2080 lines
62 KiB
C
2080 lines
62 KiB
C
/*
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* The simplest AC-3 encoder
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* Copyright (c) 2000 Fabrice Bellard
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* Copyright (c) 2006-2010 Justin Ruggles <justin.ruggles@gmail.com>
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* Copyright (c) 2006-2010 Prakash Punnoor <prakash@punnoor.de>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* The simplest AC-3 encoder.
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*/
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//#define DEBUG
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#include "libavcore/audioconvert.h"
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#include "libavutil/crc.h"
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#include "avcodec.h"
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#include "put_bits.h"
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#include "dsputil.h"
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#include "ac3.h"
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#include "audioconvert.h"
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/** Maximum number of exponent groups. +1 for separate DC exponent. */
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#define AC3_MAX_EXP_GROUPS 85
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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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/** Scale a float value by 2^15, convert to an integer, and clip to range -32767..32767. */
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#define FIX15(a) av_clip(SCALE_FLOAT(a, 15), -32767, 32767)
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/**
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* Compex number.
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* Used in fixed-point MDCT calculation.
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*/
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typedef struct IComplex {
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int16_t re,im;
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} IComplex;
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typedef struct AC3MDCTContext {
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AVCodecContext *avctx; ///< parent context for av_log()
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int nbits; ///< log2(transform size)
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int16_t *costab; ///< FFT cos table
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int16_t *sintab; ///< FFT sin table
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int16_t *xcos1; ///< MDCT cos table
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int16_t *xsin1; ///< MDCT sin table
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int16_t *rot_tmp; ///< temp buffer for pre-rotated samples
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IComplex *cplx_tmp; ///< temp buffer for complex pre-rotated samples
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} AC3MDCTContext;
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/**
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* Data for a single audio block.
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*/
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typedef struct AC3Block {
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uint8_t **bap; ///< bit allocation pointers (bap)
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int32_t **mdct_coef; ///< MDCT coefficients
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uint8_t **exp; ///< original exponents
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uint8_t **grouped_exp; ///< grouped exponents
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int16_t **psd; ///< psd per frequency bin
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int16_t **band_psd; ///< psd per critical band
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int16_t **mask; ///< masking curve
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uint16_t **qmant; ///< quantized mantissas
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uint8_t exp_strategy[AC3_MAX_CHANNELS]; ///< exponent strategies
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int8_t exp_shift[AC3_MAX_CHANNELS]; ///< exponent shift values
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} AC3Block;
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/**
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* AC-3 encoder private context.
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*/
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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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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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/* 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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int16_t **planar_samples;
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uint8_t *bap_buffer;
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uint8_t *bap1_buffer;
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int32_t *mdct_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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DECLARE_ALIGNED(16, int16_t, windowed_samples)[AC3_WINDOW_SIZE];
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} AC3EncodeContext;
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/**
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* LUT for number of exponent groups.
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* exponent_group_tab[exponent strategy-1][number of coefficients]
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*/
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uint8_t exponent_group_tab[3][256];
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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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*/
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static void adjust_frame_size(AC3EncodeContext *s)
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{
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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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*/
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static void deinterleave_input_samples(AC3EncodeContext *s,
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const int16_t *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 int16_t *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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* Finalize MDCT and free allocated memory.
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*/
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static av_cold void mdct_end(AC3MDCTContext *mdct)
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{
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mdct->nbits = 0;
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av_freep(&mdct->costab);
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av_freep(&mdct->sintab);
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av_freep(&mdct->xcos1);
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av_freep(&mdct->xsin1);
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av_freep(&mdct->rot_tmp);
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av_freep(&mdct->cplx_tmp);
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}
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/**
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* Initialize FFT tables.
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* @param ln log2(FFT size)
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*/
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static av_cold int fft_init(AC3MDCTContext *mdct, int ln)
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{
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int i, n, n2;
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float alpha;
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n = 1 << ln;
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n2 = n >> 1;
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FF_ALLOC_OR_GOTO(mdct->avctx, mdct->costab, n2 * sizeof(*mdct->costab),
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fft_alloc_fail);
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FF_ALLOC_OR_GOTO(mdct->avctx, mdct->sintab, n2 * sizeof(*mdct->sintab),
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fft_alloc_fail);
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for (i = 0; i < n2; i++) {
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alpha = 2.0 * M_PI * i / n;
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mdct->costab[i] = FIX15(cos(alpha));
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mdct->sintab[i] = FIX15(sin(alpha));
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}
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return 0;
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fft_alloc_fail:
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mdct_end(mdct);
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return AVERROR(ENOMEM);
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}
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/**
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* Initialize MDCT tables.
