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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
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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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 */
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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
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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

    
91
    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)
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    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)
107
    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
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    int exponent_bits;                      ///< number of bits used for exponents
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133
    /* mantissa encoding */
134
    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;
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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;
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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
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151
    DECLARE_ALIGNED(16, SampleType, windowed_samples)[AC3_WINDOW_SIZE];
152
} AC3EncodeContext;
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/* prototypes for functions in ac3enc_fixed.c and ac3enc_float.c */
156

    
157
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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162
static void mdct512(AC3MDCTContext *mdct, CoefType *out, SampleType *in);
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164
static void apply_window(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[] = {
183
     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;
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    s->samples_written += AC3_FRAME_SIZE;
219
}
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221

    
222
/**
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;
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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->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
}
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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
            }
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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;
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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 1000
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
    for (blk = 1; blk < AC3_MAX_BLOCKS; blk++) {
453
        exp_diff = s->dsp.sad[0](NULL, exp[blk], exp[blk-1], 16, 16);
454
        if (exp_diff > EXP_DIFF_THRESHOLD)
455
            exp_strategy[blk] = EXP_NEW;
456
        else
457
            exp_strategy[blk] = EXP_REUSE;
458
    }
459
    emms_c();
460

    
461
    /* now select the encoding strategy type : if exponents are often
462
       recoded, we use a coarse encoding */
463
    blk = 0;
464
    while (blk < AC3_MAX_BLOCKS) {
465
        blk1 = blk + 1;
466
        while (blk1 < AC3_MAX_BLOCKS && exp_strategy[blk1] == EXP_REUSE)
467
            blk1++;
468
        switch (blk1 - blk) {
469
        case 1:  exp_strategy[blk] = EXP_D45; break;
470
        case 2:
471
        case 3:  exp_strategy[blk] = EXP_D25; break;
472
        default: exp_strategy[blk] = EXP_D15; break;
473
        }
474
        blk = blk1;
475
    }
476
}
477

    
478

    
479
/**
480
 * Calculate exponent strategies for all channels.
481
 * Array arrangement is reversed to simplify the per-channel calculation.
482
 */
483
static void compute_exp_strategy(AC3EncodeContext *s)
484
{
485
    uint8_t *exp1[AC3_MAX_CHANNELS][AC3_MAX_BLOCKS];
486
    uint8_t exp_str1[AC3_MAX_CHANNELS][AC3_MAX_BLOCKS];
487
    int ch, blk;
488

    
489
    for (ch = 0; ch < s->fbw_channels; ch++) {
490
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
491
            exp1[ch][blk]     = s->blocks[blk].exp[ch];
492
            exp_str1[ch][blk] = s->exp_strategy[ch][blk];
493
        }
494

    
495
        compute_exp_strategy_ch(s, exp_str1[ch], exp1[ch]);
496

    
497
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++)
498
            s->exp_strategy[ch][blk] = exp_str1[ch][blk];
499
    }
500
    if (s->lfe_on) {
501
        ch = s->lfe_channel;
502
        s->exp_strategy[ch][0] = EXP_D15;
503
        for (blk = 1; blk < AC3_MAX_BLOCKS; blk++)
504
            s->exp_strategy[ch][blk] = EXP_REUSE;
505
    }
506
}
507

    
508

    
509
/**
510
 * Set each encoded exponent in a block to the minimum of itself and the
511
 * exponent in the same frequency bin of a following block.
512
 * exp[i] = min(exp[i], exp1[i]
513
 */
514
static void exponent_min(uint8_t *exp, uint8_t *exp1, int n)
515
{
516
    int i;
517
    for (i = 0; i < n; i++) {
518
        if (exp1[i] < exp[i])
519
            exp[i] = exp1[i];
520
    }
521
}
522

    
523

    
524
/**
525
 * Update the exponents so that they are the ones the decoder will decode.
526
 */
527
static void encode_exponents_blk_ch(uint8_t *exp, int nb_exps, int exp_strategy)
528
{
529
    int nb_groups, i, k;
530

    
531
    nb_groups = exponent_group_tab[exp_strategy-1][nb_exps] * 3;
532

    
533
    /* for each group, compute the minimum exponent */
534
    switch(exp_strategy) {
535
    case EXP_D25:
536
        for (i = 1, k = 1; i <= nb_groups; i++) {
537
            uint8_t exp_min = exp[k];
538
            if (exp[k+1] < exp_min)
539
                exp_min = exp[k+1];
540
            exp[i] = exp_min;
541
            k += 2;
542
        }
543
        break;
544
    case EXP_D45:
545
        for (i = 1, k = 1; i <= nb_groups; i++) {
546
            uint8_t exp_min = exp[k];
547
            if (exp[k+1] < exp_min)
548
                exp_min = exp[k+1];
549
            if (exp[k+2] < exp_min)
550
                exp_min = exp[k+2];
551
            if (exp[k+3] < exp_min)
552
                exp_min = exp[k+3];
553
            exp[i] = exp_min;
554
            k += 4;
555
        }
556
        break;
557
    }
558

    
559
    /* constraint for DC exponent */
560
    if (exp[0] > 15)
561
        exp[0] = 15;
562

    
563
    /* decrease the delta between each groups to within 2 so that they can be
564
       differentially encoded */
565
    for (i = 1; i <= nb_groups; i++)
566
        exp[i] = FFMIN(exp[i], exp[i-1] + 2);
567
    i--;
568
    while (--i >= 0)
569
        exp[i] = FFMIN(exp[i], exp[i+1] + 2);
570

    
571
    /* now we have the exponent values the decoder will see */
572
    switch (exp_strategy) {
573
    case EXP_D25:
574
        for (i = nb_groups, k = nb_groups * 2; i > 0; i--) {
575
            uint8_t exp1 = exp[i];
576
            exp[k--] = exp1;
577
            exp[k--] = exp1;
578
        }
579
        break;
580
    case EXP_D45:
581
        for (i = nb_groups, k = nb_groups * 4; i > 0; i--) {
582
            exp[k] = exp[k-1] = exp[k-2] = exp[k-3] = exp[i];
583
            k -= 4;
584
        }
585
        break;
586
    }
587
}
588

    
589

    
590
/**
591
 * Encode exponents from original extracted form to what the decoder will see.
592
 * This copies and groups exponents based on exponent strategy and reduces
593
 * deltas between adjacent exponent groups so that they can be differentially
594
 * encoded.
595
 */
596
static void encode_exponents(AC3EncodeContext *s)
597
{
598
    int blk, blk1, blk2, ch;
599
    AC3Block *block, *block1, *block2;
600

    
601
    for (ch = 0; ch < s->channels; ch++) {
602
        blk = 0;
603
        block = &s->blocks[0];
604
        while (blk < AC3_MAX_BLOCKS) {
605
            blk1 = blk + 1;
606
            block1 = block + 1;
607
            /* for the EXP_REUSE case we select the min of the exponents */
608
            while (blk1 < AC3_MAX_BLOCKS && s->exp_strategy[ch][blk1] == EXP_REUSE) {
609
                exponent_min(block->exp[ch], block1->exp[ch], s->nb_coefs[ch]);
610
                blk1++;
611
                block1++;
612
            }
613
            encode_exponents_blk_ch(block->exp[ch], s->nb_coefs[ch],
614
                                    s->exp_strategy[ch][blk]);
615
            /* copy encoded exponents for reuse case */
616
            block2 = block + 1;
617
            for (blk2 = blk+1; blk2 < blk1; blk2++, block2++) {
618
                memcpy(block2->exp[ch], block->exp[ch],
619
                       s->nb_coefs[ch] * sizeof(uint8_t));
620
            }
621
            blk = blk1;
622
            block = block1;
623
        }
624
    }
625
}
626

