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1 de6d9b64 Fabrice Bellard
/*
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 * The simplest AC-3 encoder
3 406792e7 Diego Biurrun
 * 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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 *
7 b78e7197 Diego Biurrun
 * This file is part of FFmpeg.
8
 *
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 * FFmpeg is free software; you can redistribute it and/or
10 ff4ec49e Fabrice Bellard
 * 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
17
 * Lesser General Public License for more details.
18 de6d9b64 Fabrice Bellard
 *
19 ff4ec49e Fabrice Bellard
 * You should have received a copy of the GNU Lesser General Public
20 b78e7197 Diego Biurrun
 * License along with FFmpeg; if not, write to the Free Software
21 5509bffa Diego Biurrun
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 de6d9b64 Fabrice Bellard
 */
23 983e3246 Michael Niedermayer
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/**
25 ba87f080 Diego Biurrun
 * @file
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 * The simplest AC-3 encoder.
27 983e3246 Michael Niedermayer
 */
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29 1a565432 Fabrice Bellard
//#define DEBUG
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#include "libavutil/audioconvert.h"
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#include "libavutil/crc.h"
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#include "avcodec.h"
34 b2755007 Stefano Sabatini
#include "put_bits.h"
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#include "dsputil.h"
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#include "ac3dsp.h"
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#include "ac3.h"
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#include "audioconvert.h"
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#ifndef CONFIG_AC3ENC_FLOAT
42
#define CONFIG_AC3ENC_FLOAT 0
43
#endif
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/** Maximum number of exponent groups. +1 for separate DC exponent. */
47
#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
54
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/** Scale a float value by 2^bits and convert to an integer. */
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#define SCALE_FLOAT(a, bits) lrintf((a) * (float)(1 << (bits)))
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#if CONFIG_AC3ENC_FLOAT
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#include "ac3enc_float.h"
61
#else
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#include "ac3enc_fixed.h"
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#endif
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/**
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 * Data for a single audio block.
68
 */
69
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
75
    int16_t  **psd;                             ///< psd per frequency bin
76
    int16_t  **band_psd;                        ///< psd per critical band
77
    int16_t  **mask;                            ///< masking curve
78
    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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84
/**
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 * AC-3 encoder private context.
86
 */
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typedef struct AC3EncodeContext {
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    PutBitContext pb;                       ///< bitstream writer context
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    DSPContext dsp;
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    AC3DSPContext ac3dsp;                   ///< AC-3 optimized functions
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    AC3MDCTContext mdct;                    ///< MDCT context
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    AC3Block blocks[AC3_MAX_BLOCKS];        ///< per-block info
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    int bitstream_id;                       ///< bitstream id                           (bsid)
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    int bitstream_mode;                     ///< bitstream mode                         (bsmod)
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    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];
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    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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    int fbw_channels;                       ///< number of full-bandwidth channels      (nfchans)
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    int channels;                           ///< total number of channels               (nchans)
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    int lfe_on;                             ///< indicates if there is an LFE channel   (lfeon)
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    int lfe_channel;                        ///< channel index of the LFE channel
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    int channel_mode;                       ///< channel mode                           (acmod)
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    const uint8_t *channel_map;             ///< channel map used to reorder channels
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    int cutoff;                             ///< user-specified cutoff frequency, in Hz
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    int bandwidth_code[AC3_MAX_CHANNELS];   ///< bandwidth code (0 to 60)               (chbwcod)
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    int nb_coefs[AC3_MAX_CHANNELS];
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    int rematrixing;                        ///< determines how rematrixing strategy is calculated
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    /* bitrate allocation control */
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    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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    /* 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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    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;
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    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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    uint8_t exp_strategy[AC3_MAX_CHANNELS][AC3_MAX_BLOCKS]; ///< exponent strategies
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    DECLARE_ALIGNED(16, SampleType, windowed_samples)[AC3_WINDOW_SIZE];
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} AC3EncodeContext;
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/* prototypes for functions in ac3enc_fixed.c and ac3enc_float.c */
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static av_cold void mdct_end(AC3MDCTContext *mdct);
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static av_cold int mdct_init(AVCodecContext *avctx, AC3MDCTContext *mdct,
162
                             int nbits);
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static void mdct512(AC3MDCTContext *mdct, CoefType *out, SampleType *in);
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static void apply_window(DSPContext *dsp, SampleType *output, const SampleType *input,
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                         const SampleType *window, int n);
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static int normalize_samples(AC3EncodeContext *s);
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static void scale_coefficients(AC3EncodeContext *s);
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/**
175
 * LUT for number of exponent groups.
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 * exponent_group_tab[exponent strategy-1][number of coefficients]
177
 */
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static uint8_t exponent_group_tab[3][256];
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/**
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 * List of supported channel layouts.
183
 */
184
static const int64_t ac3_channel_layouts[] = {
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     AV_CH_LAYOUT_MONO,
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     AV_CH_LAYOUT_STEREO,
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     AV_CH_LAYOUT_2_1,
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     AV_CH_LAYOUT_SURROUND,
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     AV_CH_LAYOUT_2_2,
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     AV_CH_LAYOUT_QUAD,
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     AV_CH_LAYOUT_4POINT0,
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     AV_CH_LAYOUT_5POINT0,
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     AV_CH_LAYOUT_5POINT0_BACK,
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    (AV_CH_LAYOUT_MONO     | AV_CH_LOW_FREQUENCY),
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    (AV_CH_LAYOUT_STEREO   | AV_CH_LOW_FREQUENCY),
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    (AV_CH_LAYOUT_2_1      | AV_CH_LOW_FREQUENCY),
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    (AV_CH_LAYOUT_SURROUND | AV_CH_LOW_FREQUENCY),
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    (AV_CH_LAYOUT_2_2      | AV_CH_LOW_FREQUENCY),
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    (AV_CH_LAYOUT_QUAD     | AV_CH_LOW_FREQUENCY),
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    (AV_CH_LAYOUT_4POINT0  | AV_CH_LOW_FREQUENCY),
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     AV_CH_LAYOUT_5POINT1,
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     AV_CH_LAYOUT_5POINT1_BACK,
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     0
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};
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/**
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 * 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.
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 */
211
static void adjust_frame_size(AC3EncodeContext *s)
212
{
213
    while (s->bits_written >= s->bit_rate && s->samples_written >= s->sample_rate) {
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        s->bits_written    -= s->bit_rate;
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        s->samples_written -= s->sample_rate;
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    }
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    s->frame_size = s->frame_size_min +
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                    2 * (s->bits_written * s->sample_rate < s->samples_written * s->bit_rate);
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    s->bits_written    += s->frame_size * 8;
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    s->samples_written += AC3_FRAME_SIZE;
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}
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/**
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 * Deinterleave input samples.
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 * Channels are reordered from FFmpeg's default order to AC-3 order.
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 */
228
static void deinterleave_input_samples(AC3EncodeContext *s,
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                                       const SampleType *samples)
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{
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    int ch, i;
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    /* deinterleave and remap input samples */
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    for (ch = 0; ch < s->channels; ch++) {
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        const SampleType *sptr;
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        int sinc;
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        /* copy last 256 samples of previous frame to the start of the current frame */
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        memcpy(&s->planar_samples[ch][0], &s->planar_samples[ch][AC3_FRAME_SIZE],
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               AC3_BLOCK_SIZE * sizeof(s->planar_samples[0][0]));
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        /* deinterleave */
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        sinc = s->channels;
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        sptr = samples + s->channel_map[ch];
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        for (i = AC3_BLOCK_SIZE; i < AC3_FRAME_SIZE+AC3_BLOCK_SIZE; i++) {
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            s->planar_samples[ch][i] = *sptr;
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            sptr += sinc;
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        }
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    }
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}
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/**
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 * Apply the MDCT to input samples to generate frequency coefficients.
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 * This applies the KBD window and normalizes the input to reduce precision
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 * loss due to fixed-point calculations.
257
 */
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static void apply_mdct(AC3EncodeContext *s)
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{
260
    int blk, ch;
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    for (ch = 0; ch < s->channels; ch++) {
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        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
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            AC3Block *block = &s->blocks[blk];
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            const SampleType *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE];
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            apply_window(&s->dsp, s->windowed_samples, input_samples, s->mdct.window, AC3_WINDOW_SIZE);
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            block->exp_shift[ch] = normalize_samples(s);
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            mdct512(&s->mdct, block->mdct_coef[ch], s->windowed_samples);
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        }
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    }
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}
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/**
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 * Initialize stereo rematrixing.
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 * If the strategy does not change for each frame, set the rematrixing flags.
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 */
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static void rematrixing_init(AC3EncodeContext *s)
282
{
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    if (s->channel_mode == AC3_CHMODE_STEREO)
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        s->rematrixing = AC3_REMATRIXING_SUMS;
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    else
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        s->rematrixing = AC3_REMATRIXING_NONE;
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    /* NOTE: AC3_REMATRIXING_ALWAYS might be used in
288
             the future in conjunction with channel coupling. */
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    if (s->rematrixing & AC3_REMATRIXING_IS_STATIC) {
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        int flag = (s->rematrixing == AC3_REMATRIXING_ALWAYS);
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        s->blocks[0].new_rematrixing_strategy = 1;
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        memset(s->blocks[0].rematrixing_flags, flag,
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               sizeof(s->blocks[0].rematrixing_flags));
295
    }
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}
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/**
300
 * Determine rematrixing flags for each block and band.
301
 */
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static void compute_rematrixing_strategy(AC3EncodeContext *s)
303
{
304
    int nb_coefs;
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    int blk, bnd, i;
306
    AC3Block *block, *block0;
307
308
    if (s->rematrixing & AC3_REMATRIXING_IS_STATIC)
309
        return;
310
311
    nb_coefs = FFMIN(s->nb_coefs[0], s->nb_coefs[1]);
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    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
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        block = &s->blocks[blk];
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        block->new_rematrixing_strategy = !blk;
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        for (bnd = 0; bnd < 4; bnd++) {
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            /* calculate calculate sum of squared coeffs for one band in one block */
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            int start = ff_ac3_rematrix_band_tab[bnd];
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            int end   = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
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            CoefSumType sum[4] = {0,};
321
            for (i = start; i < end; i++) {
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                CoefType lt = block->mdct_coef[0][i];
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                CoefType rt = block->mdct_coef[1][i];
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                CoefType md = lt + rt;
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                CoefType sd = lt - rt;
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                sum[0] += lt * lt;
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                sum[1] += rt * rt;
328
                sum[2] += md * md;
329
                sum[3] += sd * sd;
330
            }
331
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            /* compare sums to determine if rematrixing will be used for this band */
333
            if (FFMIN(sum[2], sum[3]) < FFMIN(sum[0], sum[1]))
334
                block->rematrixing_flags[bnd] = 1;
335
            else
336
                block->rematrixing_flags[bnd] = 0;
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            /* determine if new rematrixing flags will be sent */
339
            if (blk &&
340
                block->rematrixing_flags[bnd] != block0->rematrixing_flags[bnd]) {
341
                block->new_rematrixing_strategy = 1;
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            }
343
        }
344
        block0 = block;
345
    }
346
}
347
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/**
350
 * Apply stereo rematrixing to coefficients based on rematrixing flags.
