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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
/**
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 * @file
26
 * The simplest AC-3 encoder.
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 */
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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)))
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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

    
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/**
69
 * Data for a single audio block.
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 */
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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
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)
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    int bitstream_mode;                     ///< bitstream mode                         (bsmod)
99

    
100
    int bit_rate;                           ///< target bit rate, in bits-per-second
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    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
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    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
114
    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)
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    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
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    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
141

    
142
    SampleType **planar_samples;
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    uint8_t *bap_buffer;
144
    uint8_t *bap1_buffer;
145
    CoefType *mdct_coef_buffer;
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    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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    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, int n);
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),
199
    (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 FFmpeg'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->exp_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
                sum[0] += lt * lt;
332
                sum[1] += rt * rt;
333
                sum[2] += md * md;
334
                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
            int exp_shift  = block->exp_shift[ch];
420
            for (i = 0; i < AC3_MAX_COEFS; i++) {
421
                int e;
422
                int v = abs(coef[i]);
423
                if (v == 0)
424
                    e = 24;
425
                else {
426
                    e = 23 - av_log2(v) + exp_shift;
427
                    if (e >= 24) {
428
                        e = 24;
429
                        coef[i] = 0;
430
                    }
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

    
654
                exp0   = exp1;
655
                exp1   = p[0];
656
                p     += group_size;
657
                delta1 = exp1 - exp0 + 2;
658

    
659
                exp0   = exp1;
660
                exp1   = p[0];
661
                p     += group_size;
662
                delta2 = exp1 - exp0 + 2;
663

    
664
                block->grouped_exp[ch][i] = ((delta0 * 5 + delta1) * 5) + delta2;
665
            }
666
        }
667
    }
668

    
669
    s->exponent_bits = bit_count;
670
}
671

    
672

    
673
/**
674
 * Calculate final exponents from the supplied MDCT coefficients and exponent shift.
675
 * Extract exponents from MDCT coefficients, calculate exponent strategies,
676
 * and encode final exponents.
677
 */
678
static void process_exponents(AC3EncodeContext *s)
679
{
680
    extract_exponents(s);
681

    
682
    compute_exp_strategy(s);
683

    
684
    encode_exponents(s);
685

    
686
    group_exponents(s);
687

    
688
    emms_c();
689
}
690

    
691

    
692
/**
693
 * Count frame bits that are based solely on fixed parameters.
694
 * This only has to be run once when the encoder is initialized.
695
 */
696
static void count_frame_bits_fixed(AC3EncodeContext *s)
697
{
698
    static const int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
699
    int blk;
700
    int frame_bits;
701

    
702
    /* assumptions:
703
     *   no dynamic range codes
704
     *   no channel coupling
705
     *   bit allocation parameters do not change between blocks
706
     *   SNR offsets do not change between blocks
707
     *   no delta bit allocation
708
     *   no skipped data
709
     *   no auxilliary data
710
     */
711

    
712
    /* header size */
713
    frame_bits = 65;
714
    frame_bits += frame_bits_inc[s->channel_mode];
715

    
716
    /* audio blocks */
717
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
718
        frame_bits += s->fbw_channels * 2 + 2; /* blksw * c, dithflag * c, dynrnge, cplstre */
719
        if (s->channel_mode == AC3_CHMODE_STEREO) {
720
            frame_bits++; /* rematstr */
721
        }
722
        frame_bits += 2 * s->fbw_channels; /* chexpstr[2] * c */
723
        if (s->lfe_on)
724
            frame_bits++; /* lfeexpstr */
725
        frame_bits++; /* baie */
726
        frame_bits++; /* snr */
727
        frame_bits += 2; /* delta / skip */
728
    }
729
    frame_bits++; /* cplinu for block 0 */
730
    /* bit alloc info */
731
    /* sdcycod[2], fdcycod[2], sgaincod[2], dbpbcod[2], floorcod[3] */
732
    /* csnroffset[6] */
733
    /* (fsnoffset[4] + fgaincod[4]) * c */
734
    frame_bits += 2*4 + 3 + 6 + s->channels * (4 + 3);
735

    
736
    /* auxdatae, crcrsv */
737
    frame_bits += 2;
738

    
739
    /* CRC */
740
    frame_bits += 16;
741

    
742
    s->frame_bits_fixed = frame_bits;
743
}
744

    
745

    
746
/**
747
 * Initialize bit allocation.
748
 * Set default parameter codes and calculate parameter values.
749
 */
750
static void bit_alloc_init(AC3EncodeContext *s)
751
{
752
    int ch;
753

    
754
    /* init default parameters */
755
    s->slow_decay_code = 2;
756
    s->fast_decay_code = 1;
757
    s->slow_gain_code  = 1;
758
    s->db_per_bit_code = 3;
759
    s->floor_code      = 7;
760
    for (ch = 0; ch < s->channels; ch++)
761
        s->fast_gain_code[ch] = 4;
762

    
763
    /* initial snr offset */
764
    s->coarse_snr_offset = 40;
765

    
766
    /* compute real values */
767
    /* currently none of these values change during encoding, so we can just
768
       set them once at initialization */
769
    s->bit_alloc.slow_decay = ff_ac3_slow_decay_tab[s->slow_decay_code] >> s->bit_alloc.sr_shift;
770
    s->bit_alloc.fast_decay = ff_ac3_fast_decay_tab[s->fast_decay_code] >> s->bit_alloc.sr_shift;
771
    s->bit_alloc.slow_gain  = ff_ac3_slow_gain_tab[s->slow_gain_code];
772
    s->bit_alloc.db_per_bit = ff_ac3_db_per_bit_tab[s->db_per_bit_code];
773
    s->bit_alloc.floor      = ff_ac3_floor_tab[s->floor_code];
774

    
775
    count_frame_bits_fixed(s);
776
}
777

    
778

    
779
/**
780
 * Count the bits used to encode the frame, minus exponents and mantissas.
781
 * Bits based on fixed parameters have already been counted, so now we just
782
 * have to add the bits based on parameters that change during encoding.
783
 */
784
static void count_frame_bits(AC3EncodeContext *s)
785
{
786
    int blk, ch;
787
    int frame_bits = 0;
788

    
789
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
790
        /* stereo rematrixing */
791
        if (s->channel_mode == AC3_CHMODE_STEREO &&
792
            s->blocks[blk].new_rematrixing_strategy) {
793
            frame_bits += s->num_rematrixing_bands;
794
        }
795