    
627

    
628
/**
629
 * Group exponents.
630
 * 3 delta-encoded exponents are in each 7-bit group. The number of groups
631
 * varies depending on exponent strategy and bandwidth.
632
 */
633
static void group_exponents(AC3EncodeContext *s)
634
{
635
    int blk, ch, i;
636
    int group_size, nb_groups, bit_count;
637
    uint8_t *p;
638
    int delta0, delta1, delta2;
639
    int exp0, exp1;
640

    
641
    bit_count = 0;
642
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
643
        AC3Block *block = &s->blocks[blk];
644
        for (ch = 0; ch < s->channels; ch++) {
645
            if (s->exp_strategy[ch][blk] == EXP_REUSE) {
646
                continue;
647
            }
648
            group_size = s->exp_strategy[ch][blk] + (s->exp_strategy[ch][blk] == EXP_D45);
649
            nb_groups = exponent_group_tab[s->exp_strategy[ch][blk]-1][s->nb_coefs[ch]];
650
            bit_count += 4 + (nb_groups * 7);
651
            p = block->exp[ch];
652

    
653
            /* DC exponent */
654
            exp1 = *p++;
655
            block->grouped_exp[ch][0] = exp1;
656

    
657
            /* remaining exponents are delta encoded */
658
            for (i = 1; i <= nb_groups; i++) {
659
                /* merge three delta in one code */
660
                exp0   = exp1;
661
                exp1   = p[0];
662
                p     += group_size;
663
                delta0 = exp1 - exp0 + 2;
664

    
665
                exp0   = exp1;
666
                exp1   = p[0];
667
                p     += group_size;
668
                delta1 = exp1 - exp0 + 2;
669

    
670
                exp0   = exp1;
671
                exp1   = p[0];
672
                p     += group_size;
673
                delta2 = exp1 - exp0 + 2;
674

    
675
                block->grouped_exp[ch][i] = ((delta0 * 5 + delta1) * 5) + delta2;
676
            }
677
        }
678
    }
679

    
680
    s->exponent_bits = bit_count;
681
}
682

    
683

    
684
/**
685
 * Calculate final exponents from the supplied MDCT coefficients and exponent shift.
686
 * Extract exponents from MDCT coefficients, calculate exponent strategies,
687
 * and encode final exponents.
688
 */
689
static void process_exponents(AC3EncodeContext *s)
690
{
691
    extract_exponents(s);
692

    
693
    compute_exp_strategy(s);
694

    
695
    encode_exponents(s);
696

    
697
    group_exponents(s);
698
}
699

    
700

    
701
/**
702
 * Count frame bits that are based solely on fixed parameters.
703
 * This only has to be run once when the encoder is initialized.
704
 */
705
static void count_frame_bits_fixed(AC3EncodeContext *s)
706
{
707
    static const int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
708
    int blk;
709
    int frame_bits;
710

    
711
    /* assumptions:
712
     *   no dynamic range codes
713
     *   no channel coupling
714
     *   bit allocation parameters do not change between blocks
715
     *   SNR offsets do not change between blocks
716
     *   no delta bit allocation
717
     *   no skipped data
718
     *   no auxilliary data
719
     */
720

    
721
    /* header size */
722
    frame_bits = 65;
723
    frame_bits += frame_bits_inc[s->channel_mode];
724

    
725
    /* audio blocks */
726
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
727
        frame_bits += s->fbw_channels * 2 + 2; /* blksw * c, dithflag * c, dynrnge, cplstre */
728
        if (s->channel_mode == AC3_CHMODE_STEREO) {
729
            frame_bits++; /* rematstr */
730
        }
731
        frame_bits += 2 * s->fbw_channels; /* chexpstr[2] * c */
732
        if (s->lfe_on)
733
            frame_bits++; /* lfeexpstr */
734
        frame_bits++; /* baie */
735
        frame_bits++; /* snr */
736
        frame_bits += 2; /* delta / skip */
737
    }
738
    frame_bits++; /* cplinu for block 0 */
739
    /* bit alloc info */
740
    /* sdcycod[2], fdcycod[2], sgaincod[2], dbpbcod[2], floorcod[3] */
741
    /* csnroffset[6] */
742
    /* (fsnoffset[4] + fgaincod[4]) * c */
743
    frame_bits += 2*4 + 3 + 6 + s->channels * (4 + 3);
744

    
745
    /* auxdatae, crcrsv */
746
    frame_bits += 2;
747

    
748
    /* CRC */
749
    frame_bits += 16;
750

    
751
    s->frame_bits_fixed = frame_bits;
752
}
753

    
754

    
755
/**
756
 * Initialize bit allocation.
757
 * Set default parameter codes and calculate parameter values.
758
 */
759
static void bit_alloc_init(AC3EncodeContext *s)
760
{
761
    int ch;
762

    
763
    /* init default parameters */
764
    s->slow_decay_code = 2;
765
    s->fast_decay_code = 1;
766
    s->slow_gain_code  = 1;
767
    s->db_per_bit_code = 3;
768
    s->floor_code      = 4;
769
    for (ch = 0; ch < s->channels; ch++)
770
        s->fast_gain_code[ch] = 4;
771

    
772
    /* initial snr offset */
773
    s->coarse_snr_offset = 40;
774

    
775
    /* compute real values */
776
    /* currently none of these values change during encoding, so we can just
777
       set them once at initialization */
778
    s->bit_alloc.slow_decay = ff_ac3_slow_decay_tab[s->slow_decay_code] >> s->bit_alloc.sr_shift;
779
    s->bit_alloc.fast_decay = ff_ac3_fast_decay_tab[s->fast_decay_code] >> s->bit_alloc.sr_shift;
780
    s->bit_alloc.slow_gain  = ff_ac3_slow_gain_tab[s->slow_gain_code];
781
    s->bit_alloc.db_per_bit = ff_ac3_db_per_bit_tab[s->db_per_bit_code];
782
    s->bit_alloc.floor      = ff_ac3_floor_tab[s->floor_code];
783

    
784
    count_frame_bits_fixed(s);
785
}
786

    
787

    
788
/**
789
 * Count the bits used to encode the frame, minus exponents and mantissas.
790
 * Bits based on fixed parameters have already been counted, so now we just
791
 * have to add the bits based on parameters that change during encoding.
792
 */
793
static void count_frame_bits(AC3EncodeContext *s)
794
{
795
    int blk, ch;
796
    int frame_bits = 0;
797

    
798
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
799
        /* stereo rematrixing */
800
        if (s->channel_mode == AC3_CHMODE_STEREO &&
801
            s->blocks[blk].new_rematrixing_strategy) {
802
            frame_bits += 4;
803
        }
804

    
805
        for (ch = 0; ch < s->fbw_channels; ch++) {
806
            if (s->exp_strategy[ch][blk] != EXP_REUSE)
807
                frame_bits += 6 + 2; /* chbwcod[6], gainrng[2] */
808
        }
809
    }
810
    s->frame_bits = s->frame_bits_fixed + frame_bits;
811
}
812