351
 */
352
static void apply_rematrixing(AC3EncodeContext *s)
353
{
354
    int nb_coefs;
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    int blk, bnd, i;
356
    int start, end;
357
    uint8_t *flags;
358
359
    if (s->rematrixing == AC3_REMATRIXING_NONE)
360
        return;
361
362
    nb_coefs = FFMIN(s->nb_coefs[0], s->nb_coefs[1]);
363
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    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
365
        AC3Block *block = &s->blocks[blk];
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        if (block->new_rematrixing_strategy)
367
            flags = block->rematrixing_flags;
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        for (bnd = 0; bnd < 4; bnd++) {
369
            if (flags[bnd]) {
370
                start = ff_ac3_rematrix_band_tab[bnd];
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                end   = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
372
                for (i = start; i < end; i++) {
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                    int32_t lt = block->fixed_coef[0][i];
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                    int32_t rt = block->fixed_coef[1][i];
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                    block->fixed_coef[0][i] = (lt + rt) >> 1;
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                    block->fixed_coef[1][i] = (lt - rt) >> 1;
377
                }
378
            }
379
        }
380
    }
381
}
382
383
384
/**
385 e86ea34d Justin Ruggles
 * Initialize exponent tables.
386
 */
387
static av_cold void exponent_init(AC3EncodeContext *s)
388
{
389
    int i;
390
    for (i = 73; i < 256; i++) {
391
        exponent_group_tab[0][i] = (i - 1) /  3;
392
        exponent_group_tab[1][i] = (i + 2) /  6;
393
        exponent_group_tab[2][i] = (i + 8) / 12;
394
    }
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    /* LFE */
396
    exponent_group_tab[0][7] = 2;
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}
398
399
400
/**
401 dfdf73eb Justin Ruggles
 * Extract exponents from the MDCT coefficients.
402
 * This takes into account the normalization that was done to the input samples
403
 * by adjusting the exponents by the exponent shift values.
404
 */
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static void extract_exponents(AC3EncodeContext *s)
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{
407
    int blk, ch, i;
408
409
    for (ch = 0; ch < s->channels; ch++) {
410
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
411 5901cebe Justin Ruggles
            AC3Block *block = &s->blocks[blk];
412 9be52d48 Justin Ruggles
            uint8_t *exp   = block->exp[ch];
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            int32_t *coef = block->fixed_coef[ch];
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            int exp_shift  = block->exp_shift[ch];
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            for (i = 0; i < AC3_MAX_COEFS; i++) {
416
                int e;
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                int v = abs(coef[i]);
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                if (v == 0)
419
                    e = 24;
420
                else {
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                    e = 23 - av_log2(v) + exp_shift;
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                    if (e >= 24) {
423
                        e = 24;
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                        coef[i] = 0;
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                    }
426
                }
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                exp[i] = e;
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            }
429
        }
430
    }
431
}
432
433
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/**
435 c36ce0f8 Justin Ruggles
 * Exponent Difference Threshold.
436
 * New exponents are sent if their SAD exceed this number.
437
 */
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#define EXP_DIFF_THRESHOLD 500
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/**
442
 * Calculate exponent strategies for all blocks in a single channel.
443
 */
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static void compute_exp_strategy_ch(AC3EncodeContext *s, uint8_t *exp_strategy,
445 5bff8590 Justin Ruggles
                                    uint8_t *exp)
446 de6d9b64 Fabrice Bellard
{
447 ce67b7cd Justin Ruggles
    int blk, blk1;
448 de6d9b64 Fabrice Bellard
    int exp_diff;
449 115329f1 Diego Biurrun
450 de6d9b64 Fabrice Bellard
    /* estimate if the exponent variation & decide if they should be
451
       reused in the next frame */
452 d7da8080 Justin Ruggles
    exp_strategy[0] = EXP_NEW;
453 5bff8590 Justin Ruggles
    exp += AC3_MAX_COEFS;
454 ce67b7cd Justin Ruggles
    for (blk = 1; blk < AC3_MAX_BLOCKS; blk++) {
455 5bff8590 Justin Ruggles
        exp_diff = s->dsp.sad[0](NULL, exp, exp - AC3_MAX_COEFS, 16, 16);
456 de6d9b64 Fabrice Bellard
        if (exp_diff > EXP_DIFF_THRESHOLD)
457 d7da8080 Justin Ruggles
            exp_strategy[blk] = EXP_NEW;
458 de6d9b64 Fabrice Bellard
        else
459 d7da8080 Justin Ruggles
            exp_strategy[blk] = EXP_REUSE;
460 5bff8590 Justin Ruggles
        exp += AC3_MAX_COEFS;
461 de6d9b64 Fabrice Bellard
    }
462 30b68f33 Zdenek Kabelac
463 de6d9b64 Fabrice Bellard
    /* now select the encoding strategy type : if exponents are often
464
       recoded, we use a coarse encoding */
465 ce67b7cd Justin Ruggles
    blk = 0;
466
    while (blk < AC3_MAX_BLOCKS) {
467
        blk1 = blk + 1;
468 d7da8080 Justin Ruggles
        while (blk1 < AC3_MAX_BLOCKS && exp_strategy[blk1] == EXP_REUSE)
469 ce67b7cd Justin Ruggles
            blk1++;
470
        switch (blk1 - blk) {
471 d7da8080 Justin Ruggles
        case 1:  exp_strategy[blk] = EXP_D45; break;
472 de6d9b64 Fabrice Bellard
        case 2:
473 d7da8080 Justin Ruggles
        case 3:  exp_strategy[blk] = EXP_D25; break;
474
        default: exp_strategy[blk] = EXP_D15; break;
475 de6d9b64 Fabrice Bellard
        }
476 ce67b7cd Justin Ruggles
        blk = blk1;
477 de6d9b64 Fabrice Bellard
    }
478
}
479
480 2f8ae522 Justin Ruggles
481 c36ce0f8 Justin Ruggles
/**
482 dfdf73eb Justin Ruggles
 * Calculate exponent strategies for all channels.
483 d7da8080 Justin Ruggles
 * Array arrangement is reversed to simplify the per-channel calculation.
484 dfdf73eb Justin Ruggles
 */
485 266d24be Justin Ruggles
static void compute_exp_strategy(AC3EncodeContext *s)
486 dfdf73eb Justin Ruggles
{
487 d7da8080 Justin Ruggles
    int ch, blk;
488 dfdf73eb Justin Ruggles
489 d7da8080 Justin Ruggles
    for (ch = 0; ch < s->fbw_channels; ch++) {
490 5bff8590 Justin Ruggles
        compute_exp_strategy_ch(s, s->exp_strategy[ch], s->blocks[0].exp[ch]);
491 d7da8080 Justin Ruggles
    }
492
    if (s->lfe_on) {
493
        ch = s->lfe_channel;
494 0429e4a6 Justin Ruggles
        s->exp_strategy[ch][0] = EXP_D15;
495 06f6f785 Justin Ruggles
        for (blk = 1; blk < AC3_MAX_BLOCKS; blk++)
496 0429e4a6 Justin Ruggles
            s->exp_strategy[ch][blk] = EXP_REUSE;
497 dfdf73eb Justin Ruggles
    }
498
}
499
500
501
/**
502 c36ce0f8 Justin Ruggles
 * Update the exponents so that they are the ones the decoder will decode.
503
 */
504 b5293036 Justin Ruggles
static void encode_exponents_blk_ch(uint8_t *exp, int nb_exps, int exp_strategy)
505 de6d9b64 Fabrice Bellard
{
506 e86ea34d Justin Ruggles
    int nb_groups, i, k;
507 de6d9b64 Fabrice Bellard
508 e86ea34d Justin Ruggles
    nb_groups = exponent_group_tab[exp_strategy-1][nb_exps] * 3;
509 de6d9b64 Fabrice Bellard
510
    /* for each group, compute the minimum exponent */
511 834550ea Justin Ruggles
    switch(exp_strategy) {
512
    case EXP_D25:
513
        for (i = 1, k = 1; i <= nb_groups; i++) {
514
            uint8_t exp_min = exp[k];
515
            if (exp[k+1] < exp_min)
516
                exp_min = exp[k+1];
517
            exp[i] = exp_min;
518
            k += 2;
519 de6d9b64 Fabrice Bellard
        }
520 834550ea Justin Ruggles
        break;
521
    case EXP_D45:
522
        for (i = 1, k = 1; i <= nb_groups; i++) {
523
            uint8_t exp_min = exp[k];
524
            if (exp[k+1] < exp_min)
525
                exp_min = exp[k+1];
526
            if (exp[k+2] < exp_min)
527
                exp_min = exp[k+2];
528
            if (exp[k+3] < exp_min)
529
                exp_min = exp[k+3];
530
            exp[i] = exp_min;
531
            k += 4;
532
        }
533
        break;
534 27af78cf Justin Ruggles
    }
535 de6d9b64 Fabrice Bellard
536
    /* constraint for DC exponent */
537 27af78cf Justin Ruggles
    if (exp[0] > 15)
538
        exp[0] = 15;
539 de6d9b64 Fabrice Bellard
540 6a988808 Justin Ruggles
    /* decrease the delta between each groups to within 2 so that they can be
541
       differentially encoded */
542
    for (i = 1; i <= nb_groups; i++)
543 27af78cf Justin Ruggles
        exp[i] = FFMIN(exp[i], exp[i-1] + 2);
544 cdedf7e6 Justin Ruggles
    i--;
545
    while (--i >= 0)
546 27af78cf Justin Ruggles
        exp[i] = FFMIN(exp[i], exp[i+1] + 2);
547 e44cad52 Jeff Muizelaar
548 de6d9b64 Fabrice Bellard
    /* now we have the exponent values the decoder will see */
549 834550ea Justin Ruggles
    switch (exp_strategy) {
550
    case EXP_D25:
551
        for (i = nb_groups, k = nb_groups * 2; i > 0; i--) {
552
            uint8_t exp1 = exp[i];
553
            exp[k--] = exp1;
554
            exp[k--] = exp1;
555
        }
556
        break;
557
    case EXP_D45:
558
        for (i = nb_groups, k = nb_groups * 4; i > 0; i--) {
559
            exp[k] = exp[k-1] = exp[k-2] = exp[k-3] = exp[i];
560
            k -= 4;
561
        }
562
        break;
563 de6d9b64 Fabrice Bellard
    }
564
}
565
566 2f8ae522 Justin Ruggles
567 c36ce0f8 Justin Ruggles
/**
568 dfdf73eb Justin Ruggles
 * Encode exponents from original extracted form to what the decoder will see.
569
 * This copies and groups exponents based on exponent strategy and reduces
570
 * deltas between adjacent exponent groups so that they can be differentially
571
 * encoded.
