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

    
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#ifndef CONFIG_AC3ENC_FLOAT
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#define CONFIG_AC3ENC_FLOAT 0
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#endif
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44

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

    
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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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54
/** 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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57

    
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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
63

    
64

    
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/**
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 * Data for a single audio block.
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 */
68
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
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} AC3Block;
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83
/**
84
 * AC-3 encoder private context.
85
 */
86
typedef struct AC3EncodeContext {
87
    PutBitContext pb;                       ///< bitstream writer context
88
    DSPContext dsp;
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    AC3MDCTContext mdct;                    ///< MDCT context
90

    
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    AC3Block blocks[AC3_MAX_BLOCKS];        ///< per-block info
92

    
93
    int bitstream_id;                       ///< bitstream id                           (bsid)
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    int bitstream_mode;                     ///< bitstream mode                         (bsmod)
95

    
96
    int bit_rate;                           ///< target bit rate, in bits-per-second
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    int sample_rate;                        ///< sampling frequency, in Hz
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    int frame_size_min;                     ///< minimum frame size in case rounding is necessary
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    int frame_size;                         ///< current frame size in bytes
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    int frame_size_code;                    ///< frame size code                        (frmsizecod)
102
    uint16_t crc_inv[2];
103
    int bits_written;                       ///< bit count    (used to avg. bitrate)
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    int samples_written;                    ///< sample count (used to avg. bitrate)
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106
    int fbw_channels;                       ///< number of full-bandwidth channels      (nfchans)
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    int channels;                           ///< total number of channels               (nchans)
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    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)
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    int nb_coefs[AC3_MAX_CHANNELS];
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117
    int rematrixing;                        ///< determines how rematrixing strategy is calculated
118

    
119
    /* bitrate allocation control */
120
    int slow_gain_code;                     ///< slow gain code                         (sgaincod)
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    int slow_decay_code;                    ///< slow decay code                        (sdcycod)
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    int fast_decay_code;                    ///< fast decay code                        (fdcycod)
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    int db_per_bit_code;                    ///< dB/bit code                            (dbpbcod)
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    int floor_code;                         ///< floor code                             (floorcod)
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    AC3BitAllocParameters bit_alloc;        ///< bit allocation parameters
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    int coarse_snr_offset;                  ///< coarse SNR offsets                     (csnroffst)
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    int fast_gain_code[AC3_MAX_CHANNELS];   ///< fast gain codes (signal-to-mask ratio) (fgaincod)
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    int fine_snr_offset[AC3_MAX_CHANNELS];  ///< fine SNR offsets                       (fsnroffst)
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    int frame_bits_fixed;                   ///< number of non-coefficient bits for fixed parameters
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    int frame_bits;                         ///< all frame bits except exponents and mantissas
131
    int exponent_bits;                      ///< number of bits used for exponents
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    /* mantissa encoding */
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    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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137
    SampleType **planar_samples;
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    uint8_t *bap_buffer;
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    uint8_t *bap1_buffer;
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    CoefType *mdct_coef_buffer;
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    int32_t *fixed_coef_buffer;
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    uint8_t *exp_buffer;
143
    uint8_t *grouped_exp_buffer;
144
    int16_t *psd_buffer;
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    int16_t *band_psd_buffer;
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    int16_t *mask_buffer;
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    uint16_t *qmant_buffer;
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149
    uint8_t exp_strategy[AC3_MAX_CHANNELS][AC3_MAX_BLOCKS]; ///< exponent strategies
150

    
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    DECLARE_ALIGNED(16, SampleType, windowed_samples)[AC3_WINDOW_SIZE];
152
} AC3EncodeContext;
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154

    
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/* prototypes for functions in ac3enc_fixed.c and ac3enc_float.c */
156

    
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static av_cold void mdct_end(AC3MDCTContext *mdct);
158

    
159
static av_cold int mdct_init(AVCodecContext *avctx, AC3MDCTContext *mdct,
160
                             int nbits);
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static void mdct512(AC3MDCTContext *mdct, CoefType *out, SampleType *in);
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164
static void apply_window(DSPContext *dsp, SampleType *output, const SampleType *input,
165
                         const SampleType *window, int n);
166

    
167
static int normalize_samples(AC3EncodeContext *s);
168

    
169
static void scale_coefficients(AC3EncodeContext *s);
170

    
171

    
172
/**
173
 * LUT for number of exponent groups.
174
 * exponent_group_tab[exponent strategy-1][number of coefficients]
175
 */
176
static uint8_t exponent_group_tab[3][256];
177

    
178

    
179
/**
180
 * List of supported channel layouts.
181
 */
182
static const int64_t ac3_channel_layouts[] = {
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     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,
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     0
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};
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/**
206
 * Adjust the frame size to make the average bit rate match the target bit rate.
207
 * This is only needed for 11025, 22050, and 44100 sample rates.
208
 */
209
static void adjust_frame_size(AC3EncodeContext *s)
210
{
211
    while (s->bits_written >= s->bit_rate && s->samples_written >= s->sample_rate) {
212
        s->bits_written    -= s->bit_rate;
213
        s->samples_written -= s->sample_rate;
214
    }
215
    s->frame_size = s->frame_size_min +
216
                    2 * (s->bits_written * s->sample_rate < s->samples_written * s->bit_rate);
217
    s->bits_written    += s->frame_size * 8;
218
    s->samples_written += AC3_FRAME_SIZE;
219
}
220

    
221

    
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/**
223
 * Deinterleave input samples.
224
 * Channels are reordered from FFmpeg's default order to AC-3 order.
225
 */
226
static void deinterleave_input_samples(AC3EncodeContext *s,
227
                                       const SampleType *samples)
228
{
229
    int ch, i;
230

    
231
    /* deinterleave and remap input samples */
232
    for (ch = 0; ch < s->channels; ch++) {
233
        const SampleType *sptr;
234
        int sinc;
235

    
236
        /* copy last 256 samples of previous frame to the start of the current frame */
237
        memcpy(&s->planar_samples[ch][0], &s->planar_samples[ch][AC3_FRAME_SIZE],
238
               AC3_BLOCK_SIZE * sizeof(s->planar_samples[0][0]));
239

    
240
        /* deinterleave */
241
        sinc = s->channels;
242
        sptr = samples + s->channel_map[ch];
243
        for (i = AC3_BLOCK_SIZE; i < AC3_FRAME_SIZE+AC3_BLOCK_SIZE; i++) {
244
            s->planar_samples[ch][i] = *sptr;
245
            sptr += sinc;
246
        }
247
    }
248
}
249

    
250

    
251
/**
252
 * Apply the MDCT to input samples to generate frequency coefficients.
253
 * This applies the KBD window and normalizes the input to reduce precision
254
 * loss due to fixed-point calculations.
255
 */
256
static void apply_mdct(AC3EncodeContext *s)
257
{
258
    int blk, ch;
259

    
260
    for (ch = 0; ch < s->channels; ch++) {
261
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
262
            AC3Block *block = &s->blocks[blk];
263
            const SampleType *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE];
264

    
265
            apply_window(&s->dsp, s->windowed_samples, input_samples, s->mdct.window, AC3_WINDOW_SIZE);
266

    
267
            block->exp_shift[ch] = normalize_samples(s);
268

    
269
            mdct512(&s->mdct, block->mdct_coef[ch], s->windowed_samples);
270
        }
271
    }
272
}
273

    
274

    
275
/**
276
 * Initialize stereo rematrixing.
277
 * If the strategy does not change for each frame, set the rematrixing flags.
278
 */
279
static void rematrixing_init(AC3EncodeContext *s)
280
{
281
    if (s->channel_mode == AC3_CHMODE_STEREO)
282
        s->rematrixing = AC3_REMATRIXING_SUMS;
283
    else
284
        s->rematrixing = AC3_REMATRIXING_NONE;
285
    /* NOTE: AC3_REMATRIXING_ALWAYS might be used in
286
             the future in conjunction with channel coupling. */
287

    
288
    if (s->rematrixing & AC3_REMATRIXING_IS_STATIC) {
289
        int flag = (s->rematrixing == AC3_REMATRIXING_ALWAYS);
290
        s->blocks[0].new_rematrixing_strategy = 1;
291
        memset(s->blocks[0].rematrixing_flags, flag,
292
               sizeof(s->blocks[0].rematrixing_flags));
293
    }
294
}
295

    
296

    
297
/**
298
 * Determine rematrixing flags for each block and band.
299
 */
300
static void compute_rematrixing_strategy(AC3EncodeContext *s)
301
{
302
    int nb_coefs;
303
    int blk, bnd, i;
304
    AC3Block *block, *block0;
305

