
            for (rbnd = 0; rbnd < s->num_rematrixing_bands; rbnd++)
1307
                put_bits(&s->pb, 1, block->rematrixing_flags[rbnd]);
1308
        }
1309
    }
1310

    
1311
    /* exponent strategy */
1312
    for (ch = 0; ch < s->fbw_channels; ch++)
1313
        put_bits(&s->pb, 2, s->exp_strategy[ch][blk]);
1314
    if (s->lfe_on)
1315
        put_bits(&s->pb, 1, s->exp_strategy[s->lfe_channel][blk]);
1316

    
1317
    /* bandwidth */
1318
    for (ch = 0; ch < s->fbw_channels; ch++) {
1319
        if (s->exp_strategy[ch][blk] != EXP_REUSE)
1320
            put_bits(&s->pb, 6, s->bandwidth_code[ch]);
1321
    }
1322

    
1323
    /* exponents */
1324
    for (ch = 0; ch < s->channels; ch++) {
1325
        int nb_groups;
1326

    
1327
        if (s->exp_strategy[ch][blk] == EXP_REUSE)
1328
            continue;
1329

    
1330
        /* DC exponent */
1331
        put_bits(&s->pb, 4, block->grouped_exp[ch][0]);
1332

    
1333
        /* exponent groups */
1334
        nb_groups = exponent_group_tab[s->exp_strategy[ch][blk]-1][s->nb_coefs[ch]];
1335
        for (i = 1; i <= nb_groups; i++)
1336
            put_bits(&s->pb, 7, block->grouped_exp[ch][i]);
1337

    
1338
        /* gain range info */
1339
        if (ch != s->lfe_channel)
1340
            put_bits(&s->pb, 2, 0);
1341
    }
1342

    
1343
    /* bit allocation info */
1344
    baie = (blk == 0);
1345
    put_bits(&s->pb, 1, baie);
1346
    if (baie) {
1347
        put_bits(&s->pb, 2, s->slow_decay_code);
1348
        put_bits(&s->pb, 2, s->fast_decay_code);
1349
        put_bits(&s->pb, 2, s->slow_gain_code);
1350
        put_bits(&s->pb, 2, s->db_per_bit_code);
1351
        put_bits(&s->pb, 3, s->floor_code);
1352
    }
1353

    
1354
    /* snr offset */
1355
    put_bits(&s->pb, 1, baie);
1356
    if (baie) {
1357
        put_bits(&s->pb, 6, s->coarse_snr_offset);
1358
        for (ch = 0; ch < s->channels; ch++) {
1359
            put_bits(&s->pb, 4, s->fine_snr_offset[ch]);
1360
            put_bits(&s->pb, 3, s->fast_gain_code[ch]);
1361
        }
1362
    }
1363

    
1364
    put_bits(&s->pb, 1, 0); /* no delta bit allocation */
1365
    put_bits(&s->pb, 1, 0); /* no data to skip */
1366

    
1367
    /* mantissas */
1368
    for (ch = 0; ch < s->channels; ch++) {
1369
        int b, q;
1370
        for (i = 0; i < s->nb_coefs[ch]; i++) {
1371
            q = block->qmant[ch][i];
1372
            b = block->bap[ch][i];
1373
            switch (b) {
1374
            case 0:                                         break;
1375
            case 1: if (q != 128) put_bits(&s->pb,   5, q); break;
1376
            case 2: if (q != 128) put_bits(&s->pb,   7, q); break;
1377
            case 3:               put_bits(&s->pb,   3, q); break;
1378
            case 4: if (q != 128) put_bits(&s->pb,   7, q); break;
1379
            case 14:              put_bits(&s->pb,  14, q); break;
1380
            case 15:              put_bits(&s->pb,  16, q); break;
1381
            default:              put_bits(&s->pb, b-1, q); break;
1382
            }
1383
        }
1384
    }
1385
}
1386

    
1387

    
1388
/** CRC-16 Polynomial */
1389
#define CRC16_POLY ((1 << 0) | (1 << 2) | (1 << 15) | (1 << 16))
1390

    
1391

    
1392
static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly)
1393
{
1394
    unsigned int c;
1395

    
1396
    c = 0;
1397
    while (a) {
1398
        if (a & 1)
1399
            c ^= b;
1400
        a = a >> 1;
1401
        b = b << 1;
1402
        if (b & (1 << 16))
1403
            b ^= poly;
1404
    }
1405
    return c;
1406
}
1407