    
813

    
814
/**
815
 * Calculate the number of bits needed to encode a set of mantissas.
816
 */
817
static int compute_mantissa_size(int mant_cnt[5], uint8_t *bap, int nb_coefs)
818
{
819
    int bits, b, i;
820

    
821
    bits = 0;
822
    for (i = 0; i < nb_coefs; i++) {
823
        b = bap[i];
824
        if (b <= 4) {
825
            // bap=1 to bap=4 will be counted in compute_mantissa_size_final
826
            mant_cnt[b]++;
827
        } else if (b <= 13) {
828
            // bap=5 to bap=13 use (bap-1) bits
829
            bits += b - 1;
830
        } else {
831
            // bap=14 uses 14 bits and bap=15 uses 16 bits
832
            bits += (b == 14) ? 14 : 16;
833
        }
834
    }
835
    return bits;
836
}
837

    
838

    
839
/**
840
 * Finalize the mantissa bit count by adding in the grouped mantissas.
841
 */
842
static int compute_mantissa_size_final(int mant_cnt[5])
843
{
844
    // bap=1 : 3 mantissas in 5 bits
845
    int bits = (mant_cnt[1] / 3) * 5;
846
    // bap=2 : 3 mantissas in 7 bits
847
    // bap=4 : 2 mantissas in 7 bits
848
    bits += ((mant_cnt[2] / 3) + (mant_cnt[4] >> 1)) * 7;
849
    // bap=3 : each mantissa is 3 bits
850
    bits += mant_cnt[3] * 3;
851
    return bits;
852
}
853

    
854

    
855
/**
856
 * Calculate masking curve based on the final exponents.
857
 * Also calculate the power spectral densities to use in future calculations.
858
 */
859
static void bit_alloc_masking(AC3EncodeContext *s)
860
{
861
    int blk, ch;
862

    
863
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
864
        AC3Block *block = &s->blocks[blk];
865
        for (ch = 0; ch < s->channels; ch++) {
866
            /* We only need psd and mask for calculating bap.
867
               Since we currently do not calculate bap when exponent
868
               strategy is EXP_REUSE we do not need to calculate psd or mask. */
869
            if (s->exp_strategy[ch][blk] != EXP_REUSE) {
870
                ff_ac3_bit_alloc_calc_psd(block->exp[ch], 0,
871
                                          s->nb_coefs[ch],
872
                                          block->psd[ch], block->band_psd[ch]);
873
                ff_ac3_bit_alloc_calc_mask(&s->bit_alloc, block->band_psd[ch],
874
                                           0, s->nb_coefs[ch],
875
                                           ff_ac3_fast_gain_tab[s->fast_gain_code[ch]],
876
                                           ch == s->lfe_channel,
877
                                           DBA_NONE, 0, NULL, NULL, NULL,
878
                                           block->mask[ch]);
879
            }
880
        }
881
    }
882
}
883

    
884

    
885
/**
886
 * Ensure that bap for each block and channel point to the current bap_buffer.
887
 * They may have been switched during the bit allocation search.
888
 */
889
static void reset_block_bap(AC3EncodeContext *s)
890
{
891
    int blk, ch;
892
    if (s->blocks[0].bap[0] == s->bap_buffer)
893
        return;
894
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
895
        for (ch = 0; ch < s->channels; ch++) {
896
            s->blocks[blk].bap[ch] = &s->bap_buffer[AC3_MAX_COEFS * (blk * s->channels + ch)];
897
        }
898
    }
899
}
900

    
901

    
902
/**
903
 * Run the bit allocation with a given SNR offset.
904
 * This calculates the bit allocation pointers that will be used to determine
905
 * the quantization of each mantissa.
906
 * @return the number of bits needed for mantissas if the given SNR offset is
907
 *         is used.
908
 */
909
static int bit_alloc(AC3EncodeContext *s, int snr_offset)
910
{
911
    int blk, ch;
912
    int mantissa_bits;
913
    int mant_cnt[5];
914

    
915
    snr_offset = (snr_offset - 240) << 2;
916

    
917
    reset_block_bap(s);
918
    mantissa_bits = 0;
919
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
920
        AC3Block *block = &s->blocks[blk];
921
        // initialize grouped mantissa counts. these are set so that they are
922
        // padded to the next whole group size when bits are counted in
923
        // compute_mantissa_size_final
924
        mant_cnt[0] = mant_cnt[3] = 0;
925
        mant_cnt[1] = mant_cnt[2] = 2;
926
        mant_cnt[4] = 1;
927
        for (ch = 0; ch < s->channels; ch++) {
928
            /* Currently the only bit allocation parameters which vary across
929
               blocks within a frame are the exponent values.  We can take
930
               advantage of that by reusing the bit allocation pointers
931
               whenever we reuse exponents. */
932
            if (s->exp_strategy[ch][blk] == EXP_REUSE) {
933
                memcpy(block->bap[ch], s->blocks[blk-1].bap[ch], AC3_MAX_COEFS);
934
            } else {
935
                ff_ac3_bit_alloc_calc_bap(block->mask[ch], block->psd[ch], 0,
936
                                          s->nb_coefs[ch], snr_offset,
937
                                          s->bit_alloc.floor, ff_ac3_bap_tab,
938
                                          block->bap[ch]);
939
            }
940
            mantissa_bits += compute_mantissa_size(mant_cnt, block->bap[ch], s->nb_coefs[ch]);
941
        }
942
        mantissa_bits += compute_mantissa_size_final(mant_cnt);
943
    }
944
    return mantissa_bits;
945
}
946

    
947

    
948
/**
949
 * Constant bitrate bit allocation search.
950
 * Find the largest SNR offset that will allow data to fit in the frame.
951
 */
952
static int cbr_bit_allocation(AC3EncodeContext *s)
953
{
954
    int ch;
955
    int bits_left;
956
    int snr_offset, snr_incr;
957

    
958
    bits_left = 8 * s->frame_size - (s->frame_bits + s->exponent_bits);
959

    
960
    snr_offset = s->coarse_snr_offset << 4;
961

    
962
    /* if previous frame SNR offset was 1023, check if current frame can also
963
       use SNR offset of 1023. if so, skip the search. */
964
    if ((snr_offset | s->fine_snr_offset[0]) == 1023) {
965
        if (bit_alloc(s, 1023) <= bits_left)
966
            return 0;
967
    }
968

    
969
    while (snr_offset >= 0 &&
970
           bit_alloc(s, snr_offset) > bits_left) {
971
        snr_offset -= 64;
972
    }
973
    if (snr_offset < 0)
974
        return AVERROR(EINVAL);
975

    
976
    FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
977
    for (snr_incr = 64; snr_incr > 0; snr_incr >>= 2) {
978
        while (snr_offset + snr_incr <= 1023 &&
979
               bit_alloc(s, snr_offset + snr_incr) <= bits_left) {
980
            snr_offset += snr_incr;
981
            FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
982
        }
983
    }
984
    FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
985
    reset_block_bap(s);
986

    
987
    s->coarse_snr_offset = snr_offset >> 4;
988
    for (ch = 0; ch < s->channels; ch++)
989
        s->fine_snr_offset[ch] = snr_offset & 0xF;
990