    
306
    if (s->rematrixing & AC3_REMATRIXING_IS_STATIC)
307
        return;
308

    
309
    nb_coefs = FFMIN(s->nb_coefs[0], s->nb_coefs[1]);
310

    
311
    s->blocks[0].new_rematrixing_strategy = 1;
312
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
313
        block = &s->blocks[blk];
314
        for (bnd = 0; bnd < 4; bnd++) {
315
            /* calculate calculate sum of squared coeffs for one band in one block */
316
            int start = ff_ac3_rematrix_band_tab[bnd];
317
            int end   = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
318
            CoefSumType sum[4] = {0,};
319
            for (i = start; i < end; i++) {
320
                CoefType lt = block->mdct_coef[0][i];
321
                CoefType rt = block->mdct_coef[1][i];
322
                CoefType md = lt + rt;
323
                CoefType sd = lt - rt;
324
                sum[0] += lt * lt;
325
                sum[1] += rt * rt;
326
                sum[2] += md * md;
327
                sum[3] += sd * sd;
328
            }
329

    
330
            /* compare sums to determine if rematrixing will be used for this band */
331
            if (FFMIN(sum[2], sum[3]) < FFMIN(sum[0], sum[1]))
332
                block->rematrixing_flags[bnd] = 1;
333
            else
334
                block->rematrixing_flags[bnd] = 0;
335

    
336
            /* determine if new rematrixing flags will be sent */
337
            if (blk &&
338
                !block->new_rematrixing_strategy &&
339
                block->rematrixing_flags[bnd] != block0->rematrixing_flags[bnd]) {
340
                block->new_rematrixing_strategy = 1;
341
            }
342
        }
343
        block0 = block;
344
    }
345
}
346

    
347

    
348
/**
349
 * Apply stereo rematrixing to coefficients based on rematrixing flags.
350
 */
351
static void apply_rematrixing(AC3EncodeContext *s)
352
{
353
    int nb_coefs;
354
    int blk, bnd, i;
355
    int start, end;
356
    uint8_t *flags;
357

    
358
    if (s->rematrixing == AC3_REMATRIXING_NONE)
359
        return;
360

    
361
    nb_coefs = FFMIN(s->nb_coefs[0], s->nb_coefs[1]);
362

    
363
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
364
        AC3Block *block = &s->blocks[blk];
365
        if (block->new_rematrixing_strategy)
366
            flags = block->rematrixing_flags;
367
        for (bnd = 0; bnd < 4; bnd++) {
368
            if (flags[bnd]) {
369
                start = ff_ac3_rematrix_band_tab[bnd];
370
                end   = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
371
                for (i = start; i < end; i++) {
372
                    int32_t lt = block->fixed_coef[0][i];
373
                    int32_t rt = block->fixed_coef[1][i];
374
                    block->fixed_coef[0][i] = (lt + rt) >> 1;
375
                    block->fixed_coef[1][i] = (lt - rt) >> 1;
376
                }
377
            }
378
        }
379
    }
380
}
381

    
382

    
383
/**
384
 * Initialize exponent tables.
385
 */
386
static av_cold void exponent_init(AC3EncodeContext *s)
387
{
388
    int i;
389
    for (i = 73; i < 256; i++) {
390
        exponent_group_tab[0][i] = (i - 1) /  3;
391
        exponent_group_tab[1][i] = (i + 2) /  6;
392
        exponent_group_tab[2][i] = (i + 8) / 12;
393
    }
394
    /* LFE */
395
    exponent_group_tab[0][7] = 2;
396
}
397

    
398

    
399
/**
400
 * Extract exponents from the MDCT coefficients.
401
 * This takes into account the normalization that was done to the input samples
402
 * by adjusting the exponents by the exponent shift values.
403
 */
404
static void extract_exponents(AC3EncodeContext *s)
405
{
406
    int blk, ch, i;
407

    
408
    for (ch = 0; ch < s->channels; ch++) {
409
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
410
            AC3Block *block = &s->blocks[blk];
411
            uint8_t *exp   = block->exp[ch];
412
            int32_t *coef = block->fixed_coef[ch];
413
            int exp_shift  = block->exp_shift[ch];
414
            for (i = 0; i < AC3_MAX_COEFS; i++) {
415
                int e;
416
                int v = abs(coef[i]);
417
                if (v == 0)
418
                    e = 24;
419
                else {
420
                    e = 23 - av_log2(v) + exp_shift;
421
                    if (e >= 24) {
422
                        e = 24;
423
                        coef[i] = 0;
424
                    }
425
                }
426
                exp[i] = e;
427
            }
428
        }
429
    }
430
}
431

    
432

    
433
/**
434
 * Exponent Difference Threshold.
435
 * New exponents are sent if their SAD exceed this number.
436
 */
437
#define EXP_DIFF_THRESHOLD 500
438

    
439

    
440
/**
441
 * Calculate exponent strategies for all blocks in a single channel.
442
 */
443
static void compute_exp_strategy_ch(AC3EncodeContext *s, uint8_t *exp_strategy,
444
                                    uint8_t *exp)
445
{
446
    int blk, blk1;
447
    int exp_diff;
448

    
449
    /* estimate if the exponent variation & decide if they should be
450
       reused in the next frame */
451
    exp_strategy[0] = EXP_NEW;
452
    exp += AC3_MAX_COEFS;
453
    for (blk = 1; blk < AC3_MAX_BLOCKS; blk++) {
454
        exp_diff = s->dsp.sad[0](NULL, exp, exp - AC3_MAX_COEFS, 16, 16);
455
        if (exp_diff > EXP_DIFF_THRESHOLD)
456
            exp_strategy[blk] = EXP_NEW;
457
        else
458
            exp_strategy[blk] = EXP_REUSE;
459
        exp += AC3_MAX_COEFS;
460
    }
461
    emms_c();
462

    
463
    /* now select the encoding strategy type : if exponents are often
464
       recoded, we use a coarse encoding */
465
    blk = 0;
466
    while (blk < AC3_MAX_BLOCKS) {
467
        blk1 = blk + 1;
468
        while (blk1 < AC3_MAX_BLOCKS && exp_strategy[blk1] == EXP_REUSE)
469
            blk1++;
470
        switch (blk1 - blk) {
471
        case 1:  exp_strategy[blk] = EXP_D45; break;
472
        case 2:
473
        case 3:  exp_strategy[blk] = EXP_D25; break;
474
        default: exp_strategy[blk] = EXP_D15; break;
475
        }
476
        blk = blk1;
477
    }
478
}
479

    
480

    
481
/**
482
 * Calculate exponent strategies for all channels.
483
 * Array arrangement is reversed to simplify the per-channel calculation.
484
 */
485
static void compute_exp_strategy(AC3EncodeContext *s)
486
{
487
    int ch, blk;
488

    
489
    for (ch = 0; ch < s->fbw_channels; ch++) {
490
        compute_exp_strategy_ch(s, s->exp_strategy[ch], s->blocks[0].exp[ch]);
491
    }
492
    if (s->lfe_on) {
493
        ch = s->lfe_channel;
494
        s->exp_strategy[ch][0] = EXP_D15;
495
        for (blk = 1; blk < AC3_MAX_BLOCKS; blk++)
496
            s->exp_strategy[ch][blk] = EXP_REUSE;
497
    }
498
}
499

    
500

    
501
/**
502
 * Set each encoded exponent in a block to the minimum of itself and the
503
 * exponents in the same frequency bin of up to 5 following blocks.
504
 */
505
static void exponent_min(uint8_t *exp, int num_reuse_blocks, int nb_coefs)
506
{
507
    int blk, i;
508

    
509
    if (!num_reuse_blocks)
510
        return;
511

    
512
    for (i = 0; i < nb_coefs; i++) {
513
        uint8_t min_exp = *exp;
514
        uint8_t *exp1 = exp + AC3_MAX_COEFS;
515
        for (blk = 0; blk < num_reuse_blocks; blk++) {
516
            uint8_t next_exp = *exp1;
517
            if (next_exp < min_exp)
518
                min_exp = next_exp;
519
            exp1 += AC3_MAX_COEFS;
520
        }
521
        *exp++ = min_exp;
522
    }
523
}
524

    
525

    
526
/**
527
 * Update the exponents so that they are the ones the decoder will decode.
528
 */
529
static void encode_exponents_blk_ch(uint8_t *exp, int nb_exps, int exp_strategy)
530
{
531
    int nb_groups, i, k;
532

    
533
    nb_groups = exponent_group_tab[exp_strategy-1][nb_exps] * 3;
534

    
535
    /* for each group, compute the minimum exponent */
536
    switch(exp_strategy) {
537
    case EXP_D25:
538
        for (i = 1, k = 1; i <= nb_groups; i++) {
539
            uint8_t exp_min = exp[k];
540
            if (exp[k+1] < exp_min)
541
                exp_min = exp[k+1];
542
            exp[i] = exp_min;
543
            k += 2;
544
        }
545
        break;
546
    case EXP_D45:
547
        for (i = 1, k = 1; i <= nb_groups; i++) {
548
            uint8_t exp_min = exp[k];
549
            if (exp[k+1] < exp_min)
550
                exp_min = exp[k+1];
551
            if (exp[k+2] < exp_min)
552
                exp_min = exp[k+2];
553
            if (exp[k+3] < exp_min)
554
                exp_min = exp[k+3];
555
            exp[i] = exp_min;
556
            k += 4;
557
        }
558
        break;
559
    }
560