    
796
        for (ch = 0; ch < s->fbw_channels; ch++) {
797
            if (s->exp_strategy[ch][blk] != EXP_REUSE)
798
                frame_bits += 6 + 2; /* chbwcod[6], gainrng[2] */
799
        }
800
    }
801
    s->frame_bits = s->frame_bits_fixed + frame_bits;
802
}
803

    
804

    
805
/**
806
 * Calculate the number of bits needed to encode a set of mantissas.
807
 */
808
static int compute_mantissa_size(int mant_cnt[5], uint8_t *bap, int nb_coefs)
809
{
810
    int bits, b, i;
811

    
812
    bits = 0;
813
    for (i = 0; i < nb_coefs; i++) {
814
        b = bap[i];
815
        if (b <= 4) {
816
            // bap=1 to bap=4 will be counted in compute_mantissa_size_final
817
            mant_cnt[b]++;
818
        } else if (b <= 13) {
819
            // bap=5 to bap=13 use (bap-1) bits
820
            bits += b - 1;
821
        } else {
822
            // bap=14 uses 14 bits and bap=15 uses 16 bits
823
            bits += (b == 14) ? 14 : 16;
824
        }
825
    }
826
    return bits;
827
}
828

    
829

    
830
/**
831
 * Finalize the mantissa bit count by adding in the grouped mantissas.
832
 */
833
static int compute_mantissa_size_final(int mant_cnt[5])
834
{
835
    // bap=1 : 3 mantissas in 5 bits
836
    int bits = (mant_cnt[1] / 3) * 5;
837
    // bap=2 : 3 mantissas in 7 bits
838
    // bap=4 : 2 mantissas in 7 bits
839
    bits += ((mant_cnt[2] / 3) + (mant_cnt[4] >> 1)) * 7;
840
    // bap=3 : each mantissa is 3 bits
841
    bits += mant_cnt[3] * 3;
842
    return bits;
843
}
844

    
845

    
846
/**
847
 * Calculate masking curve based on the final exponents.
848
 * Also calculate the power spectral densities to use in future calculations.
849
 */
850
static void bit_alloc_masking(AC3EncodeContext *s)
851
{
852
    int blk, ch;
853

    
854
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
855
        AC3Block *block = &s->blocks[blk];
856
        for (ch = 0; ch < s->channels; ch++) {
857
            /* We only need psd and mask for calculating bap.
858
               Since we currently do not calculate bap when exponent
859
               strategy is EXP_REUSE we do not need to calculate psd or mask. */
860
            if (s->exp_strategy[ch][blk] != EXP_REUSE) {
861
                ff_ac3_bit_alloc_calc_psd(block->exp[ch], 0,
862
                                          s->nb_coefs[ch],
863
                                          block->psd[ch], block->band_psd[ch]);
864
                ff_ac3_bit_alloc_calc_mask(&s->bit_alloc, block->band_psd[ch],
865
                                           0, s->nb_coefs[ch],
866
                                           ff_ac3_fast_gain_tab[s->fast_gain_code[ch]],
867
                                           ch == s->lfe_channel,
868
                                           DBA_NONE, 0, NULL, NULL, NULL,
869
                                           block->mask[ch]);
870
            }
871
        }
872
    }
873
}
874

    
875

    
876
/**
877
 * Ensure that bap for each block and channel point to the current bap_buffer.
878
 * They may have been switched during the bit allocation search.
879
 */
880
static void reset_block_bap(AC3EncodeContext *s)
881
{
882
    int blk, ch;
883
    if (s->blocks[0].bap[0] == s->bap_buffer)
884
        return;
885
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
886
        for (ch = 0; ch < s->channels; ch++) {
887
            s->blocks[blk].bap[ch] = &s->bap_buffer[AC3_MAX_COEFS * (blk * s->channels + ch)];
888
        }
889
    }
890
}
891

    
892

    
893
/**
894
 * Run the bit allocation with a given SNR offset.
895
 * This calculates the bit allocation pointers that will be used to determine
896
 * the quantization of each mantissa.
897
 * @return the number of bits needed for mantissas if the given SNR offset is
898
 *         is used.
899
 */
900
static int bit_alloc(AC3EncodeContext *s, int snr_offset)
901
{
902
    int blk, ch;
903
    int mantissa_bits;
904
    int mant_cnt[5];
905

    
906
    snr_offset = (snr_offset - 240) << 2;
907

    
908
    reset_block_bap(s);
909
    mantissa_bits = 0;
910
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
911
        AC3Block *block = &s->blocks[blk];
912
        // initialize grouped mantissa counts. these are set so that they are
913
        // padded to the next whole group size when bits are counted in
914
        // compute_mantissa_size_final
915
        mant_cnt[0] = mant_cnt[3] = 0;
916
        mant_cnt[1] = mant_cnt[2] = 2;
917
        mant_cnt[4] = 1;
918
        for (ch = 0; ch < s->channels; ch++) {
919
            /* Currently the only bit allocation parameters which vary across
920
               blocks within a frame are the exponent values.  We can take
921
               advantage of that by reusing the bit allocation pointers
922
               whenever we reuse exponents. */
923
            if (s->exp_strategy[ch][blk] == EXP_REUSE) {
924
                memcpy(block->bap[ch], s->blocks[blk-1].bap[ch], AC3_MAX_COEFS);
925
            } else {
926
                ff_ac3_bit_alloc_calc_bap(block->mask[ch], block->psd[ch], 0,
927
                                          s->nb_coefs[ch], snr_offset,
928
                                          s->bit_alloc.floor, ff_ac3_bap_tab,
929
                                          block->bap[ch]);
930
            }
931
            mantissa_bits += compute_mantissa_size(mant_cnt, block->bap[ch], s->nb_coefs[ch]);
932
        }
933
        mantissa_bits += compute_mantissa_size_final(mant_cnt);
934
    }
935
    return mantissa_bits;
936
}
937

    
938

    
939
/**
940
 * Constant bitrate bit allocation search.
941
 * Find the largest SNR offset that will allow data to fit in the frame.
942
 */
943
static int cbr_bit_allocation(AC3EncodeContext *s)
944
{
945
    int ch;
946
    int bits_left;
947
    int snr_offset, snr_incr;
948

    
949
    bits_left = 8 * s->frame_size - (s->frame_bits + s->exponent_bits);
950

    
951
    snr_offset = s->coarse_snr_offset << 4;
952

    
953
    /* if previous frame SNR offset was 1023, check if current frame can also
954
       use SNR offset of 1023. if so, skip the search. */
955
    if ((snr_offset | s->fine_snr_offset[0]) == 1023) {
956
        if (bit_alloc(s, 1023) <= bits_left)
957
            return 0;
958
    }
959

