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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
43

    
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

    
48
/* 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.
67
 */
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

    
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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99
    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)
104
    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)
108
    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
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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 */
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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;
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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
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

    
157
static av_cold void mdct_end(AC3MDCTContext *mdct);
158

    
159
static av_cold int mdct_init(AVCodecContext *avctx, AC3MDCTContext *mdct,
160
                             int nbits);
161

    
162
static void mdct512(AC3MDCTContext *mdct, CoefType *out, SampleType *in);
163

    
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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205
/**
206
 * Adjust the frame size to make the average bit rate match the target bit rate.
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 * 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

    
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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->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;
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                sum[1] += rt * rt;
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                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 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
    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
 * exponent in the same frequency bin of a following block.
504
 * exp[i] = min(exp[i], exp1[i]
505
 */
506
static void exponent_min(uint8_t *exp, uint8_t *exp1, int n)
507
{
508
    int i;
509
    for (i = 0; i < n; i++) {
510
        if (exp1[i] < exp[i])
511
            exp[i] = exp1[i];
512
    }
513
}
514

    
515

    
516
/**
517
 * Update the exponents so that they are the ones the decoder will decode.
518
 */
519
static void encode_exponents_blk_ch(uint8_t *exp, int nb_exps, int exp_strategy)
520
{
521
    int nb_groups, i, k;
522

    
523
    nb_groups = exponent_group_tab[exp_strategy-1][nb_exps] * 3;
524

    
525
    /* for each group, compute the minimum exponent */
526
    switch(exp_strategy) {
527
    case EXP_D25:
528
        for (i = 1, k = 1; i <= nb_groups; i++) {
529
            uint8_t exp_min = exp[k];
530
            if (exp[k+1] < exp_min)
531
                exp_min = exp[k+1];
532
            exp[i] = exp_min;
533
            k += 2;
534
        }
535
        break;
536
    case EXP_D45:
537
        for (i = 1, k = 1; i <= nb_groups; i++) {
538
            uint8_t exp_min = exp[k];
539
            if (exp[k+1] < exp_min)
540
                exp_min = exp[k+1];
541
            if (exp[k+2] < exp_min)
542
                exp_min = exp[k+2];
543
            if (exp[k+3] < exp_min)
544
                exp_min = exp[k+3];
545
            exp[i] = exp_min;
546
            k += 4;
547
        }
548
        break;
549
    }
550

    
551
    /* constraint for DC exponent */
552
    if (exp[0] > 15)
553
        exp[0] = 15;
554

    
555
    /* decrease the delta between each groups to within 2 so that they can be
556
       differentially encoded */
557
    for (i = 1; i <= nb_groups; i++)
558
        exp[i] = FFMIN(exp[i], exp[i-1] + 2);
559
    i--;
560
    while (--i >= 0)
561
        exp[i] = FFMIN(exp[i], exp[i+1] + 2);
562

    
563
    /* now we have the exponent values the decoder will see */
564
    switch (exp_strategy) {
565
    case EXP_D25:
566
        for (i = nb_groups, k = nb_groups * 2; i > 0; i--) {
567
            uint8_t exp1 = exp[i];
568
            exp[k--] = exp1;
569
            exp[k--] = exp1;
570
        }
571
        break;
572
    case EXP_D45:
573
        for (i = nb_groups, k = nb_groups * 4; i > 0; i--) {
574
            exp[k] = exp[k-1] = exp[k-2] = exp[k-3] = exp[i];
575
            k -= 4;
576
        }
577
        break;
578
    }
579
}
580

    
581

    
582
/**
583
 * Encode exponents from original extracted form to what the decoder will see.
584
 * This copies and groups exponents based on exponent strategy and reduces
585
 * deltas between adjacent exponent groups so that they can be differentially
586
 * encoded.
587
 */
588
static void encode_exponents(AC3EncodeContext *s)
589
{
590
    int blk, blk1, ch;
591
    uint8_t *exp, *exp1, *exp_strategy;
592
    int nb_coefs;
593

    
594
    for (ch = 0; ch < s->channels; ch++) {
595
        exp          = s->blocks[0].exp[ch];
596
        exp_strategy = s->exp_strategy[ch];
597
        nb_coefs     = s->nb_coefs[ch];
598

    
599
        blk = 0;
600
        while (blk < AC3_MAX_BLOCKS) {
601
            blk1 = blk + 1;
602
            exp1 = exp + AC3_MAX_COEFS;
603
            /* for the EXP_REUSE case we select the min of the exponents */
604
            while (blk1 < AC3_MAX_BLOCKS && exp_strategy[blk1] == EXP_REUSE) {
605
                exponent_min(exp, exp1, nb_coefs);
606
                blk1++;
607
                exp1 += AC3_MAX_COEFS;
608
            }
609
            encode_exponents_blk_ch(exp, nb_coefs,
610
                                    exp_strategy[blk]);
611
            /* copy encoded exponents for reuse case */
612
            exp1 = exp + AC3_MAX_COEFS;
613
            while (blk < blk1-1) {
614
                memcpy(exp1, exp, nb_coefs * sizeof(*exp));
615
                exp1 += AC3_MAX_COEFS;
616
                blk++;
617
            }
618
            blk = blk1;
619
            exp = exp1;
620
        }
621
    }
622
}
623

    
624

    
625
/**
626
 * Group exponents.
627
 * 3 delta-encoded exponents are in each 7-bit group. The number of groups
628
 * varies depending on exponent strategy and bandwidth.
629
 */
630
static void group_exponents(AC3EncodeContext *s)
631
{
632
    int blk, ch, i;
633
    int group_size, nb_groups, bit_count;
634
    uint8_t *p;
635
    int delta0, delta1, delta2;
636
    int exp0, exp1;
637

    
638
    bit_count = 0;
639
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
640
        AC3Block *block = &s->blocks[blk];
641
        for (ch = 0; ch < s->channels; ch++) {
642
            int exp_strategy = s->exp_strategy[ch][blk];
643
            if (exp_strategy == EXP_REUSE)
644
                continue;
645
            group_size = exp_strategy + (exp_strategy == EXP_D45);
646
            nb_groups = exponent_group_tab[exp_strategy-1][s->nb_coefs[ch]];
647
            bit_count += 4 + (nb_groups * 7);
648
            p = block->exp[ch];
649

    
650
            /* DC exponent */
651
            exp1 = *p++;
652
            block->grouped_exp[ch][0] = exp1;
653

    
654
            /* remaining exponents are delta encoded */
655
            for (i = 1; i <= nb_groups; i++) {
656
                /* merge three delta in one code */
657
                exp0   = exp1;
658
                exp1   = p[0];
659
                p     += group_size;
660
                delta0 = exp1 - exp0 + 2;
661

    
662
                exp0   = exp1;
663
                exp1   = p[0];
664
                p     += group_size;
665
                delta1 = exp1 - exp0 + 2;
666

    
667
                exp0   = exp1;
668
                exp1   = p[0];
669
                p     += group_size;
670
                delta2 = exp1 - exp0 + 2;
671

    
672
                block->grouped_exp[ch][i] = ((delta0 * 5 + delta1) * 5) + delta2;
673
            }
674
        }
675
    }
676