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* @param nbits log2(MDCT size)
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*/
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static av_cold int mdct_init(AC3MDCTContext *mdct, int nbits)
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{
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int i, n, n4, ret;
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n = 1 << nbits;
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n4 = n >> 2;
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mdct->nbits = nbits;
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ret = fft_init(mdct, nbits - 2);
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if (ret)
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return ret;
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FF_ALLOC_OR_GOTO(mdct->avctx, mdct->xcos1, n4 * sizeof(*mdct->xcos1),
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mdct_alloc_fail);
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FF_ALLOC_OR_GOTO(mdct->avctx, mdct->xsin1 , n4 * sizeof(*mdct->xsin1),
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mdct_alloc_fail);
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FF_ALLOC_OR_GOTO(mdct->avctx, mdct->rot_tmp, n * sizeof(*mdct->rot_tmp),
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mdct_alloc_fail);
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FF_ALLOC_OR_GOTO(mdct->avctx, mdct->cplx_tmp, n4 * sizeof(*mdct->cplx_tmp),
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mdct_alloc_fail);
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for (i = 0; i < n4; i++) {
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float alpha = 2.0 * M_PI * (i + 1.0 / 8.0) / n;
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mdct->xcos1[i] = FIX15(-cos(alpha));
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mdct->xsin1[i] = FIX15(-sin(alpha));
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}
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return 0;
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mdct_alloc_fail:
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mdct_end(mdct);
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return AVERROR(ENOMEM);
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}
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/** Butterfly op */
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#define BF(pre, pim, qre, qim, pre1, pim1, qre1, qim1) \
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{ \
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int ax, ay, bx, by; \
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bx = pre1; \
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by = pim1; \
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ax = qre1; \
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ay = qim1; \
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pre = (bx + ax) >> 1; \
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pim = (by + ay) >> 1; \
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qre = (bx - ax) >> 1; \
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qim = (by - ay) >> 1; \
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}
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/** Complex multiply */
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#define CMUL(pre, pim, are, aim, bre, bim) \
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{ \
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pre = (MUL16(are, bre) - MUL16(aim, bim)) >> 15; \
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pim = (MUL16(are, bim) + MUL16(bre, aim)) >> 15; \
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}
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/**
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* Calculate a 2^n point complex FFT on 2^ln points.
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* @param z complex input/output samples
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* @param ln log2(FFT size)
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*/
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static void fft(AC3MDCTContext *mdct, IComplex *z, int ln)
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{
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int j, l, np, np2;
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int nblocks, nloops;
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register IComplex *p,*q;
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int tmp_re, tmp_im;
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np = 1 << ln;
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/* reverse */
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for (j = 0; j < np; j++) {
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int k = av_reverse[j] >> (8 - ln);
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if (k < j)
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FFSWAP(IComplex, z[k], z[j]);
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}
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/* pass 0 */
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p = &z[0];
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j = np >> 1;
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do {
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BF(p[0].re, p[0].im, p[1].re, p[1].im,
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p[0].re, p[0].im, p[1].re, p[1].im);
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p += 2;
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} while (--j);
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/* pass 1 */
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p = &z[0];
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j = np >> 2;
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do {
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BF(p[0].re, p[0].im, p[2].re, p[2].im,
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p[0].re, p[0].im, p[2].re, p[2].im);
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BF(p[1].re, p[1].im, p[3].re, p[3].im,
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p[1].re, p[1].im, p[3].im, -p[3].re);
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p+=4;
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} while (--j);
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/* pass 2 .. ln-1 */
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nblocks = np >> 3;
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nloops = 1 << 2;
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np2 = np >> 1;
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do {
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p = z;
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q = z + nloops;
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for (j = 0; j < nblocks; j++) {
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BF(p->re, p->im, q->re, q->im,
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p->re, p->im, q->re, q->im);
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p++;
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q++;
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for(l = nblocks; l < np2; l += nblocks) {
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CMUL(tmp_re, tmp_im, mdct->costab[l], -mdct->sintab[l], q->re, q->im);
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BF(p->re, p->im, q->re, q->im,
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p->re, p->im, tmp_re, tmp_im);
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p++;
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q++;
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}
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p += nloops;
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q += nloops;
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}
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nblocks = nblocks >> 1;
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nloops = nloops << 1;
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} while (nblocks);
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}
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/**
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* Calculate a 512-point MDCT
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* @param out 256 output frequency coefficients
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* @param in 512 windowed input audio samples
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*/
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static void mdct512(AC3MDCTContext *mdct, int32_t *out, int16_t *in)
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{
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int i, re, im, n, n2, n4;
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int16_t *rot = mdct->rot_tmp;
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IComplex *x = mdct->cplx_tmp;
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n = 1 << mdct->nbits;
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n2 = n >> 1;
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n4 = n >> 2;
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/* shift to simplify computations */
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for (i = 0; i <n4; i++)
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rot[i] = -in[i + 3*n4];
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memcpy(&rot[n4], &in[0], 3*n4*sizeof(*in));
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/* pre rotation */
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for (i = 0; i < n4; i++) {
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re = ((int)rot[ 2*i] - (int)rot[ n-1-2*i]) >> 1;
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im = -((int)rot[n2+2*i] - (int)rot[n2-1-2*i]) >> 1;
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CMUL(x[i].re, x[i].im, re, im, -mdct->xcos1[i], mdct->xsin1[i]);
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}
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fft(mdct, x, mdct->nbits - 2);
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/* post rotation */
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for (i = 0; i < n4; i++) {
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re = x[i].re;
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im = x[i].im;
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CMUL(out[n2-1-2*i], out[2*i], re, im, mdct->xsin1[i], mdct->xcos1[i]);
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}
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}
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/**
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* Apply KBD window to input samples prior to MDCT.