    
991
    return 0;
992
}
993

    
994

    
995
/**
996
 * Downgrade exponent strategies to reduce the bits used by the exponents.
997
 * This is a fallback for when bit allocation fails with the normal exponent
998
 * strategies.  Each time this function is run it only downgrades the
999
 * strategy in 1 channel of 1 block.
1000
 * @return non-zero if downgrade was unsuccessful
1001
 */
1002
static int downgrade_exponents(AC3EncodeContext *s)
1003
{
1004
    int ch, blk;
1005

    
1006
    for (ch = 0; ch < s->fbw_channels; ch++) {
1007
        for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
1008
            if (s->exp_strategy[ch][blk] == EXP_D15) {
1009
                s->exp_strategy[ch][blk] = EXP_D25;
1010
                return 0;
1011
            }
1012
        }
1013
    }
1014
    for (ch = 0; ch < s->fbw_channels; ch++) {
1015
        for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
1016
            if (s->exp_strategy[ch][blk] == EXP_D25) {
1017
                s->exp_strategy[ch][blk] = EXP_D45;
1018
                return 0;
1019
            }
1020
        }
1021
    }
1022
    for (ch = 0; ch < s->fbw_channels; ch++) {
1023
        /* block 0 cannot reuse exponents, so only downgrade D45 to REUSE if
1024
           the block number > 0 */
1025
        for (blk = AC3_MAX_BLOCKS-1; blk > 0; blk--) {
1026
            if (s->exp_strategy[ch][blk] > EXP_REUSE) {
1027
                s->exp_strategy[ch][blk] = EXP_REUSE;
1028
                return 0;
1029
            }
1030
        }
1031
    }
1032
    return -1;
1033
}
1034

    
1035

    
1036
/**
1037
 * Reduce the bandwidth to reduce the number of bits used for a given SNR offset.
1038
 * This is a second fallback for when bit allocation still fails after exponents
1039
 * have been downgraded.
1040
 * @return non-zero if bandwidth reduction was unsuccessful
1041
 */
1042
static int reduce_bandwidth(AC3EncodeContext *s, int min_bw_code)
1043
{
1044
    int ch;
1045

    
1046
    if (s->bandwidth_code[0] > min_bw_code) {
1047
        for (ch = 0; ch < s->fbw_channels; ch++) {
1048
            s->bandwidth_code[ch]--;
1049
            s->nb_coefs[ch] = s->bandwidth_code[ch] * 3 + 73;
1050
        }
1051
        return 0;
1052
    }
1053
    return -1;
1054
}
1055

    
1056

    
1057
/**
1058
 * Perform bit allocation search.
1059
 * Finds the SNR offset value that maximizes quality and fits in the specified
1060
 * frame size.  Output is the SNR offset and a set of bit allocation pointers
1061
 * used to quantize the mantissas.
1062
 */
1063
static int compute_bit_allocation(AC3EncodeContext *s)
1064
{
1065
    int ret;
1066

    
1067
    count_frame_bits(s);
1068

    
1069
    bit_alloc_masking(s);
1070

    
1071
    ret = cbr_bit_allocation(s);
1072
    while (ret) {
1073
        /* fallback 1: downgrade exponents */
1074
        if (!downgrade_exponents(s)) {
1075
            extract_exponents(s);
1076
            encode_exponents(s);
1077
            group_exponents(s);
1078
            ret = compute_bit_allocation(s);
1079
            continue;
1080
        }
1081

    
1082
        /* fallback 2: reduce bandwidth */
1083
        /* only do this if the user has not specified a specific cutoff
1084
           frequency */
1085
        if (!s->cutoff && !reduce_bandwidth(s, 0)) {
1086
            process_exponents(s);
1087
            ret = compute_bit_allocation(s);
1088
            continue;
1089
        }
1090

    
1091
        /* fallbacks were not enough... */
1092
        break;
1093
    }
1094

    
1095
    return ret;
1096
}
1097

    
1098

    
1099
/**
1100
 * Symmetric quantization on 'levels' levels.
1101
 */
1102
static inline int sym_quant(int c, int e, int levels)
1103
{
1104
    int v;
1105

    
1106
    if (c >= 0) {
1107
        v = (levels * (c << e)) >> 24;
1108
        v = (v + 1) >> 1;
1109
        v = (levels >> 1) + v;
1110
    } else {
1111
        v = (levels * ((-c) << e)) >> 24;
1112
        v = (v + 1) >> 1;
1113
        v = (levels >> 1) - v;
1114
    }
1115
    assert(v >= 0 && v < levels);
1116
    return v;
1117
}
1118

    
1119

    
1120
/**
1121
 * Asymmetric quantization on 2^qbits levels.
1122
 */
1123
static inline int asym_quant(int c, int e, int qbits)
1124
{
1125
    int lshift, m, v;
1126

    
1127
    lshift = e + qbits - 24;
1128
    if (lshift >= 0)
1129
        v = c << lshift;
1130
    else
1131
        v = c >> (-lshift);
1132
    /* rounding */
1133
    v = (v + 1) >> 1;
1134
    m = (1 << (qbits-1));
1135
    if (v >= m)
1136
        v = m - 1;
1137
    assert(v >= -m);
1138
    return v & ((1 << qbits)-1);
1139
}
1140

    
1141

    
1142
/**
1143
 * Quantize a set of mantissas for a single channel in a single block.
1144
 */
1145
static void quantize_mantissas_blk_ch(AC3EncodeContext *s, int32_t *fixed_coef,
1146
                                      int8_t exp_shift, uint8_t *exp,
1147
                                      uint8_t *bap, uint16_t *qmant, int n)
1148
{
1149
    int i;
1150

    
1151
    for (i = 0; i < n; i++) {
1152
        int v;
1153
        int c = fixed_coef[i];
1154
        int e = exp[i] - exp_shift;
1155
        int b = bap[i];
1156
        switch (b) {
1157
        case 0:
1158
            v = 0;
1159
            break;
1160
        case 1:
1161
            v = sym_quant(c, e, 3);
1162
            switch (s->mant1_cnt) {
1163
            case 0:
1164
                s->qmant1_ptr = &qmant[i];
1165
                v = 9 * v;
1166
                s->mant1_cnt = 1;
1167
                break;
1168
            case 1:
1169
                *s->qmant1_ptr += 3 * v;
1170
                s->mant1_cnt = 2;
1171
                v = 128;
1172
                break;
1173
            default:
1174
                *s->qmant1_ptr += v;
1175
                s->mant1_cnt = 0;
1176
                v = 128;
1177
                break;
1178
            }
1179
            break;
1180
        case 2:
1181
            v = sym_quant(c, e, 5);
1182
            switch (s->mant2_cnt) {
1183
            case 0:
1184
                s->qmant2_ptr = &qmant[i];
1185
                v = 25 * v;
1186
                s->mant2_cnt = 1;
1187
                break;
1188
            case 1:
1189
                *s->qmant2_ptr += 5 * v;
1190
                s->mant2_cnt = 2;
1191
                v = 128;
1192
                break;
1193
            default:
1194
                *s->qmant2_ptr += v;
1195
                s->mant2_cnt = 0;
1196
                v = 128;
1197
                break;
1198
            }
1199
            break;
1200
        case 3:
1201
            v = sym_quant(c, e, 7);
1202
            break;
1203
        case 4:
1204
            v = sym_quant(c, e, 11);
1205
            switch (s->mant4_cnt) {
1206
            case 0:
1207
                s->qmant4_ptr = &qmant[i];
1208
                v = 11 * v;
1209
                s->mant4_cnt = 1;
1210
                break;
1211
            default:
1212
                *s->qmant4_ptr += v;
1213
                s->mant4_cnt = 0;
1214
                v = 128;
1215
                break;
1216
            }
1217
            break;
1218
        case 5:
1219
            v = sym_quant(c, e, 15);
1220
            break;
1221
        case 14:
1222
            v = asym_quant(c, e, 14);
1223
            break;
1224
        case 15:
1225
            v = asym_quant(c, e, 16);
1226
            break;
1227
        default:
1228
            v = asym_quant(c, e, b - 1);
1229
            break;
1230
        }
1231
        qmant[i] = v;
1232
    }
1233
}
1234