    
677
    s->exponent_bits = bit_count;
678
}
679

    
680

    
681
/**
682
 * Calculate final exponents from the supplied MDCT coefficients and exponent shift.
683
 * Extract exponents from MDCT coefficients, calculate exponent strategies,
684
 * and encode final exponents.
685
 */
686
static void process_exponents(AC3EncodeContext *s)
687
{
688
    extract_exponents(s);
689

    
690
    compute_exp_strategy(s);
691

    
692
    encode_exponents(s);
693

    
694
    group_exponents(s);
695
}
696

    
697

    
698
/**
699
 * Count frame bits that are based solely on fixed parameters.
700
 * This only has to be run once when the encoder is initialized.
701
 */
702
static void count_frame_bits_fixed(AC3EncodeContext *s)
703
{
704
    static const int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
705
    int blk;
706
    int frame_bits;
707

    
708
    /* assumptions:
709
     *   no dynamic range codes
710
     *   no channel coupling
711
     *   bit allocation parameters do not change between blocks
712
     *   SNR offsets do not change between blocks
713
     *   no delta bit allocation
714
     *   no skipped data
715
     *   no auxilliary data
716
     */
717

    
718
    /* header size */
719
    frame_bits = 65;
720
    frame_bits += frame_bits_inc[s->channel_mode];
721

    
722
    /* audio blocks */
723
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
724
        frame_bits += s->fbw_channels * 2 + 2; /* blksw * c, dithflag * c, dynrnge, cplstre */
725
        if (s->channel_mode == AC3_CHMODE_STEREO) {
726
            frame_bits++; /* rematstr */
727
        }
728
        frame_bits += 2 * s->fbw_channels; /* chexpstr[2] * c */
729
        if (s->lfe_on)
730
            frame_bits++; /* lfeexpstr */
731
        frame_bits++; /* baie */
732
        frame_bits++; /* snr */
733
        frame_bits += 2; /* delta / skip */
734
    }
735
    frame_bits++; /* cplinu for block 0 */
736
    /* bit alloc info */
737
    /* sdcycod[2], fdcycod[2], sgaincod[2], dbpbcod[2], floorcod[3] */
738
    /* csnroffset[6] */
739
    /* (fsnoffset[4] + fgaincod[4]) * c */
740
    frame_bits += 2*4 + 3 + 6 + s->channels * (4 + 3);
741

    
742
    /* auxdatae, crcrsv */
743
    frame_bits += 2;
744

    
745
    /* CRC */
746
    frame_bits += 16;
747

    
748
    s->frame_bits_fixed = frame_bits;
749
}
750

    
751

    
752
/**
753
 * Initialize bit allocation.
754
 * Set default parameter codes and calculate parameter values.
755
 */
756
static void bit_alloc_init(AC3EncodeContext *s)
757
{
758
    int ch;
759

    
760
    /* init default parameters */
761
    s->slow_decay_code = 2;
762
    s->fast_decay_code = 1;
763
    s->slow_gain_code  = 1;
764
    s->db_per_bit_code = 3;
765
    s->floor_code      = 4;
766
    for (ch = 0; ch < s->channels; ch++)
767
        s->fast_gain_code[ch] = 4;
768

    
769
    /* initial snr offset */
770
    s->coarse_snr_offset = 40;
771

    
772
    /* compute real values */
773
    /* currently none of these values change during encoding, so we can just
774
       set them once at initialization */
775
    s->bit_alloc.slow_decay = ff_ac3_slow_decay_tab[s->slow_decay_code] >> s->bit_alloc.sr_shift;
776
    s->bit_alloc.fast_decay = ff_ac3_fast_decay_tab[s->fast_decay_code] >> s->bit_alloc.sr_shift;
777
    s->bit_alloc.slow_gain  = ff_ac3_slow_gain_tab[s->slow_gain_code];
778
    s->bit_alloc.db_per_bit = ff_ac3_db_per_bit_tab[s->db_per_bit_code];
779
    s->bit_alloc.floor      = ff_ac3_floor_tab[s->floor_code];
780

    
781
    count_frame_bits_fixed(s);
782
}
783

    
784

    
785
/**
786
 * Count the bits used to encode the frame, minus exponents and mantissas.
787
 * Bits based on fixed parameters have already been counted, so now we just
788
 * have to add the bits based on parameters that change during encoding.
789
 */
790
static void count_frame_bits(AC3EncodeContext *s)
791
{
792
    int blk, ch;
793
    int frame_bits = 0;
794

    
795
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
796
        /* stereo rematrixing */
797
        if (s->channel_mode == AC3_CHMODE_STEREO &&
798
            s->blocks[blk].new_rematrixing_strategy) {
799
            frame_bits += 4;
800
        }
801

    
802
        for (ch = 0; ch < s->fbw_channels; ch++) {
803
            if (s->exp_strategy[ch][blk] != EXP_REUSE)
804
                frame_bits += 6 + 2; /* chbwcod[6], gainrng[2] */
805
        }
806
    }
807
    s->frame_bits = s->frame_bits_fixed + frame_bits;
808
}
809

    
810

    
811
/**
812
 * Calculate the number of bits needed to encode a set of mantissas.
813
 */
814
static int compute_mantissa_size(int mant_cnt[5], uint8_t *bap, int nb_coefs)
815
{
816
    int bits, b, i;
817

    
818
    bits = 0;
819
    for (i = 0; i < nb_coefs; i++) {
820
        b = bap[i];
821
        if (b <= 4) {
822
            // bap=1 to bap=4 will be counted in compute_mantissa_size_final
823
            mant_cnt[b]++;
824
        } else if (b <= 13) {
825
            // bap=5 to bap=13 use (bap-1) bits
826
            bits += b - 1;
827
        } else {
828
            // bap=14 uses 14 bits and bap=15 uses 16 bits
829
            bits += (b == 14) ? 14 : 16;
830
        }
831
    }
832
    return bits;
833
}
834

    
835

    
836
/**
837
 * Finalize the mantissa bit count by adding in the grouped mantissas.
838
 */
839
static int compute_mantissa_size_final(int mant_cnt[5])
840
{
841
    // bap=1 : 3 mantissas in 5 bits
842
    int bits = (mant_cnt[1] / 3) * 5;
843
    // bap=2 : 3 mantissas in 7 bits
844
    // bap=4 : 2 mantissas in 7 bits
845
    bits += ((mant_cnt[2] / 3) + (mant_cnt[4] >> 1)) * 7;
846
    // bap=3 : each mantissa is 3 bits
847
    bits += mant_cnt[3] * 3;
848
    return bits;
849
}
850

    
851

    
852
/**
853
 * Calculate masking curve based on the final exponents.
854
 * Also calculate the power spectral densities to use in future calculations.
855
 */
856
static void bit_alloc_masking(AC3EncodeContext *s)
857
{
858
    int blk, ch;
859