    
1408

    
1409
static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly)
1410
{
1411
    unsigned int r;
1412
    r = 1;
1413
    while (n) {
1414
        if (n & 1)
1415
            r = mul_poly(r, a, poly);
1416
        a = mul_poly(a, a, poly);
1417
        n >>= 1;
1418
    }
1419
    return r;
1420
}
1421

    
1422

    
1423
/**
1424
 * Fill the end of the frame with 0's and compute the two CRCs.
1425
 */
1426
static void output_frame_end(AC3EncodeContext *s)
1427
{
1428
    const AVCRC *crc_ctx = av_crc_get_table(AV_CRC_16_ANSI);
1429
    int frame_size_58, pad_bytes, crc1, crc2_partial, crc2, crc_inv;
1430
    uint8_t *frame;
1431

    
1432
    frame_size_58 = ((s->frame_size >> 2) + (s->frame_size >> 4)) << 1;
1433

    
1434
    /* pad the remainder of the frame with zeros */
1435
    av_assert2(s->frame_size * 8 - put_bits_count(&s->pb) >= 18);
1436
    flush_put_bits(&s->pb);
1437
    frame = s->pb.buf;
1438
    pad_bytes = s->frame_size - (put_bits_ptr(&s->pb) - frame) - 2;
1439
    av_assert2(pad_bytes >= 0);
1440
    if (pad_bytes > 0)
1441
        memset(put_bits_ptr(&s->pb), 0, pad_bytes);
1442

    
1443
    /* compute crc1 */
1444
    /* this is not so easy because it is at the beginning of the data... */
1445
    crc1    = av_bswap16(av_crc(crc_ctx, 0, frame + 4, frame_size_58 - 4));
1446
    crc_inv = s->crc_inv[s->frame_size > s->frame_size_min];
1447
    crc1    = mul_poly(crc_inv, crc1, CRC16_POLY);
1448
    AV_WB16(frame + 2, crc1);
1449

    
1450
    /* compute crc2 */
1451
    crc2_partial = av_crc(crc_ctx, 0, frame + frame_size_58,
1452
                          s->frame_size - frame_size_58 - 3);
1453
    crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
1454
    /* ensure crc2 does not match sync word by flipping crcrsv bit if needed */
1455
    if (crc2 == 0x770B) {
1456
        frame[s->frame_size - 3] ^= 0x1;
1457
        crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
1458
    }
1459
    crc2 = av_bswap16(crc2);
1460
    AV_WB16(frame + s->frame_size - 2, crc2);
1461
}
1462

    
1463

    
1464
/**
1465
 * Write the frame to the output bitstream.
1466
 */
1467
static void output_frame(AC3EncodeContext *s, unsigned char *frame)
1468
{
1469
    int blk;
1470

    
1471
    init_put_bits(&s->pb, frame, AC3_MAX_CODED_FRAME_SIZE);
1472

    
1473
    output_frame_header(s);
1474

    
1475
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++)
1476
        output_audio_block(s, blk);
1477

    
1478
    output_frame_end(s);
1479
}
1480

    
1481

    
1482
/**
1483
 * Encode a single AC-3 frame.
1484
 */
1485
static int ac3_encode_frame(AVCodecContext *avctx, unsigned char *frame,
1486
                            int buf_size, void *data)
1487
{
1488
    AC3EncodeContext *s = avctx->priv_data;
1489
    const SampleType *samples = data;
1490
    int ret;
1491

    
1492
    if (s->bit_alloc.sr_code == 1)
1493
        adjust_frame_size(s);
1494

    
1495
    deinterleave_input_samples(s, samples);
1496

    
1497
    apply_mdct(s);
1498

    
1499
    scale_coefficients(s);
1500

    
1501
    compute_rematrixing_strategy(s);
1502

    
1503
    apply_rematrixing(s);
1504

    
1505
    process_exponents(s);
1506

    
1507
    ret = compute_bit_allocation(s);
1508
    if (ret) {
1509
        av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
1510
        return ret;
1511
    }
1512

    
1513
    quantize_mantissas(s);
1514

    
1515
    output_frame(s, frame);
1516

    
1517
    return s->frame_size;
1518
}
1519

    
1520

    
1521
/**
1522
 * Finalize encoding and free any memory allocated by the encoder.
1523
 */
1524
static av_cold int ac3_encode_close(AVCodecContext *avctx)
1525
{
1526
    int blk, ch;
1527
    AC3EncodeContext *s = avctx->priv_data;
1528