    
1235

    
1236
/**
1237
 * Quantize mantissas using coefficients, exponents, and bit allocation pointers.
1238
 */
1239
static void quantize_mantissas(AC3EncodeContext *s)
1240
{
1241
    int blk, ch;
1242

    
1243

    
1244
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1245
        AC3Block *block = &s->blocks[blk];
1246
        s->mant1_cnt  = s->mant2_cnt  = s->mant4_cnt  = 0;
1247
        s->qmant1_ptr = s->qmant2_ptr = s->qmant4_ptr = NULL;
1248

    
1249
        for (ch = 0; ch < s->channels; ch++) {
1250
            quantize_mantissas_blk_ch(s, block->fixed_coef[ch], block->exp_shift[ch],
1251
                                      block->exp[ch], block->bap[ch],
1252
                                      block->qmant[ch], s->nb_coefs[ch]);
1253
        }
1254
    }
1255
}
1256

    
1257

    
1258
/**
1259
 * Write the AC-3 frame header to the output bitstream.
1260
 */
1261
static void output_frame_header(AC3EncodeContext *s)
1262
{
1263
    put_bits(&s->pb, 16, 0x0b77);   /* frame header */
1264
    put_bits(&s->pb, 16, 0);        /* crc1: will be filled later */
1265
    put_bits(&s->pb, 2,  s->bit_alloc.sr_code);
1266
    put_bits(&s->pb, 6,  s->frame_size_code + (s->frame_size - s->frame_size_min) / 2);
1267
    put_bits(&s->pb, 5,  s->bitstream_id);
1268
    put_bits(&s->pb, 3,  s->bitstream_mode);
1269
    put_bits(&s->pb, 3,  s->channel_mode);
1270
    if ((s->channel_mode & 0x01) && s->channel_mode != AC3_CHMODE_MONO)
1271
        put_bits(&s->pb, 2, 1);     /* XXX -4.5 dB */
1272
    if (s->channel_mode & 0x04)
1273
        put_bits(&s->pb, 2, 1);     /* XXX -6 dB */
1274
    if (s->channel_mode == AC3_CHMODE_STEREO)
1275
        put_bits(&s->pb, 2, 0);     /* surround not indicated */
1276
    put_bits(&s->pb, 1, s->lfe_on); /* LFE */
1277
    put_bits(&s->pb, 5, 31);        /* dialog norm: -31 db */
1278
    put_bits(&s->pb, 1, 0);         /* no compression control word */
1279
    put_bits(&s->pb, 1, 0);         /* no lang code */
1280
    put_bits(&s->pb, 1, 0);         /* no audio production info */
1281
    put_bits(&s->pb, 1, 0);         /* no copyright */
1282
    put_bits(&s->pb, 1, 1);         /* original bitstream */
1283
    put_bits(&s->pb, 1, 0);         /* no time code 1 */
1284
    put_bits(&s->pb, 1, 0);         /* no time code 2 */
1285
    put_bits(&s->pb, 1, 0);         /* no additional bit stream info */
1286
}
1287

    
1288

    
1289
/**
1290
 * Write one audio block to the output bitstream.
1291
 */
1292
static void output_audio_block(AC3EncodeContext *s, int block_num)
1293
{
1294
    int ch, i, baie, rbnd;
1295
    AC3Block *block = &s->blocks[block_num];
1296

    
1297
    /* block switching */
1298
    for (ch = 0; ch < s->fbw_channels; ch++)
1299
        put_bits(&s->pb, 1, 0);
1300

    
1301
    /* dither flags */
1302
    for (ch = 0; ch < s->fbw_channels; ch++)
1303
        put_bits(&s->pb, 1, 1);
1304

    
1305
    /* dynamic range codes */
1306
    put_bits(&s->pb, 1, 0);
1307

    
1308
    /* channel coupling */
1309
    if (!block_num) {
1310
        put_bits(&s->pb, 1, 1); /* coupling strategy present */
1311
        put_bits(&s->pb, 1, 0); /* no coupling strategy */
1312
    } else {
1313
        put_bits(&s->pb, 1, 0); /* no new coupling strategy */
1314
    }
1315

    
1316
    /* stereo rematrixing */
1317
    if (s->channel_mode == AC3_CHMODE_STEREO) {
1318
        put_bits(&s->pb, 1, block->new_rematrixing_strategy);
1319
        if (block->new_rematrixing_strategy) {
1320
            /* rematrixing flags */
1321
            for (rbnd = 0; rbnd < 4; rbnd++)
1322
                put_bits(&s->pb, 1, block->rematrixing_flags[rbnd]);
1323
        }
1324
    }
1325

    
1326
    /* exponent strategy */
1327
    for (ch = 0; ch < s->fbw_channels; ch++)
1328
        put_bits(&s->pb, 2, s->exp_strategy[ch][block_num]);
1329
    if (s->lfe_on)
1330
        put_bits(&s->pb, 1, s->exp_strategy[s->lfe_channel][block_num]);
1331

    
1332
    /* bandwidth */
1333
    for (ch = 0; ch < s->fbw_channels; ch++) {
1334
        if (s->exp_strategy[ch][block_num] != EXP_REUSE)
1335
            put_bits(&s->pb, 6, s->bandwidth_code[ch]);
1336
    }
1337

    
1338
    /* exponents */
1339
    for (ch = 0; ch < s->channels; ch++) {
1340
        int nb_groups;
1341

    
1342
        if (s->exp_strategy[ch][block_num] == EXP_REUSE)
1343
            continue;
1344

    
1345
        /* DC exponent */
1346
        put_bits(&s->pb, 4, block->grouped_exp[ch][0]);
1347

    
1348
        /* exponent groups */
1349
        nb_groups = exponent_group_tab[s->exp_strategy[ch][block_num]-1][s->nb_coefs[ch]];
1350
        for (i = 1; i <= nb_groups; i++)
1351
            put_bits(&s->pb, 7, block->grouped_exp[ch][i]);
1352

    
1353
        /* gain range info */
1354
        if (ch != s->lfe_channel)
1355
            put_bits(&s->pb, 2, 0);
1356
    }
1357

    
1358
    /* bit allocation info */
1359
    baie = (block_num == 0);
1360
    put_bits(&s->pb, 1, baie);
1361
    if (baie) {
1362
        put_bits(&s->pb, 2, s->slow_decay_code);
1363
        put_bits(&s->pb, 2, s->fast_decay_code);
1364
        put_bits(&s->pb, 2, s->slow_gain_code);
1365
        put_bits(&s->pb, 2, s->db_per_bit_code);
1366
        put_bits(&s->pb, 3, s->floor_code);
1367
    }
1368