    
860
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
861
        AC3Block *block = &s->blocks[blk];
862
        for (ch = 0; ch < s->channels; ch++) {
863
            /* We only need psd and mask for calculating bap.
864
               Since we currently do not calculate bap when exponent
865
               strategy is EXP_REUSE we do not need to calculate psd or mask. */
866
            if (s->exp_strategy[ch][blk] != EXP_REUSE) {
867
                ff_ac3_bit_alloc_calc_psd(block->exp[ch], 0,
868
                                          s->nb_coefs[ch],
869
                                          block->psd[ch], block->band_psd[ch]);
870
                ff_ac3_bit_alloc_calc_mask(&s->bit_alloc, block->band_psd[ch],
871
                                           0, s->nb_coefs[ch],
872
                                           ff_ac3_fast_gain_tab[s->fast_gain_code[ch]],
873
                                           ch == s->lfe_channel,
874
                                           DBA_NONE, 0, NULL, NULL, NULL,
875
                                           block->mask[ch]);
876
            }
877
        }
878
    }
879
}
880

    
881

    
882
/**
883
 * Ensure that bap for each block and channel point to the current bap_buffer.
884
 * They may have been switched during the bit allocation search.
885
 */
886
static void reset_block_bap(AC3EncodeContext *s)
887
{
888
    int blk, ch;
889
    if (s->blocks[0].bap[0] == s->bap_buffer)
890
        return;
891
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
892
        for (ch = 0; ch < s->channels; ch++) {
893
            s->blocks[blk].bap[ch] = &s->bap_buffer[AC3_MAX_COEFS * (blk * s->channels + ch)];
894
        }
895
    }
896
}
897

    
898

    
899
/**
900
 * Run the bit allocation with a given SNR offset.
901
 * This calculates the bit allocation pointers that will be used to determine
902
 * the quantization of each mantissa.
903
 * @return the number of bits needed for mantissas if the given SNR offset is
904
 *         is used.
905
 */
906
static int bit_alloc(AC3EncodeContext *s, int snr_offset)
907
{
908
    int blk, ch;
909
    int mantissa_bits;
910
    int mant_cnt[5];
911

    
912
    snr_offset = (snr_offset - 240) << 2;
913

    
914
    reset_block_bap(s);
915
    mantissa_bits = 0;
916
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
917
        AC3Block *block = &s->blocks[blk];
918
        // initialize grouped mantissa counts. these are set so that they are
919
        // padded to the next whole group size when bits are counted in
920
        // compute_mantissa_size_final
921
        mant_cnt[0] = mant_cnt[3] = 0;
922
        mant_cnt[1] = mant_cnt[2] = 2;
923
        mant_cnt[4] = 1;
924
        for (ch = 0; ch < s->channels; ch++) {
925
            /* Currently the only bit allocation parameters which vary across
926
               blocks within a frame are the exponent values.  We can take
927
               advantage of that by reusing the bit allocation pointers
928
               whenever we reuse exponents. */
929
            if (s->exp_strategy[ch][blk] == EXP_REUSE) {
930
                memcpy(block->bap[ch], s->blocks[blk-1].bap[ch], AC3_MAX_COEFS);
931
            } else {
932
                ff_ac3_bit_alloc_calc_bap(block->mask[ch], block->psd[ch], 0,
933
                                          s->nb_coefs[ch], snr_offset,
934
                                          s->bit_alloc.floor, ff_ac3_bap_tab,
935
                                          block->bap[ch]);
936
            }
937
            mantissa_bits += compute_mantissa_size(mant_cnt, block->bap[ch], s->nb_coefs[ch]);
938
        }
939
        mantissa_bits += compute_mantissa_size_final(mant_cnt);
940
    }
941
    return mantissa_bits;
942
}
943

    
944

    
945
/**
946
 * Constant bitrate bit allocation search.
947
 * Find the largest SNR offset that will allow data to fit in the frame.
948
 */
949
static int cbr_bit_allocation(AC3EncodeContext *s)
950
{
951
    int ch;
952
    int bits_left;
953
    int snr_offset, snr_incr;
954

    
955
    bits_left = 8 * s->frame_size - (s->frame_bits + s->exponent_bits);
956

    
957
    snr_offset = s->coarse_snr_offset << 4;
958

    
959
    /* if previous frame SNR offset was 1023, check if current frame can also
960
       use SNR offset of 1023. if so, skip the search. */
961
    if ((snr_offset | s->fine_snr_offset[0]) == 1023) {
962
        if (bit_alloc(s, 1023) <= bits_left)
963
            return 0;
964
    }
965

    
966
    while (snr_offset >= 0 &&
967
           bit_alloc(s, snr_offset) > bits_left) {
968
        snr_offset -= 64;
969
    }
970
    if (snr_offset < 0)
971
        return AVERROR(EINVAL);
972

    
973
    FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
974
    for (snr_incr = 64; snr_incr > 0; snr_incr >>= 2) {
975
        while (snr_offset + snr_incr <= 1023 &&
976
               bit_alloc(s, snr_offset + snr_incr) <= bits_left) {
977
            snr_offset += snr_incr;
978
            FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
979
        }
980
    }
981
    FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
982
    reset_block_bap(s);
983

    
984
    s->coarse_snr_offset = snr_offset >> 4;
985
    for (ch = 0; ch < s->channels; ch++)
986
        s->fine_snr_offset[ch] = snr_offset & 0xF;
987

    
988
    return 0;
989
}
990

    
991

    
992
/**
993
 * Downgrade exponent strategies to reduce the bits used by the exponents.
994
 * This is a fallback for when bit allocation fails with the normal exponent
995
 * strategies.  Each time this function is run it only downgrades the
996
 * strategy in 1 channel of 1 block.
997
 * @return non-zero if downgrade was unsuccessful
998
 */
999
static int downgrade_exponents(AC3EncodeContext *s)
1000
{
1001
    int ch, blk;
1002

    
1003
    for (ch = 0; ch < s->fbw_channels; ch++) {
1004
        for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
1005
            if (s->exp_strategy[ch][blk] == EXP_D15) {
1006
                s->exp_strategy[ch][blk] = EXP_D25;
1007
                return 0;
1008
            }
1009
        }
1010
    }
1011
    for (ch = 0; ch < s->fbw_channels; ch++) {
1012
        for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
1013
            if (s->exp_strategy[ch][blk] == EXP_D25) {
1014
                s->exp_strategy[ch][blk] = EXP_D45;
1015
                return 0;
1016
            }
1017
        }
1018
    }
1019
    for (ch = 0; ch < s->fbw_channels; ch++) {
1020
        /* block 0 cannot reuse exponents, so only downgrade D45 to REUSE if
1021
           the block number > 0 */
1022
        for (blk = AC3_MAX_BLOCKS-1; blk > 0; blk--) {
1023
            if (s->exp_strategy[ch][blk] > EXP_REUSE) {
1024
                s->exp_strategy[ch][blk] = EXP_REUSE;
1025
                return 0;
1026
            }
1027
        }
1028
    }
1029
    return -1;
1030
}
1031

    
1032

    
1033
/**
1034
 * Reduce the bandwidth to reduce the number of bits used for a given SNR offset.
1035
 * This is a second fallback for when bit allocation still fails after exponents
1036
 * have been downgraded.
1037
 * @return non-zero if bandwidth reduction was unsuccessful
1038
 */
1039
static int reduce_bandwidth(AC3EncodeContext *s, int min_bw_code)
1040
{
1041
    int ch;
1042