572
 */
573 266d24be Justin Ruggles
static void encode_exponents(AC3EncodeContext *s)
574 dfdf73eb Justin Ruggles
{
575 7d87d56f Justin Ruggles
    int blk, blk1, ch;
576
    uint8_t *exp, *exp1, *exp_strategy;
577 964f2cf2 Justin Ruggles
    int nb_coefs, num_reuse_blocks;
578 dfdf73eb Justin Ruggles
579
    for (ch = 0; ch < s->channels; ch++) {
580 7d87d56f Justin Ruggles
        exp          = s->blocks[0].exp[ch];
581
        exp_strategy = s->exp_strategy[ch];
582
        nb_coefs     = s->nb_coefs[ch];
583
584 dfdf73eb Justin Ruggles
        blk = 0;
585
        while (blk < AC3_MAX_BLOCKS) {
586
            blk1 = blk + 1;
587 964f2cf2 Justin Ruggles
588
            /* count the number of EXP_REUSE blocks after the current block */
589 0db5d2b0 Justin Ruggles
            while (blk1 < AC3_MAX_BLOCKS && exp_strategy[blk1] == EXP_REUSE)
590 dfdf73eb Justin Ruggles
                blk1++;
591 964f2cf2 Justin Ruggles
            num_reuse_blocks = blk1 - blk - 1;
592
593
            /* for the EXP_REUSE case we select the min of the exponents */
594 a30ac54a Justin Ruggles
            s->ac3dsp.ac3_exponent_min(exp, num_reuse_blocks, nb_coefs);
595 964f2cf2 Justin Ruggles
596 0db5d2b0 Justin Ruggles
            encode_exponents_blk_ch(exp, nb_coefs, exp_strategy[blk]);
597
598 dfdf73eb Justin Ruggles
            /* copy encoded exponents for reuse case */
599 7d87d56f Justin Ruggles
            exp1 = exp + AC3_MAX_COEFS;
600
            while (blk < blk1-1) {
601
                memcpy(exp1, exp, nb_coefs * sizeof(*exp));
602
                exp1 += AC3_MAX_COEFS;
603
                blk++;
604 dfdf73eb Justin Ruggles
            }
605
            blk = blk1;
606 7d87d56f Justin Ruggles
            exp = exp1;
607 dfdf73eb Justin Ruggles
        }
608
    }
609 f94bacc5 Justin Ruggles
}
610
611
612
/**
613
 * Group exponents.
614
 * 3 delta-encoded exponents are in each 7-bit group. The number of groups
615
 * varies depending on exponent strategy and bandwidth.
616
 */
617 266d24be Justin Ruggles
static void group_exponents(AC3EncodeContext *s)
618 f94bacc5 Justin Ruggles
{
619
    int blk, ch, i;
620 e86ea34d Justin Ruggles
    int group_size, nb_groups, bit_count;
621 f94bacc5 Justin Ruggles
    uint8_t *p;
622
    int delta0, delta1, delta2;
623
    int exp0, exp1;
624
625
    bit_count = 0;
626
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
627 5901cebe Justin Ruggles
        AC3Block *block = &s->blocks[blk];
628 f94bacc5 Justin Ruggles
        for (ch = 0; ch < s->channels; ch++) {
629 4b90c35d Justin Ruggles
            int exp_strategy = s->exp_strategy[ch][blk];
630
            if (exp_strategy == EXP_REUSE)
631 f94bacc5 Justin Ruggles
                continue;
632 4b90c35d Justin Ruggles
            group_size = exp_strategy + (exp_strategy == EXP_D45);
633
            nb_groups = exponent_group_tab[exp_strategy-1][s->nb_coefs[ch]];
634 e86ea34d Justin Ruggles
            bit_count += 4 + (nb_groups * 7);
635 27af78cf Justin Ruggles
            p = block->exp[ch];
636 f94bacc5 Justin Ruggles
637
            /* DC exponent */
638
            exp1 = *p++;
639 5901cebe Justin Ruggles
            block->grouped_exp[ch][0] = exp1;
640 f94bacc5 Justin Ruggles
641
            /* remaining exponents are delta encoded */
642 e86ea34d Justin Ruggles
            for (i = 1; i <= nb_groups; i++) {
643 f94bacc5 Justin Ruggles
                /* merge three delta in one code */
644
                exp0   = exp1;
645
                exp1   = p[0];
646
                p     += group_size;
647
                delta0 = exp1 - exp0 + 2;
648
649
                exp0   = exp1;
650
                exp1   = p[0];
651
                p     += group_size;
652
                delta1 = exp1 - exp0 + 2;
653
654
                exp0   = exp1;
655
                exp1   = p[0];
656
                p     += group_size;
657
                delta2 = exp1 - exp0 + 2;
658
659 5901cebe Justin Ruggles
                block->grouped_exp[ch][i] = ((delta0 * 5 + delta1) * 5) + delta2;
660 f94bacc5 Justin Ruggles
            }
661
        }
662
    }
663 dfdf73eb Justin Ruggles
664 359c1d19 Justin Ruggles
    s->exponent_bits = bit_count;
665 dfdf73eb Justin Ruggles
}
666
667
668
/**
669
 * Calculate final exponents from the supplied MDCT coefficients and exponent shift.
670
 * Extract exponents from MDCT coefficients, calculate exponent strategies,
671
 * and encode final exponents.
672
 */
673 266d24be Justin Ruggles
static void process_exponents(AC3EncodeContext *s)
674 dfdf73eb Justin Ruggles
{
675 266d24be Justin Ruggles
    extract_exponents(s);
676 dfdf73eb Justin Ruggles
677 266d24be Justin Ruggles
    compute_exp_strategy(s);
678 dfdf73eb Justin Ruggles
679 266d24be Justin Ruggles
    encode_exponents(s);
680 f94bacc5 Justin Ruggles
681 266d24be Justin Ruggles
    group_exponents(s);
682 a30ac54a Justin Ruggles
683
    emms_c();
684 dfdf73eb Justin Ruggles
}
685
686
687
/**
688 e7536ac5 Justin Ruggles
 * Count frame bits that are based solely on fixed parameters.
689
 * This only has to be run once when the encoder is initialized.
690
 */
691
static void count_frame_bits_fixed(AC3EncodeContext *s)
692
{
693
    static const int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
694
    int blk;
695
    int frame_bits;
696
697
    /* assumptions:
698
     *   no dynamic range codes
699
     *   no channel coupling
700
     *   bit allocation parameters do not change between blocks
701
     *   SNR offsets do not change between blocks
702
     *   no delta bit allocation
703
     *   no skipped data
704
     *   no auxilliary data
705
     */
706
707
    /* header size */
708
    frame_bits = 65;
709
    frame_bits += frame_bits_inc[s->channel_mode];
710
711
    /* audio blocks */
712
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
713
        frame_bits += s->fbw_channels * 2 + 2; /* blksw * c, dithflag * c, dynrnge, cplstre */
714
        if (s->channel_mode == AC3_CHMODE_STEREO) {
715
            frame_bits++; /* rematstr */
716
        }
717
        frame_bits += 2 * s->fbw_channels; /* chexpstr[2] * c */
718
        if (s->lfe_on)
719
            frame_bits++; /* lfeexpstr */
720
        frame_bits++; /* baie */
721
        frame_bits++; /* snr */
722
        frame_bits += 2; /* delta / skip */
723
    }
724
    frame_bits++; /* cplinu for block 0 */
725
    /* bit alloc info */
726
    /* sdcycod[2], fdcycod[2], sgaincod[2], dbpbcod[2], floorcod[3] */
727
    /* csnroffset[6] */
728
    /* (fsnoffset[4] + fgaincod[4]) * c */
729
    frame_bits += 2*4 + 3 + 6 + s->channels * (4 + 3);
730
731
    /* auxdatae, crcrsv */
732
    frame_bits += 2;
733
734
    /* CRC */
735
    frame_bits += 16;
736
737
    s->frame_bits_fixed = frame_bits;
738
}
739
740
741
/**
742 793bbf95 Justin Ruggles
 * Initialize bit allocation.
743
 * Set default parameter codes and calculate parameter values.
744
 */
745
static void bit_alloc_init(AC3EncodeContext *s)
746
{
747
    int ch;
748
749
    /* init default parameters */
750
    s->slow_decay_code = 2;
751
    s->fast_decay_code = 1;
752
    s->slow_gain_code  = 1;
753 ec44dd5f Justin Ruggles
    s->db_per_bit_code = 3;
754 660ab0e6 Justin Ruggles
    s->floor_code      = 7;
755 793bbf95 Justin Ruggles
    for (ch = 0; ch < s->channels; ch++)
756
        s->fast_gain_code[ch] = 4;
757
758
    /* initial snr offset */
759
    s->coarse_snr_offset = 40;
760
761
    /* compute real values */
762
    /* currently none of these values change during encoding, so we can just
763
       set them once at initialization */
764
    s->bit_alloc.slow_decay = ff_ac3_slow_decay_tab[s->slow_decay_code] >> s->bit_alloc.sr_shift;
765
    s->bit_alloc.fast_decay = ff_ac3_fast_decay_tab[s->fast_decay_code] >> s->bit_alloc.sr_shift;
766
    s->bit_alloc.slow_gain  = ff_ac3_slow_gain_tab[s->slow_gain_code];
767
    s->bit_alloc.db_per_bit = ff_ac3_db_per_bit_tab[s->db_per_bit_code];
768
    s->bit_alloc.floor      = ff_ac3_floor_tab[s->floor_code];
769 e7536ac5 Justin Ruggles
770
    count_frame_bits_fixed(s);
771 793bbf95 Justin Ruggles
}
772
773
774
/**
775 8999944e Justin Ruggles
 * Count the bits used to encode the frame, minus exponents and mantissas.
776 e7536ac5 Justin Ruggles
 * Bits based on fixed parameters have already been counted, so now we just
777
 * have to add the bits based on parameters that change during encoding.
778 8999944e Justin Ruggles
 */
779 266d24be Justin Ruggles
static void count_frame_bits(AC3EncodeContext *s)
780 8999944e Justin Ruggles
{
781
    int blk, ch;
782 e7536ac5 Justin Ruggles
    int frame_bits = 0;
783 8999944e Justin Ruggles
784
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
785 dc7e07ac Justin Ruggles
        /* stereo rematrixing */
786
        if (s->channel_mode == AC3_CHMODE_STEREO &&
787
            s->blocks[blk].new_rematrixing_strategy) {
788
            frame_bits += 4;
789
        }
790
791 8999944e Justin Ruggles
        for (ch = 0; ch < s->fbw_channels; ch++) {
792 0429e4a6 Justin Ruggles
            if (s->exp_strategy[ch][blk] != EXP_REUSE)
793 8999944e Justin Ruggles
                frame_bits += 6 + 2; /* chbwcod[6], gainrng[2] */
794
        }
795
    }
796 e7536ac5 Justin Ruggles
    s->frame_bits = s->frame_bits_fixed + frame_bits;
797 8999944e Justin Ruggles
}
798
799
800
/**
801 c36ce0f8 Justin Ruggles
 * Calculate the number of bits needed to encode a set of mantissas.
802
 */
803 126a29b8 Justin Ruggles
static int compute_mantissa_size(int mant_cnt[5], uint8_t *bap, int nb_coefs)
804 de6d9b64 Fabrice Bellard
{
805 2d82d9b1 Justin Ruggles
    int bits, b, i;
806 de6d9b64 Fabrice Bellard
807
    bits = 0;
808 6a988808 Justin Ruggles
    for (i = 0; i < nb_coefs; i++) {
809 2d82d9b1 Justin Ruggles
        b = bap[i];
810 126a29b8 Justin Ruggles
        if (b <= 4) {
811
            // bap=1 to bap=4 will be counted in compute_mantissa_size_final
812
            mant_cnt[b]++;
813
        } else if (b <= 13) {
814
            // bap=5 to bap=13 use (bap-1) bits
815 2d82d9b1 Justin Ruggles
            bits += b - 1;
816 126a29b8 Justin Ruggles
        } else {
817
            // bap=14 uses 14 bits and bap=15 uses 16 bits
818
            bits += (b == 14) ? 14 : 16;
819 de6d9b64 Fabrice Bellard
        }
820
    }
821
    return bits;
822
}
823
824
825 c36ce0f8 Justin Ruggles
/**
826 126a29b8 Justin Ruggles
 * Finalize the mantissa bit count by adding in the grouped mantissas.