    
561
    /* constraint for DC exponent */
562
    if (exp[0] > 15)
563
        exp[0] = 15;
564

    
565
    /* decrease the delta between each groups to within 2 so that they can be
566
       differentially encoded */
567
    for (i = 1; i <= nb_groups; i++)
568
        exp[i] = FFMIN(exp[i], exp[i-1] + 2);
569
    i--;
570
    while (--i >= 0)
571
        exp[i] = FFMIN(exp[i], exp[i+1] + 2);
572

    
573
    /* now we have the exponent values the decoder will see */
574
    switch (exp_strategy) {
575
    case EXP_D25:
576
        for (i = nb_groups, k = nb_groups * 2; i > 0; i--) {
577
            uint8_t exp1 = exp[i];
578
            exp[k--] = exp1;
579
            exp[k--] = exp1;
580
        }
581
        break;
582
    case EXP_D45:
583
        for (i = nb_groups, k = nb_groups * 4; i > 0; i--) {
584
            exp[k] = exp[k-1] = exp[k-2] = exp[k-3] = exp[i];
585
            k -= 4;
586
        }
587
        break;
588
    }
589
}
590

    
591

    
592
/**
593
 * Encode exponents from original extracted form to what the decoder will see.
594
 * This copies and groups exponents based on exponent strategy and reduces
595
 * deltas between adjacent exponent groups so that they can be differentially
596
 * encoded.
597
 */
598
static void encode_exponents(AC3EncodeContext *s)
599
{
600
    int blk, blk1, ch;
601
    uint8_t *exp, *exp1, *exp_strategy;
602
    int nb_coefs, num_reuse_blocks;
603

    
604
    for (ch = 0; ch < s->channels; ch++) {
605
        exp          = s->blocks[0].exp[ch];
606
        exp_strategy = s->exp_strategy[ch];
607
        nb_coefs     = s->nb_coefs[ch];
608

    
609
        blk = 0;
610
        while (blk < AC3_MAX_BLOCKS) {
611
            blk1 = blk + 1;
612

    
613
            /* count the number of EXP_REUSE blocks after the current block */
614
            while (blk1 < AC3_MAX_BLOCKS && exp_strategy[blk1] == EXP_REUSE)
615
                blk1++;
616
            num_reuse_blocks = blk1 - blk - 1;
617

    
618
            /* for the EXP_REUSE case we select the min of the exponents */
619
            exponent_min(exp, num_reuse_blocks, nb_coefs);
620

    
621
            encode_exponents_blk_ch(exp, nb_coefs, exp_strategy[blk]);
622

    
623
            /* copy encoded exponents for reuse case */
624
            exp1 = exp + AC3_MAX_COEFS;
625
            while (blk < blk1-1) {
626
                memcpy(exp1, exp, nb_coefs * sizeof(*exp));
627
                exp1 += AC3_MAX_COEFS;
628
                blk++;
629
            }
630
            blk = blk1;
631
            exp = exp1;
632
        }
633
    }
634
}
635

    
636

    
637
/**
638
 * Group exponents.
639
 * 3 delta-encoded exponents are in each 7-bit group. The number of groups
640
 * varies depending on exponent strategy and bandwidth.
641
 */
642
static void group_exponents(AC3EncodeContext *s)
643
{
644
    int blk, ch, i;
645
    int group_size, nb_groups, bit_count;
646
    uint8_t *p;
647
    int delta0, delta1, delta2;
648
    int exp0, exp1;
649

    
650
    bit_count = 0;
651
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
652
        AC3Block *block = &s->blocks[blk];
653
        for (ch = 0; ch < s->channels; ch++) {
654
            int exp_strategy = s->exp_strategy[ch][blk];
655
            if (exp_strategy == EXP_REUSE)
656
                continue;
657
            group_size = exp_strategy + (exp_strategy == EXP_D45);
658
            nb_groups = exponent_group_tab[exp_strategy-1][s->nb_coefs[ch]];
659
            bit_count += 4 + (nb_groups * 7);
660
            p = block->exp[ch];
661

    
662
            /* DC exponent */
663
            exp1 = *p++;
664
            block->grouped_exp[ch][0] = exp1;
665

    
666
            /* remaining exponents are delta encoded */
667
            for (i = 1; i <= nb_groups; i++) {
668
                /* merge three delta in one code */
669
                exp0   = exp1;
670
                exp1   = p[0];
671
                p     += group_size;
672
                delta0 = exp1 - exp0 + 2;
673

    
674
                exp0   = exp1;
675
                exp1   = p[0];
676
                p     += group_size;
677
                delta1 = exp1 - exp0 + 2;
678

    
679
                exp0   = exp1;
680
                exp1   = p[0];
681
                p     += group_size;
682
                delta2 = exp1 - exp0 + 2;
683

    
684
                block->grouped_exp[ch][i] = ((delta0 * 5 + delta1) * 5) + delta2;
685
            }
686
        }
687
    }
688

    
689
    s->exponent_bits = bit_count;
690
}
691

    
692

    
693
/**
694
 * Calculate final exponents from the supplied MDCT coefficients and exponent shift.
695
 * Extract exponents from MDCT coefficients, calculate exponent strategies,
696
 * and encode final exponents.
697
 */
698
static void process_exponents(AC3EncodeContext *s)
699
{
700
    extract_exponents(s);
701

    
702
    compute_exp_strategy(s);
703

    
704
    encode_exponents(s);
705

    
706
    group_exponents(s);
707
}
708

    
709

    
710
/**
711
 * Count frame bits that are based solely on fixed parameters.
712
 * This only has to be run once when the encoder is initialized.
713
 */
714
static void count_frame_bits_fixed(AC3EncodeContext *s)
715
{
716
    static const int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
717
    int blk;
718
    int frame_bits;
719

    
720
    /* assumptions:
721
     *   no dynamic range codes
722
     *   no channel coupling
723
     *   bit allocation parameters do not change between blocks
724
     *   SNR offsets do not change between blocks
725
     *   no delta bit allocation
726
     *   no skipped data
727
     *   no auxilliary data
728
     */
729

    
730
    /* header size */
731
    frame_bits = 65;
732
    frame_bits += frame_bits_inc[s->channel_mode];
733

    
734
    /* audio blocks */
735
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
736
        frame_bits += s->fbw_channels * 2 + 2; /* blksw * c, dithflag * c, dynrnge, cplstre */
737
        if (s->channel_mode == AC3_CHMODE_STEREO) {
738
            frame_bits++; /* rematstr */
739
        }
740
        frame_bits += 2 * s->fbw_channels; /* chexpstr[2] * c */
741
        if (s->lfe_on)
742
            frame_bits++; /* lfeexpstr */
743
        frame_bits++; /* baie */
744
        frame_bits++; /* snr */
745
        frame_bits += 2; /* delta / skip */
746
    }
747
    frame_bits++; /* cplinu for block 0 */
748
    /* bit alloc info */
749
    /* sdcycod[2], fdcycod[2], sgaincod[2], dbpbcod[2], floorcod[3] */
750
    /* csnroffset[6] */
751
    /* (fsnoffset[4] + fgaincod[4]) * c */
752
    frame_bits += 2*4 + 3 + 6 + s->channels * (4 + 3);
753

    
754
    /* auxdatae, crcrsv */
755
    frame_bits += 2;
756

    
757
    /* CRC */
758
    frame_bits += 16;
759

    
760
    s->frame_bits_fixed = frame_bits;
761
}
762

    
763

    
764
/**
765
 * Initialize bit allocation.
766
 * Set default parameter codes and calculate parameter values.
767
 */
768
static void bit_alloc_init(AC3EncodeContext *s)
769
{
770
    int ch;
771

    
772
    /* init default parameters */
773
    s->slow_decay_code = 2;
774
    s->fast_decay_code = 1;
775
    s->slow_gain_code  = 1;
776
    s->db_per_bit_code = 3;
777
    s->floor_code      = 4;
778
    for (ch = 0; ch < s->channels; ch++)
779
        s->fast_gain_code[ch] = 4;
780

    
781
    /* initial snr offset */
782
    s->coarse_snr_offset = 40;
783

    
784
    /* compute real values */
785
    /* currently none of these values change during encoding, so we can just
786
       set them once at initialization */
787
    s->bit_alloc.slow_decay = ff_ac3_slow_decay_tab[s->slow_decay_code] >> s->bit_alloc.sr_shift;
788
    s->bit_alloc.fast_decay = ff_ac3_fast_decay_tab[s->fast_decay_code] >> s->bit_alloc.sr_shift;
789
    s->bit_alloc.slow_gain  = ff_ac3_slow_gain_tab[s->slow_gain_code];
790
    s->bit_alloc.db_per_bit = ff_ac3_db_per_bit_tab[s->db_per_bit_code];
791
    s->bit_alloc.floor      = ff_ac3_floor_tab[s->floor_code];
792