    
1043
    if (s->bandwidth_code[0] > min_bw_code) {
1044
        for (ch = 0; ch < s->fbw_channels; ch++) {
1045
            s->bandwidth_code[ch]--;
1046
            s->nb_coefs[ch] = s->bandwidth_code[ch] * 3 + 73;
1047
        }
1048
        return 0;
1049
    }
1050
    return -1;
1051
}
1052

    
1053

    
1054
/**
1055
 * Perform bit allocation search.
1056
 * Finds the SNR offset value that maximizes quality and fits in the specified
1057
 * frame size.  Output is the SNR offset and a set of bit allocation pointers
1058
 * used to quantize the mantissas.
1059
 */
1060
static int compute_bit_allocation(AC3EncodeContext *s)
1061
{
1062
    int ret;
1063

    
1064
    count_frame_bits(s);
1065

    
1066
    bit_alloc_masking(s);
1067

    
1068
    ret = cbr_bit_allocation(s);
1069
    while (ret) {
1070
        /* fallback 1: downgrade exponents */
1071
        if (!downgrade_exponents(s)) {
1072
            extract_exponents(s);
1073
            encode_exponents(s);
1074
            group_exponents(s);
1075
            ret = compute_bit_allocation(s);
1076
            continue;
1077
        }
1078

    
1079
        /* fallback 2: reduce bandwidth */
1080
        /* only do this if the user has not specified a specific cutoff
1081
           frequency */
1082
        if (!s->cutoff && !reduce_bandwidth(s, 0)) {
1083
            process_exponents(s);
1084
            ret = compute_bit_allocation(s);
1085
            continue;
1086
        }
1087

    
1088
        /* fallbacks were not enough... */
1089
        break;
1090
    }
1091

    
1092
    return ret;
1093
}
1094

    
1095

    
1096
/**
1097
 * Symmetric quantization on 'levels' levels.
1098
 */
1099
static inline int sym_quant(int c, int e, int levels)
1100
{
1101
    int v;
1102

    
1103
    if (c >= 0) {
1104
        v = (levels * (c << e)) >> 24;
1105
        v = (v + 1) >> 1;
1106
        v = (levels >> 1) + v;
1107
    } else {
1108
        v = (levels * ((-c) << e)) >> 24;
1109
        v = (v + 1) >> 1;
1110
        v = (levels >> 1) - v;
1111
    }
1112
    assert(v >= 0 && v < levels);
1113
    return v;
1114
}
1115

    
1116

    
1117
/**
1118
 * Asymmetric quantization on 2^qbits levels.
1119
 */
1120
static inline int asym_quant(int c, int e, int qbits)
1121
{
1122
    int lshift, m, v;
1123

    
1124
    lshift = e + qbits - 24;
1125
    if (lshift >= 0)
1126
        v = c << lshift;
1127
    else
1128
        v = c >> (-lshift);
1129
    /* rounding */
1130
    v = (v + 1) >> 1;
1131
    m = (1 << (qbits-1));
1132
    if (v >= m)
1133
        v = m - 1;
1134
    assert(v >= -m);
1135
    return v & ((1 << qbits)-1);
1136
}
1137

    
1138

    
1139
/**
1140
 * Quantize a set of mantissas for a single channel in a single block.
1141
 */
1142
static void quantize_mantissas_blk_ch(AC3EncodeContext *s, int32_t *fixed_coef,
1143
                                      int8_t exp_shift, uint8_t *exp,
1144
                                      uint8_t *bap, uint16_t *qmant, int n)
1145
{
1146
    int i;
1147

    
1148
    for (i = 0; i < n; i++) {
1149
        int v;
1150
        int c = fixed_coef[i];
1151
        int e = exp[i] - exp_shift;
1152
        int b = bap[i];
1153
        switch (b) {
1154
        case 0:
1155
            v = 0;
1156
            break;
1157
        case 1:
1158
            v = sym_quant(c, e, 3);
1159
            switch (s->mant1_cnt) {
1160
            case 0:
1161
                s->qmant1_ptr = &qmant[i];
1162
                v = 9 * v;
1163
                s->mant1_cnt = 1;
1164
                break;
1165
            case 1:
1166
                *s->qmant1_ptr += 3 * v;
1167
                s->mant1_cnt = 2;
1168
                v = 128;
1169
                break;
1170
            default:
1171
                *s->qmant1_ptr += v;
1172
                s->mant1_cnt = 0;
1173
                v = 128;
1174
                break;
1175
            }
1176
            break;
1177
        case 2:
1178
            v = sym_quant(c, e, 5);
1179
            switch (s->mant2_cnt) {
1180
            case 0:
1181
                s->qmant2_ptr = &qmant[i];
1182
                v = 25 * v;
1183
                s->mant2_cnt = 1;
1184
                break;
1185
            case 1:
1186
                *s->qmant2_ptr += 5 * v;
1187
                s->mant2_cnt = 2;
1188
                v = 128;
1189
                break;
1190
            default:
1191
                *s->qmant2_ptr += v;
1192
                s->mant2_cnt = 0;
1193
                v = 128;
1194
                break;
1195
            }
1196
            break;
1197
        case 3:
1198
            v = sym_quant(c, e, 7);
1199
            break;
1200
        case 4:
1201
            v = sym_quant(c, e, 11);
1202
            switch (s->mant4_cnt) {
1203
            case 0:
1204
                s->qmant4_ptr = &qmant[i];
1205
                v = 11 * v;
1206
                s->mant4_cnt = 1;
1207
                break;
1208
            default:
1209
                *s->qmant4_ptr += v;
1210
                s->mant4_cnt = 0;
1211
                v = 128;
1212
                break;
1213
            }
1214
            break;
1215
        case 5:
1216
            v = sym_quant(c, e, 15);
1217
            break;
1218
        case 14:
1219
            v = asym_quant(c, e, 14);
1220
            break;
1221
        case 15:
1222
            v = asym_quant(c, e, 16);
1223
            break;
1224
        default:
1225
            v = asym_quant(c, e, b - 1);
1226
            break;
1227
        }
1228
        qmant[i] = v;
1229
    }
1230
}
1231

    
1232

    
1233
/**
1234
 * Quantize mantissas using coefficients, exponents, and bit allocation pointers.
1235
 */
1236
static void quantize_mantissas(AC3EncodeContext *s)
1237
{
1238
    int blk, ch;
1239

    
1240

    
1241
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1242
        AC3Block *block = &s->blocks[blk];
1243
        s->mant1_cnt  = s->mant2_cnt  = s->mant4_cnt  = 0;
1244
        s->qmant1_ptr = s->qmant2_ptr = s->qmant4_ptr = NULL;
1245

    
1246
        for (ch = 0; ch < s->channels; ch++) {
1247
            quantize_mantissas_blk_ch(s, block->fixed_coef[ch], block->exp_shift[ch],
1248
                                      block->exp[ch], block->bap[ch],
1249
                                      block->qmant[ch], s->nb_coefs[ch]);
1250
        }
1251
    }
1252
}
1253