827
 */
828
static int compute_mantissa_size_final(int mant_cnt[5])
829
{
830
    // bap=1 : 3 mantissas in 5 bits
831
    int bits = (mant_cnt[1] / 3) * 5;
832
    // bap=2 : 3 mantissas in 7 bits
833
    // bap=4 : 2 mantissas in 7 bits
834
    bits += ((mant_cnt[2] / 3) + (mant_cnt[4] >> 1)) * 7;
835
    // bap=3 : each mantissa is 3 bits
836
    bits += mant_cnt[3] * 3;
837
    return bits;
838
}
839
840
841
/**
842 c36ce0f8 Justin Ruggles
 * Calculate masking curve based on the final exponents.
843
 * Also calculate the power spectral densities to use in future calculations.
844
 */
845 266d24be Justin Ruggles
static void bit_alloc_masking(AC3EncodeContext *s)
846 bbd16dea Justin Ruggles
{
847
    int blk, ch;
848
849 6a988808 Justin Ruggles
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
850 5901cebe Justin Ruggles
        AC3Block *block = &s->blocks[blk];
851 6a988808 Justin Ruggles
        for (ch = 0; ch < s->channels; ch++) {
852 cf7c961b Justin Ruggles
            /* We only need psd and mask for calculating bap.
853
               Since we currently do not calculate bap when exponent
854
               strategy is EXP_REUSE we do not need to calculate psd or mask. */
855 0429e4a6 Justin Ruggles
            if (s->exp_strategy[ch][blk] != EXP_REUSE) {
856 27af78cf Justin Ruggles
                ff_ac3_bit_alloc_calc_psd(block->exp[ch], 0,
857 bbd16dea Justin Ruggles
                                          s->nb_coefs[ch],
858 5901cebe Justin Ruggles
                                          block->psd[ch], block->band_psd[ch]);
859
                ff_ac3_bit_alloc_calc_mask(&s->bit_alloc, block->band_psd[ch],
860 bbd16dea Justin Ruggles
                                           0, s->nb_coefs[ch],
861 5ce21342 Justin Ruggles
                                           ff_ac3_fast_gain_tab[s->fast_gain_code[ch]],
862 bbd16dea Justin Ruggles
                                           ch == s->lfe_channel,
863 cc2a8443 Justin Ruggles
                                           DBA_NONE, 0, NULL, NULL, NULL,
864 5901cebe Justin Ruggles
                                           block->mask[ch]);
865 bbd16dea Justin Ruggles
            }
866
        }
867
    }
868
}
869
870 2f8ae522 Justin Ruggles
871 c36ce0f8 Justin Ruggles
/**
872 171bc51c Justin Ruggles
 * Ensure that bap for each block and channel point to the current bap_buffer.
873
 * They may have been switched during the bit allocation search.
874
 */
875
static void reset_block_bap(AC3EncodeContext *s)
876
{
877
    int blk, ch;
878
    if (s->blocks[0].bap[0] == s->bap_buffer)
879
        return;
880
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
881
        for (ch = 0; ch < s->channels; ch++) {
882
            s->blocks[blk].bap[ch] = &s->bap_buffer[AC3_MAX_COEFS * (blk * s->channels + ch)];
883
        }
884
    }
885
}
886
887
888
/**
889 c36ce0f8 Justin Ruggles
 * Run the bit allocation with a given SNR offset.
890
 * This calculates the bit allocation pointers that will be used to determine
891
 * the quantization of each mantissa.
892 70fcd7ea Justin Ruggles
 * @return the number of bits needed for mantissas if the given SNR offset is
893
 *         is used.
894 c36ce0f8 Justin Ruggles
 */
895 b5293036 Justin Ruggles
static int bit_alloc(AC3EncodeContext *s, int snr_offset)
896 de6d9b64 Fabrice Bellard
{
897 ce67b7cd Justin Ruggles
    int blk, ch;
898 a0d763fc Justin Ruggles
    int mantissa_bits;
899 126a29b8 Justin Ruggles
    int mant_cnt[5];
900 319708da Justin Ruggles
901 a0d763fc Justin Ruggles
    snr_offset = (snr_offset - 240) << 2;
902 de6d9b64 Fabrice Bellard
903 171bc51c Justin Ruggles
    reset_block_bap(s);
904 70fcd7ea Justin Ruggles
    mantissa_bits = 0;
905 ce67b7cd Justin Ruggles
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
906 5901cebe Justin Ruggles
        AC3Block *block = &s->blocks[blk];
907 126a29b8 Justin Ruggles
        // initialize grouped mantissa counts. these are set so that they are
908
        // padded to the next whole group size when bits are counted in
909
        // compute_mantissa_size_final
910
        mant_cnt[0] = mant_cnt[3] = 0;
911
        mant_cnt[1] = mant_cnt[2] = 2;
912
        mant_cnt[4] = 1;
913 6a988808 Justin Ruggles
        for (ch = 0; ch < s->channels; ch++) {
914 795063db Justin Ruggles
            /* Currently the only bit allocation parameters which vary across
915
               blocks within a frame are the exponent values.  We can take
916
               advantage of that by reusing the bit allocation pointers
917
               whenever we reuse exponents. */
918 0429e4a6 Justin Ruggles
            if (s->exp_strategy[ch][blk] == EXP_REUSE) {
919 795063db Justin Ruggles
                memcpy(block->bap[ch], s->blocks[blk-1].bap[ch], AC3_MAX_COEFS);
920
            } else {
921 68e6b099 Justin Ruggles
                ff_ac3_bit_alloc_calc_bap(block->mask[ch], block->psd[ch], 0,
922
                                          s->nb_coefs[ch], snr_offset,
923
                                          s->bit_alloc.floor, ff_ac3_bap_tab,
924
                                          block->bap[ch]);
925 795063db Justin Ruggles
            }
926 126a29b8 Justin Ruggles
            mantissa_bits += compute_mantissa_size(mant_cnt, block->bap[ch], s->nb_coefs[ch]);
927 de6d9b64 Fabrice Bellard
        }
928 126a29b8 Justin Ruggles
        mantissa_bits += compute_mantissa_size_final(mant_cnt);
929 de6d9b64 Fabrice Bellard
    }
930 70fcd7ea Justin Ruggles
    return mantissa_bits;
931 de6d9b64 Fabrice Bellard
}
932
933 2f8ae522 Justin Ruggles
934 c36ce0f8 Justin Ruggles
/**
935 cb6247cb Justin Ruggles
 * Constant bitrate bit allocation search.
936
 * Find the largest SNR offset that will allow data to fit in the frame.
937 c36ce0f8 Justin Ruggles
 */
938 cb6247cb Justin Ruggles
static int cbr_bit_allocation(AC3EncodeContext *s)
939 de6d9b64 Fabrice Bellard
{
940 8999944e Justin Ruggles
    int ch;
941 70fcd7ea Justin Ruggles
    int bits_left;
942 98e34e71 Justin Ruggles
    int snr_offset, snr_incr;
943 de6d9b64 Fabrice Bellard
944 70fcd7ea Justin Ruggles
    bits_left = 8 * s->frame_size - (s->frame_bits + s->exponent_bits);
945 7da4dc17 Justin Ruggles
946 a0d763fc Justin Ruggles
    snr_offset = s->coarse_snr_offset << 4;
947 7da4dc17 Justin Ruggles
948 9c84a72a Justin Ruggles
    /* if previous frame SNR offset was 1023, check if current frame can also
949
       use SNR offset of 1023. if so, skip the search. */
950
    if ((snr_offset | s->fine_snr_offset[0]) == 1023) {
951
        if (bit_alloc(s, 1023) <= bits_left)
952
            return 0;
953
    }
954
955 a0d763fc Justin Ruggles
    while (snr_offset >= 0 &&
956 171bc51c Justin Ruggles
           bit_alloc(s, snr_offset) > bits_left) {
957 a0d763fc Justin Ruggles
        snr_offset -= 64;
958 7da4dc17 Justin Ruggles
    }
959 2d82d9b1 Justin Ruggles
    if (snr_offset < 0)
960 dc0bc0f8 Justin Ruggles
        return AVERROR(EINVAL);
961 7da4dc17 Justin Ruggles
962 171bc51c Justin Ruggles
    FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
963 98e34e71 Justin Ruggles
    for (snr_incr = 64; snr_incr > 0; snr_incr >>= 2) {
964 5128842e Justin Ruggles
        while (snr_offset + snr_incr <= 1023 &&
965 234b70d3 Justin Ruggles
               bit_alloc(s, snr_offset + snr_incr) <= bits_left) {
966
            snr_offset += snr_incr;
967
            FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
968
        }
969 de6d9b64 Fabrice Bellard
    }
970 171bc51c Justin Ruggles
    FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
971
    reset_block_bap(s);
972 115329f1 Diego Biurrun
973 a0d763fc Justin Ruggles
    s->coarse_snr_offset = snr_offset >> 4;
974 6a988808 Justin Ruggles
    for (ch = 0; ch < s->channels; ch++)
975 a0d763fc Justin Ruggles
        s->fine_snr_offset[ch] = snr_offset & 0xF;
976 22c0b03c Justin Ruggles
977 de6d9b64 Fabrice Bellard
    return 0;
978
}
979
980 2f8ae522 Justin Ruggles
981 c36ce0f8 Justin Ruggles
/**
982 386268df Justin Ruggles
 * Downgrade exponent strategies to reduce the bits used by the exponents.
983
 * This is a fallback for when bit allocation fails with the normal exponent
984
 * strategies.  Each time this function is run it only downgrades the
985
 * strategy in 1 channel of 1 block.
986
 * @return non-zero if downgrade was unsuccessful
987
 */
988
static int downgrade_exponents(AC3EncodeContext *s)
989
{
990
    int ch, blk;
991
992
    for (ch = 0; ch < s->fbw_channels; ch++) {
993
        for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
994 0429e4a6 Justin Ruggles
            if (s->exp_strategy[ch][blk] == EXP_D15) {
995
                s->exp_strategy[ch][blk] = EXP_D25;
996 386268df Justin Ruggles
                return 0;
997
            }
998
        }
999
    }
1000
    for (ch = 0; ch < s->fbw_channels; ch++) {
1001
        for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
1002 0429e4a6 Justin Ruggles
            if (s->exp_strategy[ch][blk] == EXP_D25) {
1003
                s->exp_strategy[ch][blk] = EXP_D45;
1004 386268df Justin Ruggles
                return 0;
1005
            }
1006
        }
1007
    }
1008
    for (ch = 0; ch < s->fbw_channels; ch++) {
1009
        /* block 0 cannot reuse exponents, so only downgrade D45 to REUSE if
1010
           the block number > 0 */
1011
        for (blk = AC3_MAX_BLOCKS-1; blk > 0; blk--) {
1012 0429e4a6 Justin Ruggles
            if (s->exp_strategy[ch][blk] > EXP_REUSE) {
1013
                s->exp_strategy[ch][blk] = EXP_REUSE;
1014 386268df Justin Ruggles
                return 0;
1015
            }
1016
        }
1017
    }
1018
    return -1;
1019
}
1020
1021
1022
/**
1023
 * Reduce the bandwidth to reduce the number of bits used for a given SNR offset.
1024
 * This is a second fallback for when bit allocation still fails after exponents
1025
 * have been downgraded.