    
1529
    for (ch = 0; ch < s->channels; ch++)
1530
        av_freep(&s->planar_samples[ch]);
1531
    av_freep(&s->planar_samples);
1532
    av_freep(&s->bap_buffer);
1533
    av_freep(&s->bap1_buffer);
1534
    av_freep(&s->mdct_coef_buffer);
1535
    av_freep(&s->fixed_coef_buffer);
1536
    av_freep(&s->exp_buffer);
1537
    av_freep(&s->grouped_exp_buffer);
1538
    av_freep(&s->psd_buffer);
1539
    av_freep(&s->band_psd_buffer);
1540
    av_freep(&s->mask_buffer);
1541
    av_freep(&s->qmant_buffer);
1542
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1543
        AC3Block *block = &s->blocks[blk];
1544
        av_freep(&block->bap);
1545
        av_freep(&block->mdct_coef);
1546
        av_freep(&block->fixed_coef);
1547
        av_freep(&block->exp);
1548
        av_freep(&block->grouped_exp);
1549
        av_freep(&block->psd);
1550
        av_freep(&block->band_psd);
1551
        av_freep(&block->mask);
1552
        av_freep(&block->qmant);
1553
    }
1554

    
1555
    mdct_end(&s->mdct);
1556

    
1557
    av_freep(&avctx->coded_frame);
1558
    return 0;
1559
}
1560

    
1561

    
1562
/**
1563
 * Set channel information during initialization.
1564
 */
1565
static av_cold int set_channel_info(AC3EncodeContext *s, int channels,
1566
                                    int64_t *channel_layout)
1567
{
1568
    int ch_layout;
1569

    
1570
    if (channels < 1 || channels > AC3_MAX_CHANNELS)
1571
        return AVERROR(EINVAL);
1572
    if ((uint64_t)*channel_layout > 0x7FF)
1573
        return AVERROR(EINVAL);
1574
    ch_layout = *channel_layout;
1575
    if (!ch_layout)
1576
        ch_layout = avcodec_guess_channel_layout(channels, CODEC_ID_AC3, NULL);
1577
    if (av_get_channel_layout_nb_channels(ch_layout) != channels)
1578
        return AVERROR(EINVAL);
1579

    
1580
    s->lfe_on       = !!(ch_layout & AV_CH_LOW_FREQUENCY);
1581
    s->channels     = channels;
1582
    s->fbw_channels = channels - s->lfe_on;
1583
    s->lfe_channel  = s->lfe_on ? s->fbw_channels : -1;
1584
    if (s->lfe_on)
1585
        ch_layout -= AV_CH_LOW_FREQUENCY;
1586

    
1587
    switch (ch_layout) {
1588
    case AV_CH_LAYOUT_MONO:           s->channel_mode = AC3_CHMODE_MONO;   break;
1589
    case AV_CH_LAYOUT_STEREO:         s->channel_mode = AC3_CHMODE_STEREO; break;
1590
    case AV_CH_LAYOUT_SURROUND:       s->channel_mode = AC3_CHMODE_3F;     break;
1591
    case AV_CH_LAYOUT_2_1:            s->channel_mode = AC3_CHMODE_2F1R;   break;
1592
    case AV_CH_LAYOUT_4POINT0:        s->channel_mode = AC3_CHMODE_3F1R;   break;
1593
    case AV_CH_LAYOUT_QUAD:
1594
    case AV_CH_LAYOUT_2_2:            s->channel_mode = AC3_CHMODE_2F2R;   break;
1595
    case AV_CH_LAYOUT_5POINT0:
1596
    case AV_CH_LAYOUT_5POINT0_BACK:   s->channel_mode = AC3_CHMODE_3F2R;   break;
1597
    default:
1598
        return AVERROR(EINVAL);
1599
    }
1600

    
1601
    s->channel_map  = ff_ac3_enc_channel_map[s->channel_mode][s->lfe_on];
1602
    *channel_layout = ch_layout;
1603
    if (s->lfe_on)
1604
        *channel_layout |= AV_CH_LOW_FREQUENCY;
1605

    
1606
    return 0;
1607
}
1608

    
1609

    
1610
static av_cold int validate_options(AVCodecContext *avctx, AC3EncodeContext *s)
1611
{
1612
    int i, ret;
1613