    
1254

    
1255
/**
1256
 * Write the AC-3 frame header to the output bitstream.
1257
 */
1258
static void output_frame_header(AC3EncodeContext *s)
1259
{
1260
    put_bits(&s->pb, 16, 0x0b77);   /* frame header */
1261
    put_bits(&s->pb, 16, 0);        /* crc1: will be filled later */
1262
    put_bits(&s->pb, 2,  s->bit_alloc.sr_code);
1263
    put_bits(&s->pb, 6,  s->frame_size_code + (s->frame_size - s->frame_size_min) / 2);
1264
    put_bits(&s->pb, 5,  s->bitstream_id);
1265
    put_bits(&s->pb, 3,  s->bitstream_mode);
1266
    put_bits(&s->pb, 3,  s->channel_mode);
1267
    if ((s->channel_mode & 0x01) && s->channel_mode != AC3_CHMODE_MONO)
1268
        put_bits(&s->pb, 2, 1);     /* XXX -4.5 dB */
1269
    if (s->channel_mode & 0x04)
1270
        put_bits(&s->pb, 2, 1);     /* XXX -6 dB */
1271
    if (s->channel_mode == AC3_CHMODE_STEREO)
1272
        put_bits(&s->pb, 2, 0);     /* surround not indicated */
1273
    put_bits(&s->pb, 1, s->lfe_on); /* LFE */
1274
    put_bits(&s->pb, 5, 31);        /* dialog norm: -31 db */
1275
    put_bits(&s->pb, 1, 0);         /* no compression control word */
1276
    put_bits(&s->pb, 1, 0);         /* no lang code */
1277
    put_bits(&s->pb, 1, 0);         /* no audio production info */
1278
    put_bits(&s->pb, 1, 0);         /* no copyright */
1279
    put_bits(&s->pb, 1, 1);         /* original bitstream */
1280
    put_bits(&s->pb, 1, 0);         /* no time code 1 */
1281
    put_bits(&s->pb, 1, 0);         /* no time code 2 */
1282
    put_bits(&s->pb, 1, 0);         /* no additional bit stream info */
1283
}
1284

    
1285

    
1286
/**
1287
 * Write one audio block to the output bitstream.
1288
 */
1289
static void output_audio_block(AC3EncodeContext *s, int blk)
1290
{
1291
    int ch, i, baie, rbnd;
1292
    AC3Block *block = &s->blocks[blk];
1293

    
1294
    /* block switching */
1295
    for (ch = 0; ch < s->fbw_channels; ch++)
1296
        put_bits(&s->pb, 1, 0);
1297

    
1298
    /* dither flags */
1299
    for (ch = 0; ch < s->fbw_channels; ch++)
1300
        put_bits(&s->pb, 1, 1);
1301

    
1302
    /* dynamic range codes */
1303
    put_bits(&s->pb, 1, 0);
1304

    
1305
    /* channel coupling */
1306
    if (!blk) {
1307
        put_bits(&s->pb, 1, 1); /* coupling strategy present */
1308
        put_bits(&s->pb, 1, 0); /* no coupling strategy */
1309
    } else {
1310
        put_bits(&s->pb, 1, 0); /* no new coupling strategy */
1311
    }
1312

    
1313
    /* stereo rematrixing */
1314
    if (s->channel_mode == AC3_CHMODE_STEREO) {
1315
        put_bits(&s->pb, 1, block->new_rematrixing_strategy);
1316
        if (block->new_rematrixing_strategy) {
1317
            /* rematrixing flags */
1318
            for (rbnd = 0; rbnd < 4; rbnd++)
1319
                put_bits(&s->pb, 1, block->rematrixing_flags[rbnd]);
1320
        }
1321
    }
1322

    
1323
    /* exponent strategy */
1324
    for (ch = 0; ch < s->fbw_channels; ch++)
1325
        put_bits(&s->pb, 2, s->exp_strategy[ch][blk]);
1326
    if (s->lfe_on)
1327
        put_bits(&s->pb, 1, s->exp_strategy[s->lfe_channel][blk]);
1328

    
1329
    /* bandwidth */
1330
    for (ch = 0; ch < s->fbw_channels; ch++) {
1331
        if (s->exp_strategy[ch][blk] != EXP_REUSE)
1332
            put_bits(&s->pb, 6, s->bandwidth_code[ch]);
1333
    }
1334

    
1335
    /* exponents */
1336
    for (ch = 0; ch < s->channels; ch++) {
1337
        int nb_groups;
1338

    
1339
        if (s->exp_strategy[ch][blk] == EXP_REUSE)
1340
            continue;
1341

    
1342
        /* DC exponent */
1343
        put_bits(&s->pb, 4, block->grouped_exp[ch][0]);
1344

    
1345
        /* exponent groups */
1346
        nb_groups = exponent_group_tab[s->exp_strategy[ch][blk]-1][s->nb_coefs[ch]];
1347
        for (i = 1; i <= nb_groups; i++)
1348
            put_bits(&s->pb, 7, block->grouped_exp[ch][i]);
1349

    
1350
        /* gain range info */
1351
        if (ch != s->lfe_channel)
1352
            put_bits(&s->pb, 2, 0);
1353
    }
1354

    
1355
    /* bit allocation info */
1356
    baie = (blk == 0);
1357
    put_bits(&s->pb, 1, baie);
1358
    if (baie) {
1359
        put_bits(&s->pb, 2, s->slow_decay_code);
1360
        put_bits(&s->pb, 2, s->fast_decay_code);
1361
        put_bits(&s->pb, 2, s->slow_gain_code);
1362
        put_bits(&s->pb, 2, s->db_per_bit_code);
1363
        put_bits(&s->pb, 3, s->floor_code);
1364
    }
1365

    
1366
    /* snr offset */
1367
    put_bits(&s->pb, 1, baie);
1368
    if (baie) {
1369
        put_bits(&s->pb, 6, s->coarse_snr_offset);
1370
        for (ch = 0; ch < s->channels; ch++) {
1371
            put_bits(&s->pb, 4, s->fine_snr_offset[ch]);
1372
            put_bits(&s->pb, 3, s->fast_gain_code[ch]);
1373
        }
1374
    }
1375

    
1376
    put_bits(&s->pb, 1, 0); /* no delta bit allocation */
1377
    put_bits(&s->pb, 1, 0); /* no data to skip */
1378

    
1379
    /* mantissas */
1380
    for (ch = 0; ch < s->channels; ch++) {
1381
        int b, q;
1382
        for (i = 0; i < s->nb_coefs[ch]; i++) {
1383
            q = block->qmant[ch][i];
1384
            b = block->bap[ch][i];
1385
            switch (b) {
1386
            case 0:                                         break;
1387
            case 1: if (q != 128) put_bits(&s->pb,   5, q); break;
1388
            case 2: if (q != 128) put_bits(&s->pb,   7, q); break;
1389
            case 3:               put_bits(&s->pb,   3, q); break;
1390
            case 4: if (q != 128) put_bits(&s->pb,   7, q); break;
1391
            case 14:              put_bits(&s->pb,  14, q); break;
1392
            case 15:              put_bits(&s->pb,  16, q); break;
1393
            default:              put_bits(&s->pb, b-1, q); break;
1394
            }
1395
        }
1396
    }
1397
}
1398