1026
 * @return non-zero if bandwidth reduction was unsuccessful
1027
 */
1028
static int reduce_bandwidth(AC3EncodeContext *s, int min_bw_code)
1029
{
1030
    int ch;
1031
1032
    if (s->bandwidth_code[0] > min_bw_code) {
1033
        for (ch = 0; ch < s->fbw_channels; ch++) {
1034
            s->bandwidth_code[ch]--;
1035
            s->nb_coefs[ch] = s->bandwidth_code[ch] * 3 + 73;
1036
        }
1037
        return 0;
1038
    }
1039
    return -1;
1040
}
1041
1042
1043
/**
1044 cb6247cb Justin Ruggles
 * Perform bit allocation search.
1045
 * Finds the SNR offset value that maximizes quality and fits in the specified
1046
 * frame size.  Output is the SNR offset and a set of bit allocation pointers
1047
 * used to quantize the mantissas.
1048
 */
1049
static int compute_bit_allocation(AC3EncodeContext *s)
1050
{
1051 386268df Justin Ruggles
    int ret;
1052
1053 cb6247cb Justin Ruggles
    count_frame_bits(s);
1054
1055
    bit_alloc_masking(s);
1056
1057 386268df Justin Ruggles
    ret = cbr_bit_allocation(s);
1058
    while (ret) {
1059
        /* fallback 1: downgrade exponents */
1060
        if (!downgrade_exponents(s)) {
1061
            extract_exponents(s);
1062
            encode_exponents(s);
1063
            group_exponents(s);
1064
            ret = compute_bit_allocation(s);
1065
            continue;
1066
        }
1067
1068
        /* fallback 2: reduce bandwidth */
1069
        /* only do this if the user has not specified a specific cutoff
1070
           frequency */
1071
        if (!s->cutoff && !reduce_bandwidth(s, 0)) {
1072
            process_exponents(s);
1073
            ret = compute_bit_allocation(s);
1074
            continue;
1075
        }
1076
1077
        /* fallbacks were not enough... */
1078
        break;
1079
    }
1080
1081
    return ret;
1082 cb6247cb Justin Ruggles
}
1083
1084
1085
/**
1086 c36ce0f8 Justin Ruggles
 * Symmetric quantization on 'levels' levels.
1087
 */
1088 de6d9b64 Fabrice Bellard
static inline int sym_quant(int c, int e, int levels)
1089
{
1090
    int v;
1091
1092
    if (c >= 0) {
1093 8d67072f Fabrice Bellard
        v = (levels * (c << e)) >> 24;
1094
        v = (v + 1) >> 1;
1095 de6d9b64 Fabrice Bellard
        v = (levels >> 1) + v;
1096
    } else {
1097 8d67072f Fabrice Bellard
        v = (levels * ((-c) << e)) >> 24;
1098
        v = (v + 1) >> 1;
1099 de6d9b64 Fabrice Bellard
        v = (levels >> 1) - v;
1100
    }
1101 2d82d9b1 Justin Ruggles
    assert(v >= 0 && v < levels);
1102 de6d9b64 Fabrice Bellard
    return v;
1103
}
1104
1105 2f8ae522 Justin Ruggles
1106 c36ce0f8 Justin Ruggles
/**
1107
 * Asymmetric quantization on 2^qbits levels.
1108
 */
1109 de6d9b64 Fabrice Bellard
static inline int asym_quant(int c, int e, int qbits)
1110
{
1111
    int lshift, m, v;
1112
1113
    lshift = e + qbits - 24;
1114
    if (lshift >= 0)
1115
        v = c << lshift;
1116
    else
1117
        v = c >> (-lshift);
1118
    /* rounding */
1119
    v = (v + 1) >> 1;
1120
    m = (1 << (qbits-1));
1121
    if (v >= m)
1122
        v = m - 1;
1123
    assert(v >= -m);
1124
    return v & ((1 << qbits)-1);
1125
}
1126
1127 2f8ae522 Justin Ruggles
1128 c36ce0f8 Justin Ruggles
/**
1129 b6a1e523 Justin Ruggles
 * Quantize a set of mantissas for a single channel in a single block.
1130
 */
1131 ac05f903 Justin Ruggles
static void quantize_mantissas_blk_ch(AC3EncodeContext *s, int32_t *fixed_coef,
1132 b5293036 Justin Ruggles
                                      int8_t exp_shift, uint8_t *exp,
1133
                                      uint8_t *bap, uint16_t *qmant, int n)
1134 b6a1e523 Justin Ruggles
{
1135
    int i;
1136
1137
    for (i = 0; i < n; i++) {
1138
        int v;
1139 ac05f903 Justin Ruggles
        int c = fixed_coef[i];
1140 27af78cf Justin Ruggles
        int e = exp[i] - exp_shift;
1141 b6a1e523 Justin Ruggles
        int b = bap[i];
1142
        switch (b) {
1143
        case 0:
1144
            v = 0;
1145
            break;
1146
        case 1:
1147
            v = sym_quant(c, e, 3);
1148
            switch (s->mant1_cnt) {
1149
            case 0:
1150
                s->qmant1_ptr = &qmant[i];
1151
                v = 9 * v;
1152
                s->mant1_cnt = 1;
1153
                break;
1154
            case 1:
1155
                *s->qmant1_ptr += 3 * v;
1156
                s->mant1_cnt = 2;
1157
                v = 128;
1158
                break;
1159
            default:
1160
                *s->qmant1_ptr += v;
1161
                s->mant1_cnt = 0;
1162
                v = 128;
1163
                break;
1164
            }
1165
            break;
1166
        case 2:
1167
            v = sym_quant(c, e, 5);
1168
            switch (s->mant2_cnt) {
1169
            case 0:
1170
                s->qmant2_ptr = &qmant[i];
1171
                v = 25 * v;
1172
                s->mant2_cnt = 1;
1173
                break;
1174
            case 1:
1175
                *s->qmant2_ptr += 5 * v;
1176
                s->mant2_cnt = 2;
1177
                v = 128;
1178
                break;
1179
            default:
1180
                *s->qmant2_ptr += v;
1181
                s->mant2_cnt = 0;
1182
                v = 128;
1183
                break;
1184
            }
1185
            break;
1186
        case 3:
1187
            v = sym_quant(c, e, 7);
1188
            break;
1189
        case 4:
1190
            v = sym_quant(c, e, 11);
1191
            switch (s->mant4_cnt) {
1192
            case 0:
1193
                s->qmant4_ptr = &qmant[i];
1194
                v = 11 * v;
1195
                s->mant4_cnt = 1;
1196
                break;
1197
            default:
1198
                *s->qmant4_ptr += v;
1199
                s->mant4_cnt = 0;
1200
                v = 128;
1201
                break;
1202
            }
1203
            break;
1204
        case 5:
1205
            v = sym_quant(c, e, 15);
1206
            break;
1207
        case 14:
1208
            v = asym_quant(c, e, 14);
1209
            break;
1210
        case 15:
1211
            v = asym_quant(c, e, 16);
1212
            break;
1213
        default:
1214
            v = asym_quant(c, e, b - 1);
1215
            break;
1216
        }
1217
        qmant[i] = v;
1218
    }
1219
}
1220
1221
1222
/**
1223
 * Quantize mantissas using coefficients, exponents, and bit allocation pointers.
1224
 */
1225 266d24be Justin Ruggles
static void quantize_mantissas(AC3EncodeContext *s)
1226 b6a1e523 Justin Ruggles
{
1227
    int blk, ch;
1228
1229
1230
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1231 5901cebe Justin Ruggles
        AC3Block *block = &s->blocks[blk];
1232 b6a1e523 Justin Ruggles
        s->mant1_cnt  = s->mant2_cnt  = s->mant4_cnt  = 0;
1233
        s->qmant1_ptr = s->qmant2_ptr = s->qmant4_ptr = NULL;
1234
1235
        for (ch = 0; ch < s->channels; ch++) {
1236 ac05f903 Justin Ruggles
            quantize_mantissas_blk_ch(s, block->fixed_coef[ch], block->exp_shift[ch],
1237 27af78cf Justin Ruggles
                                      block->exp[ch], block->bap[ch],
1238 5901cebe Justin Ruggles
                                      block->qmant[ch], s->nb_coefs[ch]);
1239 b6a1e523 Justin Ruggles
        }
1240
    }
1241
}
1242
1243
1244
/**
1245 5b44ede0 Justin Ruggles
 * Write the AC-3 frame header to the output bitstream.
1246
 */
1247
static void output_frame_header(AC3EncodeContext *s)
1248
{
1249
    put_bits(&s->pb, 16, 0x0b77);   /* frame header */
1250
    put_bits(&s->pb, 16, 0);        /* crc1: will be filled later */
1251
    put_bits(&s->pb, 2,  s->bit_alloc.sr_code);
1252
    put_bits(&s->pb, 6,  s->frame_size_code + (s->frame_size - s->frame_size_min) / 2);
1253
    put_bits(&s->pb, 5,  s->bitstream_id);
1254
    put_bits(&s->pb, 3,  s->bitstream_mode);
1255
    put_bits(&s->pb, 3,  s->channel_mode);
1256
    if ((s->channel_mode & 0x01) && s->channel_mode != AC3_CHMODE_MONO)
1257
        put_bits(&s->pb, 2, 1);     /* XXX -4.5 dB */
1258
    if (s->channel_mode & 0x04)
1259
        put_bits(&s->pb, 2, 1);     /* XXX -6 dB */
1260
    if (s->channel_mode == AC3_CHMODE_STEREO)
1261
        put_bits(&s->pb, 2, 0);     /* surround not indicated */
1262
    put_bits(&s->pb, 1, s->lfe_on); /* LFE */
1263
    put_bits(&s->pb, 5, 31);        /* dialog norm: -31 db */
1264
    put_bits(&s->pb, 1, 0);         /* no compression control word */
1265
    put_bits(&s->pb, 1, 0);         /* no lang code */
1266
    put_bits(&s->pb, 1, 0);         /* no audio production info */
1267
    put_bits(&s->pb, 1, 0);         /* no copyright */
1268
    put_bits(&s->pb, 1, 1);         /* original bitstream */
1269
    put_bits(&s->pb, 1, 0);         /* no time code 1 */
1270
    put_bits(&s->pb, 1, 0);         /* no time code 2 */
1271
    put_bits(&s->pb, 1, 0);         /* no additional bit stream info */
1272
}
1273
1274
1275
/**
1276 c36ce0f8 Justin Ruggles
 * Write one audio block to the output bitstream.