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*/
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static void apply_window(int16_t *output, const int16_t *input,
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const int16_t *window, int n)
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{
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int i;
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int n2 = n >> 1;
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for (i = 0; i < n2; i++) {
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output[i] = MUL16(input[i], window[i]) >> 15;
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output[n-i-1] = MUL16(input[n-i-1], window[i]) >> 15;
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}
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}
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/**
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* Calculate the log2() of the maximum absolute value in an array.
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* @param tab input array
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* @param n number of values in the array
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* @return log2(max(abs(tab[])))
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*/
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static int log2_tab(int16_t *tab, int n)
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{
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int i, v;
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v = 0;
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for (i = 0; i < n; i++)
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v |= abs(tab[i]);
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return av_log2(v);
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}
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/**
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* Left-shift each value in an array by a specified amount.
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* @param tab input array
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* @param n number of values in the array
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* @param lshift left shift amount. a negative value means right shift.
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*/
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static void lshift_tab(int16_t *tab, int n, int lshift)
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{
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int i;
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if (lshift > 0) {
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for (i = 0; i < n; i++)
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tab[i] <<= lshift;
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} else if (lshift < 0) {
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lshift = -lshift;
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for (i = 0; i < n; i++)
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tab[i] >>= lshift;
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}
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}
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/**
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* Normalize the input samples to use the maximum available precision.
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* This assumes signed 16-bit input samples. Exponents are reduced by 9 to
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* match the 24-bit internal precision for MDCT coefficients.
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*
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* @return exponent shift
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*/
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static int normalize_samples(AC3EncodeContext *s)
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{
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int v = 14 - log2_tab(s->windowed_samples, AC3_WINDOW_SIZE);
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v = FFMAX(0, v);
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|
lshift_tab(s->windowed_samples, AC3_WINDOW_SIZE, v);
|
|
return v - 9;
|
|
}
|
|
|
|
|
|
/**
|
|
* Apply the MDCT to input samples to generate frequency coefficients.
|
|
* This applies the KBD window and normalizes the input to reduce precision
|
|
* loss due to fixed-point calculations.
|
|
*/
|
|
static void apply_mdct(AC3EncodeContext *s)
|
|
{
|
|
int blk, ch;
|
|
|
|
for (ch = 0; ch < s->channels; ch++) {
|
|
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
|
|
AC3Block *block = &s->blocks[blk];
|
|
const int16_t *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE];
|
|
|
|
apply_window(s->windowed_samples, input_samples, ff_ac3_window, AC3_WINDOW_SIZE);
|
|
|
|
block->exp_shift[ch] = normalize_samples(s);
|
|
|
|
mdct512(&s->mdct, block->mdct_coef[ch], s->windowed_samples);
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/**
|
|
* Initialize exponent tables.
|
|
*/
|
|
static av_cold void exponent_init(AC3EncodeContext *s)
|
|
{
|
|
int i;
|
|
for (i = 73; i < 256; i++) {
|
|
exponent_group_tab[0][i] = (i - 1) / 3;
|
|
exponent_group_tab[1][i] = (i + 2) / 6;
|
|
exponent_group_tab[2][i] = (i + 8) / 12;
|
|
}
|
|
/* LFE */
|
|
exponent_group_tab[0][7] = 2;
|
|
}
|
|
|
|
|
|
/**
|
|
* Extract exponents from the MDCT coefficients.
|
|
* This takes into account the normalization that was done to the input samples
|
|
* by adjusting the exponents by the exponent shift values.