    
1614
    /* validate channel layout */
1615
    if (!avctx->channel_layout) {
1616
        av_log(avctx, AV_LOG_WARNING, "No channel layout specified. The "
1617
                                      "encoder will guess the layout, but it "
1618
                                      "might be incorrect.\n");
1619
    }
1620
    ret = set_channel_info(s, avctx->channels, &avctx->channel_layout);
1621
    if (ret) {
1622
        av_log(avctx, AV_LOG_ERROR, "invalid channel layout\n");
1623
        return ret;
1624
    }
1625

    
1626
    /* validate sample rate */
1627
    for (i = 0; i < 9; i++) {
1628
        if ((ff_ac3_sample_rate_tab[i / 3] >> (i % 3)) == avctx->sample_rate)
1629
            break;
1630
    }
1631
    if (i == 9) {
1632
        av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1633
        return AVERROR(EINVAL);
1634
    }
1635
    s->sample_rate        = avctx->sample_rate;
1636
    s->bit_alloc.sr_shift = i % 3;
1637
    s->bit_alloc.sr_code  = i / 3;
1638

    
1639
    /* validate bit rate */
1640
    for (i = 0; i < 19; i++) {
1641
        if ((ff_ac3_bitrate_tab[i] >> s->bit_alloc.sr_shift)*1000 == avctx->bit_rate)
1642
            break;
1643
    }
1644
    if (i == 19) {
1645
        av_log(avctx, AV_LOG_ERROR, "invalid bit rate\n");
1646
        return AVERROR(EINVAL);
1647
    }
1648
    s->bit_rate        = avctx->bit_rate;
1649
    s->frame_size_code = i << 1;
1650

    
1651
    /* validate cutoff */
1652
    if (avctx->cutoff < 0) {
1653
        av_log(avctx, AV_LOG_ERROR, "invalid cutoff frequency\n");
1654
        return AVERROR(EINVAL);
1655
    }
1656
    s->cutoff = avctx->cutoff;
1657
    if (s->cutoff > (s->sample_rate >> 1))
1658
        s->cutoff = s->sample_rate >> 1;
1659

    
1660
    /* validate audio service type / channels combination */
1661
    if ((avctx->audio_service_type == AV_AUDIO_SERVICE_TYPE_KARAOKE &&
1662
         avctx->channels == 1) ||
1663
        ((avctx->audio_service_type == AV_AUDIO_SERVICE_TYPE_COMMENTARY ||
1664
          avctx->audio_service_type == AV_AUDIO_SERVICE_TYPE_EMERGENCY  ||
1665
          avctx->audio_service_type == AV_AUDIO_SERVICE_TYPE_VOICE_OVER)
1666
         && avctx->channels > 1)) {
1667
        av_log(avctx, AV_LOG_ERROR, "invalid audio service type for the "
1668
                                    "specified number of channels\n");
1669
        return AVERROR(EINVAL);
1670
    }
1671

    
1672
    return 0;
1673
}
1674

    
1675

    
1676
/**
1677
 * Set bandwidth for all channels.
1678
 * The user can optionally supply a cutoff frequency. Otherwise an appropriate
1679
 * default value will be used.
1680
 */
1681
static av_cold void set_bandwidth(AC3EncodeContext *s)
1682
{
1683
    int ch, bw_code;
1684

    
1685
    if (s->cutoff) {
1686
        /* calculate bandwidth based on user-specified cutoff frequency */
1687
        int fbw_coeffs;
1688
        fbw_coeffs     = s->cutoff * 2 * AC3_MAX_COEFS / s->sample_rate;
1689
        bw_code        = av_clip((fbw_coeffs - 73) / 3, 0, 60);
1690
    } else {
1691
        /* use default bandwidth setting */
1692
        /* XXX: should compute the bandwidth according to the frame
1693
           size, so that we avoid annoying high frequency artifacts */
1694
        bw_code = 50;
1695
    }
1696

    
1697
    /* set number of coefficients for each channel */
1698
    for (ch = 0; ch < s->fbw_channels; ch++) {
1699
        s->bandwidth_code[ch] = bw_code;
1700
        s->nb_coefs[ch]       = bw_code * 3 + 73;
1701
    }
1702
    if (s->lfe_on)
1703
        s->nb_coefs[s->lfe_channel] = 7; /* LFE channel always has 7 coefs */
1704
}
1705

    
1706

    
1707
static av_cold int allocate_buffers(AVCodecContext *avctx)
1708
{
1709
    int blk, ch;
1710
    AC3EncodeContext *s = avctx->priv_data;
1711