1277
 */
1278 5fc2e007 Justin Ruggles
static void output_audio_block(AC3EncodeContext *s, int blk)
1279 de6d9b64 Fabrice Bellard
{
1280 f94bacc5 Justin Ruggles
    int ch, i, baie, rbnd;
1281 5fc2e007 Justin Ruggles
    AC3Block *block = &s->blocks[blk];
1282 de6d9b64 Fabrice Bellard
1283 2d82d9b1 Justin Ruggles
    /* block switching */
1284 6a988808 Justin Ruggles
    for (ch = 0; ch < s->fbw_channels; ch++)
1285 2d82d9b1 Justin Ruggles
        put_bits(&s->pb, 1, 0);
1286
1287
    /* dither flags */
1288 6a988808 Justin Ruggles
    for (ch = 0; ch < s->fbw_channels; ch++)
1289 2d82d9b1 Justin Ruggles
        put_bits(&s->pb, 1, 1);
1290
1291
    /* dynamic range codes */
1292
    put_bits(&s->pb, 1, 0);
1293
1294
    /* channel coupling */
1295 5fc2e007 Justin Ruggles
    if (!blk) {
1296 de6d9b64 Fabrice Bellard
        put_bits(&s->pb, 1, 1); /* coupling strategy present */
1297
        put_bits(&s->pb, 1, 0); /* no coupling strategy */
1298
    } else {
1299
        put_bits(&s->pb, 1, 0); /* no new coupling strategy */
1300
    }
1301
1302 2d82d9b1 Justin Ruggles
    /* stereo rematrixing */
1303 6a988808 Justin Ruggles
    if (s->channel_mode == AC3_CHMODE_STEREO) {
1304 dc7e07ac Justin Ruggles
        put_bits(&s->pb, 1, block->new_rematrixing_strategy);
1305
        if (block->new_rematrixing_strategy) {
1306
            /* rematrixing flags */
1307 6a988808 Justin Ruggles
            for (rbnd = 0; rbnd < 4; rbnd++)
1308 dc7e07ac Justin Ruggles
                put_bits(&s->pb, 1, block->rematrixing_flags[rbnd]);
1309 6a988808 Justin Ruggles
        }
1310
    }
1311 de6d9b64 Fabrice Bellard
1312
    /* exponent strategy */
1313 6a988808 Justin Ruggles
    for (ch = 0; ch < s->fbw_channels; ch++)
1314 5fc2e007 Justin Ruggles
        put_bits(&s->pb, 2, s->exp_strategy[ch][blk]);
1315 6a988808 Justin Ruggles
    if (s->lfe_on)
1316 5fc2e007 Justin Ruggles
        put_bits(&s->pb, 1, s->exp_strategy[s->lfe_channel][blk]);
1317 30b68f33 Zdenek Kabelac
1318 6a988808 Justin Ruggles
    /* bandwidth */
1319
    for (ch = 0; ch < s->fbw_channels; ch++) {
1320 5fc2e007 Justin Ruggles
        if (s->exp_strategy[ch][blk] != EXP_REUSE)
1321 2d2692eb Justin Ruggles
            put_bits(&s->pb, 6, s->bandwidth_code[ch]);
1322 de6d9b64 Fabrice Bellard
    }
1323 115329f1 Diego Biurrun
1324 de6d9b64 Fabrice Bellard
    /* exponents */
1325 2d2692eb Justin Ruggles
    for (ch = 0; ch < s->channels; ch++) {
1326 e86ea34d Justin Ruggles
        int nb_groups;
1327
1328 5fc2e007 Justin Ruggles
        if (s->exp_strategy[ch][blk] == EXP_REUSE)
1329 de6d9b64 Fabrice Bellard
            continue;
1330
1331 2d82d9b1 Justin Ruggles
        /* DC exponent */
1332 5901cebe Justin Ruggles
        put_bits(&s->pb, 4, block->grouped_exp[ch][0]);
1333 f94bacc5 Justin Ruggles
1334 2d82d9b1 Justin Ruggles
        /* exponent groups */
1335 5fc2e007 Justin Ruggles
        nb_groups = exponent_group_tab[s->exp_strategy[ch][blk]-1][s->nb_coefs[ch]];
1336 e86ea34d Justin Ruggles
        for (i = 1; i <= nb_groups; i++)
1337 5901cebe Justin Ruggles
            put_bits(&s->pb, 7, block->grouped_exp[ch][i]);
1338 de6d9b64 Fabrice Bellard
1339 2d82d9b1 Justin Ruggles
        /* gain range info */
1340 bb270c08 Diego Biurrun
        if (ch != s->lfe_channel)
1341 2d82d9b1 Justin Ruggles
            put_bits(&s->pb, 2, 0);
1342 de6d9b64 Fabrice Bellard
    }
1343
1344
    /* bit allocation info */
1345 5fc2e007 Justin Ruggles
    baie = (blk == 0);
1346 de6d9b64 Fabrice Bellard
    put_bits(&s->pb, 1, baie);
1347
    if (baie) {
1348 5ce21342 Justin Ruggles
        put_bits(&s->pb, 2, s->slow_decay_code);
1349
        put_bits(&s->pb, 2, s->fast_decay_code);
1350
        put_bits(&s->pb, 2, s->slow_gain_code);
1351
        put_bits(&s->pb, 2, s->db_per_bit_code);
1352
        put_bits(&s->pb, 3, s->floor_code);
1353 de6d9b64 Fabrice Bellard
    }
1354
1355
    /* snr offset */
1356 6a988808 Justin Ruggles
    put_bits(&s->pb, 1, baie);
1357 de6d9b64 Fabrice Bellard
    if (baie) {
1358 5ce21342 Justin Ruggles
        put_bits(&s->pb, 6, s->coarse_snr_offset);
1359 6a988808 Justin Ruggles
        for (ch = 0; ch < s->channels; ch++) {
1360 5ce21342 Justin Ruggles
            put_bits(&s->pb, 4, s->fine_snr_offset[ch]);
1361
            put_bits(&s->pb, 3, s->fast_gain_code[ch]);
1362 de6d9b64 Fabrice Bellard
        }
1363
    }
1364 115329f1 Diego Biurrun
1365 de6d9b64 Fabrice Bellard
    put_bits(&s->pb, 1, 0); /* no delta bit allocation */
1366
    put_bits(&s->pb, 1, 0); /* no data to skip */
1367
1368 2d82d9b1 Justin Ruggles
    /* mantissas */
1369 2d2692eb Justin Ruggles
    for (ch = 0; ch < s->channels; ch++) {
1370 de6d9b64 Fabrice Bellard
        int b, q;
1371 6a988808 Justin Ruggles
        for (i = 0; i < s->nb_coefs[ch]; i++) {
1372 5901cebe Justin Ruggles
            q = block->qmant[ch][i];
1373 171bc51c Justin Ruggles
            b = block->bap[ch][i];
1374 6a988808 Justin Ruggles
            switch (b) {
1375
            case 0:                                         break;
1376
            case 1: if (q != 128) put_bits(&s->pb,   5, q); break;
1377
            case 2: if (q != 128) put_bits(&s->pb,   7, q); break;
1378
            case 3:               put_bits(&s->pb,   3, q); break;
1379
            case 4: if (q != 128) put_bits(&s->pb,   7, q); break;
1380
            case 14:              put_bits(&s->pb,  14, q); break;
1381
            case 15:              put_bits(&s->pb,  16, q); break;
1382
            default:              put_bits(&s->pb, b-1, q); break;
1383 de6d9b64 Fabrice Bellard
            }
1384
        }
1385
    }
1386
}
1387
1388 2f8ae522 Justin Ruggles
1389 c36ce0f8 Justin Ruggles
/** CRC-16 Polynomial */
1390 de6d9b64 Fabrice Bellard
#define CRC16_POLY ((1 << 0) | (1 << 2) | (1 << 15) | (1 << 16))
1391
1392 2f8ae522 Justin Ruggles
1393 de6d9b64 Fabrice Bellard
static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly)
1394
{
1395
    unsigned int c;
1396
1397
    c = 0;
1398
    while (a) {
1399
        if (a & 1)
1400
            c ^= b;
1401
        a = a >> 1;
1402
        b = b << 1;
1403
        if (b & (1 << 16))
1404
            b ^= poly;
1405
    }
1406
    return c;
1407
}
1408
1409 2f8ae522 Justin Ruggles
1410 de6d9b64 Fabrice Bellard
static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly)
1411
{
1412
    unsigned int r;
1413
    r = 1;
1414
    while (n) {
1415
        if (n & 1)
1416
            r = mul_poly(r, a, poly);
1417
        a = mul_poly(a, a, poly);
1418
        n >>= 1;
1419
    }
1420
    return r;
1421
}
1422
1423 2f8ae522 Justin Ruggles
1424 c36ce0f8 Justin Ruggles
/**
1425
 * Fill the end of the frame with 0's and compute the two CRCs.
1426
 */
1427 1971ab6e Justin Ruggles
static void output_frame_end(AC3EncodeContext *s)
1428 de6d9b64 Fabrice Bellard
{
1429 a897423b Justin Ruggles
    const AVCRC *crc_ctx = av_crc_get_table(AV_CRC_16_ANSI);
1430 e96dc767 Justin Ruggles
    int frame_size_58, pad_bytes, crc1, crc2_partial, crc2, crc_inv;
1431 0c1a9eda Zdenek Kabelac
    uint8_t *frame;
1432 de6d9b64 Fabrice Bellard
1433 0e9b0643 Justin Ruggles
    frame_size_58 = ((s->frame_size >> 2) + (s->frame_size >> 4)) << 1;
1434 2d82d9b1 Justin Ruggles
1435
    /* pad the remainder of the frame with zeros */
1436 de6d9b64 Fabrice Bellard
    flush_put_bits(&s->pb);
1437
    frame = s->pb.buf;
1438 427e2293 Justin Ruggles
    pad_bytes = s->frame_size - (put_bits_ptr(&s->pb) - frame) - 2;
1439 eed00252 Justin Ruggles
    assert(pad_bytes >= 0);
1440
    if (pad_bytes > 0)
1441
        memset(put_bits_ptr(&s->pb), 0, pad_bytes);
1442 115329f1 Diego Biurrun
1443 2d82d9b1 Justin Ruggles
    /* compute crc1 */
1444
    /* this is not so easy because it is at the beginning of the data... */
1445 b51c740e Justin Ruggles
    crc1    = av_bswap16(av_crc(crc_ctx, 0, frame + 4, frame_size_58 - 4));
1446 a81d7c6a Justin Ruggles
    crc_inv = s->crc_inv[s->frame_size > s->frame_size_min];
1447 6a988808 Justin Ruggles
    crc1    = mul_poly(crc_inv, crc1, CRC16_POLY);
1448
    AV_WB16(frame + 2, crc1);
1449 115329f1 Diego Biurrun
1450 2d82d9b1 Justin Ruggles
    /* compute crc2 */
1451 e96dc767 Justin Ruggles
    crc2_partial = av_crc(crc_ctx, 0, frame + frame_size_58,
1452
                          s->frame_size - frame_size_58 - 3);
1453
    crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
1454
    /* ensure crc2 does not match sync word by flipping crcrsv bit if needed */
1455
    if (crc2 == 0x770B) {
1456
        frame[s->frame_size - 3] ^= 0x1;
1457
        crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
1458
    }
1459
    crc2 = av_bswap16(crc2);
1460 0e9b0643 Justin Ruggles
    AV_WB16(frame + s->frame_size - 2, crc2);
1461 de6d9b64 Fabrice Bellard
}
1462
1463 2f8ae522 Justin Ruggles
1464 c36ce0f8 Justin Ruggles
/**
1465 67d979fe Justin Ruggles
 * Write the frame to the output bitstream.
1466
 */
1467 b5293036 Justin Ruggles
static void output_frame(AC3EncodeContext *s, unsigned char *frame)
1468 67d979fe Justin Ruggles
{
1469
    int blk;
1470
1471
    init_put_bits(&s->pb, frame, AC3_MAX_CODED_FRAME_SIZE);
1472
1473
    output_frame_header(s);
1474
1475 2d82d9b1 Justin Ruggles
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++)
1476 266d24be Justin Ruggles
        output_audio_block(s, blk);
1477 67d979fe Justin Ruggles
1478
    output_frame_end(s);
1479
}
1480
1481
1482
/**
1483 c36ce0f8 Justin Ruggles
 * Encode a single AC-3 frame.