    
793
    count_frame_bits_fixed(s);
794
}
795

    
796

    
797
/**
798
 * Count the bits used to encode the frame, minus exponents and mantissas.
799
 * Bits based on fixed parameters have already been counted, so now we just
800
 * have to add the bits based on parameters that change during encoding.
801
 */
802
static void count_frame_bits(AC3EncodeContext *s)
803
{
804
    int blk, ch;
805
    int frame_bits = 0;
806

    
807
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
808
        /* stereo rematrixing */
809
        if (s->channel_mode == AC3_CHMODE_STEREO &&
810
            s->blocks[blk].new_rematrixing_strategy) {
811
            frame_bits += 4;
812
        }
813

    
814
        for (ch = 0; ch < s->fbw_channels; ch++) {
815
            if (s->exp_strategy[ch][blk] != EXP_REUSE)
816
                frame_bits += 6 + 2; /* chbwcod[6], gainrng[2] */
817
        }
818
    }
819
    s->frame_bits = s->frame_bits_fixed + frame_bits;
820
}
821

    
822

    
823
/**
824
 * Calculate the number of bits needed to encode a set of mantissas.
825
 */
826
static int compute_mantissa_size(int mant_cnt[5], uint8_t *bap, int nb_coefs)
827
{
828
    int bits, b, i;
829

    
830
    bits = 0;
831
    for (i = 0; i < nb_coefs; i++) {
832
        b = bap[i];
833
        if (b <= 4) {
834
            // bap=1 to bap=4 will be counted in compute_mantissa_size_final
835
            mant_cnt[b]++;
836
        } else if (b <= 13) {
837
            // bap=5 to bap=13 use (bap-1) bits
838
            bits += b - 1;
839
        } else {
840
            // bap=14 uses 14 bits and bap=15 uses 16 bits
841
            bits += (b == 14) ? 14 : 16;
842
        }
843
    }
844
    return bits;
845
}
846

    
847

    
848
/**
849
 * Finalize the mantissa bit count by adding in the grouped mantissas.
850
 */
851
static int compute_mantissa_size_final(int mant_cnt[5])
852
{
853
    // bap=1 : 3 mantissas in 5 bits
854
    int bits = (mant_cnt[1] / 3) * 5;
855
    // bap=2 : 3 mantissas in 7 bits
856
    // bap=4 : 2 mantissas in 7 bits
857
    bits += ((mant_cnt[2] / 3) + (mant_cnt[4] >> 1)) * 7;
858
    // bap=3 : each mantissa is 3 bits
859
    bits += mant_cnt[3] * 3;
860
    return bits;
861
}
862

    
863

    
864
/**
865
 * Calculate masking curve based on the final exponents.
866
 * Also calculate the power spectral densities to use in future calculations.
867
 */
868
static void bit_alloc_masking(AC3EncodeContext *s)
869
{
870
    int blk, ch;
871

    
872
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
873
        AC3Block *block = &s->blocks[blk];
874
        for (ch = 0; ch < s->channels; ch++) {
875
            /* We only need psd and mask for calculating bap.
876
               Since we currently do not calculate bap when exponent
877
               strategy is EXP_REUSE we do not need to calculate psd or mask. */
878
            if (s->exp_strategy[ch][blk] != EXP_REUSE) {
879
                ff_ac3_bit_alloc_calc_psd(block->exp[ch], 0,
880
                                          s->nb_coefs[ch],
881
                                          block->psd[ch], block->band_psd[ch]);
882
                ff_ac3_bit_alloc_calc_mask(&s->bit_alloc, block->band_psd[ch],
883
                                           0, s->nb_coefs[ch],
884
                                           ff_ac3_fast_gain_tab[s->fast_gain_code[ch]],
885
                                           ch == s->lfe_channel,
886
                                           DBA_NONE, 0, NULL, NULL, NULL,
887
                                           block->mask[ch]);
888
            }
889
        }
890
    }
891
}
892

    
893

    
894
/**
895
 * Ensure that bap for each block and channel point to the current bap_buffer.
896
 * They may have been switched during the bit allocation search.
897
 */
898
static void reset_block_bap(AC3EncodeContext *s)
899
{
900
    int blk, ch;
901
    if (s->blocks[0].bap[0] == s->bap_buffer)
902
        return;
903
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
904
        for (ch = 0; ch < s->channels; ch++) {
905
            s->blocks[blk].bap[ch] = &s->bap_buffer[AC3_MAX_COEFS * (blk * s->channels + ch)];
906
        }
907
    }
908
}
909

    
910

    
911
/**
912
 * Run the bit allocation with a given SNR offset.
913
 * This calculates the bit allocation pointers that will be used to determine
914
 * the quantization of each mantissa.
915
 * @return the number of bits needed for mantissas if the given SNR offset is
916
 *         is used.
917
 */
918
static int bit_alloc(AC3EncodeContext *s, int snr_offset)
919
{
920
    int blk, ch;
921
    int mantissa_bits;
922
    int mant_cnt[5];
923

    
924
    snr_offset = (snr_offset - 240) << 2;
925

    
926
    reset_block_bap(s);
927
    mantissa_bits = 0;
928
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
929
        AC3Block *block = &s->blocks[blk];
930
        // initialize grouped mantissa counts. these are set so that they are
931
        // padded to the next whole group size when bits are counted in
932
        // compute_mantissa_size_final
933
        mant_cnt[0] = mant_cnt[3] = 0;
934
        mant_cnt[1] = mant_cnt[2] = 2;
935
        mant_cnt[4] = 1;
936
        for (ch = 0; ch < s->channels; ch++) {
937
            /* Currently the only bit allocation parameters which vary across
938
               blocks within a frame are the exponent values.  We can take
939
               advantage of that by reusing the bit allocation pointers
940
               whenever we reuse exponents. */
941
            if (s->exp_strategy[ch][blk] == EXP_REUSE) {
942
                memcpy(block->bap[ch], s->blocks[blk-1].bap[ch], AC3_MAX_COEFS);
943
            } else {
944
                ff_ac3_bit_alloc_calc_bap(block->mask[ch], block->psd[ch], 0,
945
                                          s->nb_coefs[ch], snr_offset,
946
                                          s->bit_alloc.floor, ff_ac3_bap_tab,
947
                                          block->bap[ch]);
948
            }
949
            mantissa_bits += compute_mantissa_size(mant_cnt, block->bap[ch], s->nb_coefs[ch]);
950
        }
951
        mantissa_bits += compute_mantissa_size_final(mant_cnt);
952
    }
953
    return mantissa_bits;
954
}
955

    
956

    
957
/**
958
 * Constant bitrate bit allocation search.
959
 * Find the largest SNR offset that will allow data to fit in the frame.
960
 */
961
static int cbr_bit_allocation(AC3EncodeContext *s)
962
{
963
    int ch;
964
    int bits_left;
965
    int snr_offset, snr_incr;
966

    
967
    bits_left = 8 * s->frame_size - (s->frame_bits + s->exponent_bits);
968

    
969
    snr_offset = s->coarse_snr_offset << 4;
970

    
971
    /* if previous frame SNR offset was 1023, check if current frame can also
972
       use SNR offset of 1023. if so, skip the search. */
973
    if ((snr_offset | s->fine_snr_offset[0]) == 1023) {
974
        if (bit_alloc(s, 1023) <= bits_left)
975
            return 0;
976
    }
977

    
978
    while (snr_offset >= 0 &&
979
           bit_alloc(s, snr_offset) > bits_left) {
980
        snr_offset -= 64;
981
    }
982
    if (snr_offset < 0)
983
        return AVERROR(EINVAL);
984

    
985
    FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
986
    for (snr_incr = 64; snr_incr > 0; snr_incr >>= 2) {
987
        while (snr_offset + snr_incr <= 1023 &&
988
               bit_alloc(s, snr_offset + snr_incr) <= bits_left) {
989
            snr_offset += snr_incr;
990
            FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
991
        }
992
    }
993
    FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
994
    reset_block_bap(s);
995

    
996
    s->coarse_snr_offset = snr_offset >> 4;
997
    for (ch = 0; ch < s->channels; ch++)
998
        s->fine_snr_offset[ch] = snr_offset & 0xF;
999

    
1000
    return 0;
1001
}
1002

    
1003

    
1004
/**
1005
 * Downgrade exponent strategies to reduce the bits used by the exponents.
1006
 * This is a fallback for when bit allocation fails with the normal exponent
1007
 * strategies.  Each time this function is run it only downgrades the
1008
 * strategy in 1 channel of 1 block.
1009
 * @return non-zero if downgrade was unsuccessful
1010
 */
1011
static int downgrade_exponents(AC3EncodeContext *s)
1012
{
1013
    int ch, blk;
1014