    
1712
    FF_ALLOC_OR_GOTO(avctx, s->planar_samples, s->channels * sizeof(*s->planar_samples),
1713
                     alloc_fail);
1714
    for (ch = 0; ch < s->channels; ch++) {
1715
        FF_ALLOCZ_OR_GOTO(avctx, s->planar_samples[ch],
1716
                          (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),
1717
                          alloc_fail);
1718
    }
1719
    FF_ALLOC_OR_GOTO(avctx, s->bap_buffer,  AC3_MAX_BLOCKS * s->channels *
1720
                     AC3_MAX_COEFS * sizeof(*s->bap_buffer),  alloc_fail);
1721
    FF_ALLOC_OR_GOTO(avctx, s->bap1_buffer, AC3_MAX_BLOCKS * s->channels *
1722
                     AC3_MAX_COEFS * sizeof(*s->bap1_buffer), alloc_fail);
1723
    FF_ALLOC_OR_GOTO(avctx, s->mdct_coef_buffer, AC3_MAX_BLOCKS * s->channels *
1724
                     AC3_MAX_COEFS * sizeof(*s->mdct_coef_buffer), alloc_fail);
1725
    FF_ALLOC_OR_GOTO(avctx, s->exp_buffer, AC3_MAX_BLOCKS * s->channels *
1726
                     AC3_MAX_COEFS * sizeof(*s->exp_buffer), alloc_fail);
1727
    FF_ALLOC_OR_GOTO(avctx, s->grouped_exp_buffer, AC3_MAX_BLOCKS * s->channels *
1728
                     128 * sizeof(*s->grouped_exp_buffer), alloc_fail);
1729
    FF_ALLOC_OR_GOTO(avctx, s->psd_buffer, AC3_MAX_BLOCKS * s->channels *
1730
                     AC3_MAX_COEFS * sizeof(*s->psd_buffer), alloc_fail);
1731
    FF_ALLOC_OR_GOTO(avctx, s->band_psd_buffer, AC3_MAX_BLOCKS * s->channels *
1732
                     64 * sizeof(*s->band_psd_buffer), alloc_fail);
1733
    FF_ALLOC_OR_GOTO(avctx, s->mask_buffer, AC3_MAX_BLOCKS * s->channels *
1734
                     64 * sizeof(*s->mask_buffer), alloc_fail);
1735
    FF_ALLOC_OR_GOTO(avctx, s->qmant_buffer, AC3_MAX_BLOCKS * s->channels *
1736
                     AC3_MAX_COEFS * sizeof(*s->qmant_buffer), alloc_fail);
1737
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1738
        AC3Block *block = &s->blocks[blk];
1739
        FF_ALLOC_OR_GOTO(avctx, block->bap, s->channels * sizeof(*block->bap),
1740
                         alloc_fail);
1741
        FF_ALLOCZ_OR_GOTO(avctx, block->mdct_coef, s->channels * sizeof(*block->mdct_coef),
1742
                          alloc_fail);
1743
        FF_ALLOCZ_OR_GOTO(avctx, block->exp, s->channels * sizeof(*block->exp),
1744
                          alloc_fail);
1745
        FF_ALLOCZ_OR_GOTO(avctx, block->grouped_exp, s->channels * sizeof(*block->grouped_exp),
1746
                          alloc_fail);
1747
        FF_ALLOCZ_OR_GOTO(avctx, block->psd, s->channels * sizeof(*block->psd),
1748
                          alloc_fail);
1749
        FF_ALLOCZ_OR_GOTO(avctx, block->band_psd, s->channels * sizeof(*block->band_psd),
1750
                          alloc_fail);
1751
        FF_ALLOCZ_OR_GOTO(avctx, block->mask, s->channels * sizeof(*block->mask),
1752
                          alloc_fail);
1753
        FF_ALLOCZ_OR_GOTO(avctx, block->qmant, s->channels * sizeof(*block->qmant),
1754
                          alloc_fail);
1755

    
1756
        for (ch = 0; ch < s->channels; ch++) {
1757
            /* arrangement: block, channel, coeff */
1758
            block->bap[ch]         = &s->bap_buffer        [AC3_MAX_COEFS * (blk * s->channels + ch)];
1759
            block->mdct_coef[ch]   = &s->mdct_coef_buffer  [AC3_MAX_COEFS * (blk * s->channels + ch)];
1760
            block->grouped_exp[ch] = &s->grouped_exp_buffer[128           * (blk * s->channels + ch)];
1761
            block->psd[ch]         = &s->psd_buffer        [AC3_MAX_COEFS * (blk * s->channels + ch)];
1762
            block->band_psd[ch]    = &s->band_psd_buffer   [64            * (blk * s->channels + ch)];
1763
            block->mask[ch]        = &s->mask_buffer       [64            * (blk * s->channels + ch)];
1764
            block->qmant[ch]       = &s->qmant_buffer      [AC3_MAX_COEFS * (blk * s->channels + ch)];
1765