    
1399

    
1400
/** CRC-16 Polynomial */
1401
#define CRC16_POLY ((1 << 0) | (1 << 2) | (1 << 15) | (1 << 16))
1402

    
1403

    
1404
static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly)
1405
{
1406
    unsigned int c;
1407

    
1408
    c = 0;
1409
    while (a) {
1410
        if (a & 1)
1411
            c ^= b;
1412
        a = a >> 1;
1413
        b = b << 1;
1414
        if (b & (1 << 16))
1415
            b ^= poly;
1416
    }
1417
    return c;
1418
}
1419

    
1420

    
1421
static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly)
1422
{
1423
    unsigned int r;
1424
    r = 1;
1425
    while (n) {
1426
        if (n & 1)
1427
            r = mul_poly(r, a, poly);
1428
        a = mul_poly(a, a, poly);
1429
        n >>= 1;
1430
    }
1431
    return r;
1432
}
1433

    
1434

    
1435
/**
1436
 * Fill the end of the frame with 0's and compute the two CRCs.
1437
 */
1438
static void output_frame_end(AC3EncodeContext *s)
1439
{
1440
    const AVCRC *crc_ctx = av_crc_get_table(AV_CRC_16_ANSI);
1441
    int frame_size_58, pad_bytes, crc1, crc2_partial, crc2, crc_inv;
1442
    uint8_t *frame;
1443

    
1444
    frame_size_58 = ((s->frame_size >> 2) + (s->frame_size >> 4)) << 1;
1445

    
1446
    /* pad the remainder of the frame with zeros */
1447
    flush_put_bits(&s->pb);
1448
    frame = s->pb.buf;
1449
    pad_bytes = s->frame_size - (put_bits_ptr(&s->pb) - frame) - 2;
1450
    assert(pad_bytes >= 0);
1451
    if (pad_bytes > 0)
1452
        memset(put_bits_ptr(&s->pb), 0, pad_bytes);
1453

    
1454
    /* compute crc1 */
1455
    /* this is not so easy because it is at the beginning of the data... */
1456
    crc1    = av_bswap16(av_crc(crc_ctx, 0, frame + 4, frame_size_58 - 4));
1457
    crc_inv = s->crc_inv[s->frame_size > s->frame_size_min];
1458
    crc1    = mul_poly(crc_inv, crc1, CRC16_POLY);
1459
    AV_WB16(frame + 2, crc1);
1460

    
1461
    /* compute crc2 */
1462
    crc2_partial = av_crc(crc_ctx, 0, frame + frame_size_58,
1463
                          s->frame_size - frame_size_58 - 3);
1464
    crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
1465
    /* ensure crc2 does not match sync word by flipping crcrsv bit if needed */
1466
    if (crc2 == 0x770B) {
1467
        frame[s->frame_size - 3] ^= 0x1;
1468
        crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
1469
    }
1470
    crc2 = av_bswap16(crc2);
1471
    AV_WB16(frame + s->frame_size - 2, crc2);
1472
}
1473

    
1474

    
1475
/**
1476
 * Write the frame to the output bitstream.
1477
 */
1478
static void output_frame(AC3EncodeContext *s, unsigned char *frame)
1479
{
1480
    int blk;
1481

    
1482
    init_put_bits(&s->pb, frame, AC3_MAX_CODED_FRAME_SIZE);
1483

    
1484
    output_frame_header(s);
1485

    
1486
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++)
1487
        output_audio_block(s, blk);
1488

    
1489
    output_frame_end(s);
1490
}
1491

    
1492

    
1493
/**
1494
 * Encode a single AC-3 frame.
1495
 */
1496
static int ac3_encode_frame(AVCodecContext *avctx, unsigned char *frame,
1497
                            int buf_size, void *data)
1498
{
1499
    AC3EncodeContext *s = avctx->priv_data;
1500
    const SampleType *samples = data;
1501
    int ret;
1502

    
1503
    if (s->bit_alloc.sr_code == 1)
1504
        adjust_frame_size(s);
1505

    
1506
    deinterleave_input_samples(s, samples);
1507

    
1508
    apply_mdct(s);
1509

    
1510
    compute_rematrixing_strategy(s);
1511

    
1512
    scale_coefficients(s);
1513

    
1514
    apply_rematrixing(s);
1515

    
1516
    process_exponents(s);
1517

    
1518
    ret = compute_bit_allocation(s);
1519
    if (ret) {
1520
        av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
1521
        return ret;
1522
    }
1523

    
1524
    quantize_mantissas(s);
1525

    
1526
    output_frame(s, frame);
1527

    
1528
    return s->frame_size;
1529
}
1530

    
1531

    
1532
/**
1533
 * Finalize encoding and free any memory allocated by the encoder.
1534
 */
1535
static av_cold int ac3_encode_close(AVCodecContext *avctx)
1536
{
1537
    int blk, ch;
1538
    AC3EncodeContext *s = avctx->priv_data;
1539

    
1540
    for (ch = 0; ch < s->channels; ch++)
1541
        av_freep(&s->planar_samples[ch]);
1542
    av_freep(&s->planar_samples);
1543
    av_freep(&s->bap_buffer);
1544
    av_freep(&s->bap1_buffer);
1545
    av_freep(&s->mdct_coef_buffer);
1546
    av_freep(&s->fixed_coef_buffer);
1547
    av_freep(&s->exp_buffer);
1548
    av_freep(&s->grouped_exp_buffer);
1549
    av_freep(&s->psd_buffer);
1550
    av_freep(&s->band_psd_buffer);
1551
    av_freep(&s->mask_buffer);
1552
    av_freep(&s->qmant_buffer);
1553
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1554
        AC3Block *block = &s->blocks[blk];
1555
        av_freep(&block->bap);
1556
        av_freep(&block->mdct_coef);
1557
        av_freep(&block->fixed_coef);
1558
        av_freep(&block->exp);
1559
        av_freep(&block->grouped_exp);
1560
        av_freep(&block->psd);
1561
        av_freep(&block->band_psd);
1562
        av_freep(&block->mask);
1563
        av_freep(&block->qmant);
1564
    }
1565

    
1566
    mdct_end(&s->mdct);
1567

    
1568
    av_freep(&avctx->coded_frame);
1569
    return 0;
1570
}
1571

    
1572

    
1573
/**
1574
 * Set channel information during initialization.
1575
 */
1576
static av_cold int set_channel_info(AC3EncodeContext *s, int channels,
1577
                                    int64_t *channel_layout)
1578
{
1579
    int ch_layout;
1580

    
1581
    if (channels < 1 || channels > AC3_MAX_CHANNELS)
1582
        return AVERROR(EINVAL);
1583
    if ((uint64_t)*channel_layout > 0x7FF)
1584
        return AVERROR(EINVAL);
1585
    ch_layout = *channel_layout;
1586
    if (!ch_layout)
1587
        ch_layout = avcodec_guess_channel_layout(channels, CODEC_ID_AC3, NULL);
1588
    if (av_get_channel_layout_nb_channels(ch_layout) != channels)
1589
        return AVERROR(EINVAL);
1590