    
960
    while (snr_offset >= 0 &&
961
           bit_alloc(s, snr_offset) > bits_left) {
962
        snr_offset -= 64;
963
    }
964
    if (snr_offset < 0)
965
        return AVERROR(EINVAL);
966

    
967
    FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
968
    for (snr_incr = 64; snr_incr > 0; snr_incr >>= 2) {
969
        while (snr_offset + snr_incr <= 1023 &&
970
               bit_alloc(s, snr_offset + snr_incr) <= bits_left) {
971
            snr_offset += snr_incr;
972
            FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
973
        }
974
    }
975
    FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
976
    reset_block_bap(s);
977

    
978
    s->coarse_snr_offset = snr_offset >> 4;
979
    for (ch = 0; ch < s->channels; ch++)
980
        s->fine_snr_offset[ch] = snr_offset & 0xF;
981

    
982
    return 0;
983
}
984

    
985

    
986
/**
987
 * Downgrade exponent strategies to reduce the bits used by the exponents.
988
 * This is a fallback for when bit allocation fails with the normal exponent
989
 * strategies.  Each time this function is run it only downgrades the
990
 * strategy in 1 channel of 1 block.
991
 * @return non-zero if downgrade was unsuccessful
992
 */
993
static int downgrade_exponents(AC3EncodeContext *s)
994
{
995
    int ch, blk;
996

    
997
    for (ch = 0; ch < s->fbw_channels; ch++) {
998
        for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
999
            if (s->exp_strategy[ch][blk] == EXP_D15) {
1000
                s->exp_strategy[ch][blk] = EXP_D25;
1001
                return 0;
1002
            }
1003
        }
1004
    }
1005
    for (ch = 0; ch < s->fbw_channels; ch++) {
1006
        for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
1007
            if (s->exp_strategy[ch][blk] == EXP_D25) {
1008
                s->exp_strategy[ch][blk] = EXP_D45;
1009
                return 0;
1010
            }
1011
        }
1012
    }
1013
    for (ch = 0; ch < s->fbw_channels; ch++) {
1014
        /* block 0 cannot reuse exponents, so only downgrade D45 to REUSE if
1015
           the block number > 0 */
1016
        for (blk = AC3_MAX_BLOCKS-1; blk > 0; blk--) {
1017
            if (s->exp_strategy[ch][blk] > EXP_REUSE) {
1018
                s->exp_strategy[ch][blk] = EXP_REUSE;
1019
                return 0;
1020
            }
1021
        }
1022
    }
1023
    return -1;
1024
}
1025

    
1026

    
1027
/**
1028
 * Reduce the bandwidth to reduce the number of bits used for a given SNR offset.
1029
 * This is a second fallback for when bit allocation still fails after exponents
1030
 * have been downgraded.
1031
 * @return non-zero if bandwidth reduction was unsuccessful
1032
 */
1033
static int reduce_bandwidth(AC3EncodeContext *s, int min_bw_code)
1034
{
1035
    int ch;
1036

    
1037
    if (s->bandwidth_code[0] > min_bw_code) {
1038
        for (ch = 0; ch < s->fbw_channels; ch++) {
1039
            s->bandwidth_code[ch]--;
1040
            s->nb_coefs[ch] = s->bandwidth_code[ch] * 3 + 73;
1041
        }
1042
        return 0;
1043
    }
1044
    return -1;
1045
}
1046

    
1047

    
1048
/**
1049
 * Perform bit allocation search.
1050
 * Finds the SNR offset value that maximizes quality and fits in the specified
1051
 * frame size.  Output is the SNR offset and a set of bit allocation pointers
1052
 * used to quantize the mantissas.
1053
 */
1054
static int compute_bit_allocation(AC3EncodeContext *s)
1055
{
1056
    int ret;
1057

    
1058
    count_frame_bits(s);
1059

    
1060
    bit_alloc_masking(s);
1061

    
1062
    ret = cbr_bit_allocation(s);
1063
    while (ret) {
1064
        /* fallback 1: downgrade exponents */
1065
        if (!downgrade_exponents(s)) {
1066
            extract_exponents(s);
1067
            encode_exponents(s);
1068
            group_exponents(s);
1069
            ret = compute_bit_allocation(s);
1070
            continue;
1071
        }
1072

    
1073
        /* fallback 2: reduce bandwidth */
1074
        /* only do this if the user has not specified a specific cutoff
1075
           frequency */
1076
        if (!s->cutoff && !reduce_bandwidth(s, 0)) {
1077
            process_exponents(s);
1078
            ret = compute_bit_allocation(s);
1079
            continue;
1080
        }
1081

    
1082
        /* fallbacks were not enough... */
1083
        break;
1084
    }
1085

    
1086
    return ret;
1087
}
1088

    
1089

    
1090
/**
1091
 * Symmetric quantization on 'levels' levels.
1092
 */
1093
static inline int sym_quant(int c, int e, int levels)
1094
{
1095
    int v;
1096

    
1097
    if (c >= 0) {
1098
        v = (levels * (c << e)) >> 24;
1099
        v = (v + 1) >> 1;
1100
        v = (levels >> 1) + v;
1101
    } else {
1102
        v = (levels * ((-c) << e)) >> 24;
1103
        v = (v + 1) >> 1;
1104
        v = (levels >> 1) - v;
1105
    }
1106
    av_assert2(v >= 0 && v < levels);
1107
    return v;
1108
}
1109

    
1110

    
1111
/**
1112
 * Asymmetric quantization on 2^qbits levels.
1113
 */
1114
static inline int asym_quant(int c, int e, int qbits)
1115
{
1116
    int lshift, m, v;
1117

    
1118
    lshift = e + qbits - 24;
1119
    if (lshift >= 0)
1120
        v = c << lshift;
1121
    else
1122
        v = c >> (-lshift);
1123
    /* rounding */
1124
    v = (v + 1) >> 1;
1125
    m = (1 << (qbits-1));
1126
    if (v >= m)
1127
        v = m - 1;
1128
    av_assert2(v >= -m);
1129
    return v & ((1 << qbits)-1);
1130
}
1131

    
1132

    
1133
/**
1134
 * Quantize a set of mantissas for a single channel in a single block.
1135
 */
1136
static void quantize_mantissas_blk_ch(AC3EncodeContext *s, int32_t *fixed_coef,
1137
                                      int8_t exp_shift, uint8_t *exp,
1138
                                      uint8_t *bap, uint16_t *qmant, int n)
1139
{
1140
    int i;
1141