    
1369
    /* snr offset */
1370
    put_bits(&s->pb, 1, baie);
1371
    if (baie) {
1372
        put_bits(&s->pb, 6, s->coarse_snr_offset);
1373
        for (ch = 0; ch < s->channels; ch++) {
1374
            put_bits(&s->pb, 4, s->fine_snr_offset[ch]);
1375
            put_bits(&s->pb, 3, s->fast_gain_code[ch]);
1376
        }
1377
    }
1378

    
1379
    put_bits(&s->pb, 1, 0); /* no delta bit allocation */
1380
    put_bits(&s->pb, 1, 0); /* no data to skip */
1381

    
1382
    /* mantissas */
1383
    for (ch = 0; ch < s->channels; ch++) {
1384
        int b, q;
1385
        for (i = 0; i < s->nb_coefs[ch]; i++) {
1386
            q = block->qmant[ch][i];
1387
            b = block->bap[ch][i];
1388
            switch (b) {
1389
            case 0:                                         break;
1390
            case 1: if (q != 128) put_bits(&s->pb,   5, q); break;
1391
            case 2: if (q != 128) put_bits(&s->pb,   7, q); break;
1392
            case 3:               put_bits(&s->pb,   3, q); break;
1393
            case 4: if (q != 128) put_bits(&s->pb,   7, q); break;
1394
            case 14:              put_bits(&s->pb,  14, q); break;
1395
            case 15:              put_bits(&s->pb,  16, q); break;
1396
            default:              put_bits(&s->pb, b-1, q); break;
1397
            }
1398
        }
1399
    }
1400
}
1401

    
1402

    
1403
/** CRC-16 Polynomial */
1404
#define CRC16_POLY ((1 << 0) | (1 << 2) | (1 << 15) | (1 << 16))
1405

    
1406

    
1407
static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly)
1408
{
1409
    unsigned int c;
1410

    
1411
    c = 0;
1412
    while (a) {
1413
        if (a & 1)
1414
            c ^= b;
1415
        a = a >> 1;
1416
        b = b << 1;
1417
        if (b & (1 << 16))
1418
            b ^= poly;
1419
    }
1420
    return c;
1421
}
1422

    
1423

    
1424
static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly)
1425
{
1426
    unsigned int r;
1427
    r = 1;
1428
    while (n) {
1429
        if (n & 1)
1430
            r = mul_poly(r, a, poly);
1431
        a = mul_poly(a, a, poly);
1432
        n >>= 1;
1433
    }
1434
    return r;
1435
}
1436

    
1437

    
1438
/**
1439
 * Fill the end of the frame with 0's and compute the two CRCs.
1440
 */
1441
static void output_frame_end(AC3EncodeContext *s)
1442
{
1443
    const AVCRC *crc_ctx = av_crc_get_table(AV_CRC_16_ANSI);
1444
    int frame_size_58, pad_bytes, crc1, crc2_partial, crc2, crc_inv;
1445
    uint8_t *frame;
1446

    
1447
    frame_size_58 = ((s->frame_size >> 2) + (s->frame_size >> 4)) << 1;
1448

    
1449
    /* pad the remainder of the frame with zeros */
1450
    flush_put_bits(&s->pb);
1451
    frame = s->pb.buf;
1452
    pad_bytes = s->frame_size - (put_bits_ptr(&s->pb) - frame) - 2;
1453
    assert(pad_bytes >= 0);
1454
    if (pad_bytes > 0)
1455
        memset(put_bits_ptr(&s->pb), 0, pad_bytes);
1456

    
1457
    /* compute crc1 */
1458
    /* this is not so easy because it is at the beginning of the data... */
1459
    crc1    = av_bswap16(av_crc(crc_ctx, 0, frame + 4, frame_size_58 - 4));
1460
    crc_inv = s->crc_inv[s->frame_size > s->frame_size_min];
1461
    crc1    = mul_poly(crc_inv, crc1, CRC16_POLY);
1462
    AV_WB16(frame + 2, crc1);
1463

    
1464
    /* compute crc2 */
1465
    crc2_partial = av_crc(crc_ctx, 0, frame + frame_size_58,
1466
                          s->frame_size - frame_size_58 - 3);
1467
    crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
1468
    /* ensure crc2 does not match sync word by flipping crcrsv bit if needed */
1469
    if (crc2 == 0x770B) {
1470
        frame[s->frame_size - 3] ^= 0x1;
1471
        crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
1472
    }
1473
    crc2 = av_bswap16(crc2);
1474
    AV_WB16(frame + s->frame_size - 2, crc2);
1475
}
1476

    
1477

    
1478
/**
1479
 * Write the frame to the output bitstream.
1480
 */
1481
static void output_frame(AC3EncodeContext *s, unsigned char *frame)
1482
{
1483
    int blk;
1484

    
1485
    init_put_bits(&s->pb, frame, AC3_MAX_CODED_FRAME_SIZE);
1486

    
1487
    output_frame_header(s);
1488

    
1489
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++)
1490
        output_audio_block(s, blk);
1491

    
1492
    output_frame_end(s);
1493
}
1494

    
1495

    
1496
/**
1497
 * Encode a single AC-3 frame.
1498
 */
1499
static int ac3_encode_frame(AVCodecContext *avctx, unsigned char *frame,
1500
                            int buf_size, void *data)
1501
{
1502
    AC3EncodeContext *s = avctx->priv_data;
1503
    const SampleType *samples = data;
1504
    int ret;
1505

    
1506
    if (s->bit_alloc.sr_code == 1)
1507
        adjust_frame_size(s);
1508

    
1509
    deinterleave_input_samples(s, samples);
1510

    
1511
    apply_mdct(s);
1512

    
1513
    compute_rematrixing_strategy(s);
1514

    
1515
    scale_coefficients(s);
1516

    
1517
    apply_rematrixing(s);
1518

    
1519
    process_exponents(s);
1520

    
1521
    ret = compute_bit_allocation(s);
1522
    if (ret) {
1523
        av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
1524
        return ret;
1525
    }
1526

    
1527
    quantize_mantissas(s);
1528

    
1529
    output_frame(s, frame);
1530

    
1531
    return s->frame_size;
1532
}
1533

    
1534

    
1535
/**
1536
 * Finalize encoding and free any memory allocated by the encoder.
1537
 */
1538
static av_cold int ac3_encode_close(AVCodecContext *avctx)
1539
{
1540
    int blk, ch;
1541
    AC3EncodeContext *s = avctx->priv_data;
1542

    
1543
    for (ch = 0; ch < s->channels; ch++)
1544
        av_freep(&s->planar_samples[ch]);
1545
    av_freep(&s->planar_samples);
1546
    av_freep(&s->bap_buffer);
1547
    av_freep(&s->bap1_buffer);
1548
    av_freep(&s->mdct_coef_buffer);
1549
    av_freep(&s->fixed_coef_buffer);
1550
    av_freep(&s->exp_buffer);
1551
    av_freep(&s->grouped_exp_buffer);
1552
    av_freep(&s->psd_buffer);
1553
    av_freep(&s->band_psd_buffer);
1554
    av_freep(&s->mask_buffer);
1555
    av_freep(&s->qmant_buffer);
1556
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1557
        AC3Block *block = &s->blocks[blk];
1558
        av_freep(&block->bap);
1559
        av_freep(&block->mdct_coef);
1560
        av_freep(&block->fixed_coef);
1561
        av_freep(&block->exp);
1562
        av_freep(&block->grouped_exp);
1563
        av_freep(&block->psd);
1564
        av_freep(&block->band_psd);
1565
        av_freep(&block->mask);
1566
        av_freep(&block->qmant);
1567
    }
1568