    
1015
    for (ch = 0; ch < s->fbw_channels; ch++) {
1016
        for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
1017
            if (s->exp_strategy[ch][blk] == EXP_D15) {
1018
                s->exp_strategy[ch][blk] = EXP_D25;
1019
                return 0;
1020
            }
1021
        }
1022
    }
1023
    for (ch = 0; ch < s->fbw_channels; ch++) {
1024
        for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
1025
            if (s->exp_strategy[ch][blk] == EXP_D25) {
1026
                s->exp_strategy[ch][blk] = EXP_D45;
1027
                return 0;
1028
            }
1029
        }
1030
    }
1031
    for (ch = 0; ch < s->fbw_channels; ch++) {
1032
        /* block 0 cannot reuse exponents, so only downgrade D45 to REUSE if
1033
           the block number > 0 */
1034
        for (blk = AC3_MAX_BLOCKS-1; blk > 0; blk--) {
1035
            if (s->exp_strategy[ch][blk] > EXP_REUSE) {
1036
                s->exp_strategy[ch][blk] = EXP_REUSE;
1037
                return 0;
1038
            }
1039
        }
1040
    }
1041
    return -1;
1042
}
1043

    
1044

    
1045
/**
1046
 * Reduce the bandwidth to reduce the number of bits used for a given SNR offset.
1047
 * This is a second fallback for when bit allocation still fails after exponents
1048
 * have been downgraded.
1049
 * @return non-zero if bandwidth reduction was unsuccessful
1050
 */
1051
static int reduce_bandwidth(AC3EncodeContext *s, int min_bw_code)
1052
{
1053
    int ch;
1054

    
1055
    if (s->bandwidth_code[0] > min_bw_code) {
1056
        for (ch = 0; ch < s->fbw_channels; ch++) {
1057
            s->bandwidth_code[ch]--;
1058
            s->nb_coefs[ch] = s->bandwidth_code[ch] * 3 + 73;
1059
        }
1060
        return 0;
1061
    }
1062
    return -1;
1063
}
1064

    
1065

    
1066
/**
1067
 * Perform bit allocation search.
1068
 * Finds the SNR offset value that maximizes quality and fits in the specified
1069
 * frame size.  Output is the SNR offset and a set of bit allocation pointers
1070
 * used to quantize the mantissas.
1071
 */
1072
static int compute_bit_allocation(AC3EncodeContext *s)
1073
{
1074
    int ret;
1075

    
1076
    count_frame_bits(s);
1077

    
1078
    bit_alloc_masking(s);
1079

    
1080
    ret = cbr_bit_allocation(s);
1081
    while (ret) {
1082
        /* fallback 1: downgrade exponents */
1083
        if (!downgrade_exponents(s)) {
1084
            extract_exponents(s);
1085
            encode_exponents(s);
1086
            group_exponents(s);
1087
            ret = compute_bit_allocation(s);
1088
            continue;
1089
        }
1090

    
1091
        /* fallback 2: reduce bandwidth */
1092
        /* only do this if the user has not specified a specific cutoff
1093
           frequency */
1094
        if (!s->cutoff && !reduce_bandwidth(s, 0)) {
1095
            process_exponents(s);
1096
            ret = compute_bit_allocation(s);
1097
            continue;
1098
        }
1099

    
1100
        /* fallbacks were not enough... */
1101
        break;
1102
    }
1103

    
1104
    return ret;
1105
}
1106

    
1107

    
1108
/**
1109
 * Symmetric quantization on 'levels' levels.
1110
 */
1111
static inline int sym_quant(int c, int e, int levels)
1112
{
1113
    int v;
1114

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

    
1128

    
1129
/**
1130
 * Asymmetric quantization on 2^qbits levels.
1131
 */
1132
static inline int asym_quant(int c, int e, int qbits)
1133
{
1134
    int lshift, m, v;
1135

    
1136
    lshift = e + qbits - 24;
1137
    if (lshift >= 0)
1138
        v = c << lshift;
1139
    else
1140
        v = c >> (-lshift);
1141
    /* rounding */
1142
    v = (v + 1) >> 1;
1143
    m = (1 << (qbits-1));
1144
    if (v >= m)
1145
        v = m - 1;
1146
    assert(v >= -m);
1147
    return v & ((1 << qbits)-1);
1148
}
1149

    
1150

    
1151
/**
1152
 * Quantize a set of mantissas for a single channel in a single block.
1153
 */
1154
static void quantize_mantissas_blk_ch(AC3EncodeContext *s, int32_t *fixed_coef,
1155
                                      int8_t exp_shift, uint8_t *exp,
1156
                                      uint8_t *bap, uint16_t *qmant, int n)
1157
{
1158
    int i;
1159

    
1160
    for (i = 0; i < n; i++) {
1161
        int v;
1162
        int c = fixed_coef[i];
1163
        int e = exp[i] - exp_shift;
1164
        int b = bap[i];
1165
        switch (b) {
1166
        case 0:
1167
            v = 0;
1168
            break;
1169
        case 1:
1170
            v = sym_quant(c, e, 3);
1171
            switch (s->mant1_cnt) {
1172
            case 0:
1173
                s->qmant1_ptr = &qmant[i];
1174
                v = 9 * v;
1175
                s->mant1_cnt = 1;
1176
                break;
1177
            case 1:
1178
                *s->qmant1_ptr += 3 * v;
1179
                s->mant1_cnt = 2;
1180
                v = 128;
1181
                break;
1182
            default:
1183
                *s->qmant1_ptr += v;
1184
                s->mant1_cnt = 0;
1185
                v = 128;
1186
                break;
1187
            }
1188
            break;
1189
        case 2:
1190
            v = sym_quant(c, e, 5);
1191
            switch (s->mant2_cnt) {
1192
            case 0:
1193
                s->qmant2_ptr = &qmant[i];
1194
                v = 25 * v;
1195
                s->mant2_cnt = 1;
1196
                break;
1197
            case 1:
1198
                *s->qmant2_ptr += 5 * v;
1199
                s->mant2_cnt = 2;
1200
                v = 128;
1201
                break;
1202
            default:
1203
                *s->qmant2_ptr += v;
1204
                s->mant2_cnt = 0;
1205
                v = 128;
1206
                break;
1207
            }
1208
            break;
1209
        case 3:
1210
            v = sym_quant(c, e, 7);
1211
            break;
1212
        case 4:
1213
            v = sym_quant(c, e, 11);
1214
            switch (s->mant4_cnt) {
1215
            case 0:
1216
                s->qmant4_ptr = &qmant[i];
1217
                v = 11 * v;
1218
                s->mant4_cnt = 1;
1219
                break;
1220
            default:
1221
                *s->qmant4_ptr += v;
1222
                s->mant4_cnt = 0;
1223
                v = 128;
1224
                break;
1225
            }
1226
            break;
1227
        case 5:
1228
            v = sym_quant(c, e, 15);
1229
            break;
1230
        case 14:
1231
            v = asym_quant(c, e, 14);
1232
            break;
1233
        case 15:
1234
            v = asym_quant(c, e, 16);
1235
            break;
1236
        default:
1237
            v = asym_quant(c, e, b - 1);
1238
            break;
1239
        }
1240
        qmant[i] = v;
1241
    }
1242
}
1243

    
1244

    
1245
/**
1246
 * Quantize mantissas using coefficients, exponents, and bit allocation pointers.
1247
 */
1248
static void quantize_mantissas(AC3EncodeContext *s)
1249
{
1250
    int blk, ch;
1251

    
1252

    
1253
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1254
        AC3Block *block = &s->blocks[blk];
1255
        s->mant1_cnt  = s->mant2_cnt  = s->mant4_cnt  = 0;
1256
        s->qmant1_ptr = s->qmant2_ptr = s->qmant4_ptr = NULL;
1257

    
1258
        for (ch = 0; ch < s->channels; ch++) {
1259
            quantize_mantissas_blk_ch(s, block->fixed_coef[ch], block->exp_shift[ch],
1260
                                      block->exp[ch], block->bap[ch],
1261
                                      block->qmant[ch], s->nb_coefs[ch]);
1262
        }
1263
    }
1264
}
1265

    
1266

    
1267
/**
1268
 * Write the AC-3 frame header to the output bitstream.
1269
 */
1270
static void output_frame_header(AC3EncodeContext *s)
1271
{
1272
    put_bits(&s->pb, 16, 0x0b77);   /* frame header */
1273
    put_bits(&s->pb, 16, 0);        /* crc1: will be filled later */
1274
    put_bits(&s->pb, 2,  s->bit_alloc.sr_code);
1275
    put_bits(&s->pb, 6,  s->frame_size_code + (s->frame_size - s->frame_size_min) / 2);
1276
    put_bits(&s->pb, 5,  s->bitstream_id);
1277
    put_bits(&s->pb, 3,  s->bitstream_mode);
1278
    put_bits(&s->pb, 3,  s->channel_mode);
1279
    if ((s->channel_mode & 0x01) && s->channel_mode != AC3_CHMODE_MONO)
1280
        put_bits(&s->pb, 2, 1);     /* XXX -4.5 dB */
1281
    if (s->channel_mode & 0x04)
1282
        put_bits(&s->pb, 2, 1);     /* XXX -6 dB */
1283
    if (s->channel_mode == AC3_CHMODE_STEREO)
1284
        put_bits(&s->pb, 2, 0);     /* surround not indicated */
1285
    put_bits(&s->pb, 1, s->lfe_on); /* LFE */
1286
    put_bits(&s->pb, 5, 31);        /* dialog norm: -31 db */
1287
    put_bits(&s->pb, 1, 0);         /* no compression control word */
1288
    put_bits(&s->pb, 1, 0);         /* no lang code */
1289
    put_bits(&s->pb, 1, 0);         /* no audio production info */
1290
    put_bits(&s->pb, 1, 0);         /* no copyright */
1291
    put_bits(&s->pb, 1, 1);         /* original bitstream */
1292
    put_bits(&s->pb, 1, 0);         /* no time code 1 */
1293
    put_bits(&s->pb, 1, 0);         /* no time code 2 */
1294
    put_bits(&s->pb, 1, 0);         /* no additional bit stream info */
1295
}
1296