1484
 */
1485 b5293036 Justin Ruggles
static int ac3_encode_frame(AVCodecContext *avctx, unsigned char *frame,
1486
                            int buf_size, void *data)
1487 de6d9b64 Fabrice Bellard
{
1488
    AC3EncodeContext *s = avctx->priv_data;
1489 0cbd5ff7 Justin Ruggles
    const SampleType *samples = data;
1490 dc0bc0f8 Justin Ruggles
    int ret;
1491 de6d9b64 Fabrice Bellard
1492 160d85f5 Justin Ruggles
    if (s->bit_alloc.sr_code == 1)
1493
        adjust_frame_size(s);
1494
1495 266d24be Justin Ruggles
    deinterleave_input_samples(s, samples);
1496 12ed6226 Justin Ruggles
1497 266d24be Justin Ruggles
    apply_mdct(s);
1498 115329f1 Diego Biurrun
1499 dc7e07ac Justin Ruggles
    compute_rematrixing_strategy(s);
1500
1501 ac05f903 Justin Ruggles
    scale_coefficients(s);
1502
1503 dc7e07ac Justin Ruggles
    apply_rematrixing(s);
1504
1505 266d24be Justin Ruggles
    process_exponents(s);
1506 de6d9b64 Fabrice Bellard
1507 266d24be Justin Ruggles
    ret = compute_bit_allocation(s);
1508 dc0bc0f8 Justin Ruggles
    if (ret) {
1509
        av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
1510
        return ret;
1511
    }
1512 084f5c5a Justin Ruggles
1513 266d24be Justin Ruggles
    quantize_mantissas(s);
1514 b6a1e523 Justin Ruggles
1515 266d24be Justin Ruggles
    output_frame(s, frame);
1516 1971ab6e Justin Ruggles
1517 427e2293 Justin Ruggles
    return s->frame_size;
1518 de6d9b64 Fabrice Bellard
}
1519
1520 2f8ae522 Justin Ruggles
1521 c36ce0f8 Justin Ruggles
/**
1522
 * Finalize encoding and free any memory allocated by the encoder.
1523
 */
1524 a0a9204e Justin Ruggles
static av_cold int ac3_encode_close(AVCodecContext *avctx)
1525 492cd3a9 Michael Niedermayer
{
1526 e8d21fba Justin Ruggles
    int blk, ch;
1527 171bc51c Justin Ruggles
    AC3EncodeContext *s = avctx->priv_data;
1528
1529 e8d21fba Justin Ruggles
    for (ch = 0; ch < s->channels; ch++)
1530
        av_freep(&s->planar_samples[ch]);
1531
    av_freep(&s->planar_samples);
1532 171bc51c Justin Ruggles
    av_freep(&s->bap_buffer);
1533
    av_freep(&s->bap1_buffer);
1534 b6f6204d Justin Ruggles
    av_freep(&s->mdct_coef_buffer);
1535 ac05f903 Justin Ruggles
    av_freep(&s->fixed_coef_buffer);
1536 b6f6204d Justin Ruggles
    av_freep(&s->exp_buffer);
1537
    av_freep(&s->grouped_exp_buffer);
1538
    av_freep(&s->psd_buffer);
1539
    av_freep(&s->band_psd_buffer);
1540
    av_freep(&s->mask_buffer);
1541
    av_freep(&s->qmant_buffer);
1542 171bc51c Justin Ruggles
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1543
        AC3Block *block = &s->blocks[blk];
1544
        av_freep(&block->bap);
1545 b6f6204d Justin Ruggles
        av_freep(&block->mdct_coef);
1546 ac05f903 Justin Ruggles
        av_freep(&block->fixed_coef);
1547 b6f6204d Justin Ruggles
        av_freep(&block->exp);
1548
        av_freep(&block->grouped_exp);
1549
        av_freep(&block->psd);
1550
        av_freep(&block->band_psd);
1551
        av_freep(&block->mask);
1552
        av_freep(&block->qmant);
1553 171bc51c Justin Ruggles
    }
1554
1555 c41ac4f8 Justin Ruggles
    mdct_end(&s->mdct);
1556
1557 492cd3a9 Michael Niedermayer
    av_freep(&avctx->coded_frame);
1558 ef9f7306 Måns Rullgård
    return 0;
1559 492cd3a9 Michael Niedermayer
}
1560
1561 2f8ae522 Justin Ruggles
1562 c36ce0f8 Justin Ruggles
/**
1563
 * Set channel information during initialization.
1564
 */
1565 e77fd066 Justin Ruggles
static av_cold int set_channel_info(AC3EncodeContext *s, int channels,
1566
                                    int64_t *channel_layout)
1567
{
1568
    int ch_layout;
1569
1570
    if (channels < 1 || channels > AC3_MAX_CHANNELS)
1571 ddf63d37 Justin Ruggles
        return AVERROR(EINVAL);
1572 e77fd066 Justin Ruggles
    if ((uint64_t)*channel_layout > 0x7FF)
1573 ddf63d37 Justin Ruggles
        return AVERROR(EINVAL);
1574 e77fd066 Justin Ruggles
    ch_layout = *channel_layout;
1575
    if (!ch_layout)
1576
        ch_layout = avcodec_guess_channel_layout(channels, CODEC_ID_AC3, NULL);
1577
    if (av_get_channel_layout_nb_channels(ch_layout) != channels)
1578 ddf63d37 Justin Ruggles
        return AVERROR(EINVAL);
1579 e77fd066 Justin Ruggles
1580
    s->lfe_on       = !!(ch_layout & AV_CH_LOW_FREQUENCY);
1581
    s->channels     = channels;
1582
    s->fbw_channels = channels - s->lfe_on;
1583
    s->lfe_channel  = s->lfe_on ? s->fbw_channels : -1;
1584
    if (s->lfe_on)
1585
        ch_layout -= AV_CH_LOW_FREQUENCY;
1586
1587
    switch (ch_layout) {
1588
    case AV_CH_LAYOUT_MONO:           s->channel_mode = AC3_CHMODE_MONO;   break;
1589
    case AV_CH_LAYOUT_STEREO:         s->channel_mode = AC3_CHMODE_STEREO; break;
1590
    case AV_CH_LAYOUT_SURROUND:       s->channel_mode = AC3_CHMODE_3F;     break;
1591
    case AV_CH_LAYOUT_2_1:            s->channel_mode = AC3_CHMODE_2F1R;   break;
1592
    case AV_CH_LAYOUT_4POINT0:        s->channel_mode = AC3_CHMODE_3F1R;   break;
1593
    case AV_CH_LAYOUT_QUAD:
1594
    case AV_CH_LAYOUT_2_2:            s->channel_mode = AC3_CHMODE_2F2R;   break;
1595
    case AV_CH_LAYOUT_5POINT0:
1596
    case AV_CH_LAYOUT_5POINT0_BACK:   s->channel_mode = AC3_CHMODE_3F2R;   break;
1597
    default:
1598 ddf63d37 Justin Ruggles
        return AVERROR(EINVAL);
1599 e77fd066 Justin Ruggles
    }
1600
1601
    s->channel_map  = ff_ac3_enc_channel_map[s->channel_mode][s->lfe_on];
1602
    *channel_layout = ch_layout;
1603
    if (s->lfe_on)
1604
        *channel_layout |= AV_CH_LOW_FREQUENCY;
1605
1606
    return 0;
1607
}
1608
1609 2f8ae522 Justin Ruggles
1610 8f60f70d Justin Ruggles
static av_cold int validate_options(AVCodecContext *avctx, AC3EncodeContext *s)
1611 e77fd066 Justin Ruggles
{
1612 ddf63d37 Justin Ruggles
    int i, ret;
1613 e77fd066 Justin Ruggles
1614 e0685bc9 Justin Ruggles
    /* validate channel layout */
1615 e77fd066 Justin Ruggles
    if (!avctx->channel_layout) {
1616
        av_log(avctx, AV_LOG_WARNING, "No channel layout specified. The "
1617
                                      "encoder will guess the layout, but it "
1618
                                      "might be incorrect.\n");
1619
    }
1620 ddf63d37 Justin Ruggles
    ret = set_channel_info(s, avctx->channels, &avctx->channel_layout);
1621
    if (ret) {
1622 e77fd066 Justin Ruggles
        av_log(avctx, AV_LOG_ERROR, "invalid channel layout\n");
1623 ddf63d37 Justin Ruggles
        return ret;
1624 e77fd066 Justin Ruggles
    }
1625
1626 e0685bc9 Justin Ruggles
    /* validate sample rate */
1627 99ca4f73 Justin Ruggles
    for (i = 0; i < 9; i++) {
1628
        if ((ff_ac3_sample_rate_tab[i / 3] >> (i % 3)) == avctx->sample_rate)
1629
            break;
1630 e77fd066 Justin Ruggles
    }
1631 99ca4f73 Justin Ruggles
    if (i == 9) {
1632 ddf63d37 Justin Ruggles
        av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1633
        return AVERROR(EINVAL);
1634 99ca4f73 Justin Ruggles
    }
1635 1607db0a Justin Ruggles
    s->sample_rate        = avctx->sample_rate;
1636 99ca4f73 Justin Ruggles
    s->bit_alloc.sr_shift = i % 3;
1637
    s->bit_alloc.sr_code  = i / 3;
1638 e77fd066 Justin Ruggles
1639 e0685bc9 Justin Ruggles
    /* validate bit rate */
1640 e77fd066 Justin Ruggles
    for (i = 0; i < 19; i++) {
1641 1607db0a Justin Ruggles
        if ((ff_ac3_bitrate_tab[i] >> s->bit_alloc.sr_shift)*1000 == avctx->bit_rate)
1642 e77fd066 Justin Ruggles
            break;
1643
    }
1644 ddf63d37 Justin Ruggles
    if (i == 19) {
1645
        av_log(avctx, AV_LOG_ERROR, "invalid bit rate\n");
1646
        return AVERROR(EINVAL);
1647
    }
1648 1607db0a Justin Ruggles
    s->bit_rate        = avctx->bit_rate;
1649 e77fd066 Justin Ruggles
    s->frame_size_code = i << 1;
1650 8f60f70d Justin Ruggles
1651 e62ef8f2 Justin Ruggles
    /* validate cutoff */
1652
    if (avctx->cutoff < 0) {
1653
        av_log(avctx, AV_LOG_ERROR, "invalid cutoff frequency\n");
1654
        return AVERROR(EINVAL);
1655
    }
1656
    s->cutoff = avctx->cutoff;
1657
    if (s->cutoff > (s->sample_rate >> 1))
1658
        s->cutoff = s->sample_rate >> 1;
1659
1660 8f60f70d Justin Ruggles
    return 0;
1661
}
1662
1663
1664
/**
1665 282255bb Justin Ruggles
 * Set bandwidth for all channels.
1666
 * The user can optionally supply a cutoff frequency. Otherwise an appropriate
1667
 * default value will be used.