    
1142
    for (i = 0; i < n; i++) {
1143
        int v;
1144
        int c = fixed_coef[i];
1145
        int e = exp[i] - exp_shift;
1146
        int b = bap[i];
1147
        switch (b) {
1148
        case 0:
1149
            v = 0;
1150
            break;
1151
        case 1:
1152
            v = sym_quant(c, e, 3);
1153
            switch (s->mant1_cnt) {
1154
            case 0:
1155
                s->qmant1_ptr = &qmant[i];
1156
                v = 9 * v;
1157
                s->mant1_cnt = 1;
1158
                break;
1159
            case 1:
1160
                *s->qmant1_ptr += 3 * v;
1161
                s->mant1_cnt = 2;
1162
                v = 128;
1163
                break;
1164
            default:
1165
                *s->qmant1_ptr += v;
1166
                s->mant1_cnt = 0;
1167
                v = 128;
1168
                break;
1169
            }
1170
            break;
1171
        case 2:
1172
            v = sym_quant(c, e, 5);
1173
            switch (s->mant2_cnt) {
1174
            case 0:
1175
                s->qmant2_ptr = &qmant[i];
1176
                v = 25 * v;
1177
                s->mant2_cnt = 1;
1178
                break;
1179
            case 1:
1180
                *s->qmant2_ptr += 5 * v;
1181
                s->mant2_cnt = 2;
1182
                v = 128;
1183
                break;
1184
            default:
1185
                *s->qmant2_ptr += v;
1186
                s->mant2_cnt = 0;
1187
                v = 128;
1188
                break;
1189
            }
1190
            break;
1191
        case 3:
1192
            v = sym_quant(c, e, 7);
1193
            break;
1194
        case 4:
1195
            v = sym_quant(c, e, 11);
1196
            switch (s->mant4_cnt) {
1197
            case 0:
1198
                s->qmant4_ptr = &qmant[i];
1199
                v = 11 * v;
1200
                s->mant4_cnt = 1;
1201
                break;
1202
            default:
1203
                *s->qmant4_ptr += v;
1204
                s->mant4_cnt = 0;
1205
                v = 128;
1206
                break;
1207
            }
1208
            break;
1209
        case 5:
1210
            v = sym_quant(c, e, 15);
1211
            break;
1212
        case 14:
1213
            v = asym_quant(c, e, 14);
1214
            break;
1215
        case 15:
1216
            v = asym_quant(c, e, 16);
1217
            break;
1218
        default:
1219
            v = asym_quant(c, e, b - 1);
1220
            break;
1221
        }
1222
        qmant[i] = v;
1223
    }
1224
}
1225

    
1226

    
1227
/**
1228
 * Quantize mantissas using coefficients, exponents, and bit allocation pointers.
1229
 */
1230
static void quantize_mantissas(AC3EncodeContext *s)
1231
{
1232
    int blk, ch;
1233

    
1234

    
1235
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1236
        AC3Block *block = &s->blocks[blk];
1237
        s->mant1_cnt  = s->mant2_cnt  = s->mant4_cnt  = 0;
1238
        s->qmant1_ptr = s->qmant2_ptr = s->qmant4_ptr = NULL;
1239

    
1240
        for (ch = 0; ch < s->channels; ch++) {
1241
            quantize_mantissas_blk_ch(s, block->fixed_coef[ch], block->exp_shift[ch],
1242
                                      block->exp[ch], block->bap[ch],
1243
                                      block->qmant[ch], s->nb_coefs[ch]);
1244
        }
1245
    }
1246
}
1247

    
1248

    
1249
/**
1250
 * Write the AC-3 frame header to the output bitstream.
1251
 */
1252
static void output_frame_header(AC3EncodeContext *s)
1253
{
1254
    put_bits(&s->pb, 16, 0x0b77);   /* frame header */
1255
    put_bits(&s->pb, 16, 0);        /* crc1: will be filled later */
1256
    put_bits(&s->pb, 2,  s->bit_alloc.sr_code);
1257
    put_bits(&s->pb, 6,  s->frame_size_code + (s->frame_size - s->frame_size_min) / 2);
1258
    put_bits(&s->pb, 5,  s->bitstream_id);
1259
    put_bits(&s->pb, 3,  s->bitstream_mode);
1260
    put_bits(&s->pb, 3,  s->channel_mode);
1261
    if ((s->channel_mode & 0x01) && s->channel_mode != AC3_CHMODE_MONO)
1262
        put_bits(&s->pb, 2, 1);     /* XXX -4.5 dB */
1263
    if (s->channel_mode & 0x04)
1264
        put_bits(&s->pb, 2, 1);     /* XXX -6 dB */
1265
    if (s->channel_mode == AC3_CHMODE_STEREO)
1266
        put_bits(&s->pb, 2, 0);     /* surround not indicated */
1267
    put_bits(&s->pb, 1, s->lfe_on); /* LFE */
1268
    put_bits(&s->pb, 5, 31);        /* dialog norm: -31 db */
1269
    put_bits(&s->pb, 1, 0);         /* no compression control word */
1270
    put_bits(&s->pb, 1, 0);         /* no lang code */
1271
    put_bits(&s->pb, 1, 0);         /* no audio production info */
1272
    put_bits(&s->pb, 1, 0);         /* no copyright */
1273
    put_bits(&s->pb, 1, 1);         /* original bitstream */
1274
    put_bits(&s->pb, 1, 0);         /* no time code 1 */
1275
    put_bits(&s->pb, 1, 0);         /* no time code 2 */
1276
    put_bits(&s->pb, 1, 0);         /* no additional bit stream info */
1277
}
1278

    
1279

    
1280
/**
1281
 * Write one audio block to the output bitstream.
1282
 */
1283
static void output_audio_block(AC3EncodeContext *s, int blk)
1284
{
1285
    int ch, i, baie, rbnd;
1286
    AC3Block *block = &s->blocks[blk];
1287

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

    
1292
    /* dither flags */
1293
    for (ch = 0; ch < s->fbw_channels; ch++)
1294
        put_bits(&s->pb, 1, 1);
1295