    
1297

    
1298
/**
1299
 * Write one audio block to the output bitstream.
1300
 */
1301
static void output_audio_block(AC3EncodeContext *s, int blk)
1302
{
1303
    int ch, i, baie, rbnd;
1304
    AC3Block *block = &s->blocks[blk];
1305

    
1306
    /* block switching */
1307
    for (ch = 0; ch < s->fbw_channels; ch++)
1308
        put_bits(&s->pb, 1, 0);
1309

    
1310
    /* dither flags */
1311
    for (ch = 0; ch < s->fbw_channels; ch++)
1312
        put_bits(&s->pb, 1, 1);
1313

    
1314
    /* dynamic range codes */
1315
    put_bits(&s->pb, 1, 0);
1316

    
1317
    /* channel coupling */
1318
    if (!blk) {
1319
        put_bits(&s->pb, 1, 1); /* coupling strategy present */
1320
        put_bits(&s->pb, 1, 0); /* no coupling strategy */
1321
    } else {
1322
        put_bits(&s->pb, 1, 0); /* no new coupling strategy */
1323
    }
1324

    
1325
    /* stereo rematrixing */
1326
    if (s->channel_mode == AC3_CHMODE_STEREO) {
1327
        put_bits(&s->pb, 1, block->new_rematrixing_strategy);
1328
        if (block->new_rematrixing_strategy) {
1329
            /* rematrixing flags */
1330
            for (rbnd = 0; rbnd < 4; rbnd++)
1331
                put_bits(&s->pb, 1, block->rematrixing_flags[rbnd]);
1332
        }
1333
    }
1334

    
1335
    /* exponent strategy */
1336
    for (ch = 0; ch < s->fbw_channels; ch++)
1337
        put_bits(&s->pb, 2, s->exp_strategy[ch][blk]);
1338
    if (s->lfe_on)
1339
        put_bits(&s->pb, 1, s->exp_strategy[s->lfe_channel][blk]);
1340

    
1341
    /* bandwidth */
1342
    for (ch = 0; ch < s->fbw_channels; ch++) {
1343
        if (s->exp_strategy[ch][blk] != EXP_REUSE)
1344
            put_bits(&s->pb, 6, s->bandwidth_code[ch]);
1345
    }
1346

    
1347
    /* exponents */
1348
    for (ch = 0; ch < s->channels; ch++) {
1349
        int nb_groups;
1350

    
1351
        if (s->exp_strategy[ch][blk] == EXP_REUSE)
1352
            continue;
1353

    
1354
        /* DC exponent */
1355
        put_bits(&s->pb, 4, block->grouped_exp[ch][0]);
1356

    
1357
        /* exponent groups */
1358
        nb_groups = exponent_group_tab[s->exp_strategy[ch][blk]-1][s->nb_coefs[ch]];
1359
        for (i = 1; i <= nb_groups; i++)
1360
            put_bits(&s->pb, 7, block->grouped_exp[ch][i]);
1361

    
1362
        /* gain range info */
1363
        if (ch != s->lfe_channel)
1364
            put_bits(&s->pb, 2, 0);
1365
    }
1366

    
1367
    /* bit allocation info */
1368
    baie = (blk == 0);
1369
    put_bits(&s->pb, 1, baie);
1370
    if (baie) {
1371
        put_bits(&s->pb, 2, s->slow_decay_code);
1372
        put_bits(&s->pb, 2, s->fast_decay_code);
1373
        put_bits(&s->pb, 2, s->slow_gain_code);
1374
        put_bits(&s->pb, 2, s->db_per_bit_code);
1375
        put_bits(&s->pb, 3, s->floor_code);
1376
    }
1377

    
1378
    /* snr offset */
1379
    put_bits(&s->pb, 1, baie);
1380
    if (baie) {
1381
        put_bits(&s->pb, 6, s->coarse_snr_offset);
1382
        for (ch = 0; ch < s->channels; ch++) {
1383
            put_bits(&s->pb, 4, s->fine_snr_offset[ch]);
1384
            put_bits(&s->pb, 3, s->fast_gain_code[ch]);
1385
        }
1386
    }
1387

    
1388
    put_bits(&s->pb, 1, 0); /* no delta bit allocation */
1389
    put_bits(&s->pb, 1, 0); /* no data to skip */
1390

    
1391
    /* mantissas */
1392
    for (ch = 0; ch < s->channels; ch++) {
1393
        int b, q;
1394
        for (i = 0; i < s->nb_coefs[ch]; i++) {
1395
            q = block->qmant[ch][i];
1396
            b = block->bap[ch][i];
1397
            switch (b) {
1398
            case 0:                                         break;
1399
            case 1: if (q != 128) put_bits(&s->pb,   5, q); break;
1400
            case 2: if (q != 128) put_bits(&s->pb,   7, q); break;
1401
            case 3:               put_bits(&s->pb,   3, q); break;
1402
            case 4: if (q != 128) put_bits(&s->pb,   7, q); break;
1403
            case 14:              put_bits(&s->pb,  14, q); break;
1404
            case 15:              put_bits(&s->pb,  16, q); break;
1405
            default:              put_bits(&s->pb, b-1, q); break;
1406
            }
1407
        }
1408
    }
1409
}
1410

    
1411

    
1412
/** CRC-16 Polynomial */
1413
#define CRC16_POLY ((1 << 0) | (1 << 2) | (1 << 15) | (1 << 16))
1414

    
1415

    
1416
static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly)
1417
{
1418
    unsigned int c;
1419

    
1420
    c = 0;
1421
    while (a) {
1422
        if (a & 1)
1423
            c ^= b;
1424
        a = a >> 1;
1425
        b = b << 1;
1426
        if (b & (1 << 16))
1427
            b ^= poly;
1428
    }
1429
    return c;
1430
}
1431

    
1432

    
1433
static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly)
1434
{
1435
    unsigned int r;
1436
    r = 1;
1437
    while (n) {
1438
        if (n & 1)
1439
            r = mul_poly(r, a, poly);
1440
        a = mul_poly(a, a, poly);
1441
        n >>= 1;
1442
    }
1443
    return r;
1444
}
1445

    
1446

    
1447
/**
1448
 * Fill the end of the frame with 0's and compute the two CRCs.
1449
 */
1450
static void output_frame_end(AC3EncodeContext *s)
1451
{
1452
    const AVCRC *crc_ctx = av_crc_get_table(AV_CRC_16_ANSI);
1453
    int frame_size_58, pad_bytes, crc1, crc2_partial, crc2, crc_inv;
1454
    uint8_t *frame;
1455

    
1456
    frame_size_58 = ((s->frame_size >> 2) + (s->frame_size >> 4)) << 1;
1457

    
1458
    /* pad the remainder of the frame with zeros */
1459
    flush_put_bits(&s->pb);
1460
    frame = s->pb.buf;
1461
    pad_bytes = s->frame_size - (put_bits_ptr(&s->pb) - frame) - 2;
1462
    assert(pad_bytes >= 0);
1463
    if (pad_bytes > 0)
1464
        memset(put_bits_ptr(&s->pb), 0, pad_bytes);
1465

    
1466
    /* compute crc1 */
1467
    /* this is not so easy because it is at the beginning of the data... */
1468
    crc1    = av_bswap16(av_crc(crc_ctx, 0, frame + 4, frame_size_58 - 4));
1469
    crc_inv = s->crc_inv[s->frame_size > s->frame_size_min];
1470
    crc1    = mul_poly(crc_inv, crc1, CRC16_POLY);
1471
    AV_WB16(frame + 2, crc1);
1472

    
1473
    /* compute crc2 */
1474
    crc2_partial = av_crc(crc_ctx, 0, frame + frame_size_58,
1475
                          s->frame_size - frame_size_58 - 3);
1476
    crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
1477
    /* ensure crc2 does not match sync word by flipping crcrsv bit if needed */
1478
    if (crc2 == 0x770B) {
1479
        frame[s->frame_size - 3] ^= 0x1;
1480
        crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
1481
    }
1482
    crc2 = av_bswap16(crc2);
1483
    AV_WB16(frame + s->frame_size - 2, crc2);
1484
}
1485

    
1486

    
1487
/**
1488
 * Write the frame to the output bitstream.
1489
 */
1490
static void output_frame(AC3EncodeContext *s, unsigned char *frame)
1491
{
1492
    int blk;
1493