1668
 */
1669 e62ef8f2 Justin Ruggles
static av_cold void set_bandwidth(AC3EncodeContext *s)
1670 282255bb Justin Ruggles
{
1671
    int ch, bw_code;
1672
1673 e62ef8f2 Justin Ruggles
    if (s->cutoff) {
1674 282255bb Justin Ruggles
        /* calculate bandwidth based on user-specified cutoff frequency */
1675
        int fbw_coeffs;
1676 e62ef8f2 Justin Ruggles
        fbw_coeffs     = s->cutoff * 2 * AC3_MAX_COEFS / s->sample_rate;
1677 282255bb Justin Ruggles
        bw_code        = av_clip((fbw_coeffs - 73) / 3, 0, 60);
1678
    } else {
1679
        /* use default bandwidth setting */
1680
        /* XXX: should compute the bandwidth according to the frame
1681
           size, so that we avoid annoying high frequency artifacts */
1682
        bw_code = 50;
1683
    }
1684
1685
    /* set number of coefficients for each channel */
1686
    for (ch = 0; ch < s->fbw_channels; ch++) {
1687
        s->bandwidth_code[ch] = bw_code;
1688
        s->nb_coefs[ch]       = bw_code * 3 + 73;
1689
    }
1690
    if (s->lfe_on)
1691
        s->nb_coefs[s->lfe_channel] = 7; /* LFE channel always has 7 coefs */
1692
}
1693
1694
1695 171bc51c Justin Ruggles
static av_cold int allocate_buffers(AVCodecContext *avctx)
1696
{
1697 e8d21fba Justin Ruggles
    int blk, ch;
1698 171bc51c Justin Ruggles
    AC3EncodeContext *s = avctx->priv_data;
1699
1700 e8d21fba Justin Ruggles
    FF_ALLOC_OR_GOTO(avctx, s->planar_samples, s->channels * sizeof(*s->planar_samples),
1701
                     alloc_fail);
1702
    for (ch = 0; ch < s->channels; ch++) {
1703
        FF_ALLOCZ_OR_GOTO(avctx, s->planar_samples[ch],
1704
                          (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),
1705
                          alloc_fail);
1706
    }
1707 171bc51c Justin Ruggles
    FF_ALLOC_OR_GOTO(avctx, s->bap_buffer,  AC3_MAX_BLOCKS * s->channels *
1708
                     AC3_MAX_COEFS * sizeof(*s->bap_buffer),  alloc_fail);
1709
    FF_ALLOC_OR_GOTO(avctx, s->bap1_buffer, AC3_MAX_BLOCKS * s->channels *
1710
                     AC3_MAX_COEFS * sizeof(*s->bap1_buffer), alloc_fail);
1711 b6f6204d Justin Ruggles
    FF_ALLOC_OR_GOTO(avctx, s->mdct_coef_buffer, AC3_MAX_BLOCKS * s->channels *
1712
                     AC3_MAX_COEFS * sizeof(*s->mdct_coef_buffer), alloc_fail);
1713
    FF_ALLOC_OR_GOTO(avctx, s->exp_buffer, AC3_MAX_BLOCKS * s->channels *
1714
                     AC3_MAX_COEFS * sizeof(*s->exp_buffer), alloc_fail);
1715
    FF_ALLOC_OR_GOTO(avctx, s->grouped_exp_buffer, AC3_MAX_BLOCKS * s->channels *
1716
                     128 * sizeof(*s->grouped_exp_buffer), alloc_fail);
1717
    FF_ALLOC_OR_GOTO(avctx, s->psd_buffer, AC3_MAX_BLOCKS * s->channels *
1718
                     AC3_MAX_COEFS * sizeof(*s->psd_buffer), alloc_fail);
1719
    FF_ALLOC_OR_GOTO(avctx, s->band_psd_buffer, AC3_MAX_BLOCKS * s->channels *
1720
                     64 * sizeof(*s->band_psd_buffer), alloc_fail);
1721
    FF_ALLOC_OR_GOTO(avctx, s->mask_buffer, AC3_MAX_BLOCKS * s->channels *
1722
                     64 * sizeof(*s->mask_buffer), alloc_fail);
1723
    FF_ALLOC_OR_GOTO(avctx, s->qmant_buffer, AC3_MAX_BLOCKS * s->channels *
1724
                     AC3_MAX_COEFS * sizeof(*s->qmant_buffer), alloc_fail);
1725 171bc51c Justin Ruggles
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1726
        AC3Block *block = &s->blocks[blk];
1727
        FF_ALLOC_OR_GOTO(avctx, block->bap, s->channels * sizeof(*block->bap),
1728
                         alloc_fail);
1729 b6f6204d Justin Ruggles
        FF_ALLOCZ_OR_GOTO(avctx, block->mdct_coef, s->channels * sizeof(*block->mdct_coef),
1730
                          alloc_fail);
1731
        FF_ALLOCZ_OR_GOTO(avctx, block->exp, s->channels * sizeof(*block->exp),
1732
                          alloc_fail);
1733
        FF_ALLOCZ_OR_GOTO(avctx, block->grouped_exp, s->channels * sizeof(*block->grouped_exp),
1734
                          alloc_fail);
1735
        FF_ALLOCZ_OR_GOTO(avctx, block->psd, s->channels * sizeof(*block->psd),
1736
                          alloc_fail);
1737
        FF_ALLOCZ_OR_GOTO(avctx, block->band_psd, s->channels * sizeof(*block->band_psd),
1738
                          alloc_fail);
1739
        FF_ALLOCZ_OR_GOTO(avctx, block->mask, s->channels * sizeof(*block->mask),
1740
                          alloc_fail);
1741
        FF_ALLOCZ_OR_GOTO(avctx, block->qmant, s->channels * sizeof(*block->qmant),
1742
                          alloc_fail);
1743
1744
        for (ch = 0; ch < s->channels; ch++) {
1745 7cc4be58 Justin Ruggles
            /* arrangement: block, channel, coeff */
1746 b6f6204d Justin Ruggles
            block->bap[ch]         = &s->bap_buffer        [AC3_MAX_COEFS * (blk * s->channels + ch)];
1747
            block->mdct_coef[ch]   = &s->mdct_coef_buffer  [AC3_MAX_COEFS * (blk * s->channels + ch)];
1748
            block->grouped_exp[ch] = &s->grouped_exp_buffer[128           * (blk * s->channels + ch)];
1749
            block->psd[ch]         = &s->psd_buffer        [AC3_MAX_COEFS * (blk * s->channels + ch)];
1750
            block->band_psd[ch]    = &s->band_psd_buffer   [64            * (blk * s->channels + ch)];
1751
            block->mask[ch]        = &s->mask_buffer       [64            * (blk * s->channels + ch)];
1752
            block->qmant[ch]       = &s->qmant_buffer      [AC3_MAX_COEFS * (blk * s->channels + ch)];
1753 7cc4be58 Justin Ruggles
1754
            /* arrangement: channel, block, coeff */
1755
            block->exp[ch]         = &s->exp_buffer        [AC3_MAX_COEFS * (AC3_MAX_BLOCKS * ch + blk)];
1756 b6f6204d Justin Ruggles
        }
1757 171bc51c Justin Ruggles
    }
1758
1759 ac05f903 Justin Ruggles
    if (CONFIG_AC3ENC_FLOAT) {
1760
        FF_ALLOC_OR_GOTO(avctx, s->fixed_coef_buffer, AC3_MAX_BLOCKS * s->channels *
1761
                         AC3_MAX_COEFS * sizeof(*s->fixed_coef_buffer), alloc_fail);
1762
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1763
            AC3Block *block = &s->blocks[blk];
1764
            FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, s->channels *
1765
                              sizeof(*block->fixed_coef), alloc_fail);
1766
            for (ch = 0; ch < s->channels; ch++)
1767
                block->fixed_coef[ch] = &s->fixed_coef_buffer[AC3_MAX_COEFS * (blk * s->channels + ch)];
1768
        }
1769
    } else {
1770
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1771
            AC3Block *block = &s->blocks[blk];
1772
            FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, s->channels *
1773
                              sizeof(*block->fixed_coef), alloc_fail);
1774
            for (ch = 0; ch < s->channels; ch++)
1775
                block->fixed_coef[ch] = (int32_t *)block->mdct_coef[ch];
1776
        }
1777
    }
1778
1779 171bc51c Justin Ruggles
    return 0;
1780
alloc_fail:
1781
    return AVERROR(ENOMEM);
1782
}
1783
1784
1785 282255bb Justin Ruggles
/**
1786 8f60f70d Justin Ruggles
 * Initialize the encoder.
1787
 */
1788
static av_cold int ac3_encode_init(AVCodecContext *avctx)
1789
{
1790
    AC3EncodeContext *s = avctx->priv_data;
1791 a81d7c6a Justin Ruggles
    int ret, frame_size_58;
1792 8f60f70d Justin Ruggles
1793
    avctx->frame_size = AC3_FRAME_SIZE;
1794
1795 dff80041 Justin Ruggles
    ff_ac3_common_init();
1796 8f60f70d Justin Ruggles
1797
    ret = validate_options(avctx, s);
1798
    if (ret)
1799
        return ret;
1800
1801 e35c984a Justin Ruggles
    s->bitstream_id   = 8 + s->bit_alloc.sr_shift;
1802
    s->bitstream_mode = 0; /* complete main audio service */
1803
1804 427e2293 Justin Ruggles
    s->frame_size_min  = 2 * ff_ac3_frame_size_tab[s->frame_size_code][s->bit_alloc.sr_code];
1805 e77fd066 Justin Ruggles
    s->bits_written    = 0;
1806
    s->samples_written = 0;
1807
    s->frame_size      = s->frame_size_min;
1808
1809 a81d7c6a Justin Ruggles
    /* calculate crc_inv for both possible frame sizes */
1810
    frame_size_58 = (( s->frame_size    >> 2) + ( s->frame_size    >> 4)) << 1;
1811
    s->crc_inv[0] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
1812
    if (s->bit_alloc.sr_code == 1) {
1813
        frame_size_58 = (((s->frame_size+2) >> 2) + ((s->frame_size+2) >> 4)) << 1;
1814
        s->crc_inv[1] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
1815
    }
1816
1817 e62ef8f2 Justin Ruggles
    set_bandwidth(s);
1818 e77fd066 Justin Ruggles
1819 dc7e07ac Justin Ruggles
    rematrixing_init(s);
1820
1821 e86ea34d Justin Ruggles
    exponent_init(s);
1822
1823 793bbf95 Justin Ruggles
    bit_alloc_init(s);
1824 e77fd066 Justin Ruggles
1825 14166a6d Justin Ruggles
    ret = mdct_init(avctx, &s->mdct, 9);
1826 7786c384 Justin Ruggles
    if (ret)
1827 89bedc4d Justin Ruggles
        goto init_fail;
1828 e77fd066 Justin Ruggles
1829 171bc51c Justin Ruggles
    ret = allocate_buffers(avctx);
1830 7786c384 Justin Ruggles
    if (ret)
1831 89bedc4d Justin Ruggles
        goto init_fail;
1832 171bc51c Justin Ruggles
1833 e77fd066 Justin Ruggles
    avctx->coded_frame= avcodec_alloc_frame();
1834
1835 8846ee54 Justin Ruggles
    dsputil_init(&s->dsp, avctx);
1836 a30ac54a Justin Ruggles
    ff_ac3dsp_init(&s->ac3dsp);
1837 8846ee54 Justin Ruggles
1838 e77fd066 Justin Ruggles
    return 0;
1839 89bedc4d Justin Ruggles
init_fail:
1840
    ac3_encode_close(avctx);
1841
    return ret;
1842 e77fd066 Justin Ruggles
}