    
1296
    /* dynamic range codes */
1297
    put_bits(&s->pb, 1, 0);
1298

    
1299
    /* channel coupling */
1300
    if (!blk) {
1301
        put_bits(&s->pb, 1, 1); /* coupling strategy present */
1302
        put_bits(&s->pb, 1, 0); /* no coupling strategy */
1303
    } else {
1304
        put_bits(&s->pb, 1, 0); /* no new coupling strategy */
1305
    }
1306

    
1307
    /* stereo rematrixing */
1308
    if (s->channel_mode == AC3_CHMODE_STEREO) {
1309
        put_bits(&s->pb, 1, block->new_rematrixing_strategy);
1310
        if (block->new_rematrixing_strategy) {
1311
            /* rematrixing flags */
1312
            for (rbnd = 0; rbnd < s->num_rematrixing_bands; rbnd++)
1313
                put_bits(&s->pb, 1, block->rematrixing_flags[rbnd]);
1314
        }
1315
    }
1316

    
1317
    /* exponent strategy */
1318
    for (ch = 0; ch < s->fbw_channels; ch++)
1319
        put_bits(&s->pb, 2, s->exp_strategy[ch][blk]);
1320
    if (s->lfe_on)
1321
        put_bits(&s->pb, 1, s->exp_strategy[s->lfe_channel][blk]);
1322

    
1323
    /* bandwidth */
1324
    for (ch = 0; ch < s->fbw_channels; ch++) {
1325
        if (s->exp_strategy[ch][blk] != EXP_REUSE)
1326
            put_bits(&s->pb, 6, s->bandwidth_code[ch]);
1327
    }
1328

    
1329
    /* exponents */
1330
    for (ch = 0; ch < s->channels; ch++) {
1331
        int nb_groups;
1332

    
1333
        if (s->exp_strategy[ch][blk] == EXP_REUSE)
1334
            continue;
1335

    
1336
        /* DC exponent */
1337
        put_bits(&s->pb, 4, block->grouped_exp[ch][0]);
1338

    
1339
        /* exponent groups */
1340
        nb_groups = exponent_group_tab[s->exp_strategy[ch][blk]-1][s->nb_coefs[ch]];
1341
        for (i = 1; i <= nb_groups; i++)
1342
            put_bits(&s->pb, 7, block->grouped_exp[ch][i]);
1343

    
1344
        /* gain range info */
1345
        if (ch != s->lfe_channel)
1346
            put_bits(&s->pb, 2, 0);
1347
    }
1348

    
1349
    /* bit allocation info */
1350
    baie = (blk == 0);
1351
    put_bits(&s->pb, 1, baie);
1352
    if (baie) {
1353
        put_bits(&s->pb, 2, s->slow_decay_code);
1354
        put_bits(&s->pb, 2, s->fast_decay_code);
1355
        put_bits(&s->pb, 2, s->slow_gain_code);
1356
        put_bits(&s->pb, 2, s->db_per_bit_code);
1357
        put_bits(&s->pb, 3, s->floor_code);
1358
    }
1359

    
1360
    /* snr offset */
1361
    put_bits(&s->pb, 1, baie);
1362
    if (baie) {
1363
        put_bits(&s->pb, 6, s->coarse_snr_offset);
1364
        for (ch = 0; ch < s->channels; ch++) {
1365
            put_bits(&s->pb, 4, s->fine_snr_offset[ch]);
1366
            put_bits(&s->pb, 3, s->fast_gain_code[ch]);
1367
        }
1368
    }
1369

    
1370
    put_bits(&s->pb, 1, 0); /* no delta bit allocation */
1371
    put_bits(&s->pb, 1, 0); /* no data to skip */
1372

    
1373
    /* mantissas */
1374
    for (ch = 0; ch < s->channels; ch++) {
1375
        int b, q;
1376
        for (i = 0; i < s->nb_coefs[ch]; i++) {
1377
            q = block->qmant[ch][i];
1378
            b = block->bap[ch][i];
1379
            switch (b) {
1380
            case 0:                                         break;
1381
            case 1: if (q != 128) put_bits(&s->pb,   5, q); break;
1382
            case 2: if (q != 128) put_bits(&s->pb,   7, q); break;
1383
            case 3:               put_bits(&s->pb,   3, q); break;
1384
            case 4: if (q != 128) put_bits(&s->pb,   7, q); break;
1385
            case 14:              put_bits(&s->pb,  14, q); break;
1386
            case 15:              put_bits(&s->pb,  16, q); break;
1387
            default:              put_bits(&s->pb, b-1, q); break;
1388
            }
1389
        }
1390
    }
1391
}
1392

    
1393

    
1394
/** CRC-16 Polynomial */
1395
#define CRC16_POLY ((1 << 0) | (1 << 2) | (1 << 15) | (1 << 16))
1396

    
1397

    
1398
static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly)
1399
{
1400
    unsigned int c;
1401

    
1402
    c = 0;
1403
    while (a) {
1404
        if (a & 1)
1405
            c ^= b;
1406
        a = a >> 1;
1407
        b = b << 1;
1408
        if (b & (1 << 16))
1409
            b ^= poly;
1410
    }
1411
    return c;
1412
}
1413

    
1414

    
1415
static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly)
1416
{
1417
    unsigned int r;
1418
    r = 1;
1419
    while (n) {
1420
        if (n & 1)
1421
            r = mul_poly(r, a, poly);
1422
        a = mul_poly(a, a, poly);
1423
        n >>= 1;
1424
    }
1425
    return r;
1426
}
1427

    
1428

    
1429
/**
1430
 * Fill the end of the frame with 0's and compute the two CRCs.
1431
 */
1432
static void output_frame_end(AC3EncodeContext *s)
1433
{
1434
    const AVCRC *crc_ctx = av_crc_get_table(AV_CRC_16_ANSI);
1435
    int frame_size_58, pad_bytes, crc1, crc2_partial, crc2, crc_inv;
1436
    uint8_t *frame;
1437

    
1438
    frame_size_58 = ((s->frame_size >> 2) + (s->frame_size >> 4)) << 1;
1439

    
1440
    /* pad the remainder of the frame with zeros */
1441
    flush_put_bits(&s->pb);
1442
    frame = s->pb.buf;
1443
    pad_bytes = s->frame_size - (put_bits_ptr(&s->pb) - frame) - 2;
1444
    av_assert2(pad_bytes >= 0);
1445
    if (pad_bytes > 0)
1446
        memset(put_bits_ptr(&s->pb), 0, pad_bytes);
1447