    
1494
    init_put_bits(&s->pb, frame, AC3_MAX_CODED_FRAME_SIZE);
1495

    
1496
    output_frame_header(s);
1497

    
1498
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++)
1499
        output_audio_block(s, blk);
1500

    
1501
    output_frame_end(s);
1502
}
1503

    
1504

    
1505
/**
1506
 * Encode a single AC-3 frame.
1507
 */
1508
static int ac3_encode_frame(AVCodecContext *avctx, unsigned char *frame,
1509
                            int buf_size, void *data)
1510
{
1511
    AC3EncodeContext *s = avctx->priv_data;
1512
    const SampleType *samples = data;
1513
    int ret;
1514

    
1515
    if (s->bit_alloc.sr_code == 1)
1516
        adjust_frame_size(s);
1517

    
1518
    deinterleave_input_samples(s, samples);
1519

    
1520
    apply_mdct(s);
1521

    
1522
    compute_rematrixing_strategy(s);
1523

    
1524
    scale_coefficients(s);
1525

    
1526
    apply_rematrixing(s);
1527

    
1528
    process_exponents(s);
1529

    
1530
    ret = compute_bit_allocation(s);
1531
    if (ret) {
1532
        av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
1533
        return ret;
1534
    }
1535

    
1536
    quantize_mantissas(s);
1537

    
1538
    output_frame(s, frame);
1539

    
1540
    return s->frame_size;
1541
}
1542

    
1543

    
1544
/**
1545
 * Finalize encoding and free any memory allocated by the encoder.
1546
 */
1547
static av_cold int ac3_encode_close(AVCodecContext *avctx)
1548
{
1549
    int blk, ch;
1550
    AC3EncodeContext *s = avctx->priv_data;
1551

    
1552
    for (ch = 0; ch < s->channels; ch++)
1553
        av_freep(&s->planar_samples[ch]);
1554
    av_freep(&s->planar_samples);
1555
    av_freep(&s->bap_buffer);
1556
    av_freep(&s->bap1_buffer);
1557
    av_freep(&s->mdct_coef_buffer);
1558
    av_freep(&s->fixed_coef_buffer);
1559
    av_freep(&s->exp_buffer);
1560
    av_freep(&s->grouped_exp_buffer);
1561
    av_freep(&s->psd_buffer);
1562
    av_freep(&s->band_psd_buffer);
1563
    av_freep(&s->mask_buffer);
1564
    av_freep(&s->qmant_buffer);
1565
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1566
        AC3Block *block = &s->blocks[blk];
1567
        av_freep(&block->bap);
1568
        av_freep(&block->mdct_coef);
1569
        av_freep(&block->fixed_coef);
1570
        av_freep(&block->exp);
1571
        av_freep(&block->grouped_exp);
1572
        av_freep(&block->psd);
1573
        av_freep(&block->band_psd);
1574
        av_freep(&block->mask);
1575
        av_freep(&block->qmant);
1576
    }
1577

    
1578
    mdct_end(&s->mdct);
1579

    
1580
    av_freep(&avctx->coded_frame);
1581
    return 0;
1582
}
1583

    
1584

    
1585
/**
1586
 * Set channel information during initialization.
1587
 */
1588
static av_cold int set_channel_info(AC3EncodeContext *s, int channels,
1589
                                    int64_t *channel_layout)
1590
{
1591
    int ch_layout;
1592

    
1593
    if (channels < 1 || channels > AC3_MAX_CHANNELS)
1594
        return AVERROR(EINVAL);
1595
    if ((uint64_t)*channel_layout > 0x7FF)
1596
        return AVERROR(EINVAL);
1597
    ch_layout = *channel_layout;
1598
    if (!ch_layout)
1599
        ch_layout = avcodec_guess_channel_layout(channels, CODEC_ID_AC3, NULL);
1600
    if (av_get_channel_layout_nb_channels(ch_layout) != channels)
1601
        return AVERROR(EINVAL);
1602

    
1603
    s->lfe_on       = !!(ch_layout & AV_CH_LOW_FREQUENCY);
1604
    s->channels     = channels;
1605
    s->fbw_channels = channels - s->lfe_on;
1606
    s->lfe_channel  = s->lfe_on ? s->fbw_channels : -1;
1607
    if (s->lfe_on)
1608
        ch_layout -= AV_CH_LOW_FREQUENCY;
1609

    
1610
    switch (ch_layout) {
1611
    case AV_CH_LAYOUT_MONO:           s->channel_mode = AC3_CHMODE_MONO;   break;
1612
    case AV_CH_LAYOUT_STEREO:         s->channel_mode = AC3_CHMODE_STEREO; break;
1613
    case AV_CH_LAYOUT_SURROUND:       s->channel_mode = AC3_CHMODE_3F;     break;
1614
    case AV_CH_LAYOUT_2_1:            s->channel_mode = AC3_CHMODE_2F1R;   break;
1615
    case AV_CH_LAYOUT_4POINT0:        s->channel_mode = AC3_CHMODE_3F1R;   break;
1616
    case AV_CH_LAYOUT_QUAD:
1617
    case AV_CH_LAYOUT_2_2:            s->channel_mode = AC3_CHMODE_2F2R;   break;
1618
    case AV_CH_LAYOUT_5POINT0:
1619
    case AV_CH_LAYOUT_5POINT0_BACK:   s->channel_mode = AC3_CHMODE_3F2R;   break;
1620
    default:
1621
        return AVERROR(EINVAL);
1622
    }
1623

    
1624
    s->channel_map  = ff_ac3_enc_channel_map[s->channel_mode][s->lfe_on];
1625
    *channel_layout = ch_layout;
1626
    if (s->lfe_on)
1627
        *channel_layout |= AV_CH_LOW_FREQUENCY;
1628

    
1629
    return 0;
1630
}
1631

    
1632

    
1633
static av_cold int validate_options(AVCodecContext *avctx, AC3EncodeContext *s)
1634
{
1635
    int i, ret;
1636

    
1637
    /* validate channel layout */
1638
    if (!avctx->channel_layout) {
1639
        av_log(avctx, AV_LOG_WARNING, "No channel layout specified. The "
1640
                                      "encoder will guess the layout, but it "
1641
                                      "might be incorrect.\n");
1642
    }
1643
    ret = set_channel_info(s, avctx->channels, &avctx->channel_layout);
1644
    if (ret) {
1645
        av_log(avctx, AV_LOG_ERROR, "invalid channel layout\n");
1646
        return ret;
1647
    }
1648

    
1649
    /* validate sample rate */
1650
    for (i = 0; i < 9; i++) {
1651
        if ((ff_ac3_sample_rate_tab[i / 3] >> (i % 3)) == avctx->sample_rate)
1652
            break;
1653
    }
1654
    if (i == 9) {
1655
        av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1656
        return AVERROR(EINVAL);
1657
    }
1658
    s->sample_rate        = avctx->sample_rate;
1659
    s->bit_alloc.sr_shift = i % 3;
1660
    s->bit_alloc.sr_code  = i / 3;
1661

    
1662
    /* validate bit rate */
1663
    for (i = 0; i < 19; i++) {
1664
        if ((ff_ac3_bitrate_tab[i] >> s->bit_alloc.sr_shift)*1000 == avctx->bit_rate)
1665
            break;
1666
    }
1667
    if (i == 19) {
1668
        av_log(avctx, AV_LOG_ERROR, "invalid bit rate\n");
1669
        return AVERROR(EINVAL);
1670
    }
1671
    s->bit_rate        = avctx->bit_rate;
1672
    s->frame_size_code = i << 1;
1673

    
1674
    /* validate cutoff */
1675
    if (avctx->cutoff < 0) {
1676
        av_log(avctx, AV_LOG_ERROR, "invalid cutoff frequency\n");
1677
        return AVERROR(EINVAL);
1678
    }
1679
    s->cutoff = avctx->cutoff;
1680
    if (s->cutoff > (s->sample_rate >> 1))
1681
        s->cutoff = s->sample_rate >> 1;
1682

    
1683
    return 0;
1684
}
1685

    
1686

    
1687
/**
1688
 * Set bandwidth for all channels.
1689
 * The user can optionally supply a cutoff frequency. Otherwise an appropriate
1690
 * default value will be used.
1691
 */
1692
static av_cold void set_bandwidth(AC3EncodeContext *s)
1693
{
1694
    int ch, bw_code;
1695

    
1696
    if (s->cutoff) {
1697
        /* calculate bandwidth based on user-specified cutoff frequency */
1698
        int fbw_coeffs;
1699
        fbw_coeffs     = s->cutoff * 2 * AC3_MAX_COEFS / s->sample_rate;
1700
        bw_code        = av_clip((fbw_coeffs - 73) / 3, 0, 60);
1701
    } else {
1702
        /* use default bandwidth setting */
1703
        /* XXX: should compute the bandwidth according to the frame
1704
           size, so that we avoid annoying high frequency artifacts */
1705
        bw_code = 50;
1706
    }
1707