    
1591
    s->lfe_on       = !!(ch_layout & AV_CH_LOW_FREQUENCY);
1592
    s->channels     = channels;
1593
    s->fbw_channels = channels - s->lfe_on;
1594
    s->lfe_channel  = s->lfe_on ? s->fbw_channels : -1;
1595
    if (s->lfe_on)
1596
        ch_layout -= AV_CH_LOW_FREQUENCY;
1597

    
1598
    switch (ch_layout) {
1599
    case AV_CH_LAYOUT_MONO:           s->channel_mode = AC3_CHMODE_MONO;   break;
1600
    case AV_CH_LAYOUT_STEREO:         s->channel_mode = AC3_CHMODE_STEREO; break;
1601
    case AV_CH_LAYOUT_SURROUND:       s->channel_mode = AC3_CHMODE_3F;     break;
1602
    case AV_CH_LAYOUT_2_1:            s->channel_mode = AC3_CHMODE_2F1R;   break;
1603
    case AV_CH_LAYOUT_4POINT0:        s->channel_mode = AC3_CHMODE_3F1R;   break;
1604
    case AV_CH_LAYOUT_QUAD:
1605
    case AV_CH_LAYOUT_2_2:            s->channel_mode = AC3_CHMODE_2F2R;   break;
1606
    case AV_CH_LAYOUT_5POINT0:
1607
    case AV_CH_LAYOUT_5POINT0_BACK:   s->channel_mode = AC3_CHMODE_3F2R;   break;
1608
    default:
1609
        return AVERROR(EINVAL);
1610
    }
1611

    
1612
    s->channel_map  = ff_ac3_enc_channel_map[s->channel_mode][s->lfe_on];
1613
    *channel_layout = ch_layout;
1614
    if (s->lfe_on)
1615
        *channel_layout |= AV_CH_LOW_FREQUENCY;
1616

    
1617
    return 0;
1618
}
1619

    
1620

    
1621
static av_cold int validate_options(AVCodecContext *avctx, AC3EncodeContext *s)
1622
{
1623
    int i, ret;
1624

    
1625
    /* validate channel layout */
1626
    if (!avctx->channel_layout) {
1627
        av_log(avctx, AV_LOG_WARNING, "No channel layout specified. The "
1628
                                      "encoder will guess the layout, but it "
1629
                                      "might be incorrect.\n");
1630
    }
1631
    ret = set_channel_info(s, avctx->channels, &avctx->channel_layout);
1632
    if (ret) {
1633
        av_log(avctx, AV_LOG_ERROR, "invalid channel layout\n");
1634
        return ret;
1635
    }
1636

    
1637
    /* validate sample rate */
1638
    for (i = 0; i < 9; i++) {
1639
        if ((ff_ac3_sample_rate_tab[i / 3] >> (i % 3)) == avctx->sample_rate)
1640
            break;
1641
    }
1642
    if (i == 9) {
1643
        av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1644
        return AVERROR(EINVAL);
1645
    }
1646
    s->sample_rate        = avctx->sample_rate;
1647
    s->bit_alloc.sr_shift = i % 3;
1648
    s->bit_alloc.sr_code  = i / 3;
1649

    
1650
    /* validate bit rate */
1651
    for (i = 0; i < 19; i++) {
1652
        if ((ff_ac3_bitrate_tab[i] >> s->bit_alloc.sr_shift)*1000 == avctx->bit_rate)
1653
            break;
1654
    }
1655
    if (i == 19) {
1656
        av_log(avctx, AV_LOG_ERROR, "invalid bit rate\n");
1657
        return AVERROR(EINVAL);
1658
    }
1659
    s->bit_rate        = avctx->bit_rate;
1660
    s->frame_size_code = i << 1;
1661

    
1662
    /* validate cutoff */
1663
    if (avctx->cutoff < 0) {
1664
        av_log(avctx, AV_LOG_ERROR, "invalid cutoff frequency\n");
1665
        return AVERROR(EINVAL);
1666
    }
1667
    s->cutoff = avctx->cutoff;
1668
    if (s->cutoff > (s->sample_rate >> 1))
1669
        s->cutoff = s->sample_rate >> 1;
1670

    
1671
    return 0;
1672
}
1673

    
1674

    
1675
/**
1676
 * Set bandwidth for all channels.
1677
 * The user can optionally supply a cutoff frequency. Otherwise an appropriate
1678
 * default value will be used.
1679
 */
1680
static av_cold void set_bandwidth(AC3EncodeContext *s)
1681
{
1682
    int ch, bw_code;
1683

    
1684
    if (s->cutoff) {
1685
        /* calculate bandwidth based on user-specified cutoff frequency */
1686
        int fbw_coeffs;
1687
        fbw_coeffs     = s->cutoff * 2 * AC3_MAX_COEFS / s->sample_rate;
1688
        bw_code        = av_clip((fbw_coeffs - 73) / 3, 0, 60);
1689
    } else {
1690
        /* use default bandwidth setting */
1691
        /* XXX: should compute the bandwidth according to the frame
1692
           size, so that we avoid annoying high frequency artifacts */
1693
        bw_code = 50;
1694
    }
1695

    
1696
    /* set number of coefficients for each channel */
1697
    for (ch = 0; ch < s->fbw_channels; ch++) {
1698
        s->bandwidth_code[ch] = bw_code;
1699
        s->nb_coefs[ch]       = bw_code * 3 + 73;
1700
    }
1701
    if (s->lfe_on)
1702
        s->nb_coefs[s->lfe_channel] = 7; /* LFE channel always has 7 coefs */
1703
}
1704

    
1705

    
1706
static av_cold int allocate_buffers(AVCodecContext *avctx)
1707
{
1708
    int blk, ch;
1709
    AC3EncodeContext *s = avctx->priv_data;
1710