    
1569
    mdct_end(&s->mdct);
1570

    
1571
    av_freep(&avctx->coded_frame);
1572
    return 0;
1573
}
1574

    
1575

    
1576
/**
1577
 * Set channel information during initialization.
1578
 */
1579
static av_cold int set_channel_info(AC3EncodeContext *s, int channels,
1580
                                    int64_t *channel_layout)
1581
{
1582
    int ch_layout;
1583

    
1584
    if (channels < 1 || channels > AC3_MAX_CHANNELS)
1585
        return AVERROR(EINVAL);
1586
    if ((uint64_t)*channel_layout > 0x7FF)
1587
        return AVERROR(EINVAL);
1588
    ch_layout = *channel_layout;
1589
    if (!ch_layout)
1590
        ch_layout = avcodec_guess_channel_layout(channels, CODEC_ID_AC3, NULL);
1591
    if (av_get_channel_layout_nb_channels(ch_layout) != channels)
1592
        return AVERROR(EINVAL);
1593

    
1594
    s->lfe_on       = !!(ch_layout & AV_CH_LOW_FREQUENCY);
1595
    s->channels     = channels;
1596
    s->fbw_channels = channels - s->lfe_on;
1597
    s->lfe_channel  = s->lfe_on ? s->fbw_channels : -1;
1598
    if (s->lfe_on)
1599
        ch_layout -= AV_CH_LOW_FREQUENCY;
1600

    
1601
    switch (ch_layout) {
1602
    case AV_CH_LAYOUT_MONO:           s->channel_mode = AC3_CHMODE_MONO;   break;
1603
    case AV_CH_LAYOUT_STEREO:         s->channel_mode = AC3_CHMODE_STEREO; break;
1604
    case AV_CH_LAYOUT_SURROUND:       s->channel_mode = AC3_CHMODE_3F;     break;
1605
    case AV_CH_LAYOUT_2_1:            s->channel_mode = AC3_CHMODE_2F1R;   break;
1606
    case AV_CH_LAYOUT_4POINT0:        s->channel_mode = AC3_CHMODE_3F1R;   break;
1607
    case AV_CH_LAYOUT_QUAD:
1608
    case AV_CH_LAYOUT_2_2:            s->channel_mode = AC3_CHMODE_2F2R;   break;
1609
    case AV_CH_LAYOUT_5POINT0:
1610
    case AV_CH_LAYOUT_5POINT0_BACK:   s->channel_mode = AC3_CHMODE_3F2R;   break;
1611
    default:
1612
        return AVERROR(EINVAL);
1613
    }
1614

    
1615
    s->channel_map  = ff_ac3_enc_channel_map[s->channel_mode][s->lfe_on];
1616
    *channel_layout = ch_layout;
1617
    if (s->lfe_on)
1618
        *channel_layout |= AV_CH_LOW_FREQUENCY;
1619

    
1620
    return 0;
1621
}
1622

    
1623

    
1624
static av_cold int validate_options(AVCodecContext *avctx, AC3EncodeContext *s)
1625
{
1626
    int i, ret;
1627

    
1628
    /* validate channel layout */
1629
    if (!avctx->channel_layout) {
1630
        av_log(avctx, AV_LOG_WARNING, "No channel layout specified. The "
1631
                                      "encoder will guess the layout, but it "
1632
                                      "might be incorrect.\n");
1633
    }
1634
    ret = set_channel_info(s, avctx->channels, &avctx->channel_layout);
1635
    if (ret) {
1636
        av_log(avctx, AV_LOG_ERROR, "invalid channel layout\n");
1637
        return ret;
1638
    }
1639

    
1640
    /* validate sample rate */
1641
    for (i = 0; i < 9; i++) {
1642
        if ((ff_ac3_sample_rate_tab[i / 3] >> (i % 3)) == avctx->sample_rate)
1643
            break;
1644
    }
1645
    if (i == 9) {
1646
        av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1647
        return AVERROR(EINVAL);
1648
    }
1649
    s->sample_rate        = avctx->sample_rate;
1650
    s->bit_alloc.sr_shift = i % 3;
1651
    s->bit_alloc.sr_code  = i / 3;
1652

    
1653
    /* validate bit rate */
1654
    for (i = 0; i < 19; i++) {
1655
        if ((ff_ac3_bitrate_tab[i] >> s->bit_alloc.sr_shift)*1000 == avctx->bit_rate)
1656
            break;
1657
    }
1658
    if (i == 19) {
1659
        av_log(avctx, AV_LOG_ERROR, "invalid bit rate\n");
1660
        return AVERROR(EINVAL);
1661
    }
1662
    s->bit_rate        = avctx->bit_rate;
1663
    s->frame_size_code = i << 1;
1664

    
1665
    /* validate cutoff */
1666
    if (avctx->cutoff < 0) {
1667
        av_log(avctx, AV_LOG_ERROR, "invalid cutoff frequency\n");
1668
        return AVERROR(EINVAL);
1669
    }
1670
    s->cutoff = avctx->cutoff;
1671
    if (s->cutoff > (s->sample_rate >> 1))
1672
        s->cutoff = s->sample_rate >> 1;
1673

    
1674
    return 0;
1675
}
1676

    
1677

    
1678
/**
1679
 * Set bandwidth for all channels.
1680
 * The user can optionally supply a cutoff frequency. Otherwise an appropriate
1681
 * default value will be used.
1682
 */
1683
static av_cold void set_bandwidth(AC3EncodeContext *s)
1684
{
1685
    int ch, bw_code;
1686

    
1687
    if (s->cutoff) {
1688
        /* calculate bandwidth based on user-specified cutoff frequency */
1689
        int fbw_coeffs;
1690
        fbw_coeffs     = s->cutoff * 2 * AC3_MAX_COEFS / s->sample_rate;
1691
        bw_code        = av_clip((fbw_coeffs - 73) / 3, 0, 60);
1692
    } else {
1693
        /* use default bandwidth setting */
1694
        /* XXX: should compute the bandwidth according to the frame
1695
           size, so that we avoid annoying high frequency artifacts */
1696
        bw_code = 50;
1697
    }
1698

    
1699
    /* set number of coefficients for each channel */
1700
    for (ch = 0; ch < s->fbw_channels; ch++) {
1701
        s->bandwidth_code[ch] = bw_code;
1702
        s->nb_coefs[ch]       = bw_code * 3 + 73;
1703
    }
1704
    if (s->lfe_on)
1705
        s->nb_coefs[s->lfe_channel] = 7; /* LFE channel always has 7 coefs */
1706
}
1707

    
1708

    
1709
static av_cold int allocate_buffers(AVCodecContext *avctx)
1710
{
1711
    int blk, ch;
1712
    AC3EncodeContext *s = avctx->priv_data;
1713