    
1708
    /* set number of coefficients for each channel */
1709
    for (ch = 0; ch < s->fbw_channels; ch++) {
1710
        s->bandwidth_code[ch] = bw_code;
1711
        s->nb_coefs[ch]       = bw_code * 3 + 73;
1712
    }
1713
    if (s->lfe_on)
1714
        s->nb_coefs[s->lfe_channel] = 7; /* LFE channel always has 7 coefs */
1715
}
1716

    
1717

    
1718
static av_cold int allocate_buffers(AVCodecContext *avctx)
1719
{
1720
    int blk, ch;
1721
    AC3EncodeContext *s = avctx->priv_data;
1722

    
1723
    FF_ALLOC_OR_GOTO(avctx, s->planar_samples, s->channels * sizeof(*s->planar_samples),
1724
                     alloc_fail);
1725
    for (ch = 0; ch < s->channels; ch++) {
1726
        FF_ALLOCZ_OR_GOTO(avctx, s->planar_samples[ch],
1727
                          (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),
1728
                          alloc_fail);
1729
    }
1730
    FF_ALLOC_OR_GOTO(avctx, s->bap_buffer,  AC3_MAX_BLOCKS * s->channels *
1731
                     AC3_MAX_COEFS * sizeof(*s->bap_buffer),  alloc_fail);
1732
    FF_ALLOC_OR_GOTO(avctx, s->bap1_buffer, AC3_MAX_BLOCKS * s->channels *
1733
                     AC3_MAX_COEFS * sizeof(*s->bap1_buffer), alloc_fail);
1734
    FF_ALLOC_OR_GOTO(avctx, s->mdct_coef_buffer, AC3_MAX_BLOCKS * s->channels *
1735
                     AC3_MAX_COEFS * sizeof(*s->mdct_coef_buffer), alloc_fail);
1736
    FF_ALLOC_OR_GOTO(avctx, s->exp_buffer, AC3_MAX_BLOCKS * s->channels *
1737
                     AC3_MAX_COEFS * sizeof(*s->exp_buffer), alloc_fail);
1738
    FF_ALLOC_OR_GOTO(avctx, s->grouped_exp_buffer, AC3_MAX_BLOCKS * s->channels *
1739
                     128 * sizeof(*s->grouped_exp_buffer), alloc_fail);
1740
    FF_ALLOC_OR_GOTO(avctx, s->psd_buffer, AC3_MAX_BLOCKS * s->channels *
1741
                     AC3_MAX_COEFS * sizeof(*s->psd_buffer), alloc_fail);
1742
    FF_ALLOC_OR_GOTO(avctx, s->band_psd_buffer, AC3_MAX_BLOCKS * s->channels *
1743
                     64 * sizeof(*s->band_psd_buffer), alloc_fail);
1744
    FF_ALLOC_OR_GOTO(avctx, s->mask_buffer, AC3_MAX_BLOCKS * s->channels *
1745
                     64 * sizeof(*s->mask_buffer), alloc_fail);
1746
    FF_ALLOC_OR_GOTO(avctx, s->qmant_buffer, AC3_MAX_BLOCKS * s->channels *
1747
                     AC3_MAX_COEFS * sizeof(*s->qmant_buffer), alloc_fail);
1748
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1749
        AC3Block *block = &s->blocks[blk];
1750
        FF_ALLOC_OR_GOTO(avctx, block->bap, s->channels * sizeof(*block->bap),
1751
                         alloc_fail);
1752
        FF_ALLOCZ_OR_GOTO(avctx, block->mdct_coef, s->channels * sizeof(*block->mdct_coef),
1753
                          alloc_fail);
1754
        FF_ALLOCZ_OR_GOTO(avctx, block->exp, s->channels * sizeof(*block->exp),
1755
                          alloc_fail);
1756
        FF_ALLOCZ_OR_GOTO(avctx, block->grouped_exp, s->channels * sizeof(*block->grouped_exp),
1757
                          alloc_fail);
1758
        FF_ALLOCZ_OR_GOTO(avctx, block->psd, s->channels * sizeof(*block->psd),
1759
                          alloc_fail);
1760
        FF_ALLOCZ_OR_GOTO(avctx, block->band_psd, s->channels * sizeof(*block->band_psd),
1761
                          alloc_fail);
1762
        FF_ALLOCZ_OR_GOTO(avctx, block->mask, s->channels * sizeof(*block->mask),
1763
                          alloc_fail);
1764
        FF_ALLOCZ_OR_GOTO(avctx, block->qmant, s->channels * sizeof(*block->qmant),
1765
                          alloc_fail);
1766

    
1767
        for (ch = 0; ch < s->channels; ch++) {
1768
            /* arrangement: block, channel, coeff */
1769
            block->bap[ch]         = &s->bap_buffer        [AC3_MAX_COEFS * (blk * s->channels + ch)];
1770
            block->mdct_coef[ch]   = &s->mdct_coef_buffer  [AC3_MAX_COEFS * (blk * s->channels + ch)];
1771
            block->grouped_exp[ch] = &s->grouped_exp_buffer[128           * (blk * s->channels + ch)];
1772
            block->psd[ch]         = &s->psd_buffer        [AC3_MAX_COEFS * (blk * s->channels + ch)];
1773
            block->band_psd[ch]    = &s->band_psd_buffer   [64            * (blk * s->channels + ch)];
1774
            block->mask[ch]        = &s->mask_buffer       [64            * (blk * s->channels + ch)];
1775
            block->qmant[ch]       = &s->qmant_buffer      [AC3_MAX_COEFS * (blk * s->channels + ch)];
1776

    
1777
            /* arrangement: channel, block, coeff */
1778
            block->exp[ch]         = &s->exp_buffer        [AC3_MAX_COEFS * (AC3_MAX_BLOCKS * ch + blk)];
1779
        }
1780
    }
1781

    
1782
    if (CONFIG_AC3ENC_FLOAT) {
1783
        FF_ALLOC_OR_GOTO(avctx, s->fixed_coef_buffer, AC3_MAX_BLOCKS * s->channels *
1784
                         AC3_MAX_COEFS * sizeof(*s->fixed_coef_buffer), alloc_fail);
1785
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1786
            AC3Block *block = &s->blocks[blk];
1787
            FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, s->channels *
1788
                              sizeof(*block->fixed_coef), alloc_fail);
1789
            for (ch = 0; ch < s->channels; ch++)
1790
                block->fixed_coef[ch] = &s->fixed_coef_buffer[AC3_MAX_COEFS * (blk * s->channels + ch)];
1791
        }
1792
    } else {
1793
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1794
            AC3Block *block = &s->blocks[blk];
1795
            FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, s->channels *
1796
                              sizeof(*block->fixed_coef), alloc_fail);
1797
            for (ch = 0; ch < s->channels; ch++)
1798
                block->fixed_coef[ch] = (int32_t *)block->mdct_coef[ch];
1799
        }
1800
    }
1801

    
1802
    return 0;
1803
alloc_fail:
1804
    return AVERROR(ENOMEM);
1805
}
1806

    
1807

    
1808
/**
1809
 * Initialize the encoder.
1810
 */
1811
static av_cold int ac3_encode_init(AVCodecContext *avctx)
1812
{
1813
    AC3EncodeContext *s = avctx->priv_data;
1814
    int ret, frame_size_58;
1815

    
1816
    avctx->frame_size = AC3_FRAME_SIZE;
1817

    
1818
    ff_ac3_common_init();
1819

    
1820
    ret = validate_options(avctx, s);
1821
    if (ret)
1822
        return ret;
1823

    
1824
    s->bitstream_id   = 8 + s->bit_alloc.sr_shift;
1825
    s->bitstream_mode = 0; /* complete main audio service */
1826

    
1827
    s->frame_size_min  = 2 * ff_ac3_frame_size_tab[s->frame_size_code][s->bit_alloc.sr_code];
1828
    s->bits_written    = 0;
1829
    s->samples_written = 0;
1830
    s->frame_size      = s->frame_size_min;
1831

    
1832
    /* calculate crc_inv for both possible frame sizes */
1833
    frame_size_58 = (( s->frame_size    >> 2) + ( s->frame_size    >> 4)) << 1;
1834
    s->crc_inv[0] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
1835
    if (s->bit_alloc.sr_code == 1) {
1836
        frame_size_58 = (((s->frame_size+2) >> 2) + ((s->frame_size+2) >> 4)) << 1;
1837
        s->crc_inv[1] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
1838
    }
1839

    
1840
    set_bandwidth(s);
1841

    
1842
    rematrixing_init(s);
1843

    
1844
    exponent_init(s);
1845

    
1846
    bit_alloc_init(s);
1847

    
1848
    ret = mdct_init(avctx, &s->mdct, 9);
1849
    if (ret)
1850
        goto init_fail;
1851

    
1852
    ret = allocate_buffers(avctx);
1853
    if (ret)
1854
        goto init_fail;
1855

    
1856
    avctx->coded_frame= avcodec_alloc_frame();
1857

    
1858
    dsputil_init(&s->dsp, avctx);
1859

    
1860
    return 0;
1861
init_fail:
1862
    ac3_encode_close(avctx);
1863
    return ret;
1864
}