    
1711
    FF_ALLOC_OR_GOTO(avctx, s->planar_samples, s->channels * sizeof(*s->planar_samples),
1712
                     alloc_fail);
1713
    for (ch = 0; ch < s->channels; ch++) {
1714
        FF_ALLOCZ_OR_GOTO(avctx, s->planar_samples[ch],
1715
                          (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),
1716
                          alloc_fail);
1717
    }
1718
    FF_ALLOC_OR_GOTO(avctx, s->bap_buffer,  AC3_MAX_BLOCKS * s->channels *
1719
                     AC3_MAX_COEFS * sizeof(*s->bap_buffer),  alloc_fail);
1720
    FF_ALLOC_OR_GOTO(avctx, s->bap1_buffer, AC3_MAX_BLOCKS * s->channels *
1721
                     AC3_MAX_COEFS * sizeof(*s->bap1_buffer), alloc_fail);
1722
    FF_ALLOC_OR_GOTO(avctx, s->mdct_coef_buffer, AC3_MAX_BLOCKS * s->channels *
1723
                     AC3_MAX_COEFS * sizeof(*s->mdct_coef_buffer), alloc_fail);
1724
    FF_ALLOC_OR_GOTO(avctx, s->exp_buffer, AC3_MAX_BLOCKS * s->channels *
1725
                     AC3_MAX_COEFS * sizeof(*s->exp_buffer), alloc_fail);
1726
    FF_ALLOC_OR_GOTO(avctx, s->grouped_exp_buffer, AC3_MAX_BLOCKS * s->channels *
1727
                     128 * sizeof(*s->grouped_exp_buffer), alloc_fail);
1728
    FF_ALLOC_OR_GOTO(avctx, s->psd_buffer, AC3_MAX_BLOCKS * s->channels *
1729
                     AC3_MAX_COEFS * sizeof(*s->psd_buffer), alloc_fail);
1730
    FF_ALLOC_OR_GOTO(avctx, s->band_psd_buffer, AC3_MAX_BLOCKS * s->channels *
1731
                     64 * sizeof(*s->band_psd_buffer), alloc_fail);
1732
    FF_ALLOC_OR_GOTO(avctx, s->mask_buffer, AC3_MAX_BLOCKS * s->channels *
1733
                     64 * sizeof(*s->mask_buffer), alloc_fail);
1734
    FF_ALLOC_OR_GOTO(avctx, s->qmant_buffer, AC3_MAX_BLOCKS * s->channels *
1735
                     AC3_MAX_COEFS * sizeof(*s->qmant_buffer), alloc_fail);
1736
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1737
        AC3Block *block = &s->blocks[blk];
1738
        FF_ALLOC_OR_GOTO(avctx, block->bap, s->channels * sizeof(*block->bap),
1739
                         alloc_fail);
1740
        FF_ALLOCZ_OR_GOTO(avctx, block->mdct_coef, s->channels * sizeof(*block->mdct_coef),
1741
                          alloc_fail);
1742
        FF_ALLOCZ_OR_GOTO(avctx, block->exp, s->channels * sizeof(*block->exp),
1743
                          alloc_fail);
1744
        FF_ALLOCZ_OR_GOTO(avctx, block->grouped_exp, s->channels * sizeof(*block->grouped_exp),
1745
                          alloc_fail);
1746
        FF_ALLOCZ_OR_GOTO(avctx, block->psd, s->channels * sizeof(*block->psd),
1747
                          alloc_fail);
1748
        FF_ALLOCZ_OR_GOTO(avctx, block->band_psd, s->channels * sizeof(*block->band_psd),
1749
                          alloc_fail);
1750
        FF_ALLOCZ_OR_GOTO(avctx, block->mask, s->channels * sizeof(*block->mask),
1751
                          alloc_fail);
1752
        FF_ALLOCZ_OR_GOTO(avctx, block->qmant, s->channels * sizeof(*block->qmant),
1753
                          alloc_fail);
1754

    
1755
        for (ch = 0; ch < s->channels; ch++) {
1756
            /* arrangement: block, channel, coeff */
1757
            block->bap[ch]         = &s->bap_buffer        [AC3_MAX_COEFS * (blk * s->channels + ch)];
1758
            block->mdct_coef[ch]   = &s->mdct_coef_buffer  [AC3_MAX_COEFS * (blk * s->channels + ch)];
1759
            block->grouped_exp[ch] = &s->grouped_exp_buffer[128           * (blk * s->channels + ch)];
1760
            block->psd[ch]         = &s->psd_buffer        [AC3_MAX_COEFS * (blk * s->channels + ch)];
1761
            block->band_psd[ch]    = &s->band_psd_buffer   [64            * (blk * s->channels + ch)];
1762
            block->mask[ch]        = &s->mask_buffer       [64            * (blk * s->channels + ch)];
1763
            block->qmant[ch]       = &s->qmant_buffer      [AC3_MAX_COEFS * (blk * s->channels + ch)];
1764

    
1765
            /* arrangement: channel, block, coeff */
1766
            block->exp[ch]         = &s->exp_buffer        [AC3_MAX_COEFS * (AC3_MAX_BLOCKS * ch + blk)];
1767
        }
1768
    }
1769

    
1770
    if (CONFIG_AC3ENC_FLOAT) {
1771
        FF_ALLOC_OR_GOTO(avctx, s->fixed_coef_buffer, AC3_MAX_BLOCKS * s->channels *
1772
                         AC3_MAX_COEFS * sizeof(*s->fixed_coef_buffer), alloc_fail);
1773
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1774
            AC3Block *block = &s->blocks[blk];
1775
            FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, s->channels *
1776
                              sizeof(*block->fixed_coef), alloc_fail);
1777
            for (ch = 0; ch < s->channels; ch++)
1778
                block->fixed_coef[ch] = &s->fixed_coef_buffer[AC3_MAX_COEFS * (blk * s->channels + ch)];
1779
        }
1780
    } else {
1781
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1782
            AC3Block *block = &s->blocks[blk];
1783
            FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, s->channels *
1784
                              sizeof(*block->fixed_coef), alloc_fail);
1785
            for (ch = 0; ch < s->channels; ch++)
1786
                block->fixed_coef[ch] = (int32_t *)block->mdct_coef[ch];
1787
        }
1788
    }
1789

    
1790
    return 0;
1791
alloc_fail:
1792
    return AVERROR(ENOMEM);
1793
}
1794

    
1795

    
1796
/**
1797
 * Initialize the encoder.
1798
 */
1799
static av_cold int ac3_encode_init(AVCodecContext *avctx)
1800
{
1801
    AC3EncodeContext *s = avctx->priv_data;
1802
    int ret, frame_size_58;
1803

    
1804
    avctx->frame_size = AC3_FRAME_SIZE;
1805

    
1806
    ac3_common_init();
1807

    
1808
    ret = validate_options(avctx, s);
1809
    if (ret)
1810
        return ret;
1811

    
1812
    s->bitstream_id   = 8 + s->bit_alloc.sr_shift;
1813
    s->bitstream_mode = 0; /* complete main audio service */
1814

    
1815
    s->frame_size_min  = 2 * ff_ac3_frame_size_tab[s->frame_size_code][s->bit_alloc.sr_code];
1816
    s->bits_written    = 0;
1817
    s->samples_written = 0;
1818
    s->frame_size      = s->frame_size_min;
1819

    
1820
    /* calculate crc_inv for both possible frame sizes */
1821
    frame_size_58 = (( s->frame_size    >> 2) + ( s->frame_size    >> 4)) << 1;
1822
    s->crc_inv[0] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
1823
    if (s->bit_alloc.sr_code == 1) {
1824
        frame_size_58 = (((s->frame_size+2) >> 2) + ((s->frame_size+2) >> 4)) << 1;
1825
        s->crc_inv[1] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
1826
    }
1827

    
1828
    set_bandwidth(s);
1829

    
1830
    rematrixing_init(s);
1831

    
1832
    exponent_init(s);
1833

    
1834
    bit_alloc_init(s);
1835

    
1836
    ret = mdct_init(avctx, &s->mdct, 9);
1837
    if (ret)
1838
        goto init_fail;
1839

    
1840
    ret = allocate_buffers(avctx);
1841
    if (ret)
1842
        goto init_fail;
1843

    
1844
    avctx->coded_frame= avcodec_alloc_frame();
1845

    
1846
    dsputil_init(&s->dsp, avctx);
1847

    
1848
    return 0;
1849
init_fail:
1850
    ac3_encode_close(avctx);
1851
    return ret;
1852
}