    
1766
            /* arrangement: channel, block, coeff */
1767
            block->exp[ch]         = &s->exp_buffer        [AC3_MAX_COEFS * (AC3_MAX_BLOCKS * ch + blk)];
1768
        }
1769
    }
1770

    
1771
    if (CONFIG_AC3ENC_FLOAT) {
1772
        FF_ALLOC_OR_GOTO(avctx, s->fixed_coef_buffer, AC3_MAX_BLOCKS * s->channels *
1773
                         AC3_MAX_COEFS * sizeof(*s->fixed_coef_buffer), alloc_fail);
1774
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1775
            AC3Block *block = &s->blocks[blk];
1776
            FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, s->channels *
1777
                              sizeof(*block->fixed_coef), alloc_fail);
1778
            for (ch = 0; ch < s->channels; ch++)
1779
                block->fixed_coef[ch] = &s->fixed_coef_buffer[AC3_MAX_COEFS * (blk * s->channels + ch)];
1780
        }
1781
    } else {
1782
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1783
            AC3Block *block = &s->blocks[blk];
1784
            FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, s->channels *
1785
                              sizeof(*block->fixed_coef), alloc_fail);
1786
            for (ch = 0; ch < s->channels; ch++)
1787
                block->fixed_coef[ch] = (int32_t *)block->mdct_coef[ch];
1788
        }
1789
    }
1790

    
1791
    return 0;
1792
alloc_fail:
1793
    return AVERROR(ENOMEM);
1794
}
1795

    
1796

    
1797
/**
1798
 * Initialize the encoder.
1799
 */
1800
static av_cold int ac3_encode_init(AVCodecContext *avctx)
1801
{
1802
    AC3EncodeContext *s = avctx->priv_data;
1803
    int ret, frame_size_58;
1804

    
1805
    avctx->frame_size = AC3_FRAME_SIZE;
1806

    
1807
    ff_ac3_common_init();
1808

    
1809
    ret = validate_options(avctx, s);
1810
    if (ret)
1811
        return ret;
1812

    
1813
    s->bitstream_id   = 8 + s->bit_alloc.sr_shift;
1814
    s->bitstream_mode = avctx->audio_service_type;
1815
    if (s->bitstream_mode == AV_AUDIO_SERVICE_TYPE_KARAOKE)
1816
        s->bitstream_mode = 0x7;
1817

    
1818
    s->frame_size_min  = 2 * ff_ac3_frame_size_tab[s->frame_size_code][s->bit_alloc.sr_code];
1819
    s->bits_written    = 0;
1820
    s->samples_written = 0;
1821
    s->frame_size      = s->frame_size_min;
1822

    
1823
    /* calculate crc_inv for both possible frame sizes */
1824
    frame_size_58 = (( s->frame_size    >> 2) + ( s->frame_size    >> 4)) << 1;
1825
    s->crc_inv[0] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
1826
    if (s->bit_alloc.sr_code == 1) {
1827
        frame_size_58 = (((s->frame_size+2) >> 2) + ((s->frame_size+2) >> 4)) << 1;
1828
        s->crc_inv[1] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
1829
    }
1830

    
1831
    set_bandwidth(s);
1832

    
1833
    rematrixing_init(s);
1834

    
1835
    exponent_init(s);
1836

    
1837
    bit_alloc_init(s);
1838

    
1839
    ret = mdct_init(avctx, &s->mdct, 9);
1840
    if (ret)
1841
        goto init_fail;
1842

    
1843
    ret = allocate_buffers(avctx);
1844
    if (ret)
1845
        goto init_fail;
1846

    
1847
    avctx->coded_frame= avcodec_alloc_frame();
1848

    
1849
    dsputil_init(&s->dsp, avctx);
1850
    ff_ac3dsp_init(&s->ac3dsp, avctx->flags & CODEC_FLAG_BITEXACT);
1851

    
1852
    return 0;
1853
init_fail:
1854
    ac3_encode_close(avctx);
1855
    return ret;
1856
}