    
1448
    /* compute crc1 */
1449
    /* this is not so easy because it is at the beginning of the data... */
1450
    crc1    = av_bswap16(av_crc(crc_ctx, 0, frame + 4, frame_size_58 - 4));
1451
    crc_inv = s->crc_inv[s->frame_size > s->frame_size_min];
1452
    crc1    = mul_poly(crc_inv, crc1, CRC16_POLY);
1453
    AV_WB16(frame + 2, crc1);
1454

    
1455
    /* compute crc2 */
1456
    crc2_partial = av_crc(crc_ctx, 0, frame + frame_size_58,
1457
                          s->frame_size - frame_size_58 - 3);
1458
    crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
1459
    /* ensure crc2 does not match sync word by flipping crcrsv bit if needed */
1460
    if (crc2 == 0x770B) {
1461
        frame[s->frame_size - 3] ^= 0x1;
1462
        crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
1463
    }
1464
    crc2 = av_bswap16(crc2);
1465
    AV_WB16(frame + s->frame_size - 2, crc2);
1466
}
1467

    
1468

    
1469
/**
1470
 * Write the frame to the output bitstream.
1471
 */
1472
static void output_frame(AC3EncodeContext *s, unsigned char *frame)
1473
{
1474
    int blk;
1475

    
1476
    init_put_bits(&s->pb, frame, AC3_MAX_CODED_FRAME_SIZE);
1477

    
1478
    output_frame_header(s);
1479

    
1480
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++)
1481
        output_audio_block(s, blk);
1482

    
1483
    output_frame_end(s);
1484
}
1485

    
1486

    
1487
/**
1488
 * Encode a single AC-3 frame.
1489
 */
1490
static int ac3_encode_frame(AVCodecContext *avctx, unsigned char *frame,
1491
                            int buf_size, void *data)
1492
{
1493
    AC3EncodeContext *s = avctx->priv_data;
1494
    const SampleType *samples = data;
1495
    int ret;
1496

    
1497
    if (s->bit_alloc.sr_code == 1)
1498
        adjust_frame_size(s);
1499

    
1500
    deinterleave_input_samples(s, samples);
1501

    
1502
    apply_mdct(s);
1503

    
1504
    compute_rematrixing_strategy(s);
1505

    
1506
    scale_coefficients(s);
1507

    
1508
    apply_rematrixing(s);
1509

    
1510
    process_exponents(s);
1511

    
1512
    ret = compute_bit_allocation(s);
1513
    if (ret) {
1514
        av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
1515
        return ret;
1516
    }
1517

    
1518
    quantize_mantissas(s);
1519

    
1520
    output_frame(s, frame);
1521

    
1522
    return s->frame_size;
1523
}
1524

    
1525

    
1526
/**
1527
 * Finalize encoding and free any memory allocated by the encoder.
1528
 */
1529
static av_cold int ac3_encode_close(AVCodecContext *avctx)
1530
{
1531
    int blk, ch;
1532
    AC3EncodeContext *s = avctx->priv_data;
1533

    
1534
    for (ch = 0; ch < s->channels; ch++)
1535
        av_freep(&s->planar_samples[ch]);
1536
    av_freep(&s->planar_samples);
1537
    av_freep(&s->bap_buffer);
1538
    av_freep(&s->bap1_buffer);
1539
    av_freep(&s->mdct_coef_buffer);
1540
    av_freep(&s->fixed_coef_buffer);
1541
    av_freep(&s->exp_buffer);
1542
    av_freep(&s->grouped_exp_buffer);
1543
    av_freep(&s->psd_buffer);
1544
    av_freep(&s->band_psd_buffer);
1545
    av_freep(&s->mask_buffer);
1546
    av_freep(&s->qmant_buffer);
1547
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1548
        AC3Block *block = &s->blocks[blk];
1549
        av_freep(&block->bap);
1550
        av_freep(&block->mdct_coef);
1551
        av_freep(&block->fixed_coef);
1552
        av_freep(&block->exp);
1553
        av_freep(&block->grouped_exp);
1554
        av_freep(&block->psd);
1555
        av_freep(&block->band_psd);
1556
        av_freep(&block->mask);
1557
        av_freep(&block->qmant);
1558
    }
1559

    
1560
    mdct_end(&s->mdct);
1561

    
1562
    av_freep(&avctx->coded_frame);
1563
    return 0;
1564
}
1565

    
1566

    
1567
/**
1568
 * Set channel information during initialization.
1569
 */
1570
static av_cold int set_channel_info(AC3EncodeContext *s, int channels,
1571
                                    int64_t *channel_layout)
1572
{
1573
    int ch_layout;
1574

    
1575
    if (channels < 1 || channels > AC3_MAX_CHANNELS)
1576
        return AVERROR(EINVAL);
1577
    if ((uint64_t)*channel_layout > 0x7FF)
1578
        return AVERROR(EINVAL);
1579
    ch_layout = *channel_layout;
1580
    if (!ch_layout)
1581
        ch_layout = avcodec_guess_channel_layout(channels, CODEC_ID_AC3, NULL);
1582
    if (av_get_channel_layout_nb_channels(ch_layout) != channels)
1583
        return AVERROR(EINVAL);
1584

    
1585
    s->lfe_on       = !!(ch_layout & AV_CH_LOW_FREQUENCY);
1586
    s->channels     = channels;
1587
    s->fbw_channels = channels - s->lfe_on;
1588
    s->lfe_channel  = s->lfe_on ? s->fbw_channels : -1;
1589
    if (s->lfe_on)
1590
        ch_layout -= AV_CH_LOW_FREQUENCY;
1591

    
1592
    switch (ch_layout) {
1593
    case AV_CH_LAYOUT_MONO:           s->channel_mode = AC3_CHMODE_MONO;   break;
1594
    case AV_CH_LAYOUT_STEREO:         s->channel_mode = AC3_CHMODE_STEREO; break;
1595
    case AV_CH_LAYOUT_SURROUND:       s->channel_mode = AC3_CHMODE_3F;     break;
1596
    case AV_CH_LAYOUT_2_1:            s->channel_mode = AC3_CHMODE_2F1R;   break;
1597
    case AV_CH_LAYOUT_4POINT0:        s->channel_mode = AC3_CHMODE_3F1R;   break;
1598
    case AV_CH_LAYOUT_QUAD:
1599
    case AV_CH_LAYOUT_2_2:            s->channel_mode = AC3_CHMODE_2F2R;   break;
1600
    case AV_CH_LAYOUT_5POINT0:
1601
    case AV_CH_LAYOUT_5POINT0_BACK:   s->channel_mode = AC3_CHMODE_3F2R;   break;
1602
    default:
1603
        return AVERROR(EINVAL);
1604
    }
1605