    
1714
    FF_ALLOC_OR_GOTO(avctx, s->planar_samples, s->channels * sizeof(*s->planar_samples),
1715
                     alloc_fail);
1716
    for (ch = 0; ch < s->channels; ch++) {
1717
        FF_ALLOCZ_OR_GOTO(avctx, s->planar_samples[ch],
1718
                          (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),
1719
                          alloc_fail);
1720
    }
1721
    FF_ALLOC_OR_GOTO(avctx, s->bap_buffer,  AC3_MAX_BLOCKS * s->channels *
1722
                     AC3_MAX_COEFS * sizeof(*s->bap_buffer),  alloc_fail);
1723
    FF_ALLOC_OR_GOTO(avctx, s->bap1_buffer, AC3_MAX_BLOCKS * s->channels *
1724
                     AC3_MAX_COEFS * sizeof(*s->bap1_buffer), alloc_fail);
1725
    FF_ALLOC_OR_GOTO(avctx, s->mdct_coef_buffer, AC3_MAX_BLOCKS * s->channels *
1726
                     AC3_MAX_COEFS * sizeof(*s->mdct_coef_buffer), alloc_fail);
1727
    FF_ALLOC_OR_GOTO(avctx, s->exp_buffer, AC3_MAX_BLOCKS * s->channels *
1728
                     AC3_MAX_COEFS * sizeof(*s->exp_buffer), alloc_fail);
1729
    FF_ALLOC_OR_GOTO(avctx, s->grouped_exp_buffer, AC3_MAX_BLOCKS * s->channels *
1730
                     128 * sizeof(*s->grouped_exp_buffer), alloc_fail);
1731
    FF_ALLOC_OR_GOTO(avctx, s->psd_buffer, AC3_MAX_BLOCKS * s->channels *
1732
                     AC3_MAX_COEFS * sizeof(*s->psd_buffer), alloc_fail);
1733
    FF_ALLOC_OR_GOTO(avctx, s->band_psd_buffer, AC3_MAX_BLOCKS * s->channels *
1734
                     64 * sizeof(*s->band_psd_buffer), alloc_fail);
1735
    FF_ALLOC_OR_GOTO(avctx, s->mask_buffer, AC3_MAX_BLOCKS * s->channels *
1736
                     64 * sizeof(*s->mask_buffer), alloc_fail);
1737
    FF_ALLOC_OR_GOTO(avctx, s->qmant_buffer, AC3_MAX_BLOCKS * s->channels *
1738
                     AC3_MAX_COEFS * sizeof(*s->qmant_buffer), alloc_fail);
1739
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1740
        AC3Block *block = &s->blocks[blk];
1741
        FF_ALLOC_OR_GOTO(avctx, block->bap, s->channels * sizeof(*block->bap),
1742
                         alloc_fail);
1743
        FF_ALLOCZ_OR_GOTO(avctx, block->mdct_coef, s->channels * sizeof(*block->mdct_coef),
1744
                          alloc_fail);
1745
        FF_ALLOCZ_OR_GOTO(avctx, block->exp, s->channels * sizeof(*block->exp),
1746
                          alloc_fail);
1747
        FF_ALLOCZ_OR_GOTO(avctx, block->grouped_exp, s->channels * sizeof(*block->grouped_exp),
1748
                          alloc_fail);
1749
        FF_ALLOCZ_OR_GOTO(avctx, block->psd, s->channels * sizeof(*block->psd),
1750
                          alloc_fail);
1751
        FF_ALLOCZ_OR_GOTO(avctx, block->band_psd, s->channels * sizeof(*block->band_psd),
1752
                          alloc_fail);
1753
        FF_ALLOCZ_OR_GOTO(avctx, block->mask, s->channels * sizeof(*block->mask),
1754
                          alloc_fail);
1755
        FF_ALLOCZ_OR_GOTO(avctx, block->qmant, s->channels * sizeof(*block->qmant),
1756
                          alloc_fail);
1757

    
1758
        for (ch = 0; ch < s->channels; ch++) {
1759
            /* arrangement: block, channel, coeff */
1760
            block->bap[ch]         = &s->bap_buffer        [AC3_MAX_COEFS * (blk * s->channels + ch)];
1761
            block->mdct_coef[ch]   = &s->mdct_coef_buffer  [AC3_MAX_COEFS * (blk * s->channels + ch)];
1762
            block->grouped_exp[ch] = &s->grouped_exp_buffer[128           * (blk * s->channels + ch)];
1763
            block->psd[ch]         = &s->psd_buffer        [AC3_MAX_COEFS * (blk * s->channels + ch)];
1764
            block->band_psd[ch]    = &s->band_psd_buffer   [64            * (blk * s->channels + ch)];
1765
            block->mask[ch]        = &s->mask_buffer       [64            * (blk * s->channels + ch)];
1766
            block->qmant[ch]       = &s->qmant_buffer      [AC3_MAX_COEFS * (blk * s->channels + ch)];
1767

    
1768
            /* arrangement: channel, block, coeff */
1769
            block->exp[ch]         = &s->exp_buffer        [AC3_MAX_COEFS * (AC3_MAX_BLOCKS * ch + blk)];
1770
        }
1771
    }
1772

    
1773
    if (CONFIG_AC3ENC_FLOAT) {
1774
        FF_ALLOC_OR_GOTO(avctx, s->fixed_coef_buffer, AC3_MAX_BLOCKS * s->channels *
1775
                         AC3_MAX_COEFS * sizeof(*s->fixed_coef_buffer), alloc_fail);
1776
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1777
            AC3Block *block = &s->blocks[blk];
1778
            FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, s->channels *
1779
                              sizeof(*block->fixed_coef), alloc_fail);
1780
            for (ch = 0; ch < s->channels; ch++)
1781
                block->fixed_coef[ch] = &s->fixed_coef_buffer[AC3_MAX_COEFS * (blk * s->channels + ch)];
1782
        }
1783
    } else {
1784
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1785
            AC3Block *block = &s->blocks[blk];
1786
            FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, s->channels *
1787
                              sizeof(*block->fixed_coef), alloc_fail);
1788
            for (ch = 0; ch < s->channels; ch++)
1789
                block->fixed_coef[ch] = (int32_t *)block->mdct_coef[ch];
1790
        }
1791
    }
1792

    
1793
    return 0;
1794
alloc_fail:
1795
    return AVERROR(ENOMEM);
1796
}
1797

    
1798

    
1799
/**
1800
 * Initialize the encoder.
1801
 */
1802
static av_cold int ac3_encode_init(AVCodecContext *avctx)
1803
{
1804
    AC3EncodeContext *s = avctx->priv_data;
1805
    int ret, frame_size_58;
1806

    
1807
    avctx->frame_size = AC3_FRAME_SIZE;
1808

    
1809
    ac3_common_init();
1810

    
1811
    ret = validate_options(avctx, s);
1812
    if (ret)
1813
        return ret;
1814

    
1815
    s->bitstream_id   = 8 + s->bit_alloc.sr_shift;
1816
    s->bitstream_mode = 0; /* complete main audio service */
1817

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

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

    
1831
    set_bandwidth(s);
1832

    
1833
    rematrixing_init(s);
1834

    
1835
    exponent_init(s);
1836

    
1837
    bit_alloc_init(s);
1838

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

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

    
1847
    avctx->coded_frame= avcodec_alloc_frame();
1848

    
1849
    dsputil_init(&s->dsp, avctx);
1850

    
1851
    return 0;
1852
init_fail:
1853
    ac3_encode_close(avctx);
1854
    return ret;
1855
}