    
1606
    s->channel_map  = ff_ac3_enc_channel_map[s->channel_mode][s->lfe_on];
1607
    *channel_layout = ch_layout;
1608
    if (s->lfe_on)
1609
        *channel_layout |= AV_CH_LOW_FREQUENCY;
1610

    
1611
    return 0;
1612
}
1613

    
1614

    
1615
static av_cold int validate_options(AVCodecContext *avctx, AC3EncodeContext *s)
1616
{
1617
    int i, ret;
1618

    
1619
    /* validate channel layout */
1620
    if (!avctx->channel_layout) {
1621
        av_log(avctx, AV_LOG_WARNING, "No channel layout specified. The "
1622
                                      "encoder will guess the layout, but it "
1623
                                      "might be incorrect.\n");
1624
    }
1625
    ret = set_channel_info(s, avctx->channels, &avctx->channel_layout);
1626
    if (ret) {
1627
        av_log(avctx, AV_LOG_ERROR, "invalid channel layout\n");
1628
        return ret;
1629
    }
1630

    
1631
    /* validate sample rate */
1632
    for (i = 0; i < 9; i++) {
1633
        if ((ff_ac3_sample_rate_tab[i / 3] >> (i % 3)) == avctx->sample_rate)
1634
            break;
1635
    }
1636
    if (i == 9) {
1637
        av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1638
        return AVERROR(EINVAL);
1639
    }
1640
    s->sample_rate        = avctx->sample_rate;
1641
    s->bit_alloc.sr_shift = i % 3;
1642
    s->bit_alloc.sr_code  = i / 3;
1643

    
1644
    /* validate bit rate */
1645
    for (i = 0; i < 19; i++) {
1646
        if ((ff_ac3_bitrate_tab[i] >> s->bit_alloc.sr_shift)*1000 == avctx->bit_rate)
1647
            break;
1648
    }
1649
    if (i == 19) {
1650
        av_log(avctx, AV_LOG_ERROR, "invalid bit rate\n");
1651
        return AVERROR(EINVAL);
1652
    }
1653
    s->bit_rate        = avctx->bit_rate;
1654
    s->frame_size_code = i << 1;
1655

    
1656
    /* validate cutoff */
1657
    if (avctx->cutoff < 0) {
1658
        av_log(avctx, AV_LOG_ERROR, "invalid cutoff frequency\n");
1659
        return AVERROR(EINVAL);
1660
    }
1661
    s->cutoff = avctx->cutoff;
1662
    if (s->cutoff > (s->sample_rate >> 1))
1663
        s->cutoff = s->sample_rate >> 1;
1664

    
1665
    return 0;
1666
}
1667

    
1668

    
1669
/**
1670
 * Set bandwidth for all channels.
1671
 * The user can optionally supply a cutoff frequency. Otherwise an appropriate
1672
 * default value will be used.
1673
 */
1674
static av_cold void set_bandwidth(AC3EncodeContext *s)
1675
{
1676
    int ch, bw_code;
1677

    
1678
    if (s->cutoff) {
1679
        /* calculate bandwidth based on user-specified cutoff frequency */
1680
        int fbw_coeffs;
1681
        fbw_coeffs     = s->cutoff * 2 * AC3_MAX_COEFS / s->sample_rate;
1682
        bw_code        = av_clip((fbw_coeffs - 73) / 3, 0, 60);
1683
    } else {
1684
        /* use default bandwidth setting */
1685
        /* XXX: should compute the bandwidth according to the frame
1686
           size, so that we avoid annoying high frequency artifacts */
1687
        bw_code = 50;
1688
    }
1689

    
1690
    /* set number of coefficients for each channel */
1691
    for (ch = 0; ch < s->fbw_channels; ch++) {
1692
        s->bandwidth_code[ch] = bw_code;
1693
        s->nb_coefs[ch]       = bw_code * 3 + 73;
1694
    }
1695
    if (s->lfe_on)
1696
        s->nb_coefs[s->lfe_channel] = 7; /* LFE channel always has 7 coefs */
1697
}
1698

    
1699

    
1700
static av_cold int allocate_buffers(AVCodecContext *avctx)
1701
{
1702
    int blk, ch;
1703
    AC3EncodeContext *s = avctx->priv_data;
1704

    
1705
    FF_ALLOC_OR_GOTO(avctx, s->planar_samples, s->channels * sizeof(*s->planar_samples),
1706
                     alloc_fail);
1707
    for (ch = 0; ch < s->channels; ch++) {
1708
        FF_ALLOCZ_OR_GOTO(avctx, s->planar_samples[ch],
1709
                          (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),
1710
                          alloc_fail);
1711
    }
1712
    FF_ALLOC_OR_GOTO(avctx, s->bap_buffer,  AC3_MAX_BLOCKS * s->channels *
1713
                     AC3_MAX_COEFS * sizeof(*s->bap_buffer),  alloc_fail);
1714
    FF_ALLOC_OR_GOTO(avctx, s->bap1_buffer, AC3_MAX_BLOCKS * s->channels *
1715
                     AC3_MAX_COEFS * sizeof(*s->bap1_buffer), alloc_fail);
1716
    FF_ALLOC_OR_GOTO(avctx, s->mdct_coef_buffer, AC3_MAX_BLOCKS * s->channels *
1717
                     AC3_MAX_COEFS * sizeof(*s->mdct_coef_buffer), alloc_fail);
1718
    FF_ALLOC_OR_GOTO(avctx, s->exp_buffer, AC3_MAX_BLOCKS * s->channels *
1719
                     AC3_MAX_COEFS * sizeof(*s->exp_buffer), alloc_fail);
1720
    FF_ALLOC_OR_GOTO(avctx, s->grouped_exp_buffer, AC3_MAX_BLOCKS * s->channels *
1721
                     128 * sizeof(*s->grouped_exp_buffer), alloc_fail);
1722
    FF_ALLOC_OR_GOTO(avctx, s->psd_buffer, AC3_MAX_BLOCKS * s->channels *
1723
                     AC3_MAX_COEFS * sizeof(*s->psd_buffer), alloc_fail);
1724
    FF_ALLOC_OR_GOTO(avctx, s->band_psd_buffer, AC3_MAX_BLOCKS * s->channels *
1725
                     64 * sizeof(*s->band_psd_buffer), alloc_fail);
1726
    FF_ALLOC_OR_GOTO(avctx, s->mask_buffer, AC3_MAX_BLOCKS * s->channels *
1727
                     64 * sizeof(*s->mask_buffer), alloc_fail);
1728
    FF_ALLOC_OR_GOTO(avctx, s->qmant_buffer, AC3_MAX_BLOCKS * s->channels *
1729
                     AC3_MAX_COEFS * sizeof(*s->qmant_buffer), alloc_fail);
1730
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1731
        AC3Block *block = &s->blocks[blk];
1732
        FF_ALLOC_OR_GOTO(avctx, block->bap, s->channels * sizeof(*block->bap),
1733
                         alloc_fail);
1734
        FF_ALLOCZ_OR_GOTO(avctx, block->mdct_coef, s->channels * sizeof(*block->mdct_coef),
1735
                          alloc_fail);
1736
        FF_ALLOCZ_OR_GOTO(avctx, block->exp, s->channels * sizeof(*block->exp),
1737
                          alloc_fail);
1738
        FF_ALLOCZ_OR_GOTO(avctx, block->grouped_exp, s->channels * sizeof(*block->grouped_exp),
1739
                          alloc_fail);
1740
        FF_ALLOCZ_OR_GOTO(avctx, block->psd, s->channels * sizeof(*block->psd),
1741
                          alloc_fail);
1742
        FF_ALLOCZ_OR_GOTO(avctx, block->band_psd, s->channels * sizeof(*block->band_psd),
1743
                          alloc_fail);
1744
        FF_ALLOCZ_OR_GOTO(avctx, block->mask, s->channels * sizeof(*block->mask),
1745
                          alloc_fail);
1746
        FF_ALLOCZ_OR_GOTO(avctx, block->qmant, s->channels * sizeof(*block->qmant),
1747
                          alloc_fail);
1748

    
1749
        for (ch = 0; ch < s->channels; ch++) {
1750
            /* arrangement: block, channel, coeff */
1751
            block->bap[ch]         = &s->bap_buffer        [AC3_MAX_COEFS * (blk * s->channels + ch)];
1752
            block->mdct_coef[ch]   = &s->mdct_coef_buffer  [AC3_MAX_COEFS * (blk * s->channels + ch)];
1753
            block->grouped_exp[ch] = &s->grouped_exp_buffer[128           * (blk * s->channels + ch)];
1754
            block->psd[ch]         = &s->psd_buffer        [AC3_MAX_COEFS * (blk * s->channels + ch)];
1755
            block->band_psd[ch]    = &s->band_psd_buffer   [64            * (blk * s->channels + ch)];
1756
            block->mask[ch]        = &s->mask_buffer       [64            * (blk * s->channels + ch)];
1757
            block->qmant[ch]       = &s->qmant_buffer      [AC3_MAX_COEFS * (blk * s->channels + ch)];
1758

    
1759
            /* arrangement: channel, block, coeff */
1760
            block->exp[ch]         = &s->exp_buffer        [AC3_MAX_COEFS * (AC3_MAX_BLOCKS * ch + blk)];
1761
        }
1762
    }
1763

    
1764
    if (CONFIG_AC3ENC_FLOAT) {
1765
        FF_ALLOC_OR_GOTO(avctx, s->fixed_coef_buffer, AC3_MAX_BLOCKS * s->channels *
1766
                         AC3_MAX_COEFS * sizeof(*s->fixed_coef_buffer), alloc_fail);
1767
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1768
            AC3Block *block = &s->blocks[blk];
1769
            FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, s->channels *
1770
                              sizeof(*block->fixed_coef), alloc_fail);
1771
            for (ch = 0; ch < s->channels; ch++)
1772
                block->fixed_coef[ch] = &s->fixed_coef_buffer[AC3_MAX_COEFS * (blk * s->channels + ch)];
1773
        }
1774
    } else {
1775
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1776
            AC3Block *block = &s->blocks[blk];
1777
            FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, s->channels *
1778
                              sizeof(*block->fixed_coef), alloc_fail);
1779
            for (ch = 0; ch < s->channels; ch++)
1780
                block->fixed_coef[ch] = (int32_t *)block->mdct_coef[ch];
1781
        }
1782
    }
1783

    
1784
    return 0;
1785
alloc_fail:
1786
    return AVERROR(ENOMEM);
1787
}
1788

    
1789

    
1790
/**
1791
 * Initialize the encoder.
1792
 */
1793
static av_cold int ac3_encode_init(AVCodecContext *avctx)
1794
{
1795
    AC3EncodeContext *s = avctx->priv_data;
1796
    int ret, frame_size_58;
1797

    
1798
    avctx->frame_size = AC3_FRAME_SIZE;
1799

    
1800
    ff_ac3_common_init();
1801

    
1802
    ret = validate_options(avctx, s);
1803
    if (ret)
1804
        return ret;
1805

    
1806
    s->bitstream_id   = 8 + s->bit_alloc.sr_shift;
1807
    s->bitstream_mode = 0; /* complete main audio service */
1808

    
1809
    s->frame_size_min  = 2 * ff_ac3_frame_size_tab[s->frame_size_code][s->bit_alloc.sr_code];
1810
    s->bits_written    = 0;
1811
    s->samples_written = 0;
1812
    s->frame_size      = s->frame_size_min;
1813

    
1814
    /* calculate crc_inv for both possible frame sizes */
1815
    frame_size_58 = (( s->frame_size    >> 2) + ( s->frame_size    >> 4)) << 1;
1816
    s->crc_inv[0] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
1817
    if (s->bit_alloc.sr_code == 1) {
1818
        frame_size_58 = (((s->frame_size+2) >> 2) + ((s->frame_size+2) >> 4)) << 1;
1819
        s->crc_inv[1] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
1820
    }
1821

    
1822
    set_bandwidth(s);
1823

    
1824
    rematrixing_init(s);
1825

    
1826
    exponent_init(s);
1827

    
1828
    bit_alloc_init(s);
1829

    
1830
    ret = mdct_init(avctx, &s->mdct, 9);
1831
    if (ret)
1832
        goto init_fail;
1833

    
1834
    ret = allocate_buffers(avctx);
1835
    if (ret)
1836
        goto init_fail;
1837

    
1838
    avctx->coded_frame= avcodec_alloc_frame();
1839

    
1840
    dsputil_init(&s->dsp, avctx);
1841
    ff_ac3dsp_init(&s->ac3dsp);
1842

    
1843
    return 0;
1844
init_fail:
1845
    ac3_encode_close(avctx);
1846
    return ret;
1847
}