|
|
*/
|
|
static void extract_exponents(AC3EncodeContext *s)
|
|
{
|
|
int blk, ch, i;
|
|
|
|
for (ch = 0; ch < s->channels; ch++) {
|
|
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
|
|
AC3Block *block = &s->blocks[blk];
|
|
for (i = 0; i < AC3_MAX_COEFS; i++) {
|
|
int e;
|
|
int v = abs(block->mdct_coef[ch][i]);
|
|
if (v == 0)
|
|
e = 24;
|
|
else {
|
|
e = 23 - av_log2(v) + block->exp_shift[ch];
|
|
if (e >= 24) {
|
|
e = 24;
|
|
block->mdct_coef[ch][i] = 0;
|
|
}
|
|
}
|
|
block->exp[ch][i] = e;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/**
|
|
* Exponent Difference Threshold.
|
|
* New exponents are sent if their SAD exceed this number.
|
|
*/
|
|
#define EXP_DIFF_THRESHOLD 1000
|
|
|
|
|
|
/**
|
|
* Calculate exponent strategies for all blocks in a single channel.
|
|
*/
|
|
static void compute_exp_strategy_ch(AC3EncodeContext *s, uint8_t *exp_strategy, uint8_t **exp)
|
|
{
|
|
int blk, blk1;
|
|
int exp_diff;
|
|
|
|
/* estimate if the exponent variation & decide if they should be
|
|
reused in the next frame */
|
|
exp_strategy[0] = EXP_NEW;
|
|
for (blk = 1; blk < AC3_MAX_BLOCKS; blk++) {
|
|
exp_diff = s->dsp.sad[0](NULL, exp[blk], exp[blk-1], 16, 16);
|
|
if (exp_diff > EXP_DIFF_THRESHOLD)
|
|
exp_strategy[blk] = EXP_NEW;
|
|
else
|
|
exp_strategy[blk] = EXP_REUSE;
|
|
}
|
|
emms_c();
|
|
|
|
/* now select the encoding strategy type : if exponents are often
|
|
recoded, we use a coarse encoding */
|
|
blk = 0;
|
|
while (blk < AC3_MAX_BLOCKS) {
|
|
blk1 = blk + 1;
|
|
while (blk1 < AC3_MAX_BLOCKS && exp_strategy[blk1] == EXP_REUSE)
|
|
blk1++;
|
|
switch (blk1 - blk) {
|
|
case 1: exp_strategy[blk] = EXP_D45; break;
|
|
case 2:
|
|
case 3: exp_strategy[blk] = EXP_D25; break;
|
|
default: exp_strategy[blk] = EXP_D15; break;
|
|
}
|
|
blk = blk1;
|
|
}
|
|
}
|
|
|
|
|
|
/**
|
|
* Calculate exponent strategies for all channels.
|
|
* Array arrangement is reversed to simplify the per-channel calculation.
|
|
*/
|
|
static void compute_exp_strategy(AC3EncodeContext *s)
|
|
{
|
|
uint8_t *exp1[AC3_MAX_CHANNELS][AC3_MAX_BLOCKS];
|
|
uint8_t exp_str1[AC3_MAX_CHANNELS][AC3_MAX_BLOCKS];
|
|
int ch, blk;
|
|
|
|
for (ch = 0; ch < s->fbw_channels; ch++) {
|
|
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
|
|
exp1[ch][blk] = s->blocks[blk].exp[ch];
|
|
exp_str1[ch][blk] = s->blocks[blk].exp_strategy[ch];
|
|
}
|
|
|
|
compute_exp_strategy_ch(s, exp_str1[ch], exp1[ch]);
|
|
|
|
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++)
|
|
s->blocks[blk].exp_strategy[ch] = exp_str1[ch][blk];
|
|
}
|
|
if (s->lfe_on) {
|
|
ch = s->lfe_channel;
|
|
s->blocks[0].exp_strategy[ch] = EXP_D15;
|
|
for (blk = 1; blk < AC3_MAX_BLOCKS; blk++)
|
|
s->blocks[blk].exp_strategy[ch] = EXP_REUSE;
|
|
}
|
|
}
|
|
|
|
|
|
/**
|
|
* Set each encoded exponent in a block to the minimum of itself and the
|
|
* exponent in the same frequency bin of a following block.
|
|
* exp[i] = min(exp[i], exp1[i]
|
|
*/
|
|
static void exponent_min(uint8_t *exp, uint8_t *exp1, int n)
|
|
{
|
|
int i;
|
|
for (i = 0; i < n; i++) {
|
|
if (exp1[i] < exp[i])
|
|
exp[i] = exp1[i];
|
|
}
|
|
}
|
|
|
|
|
|
/**
|
|
* Update the exponents so that they are the ones the decoder will decode.
|
|
*/
|
|
static void encode_exponents_blk_ch(uint8_t *exp,
|
|
int nb_exps, int exp_strategy)
|
|
{
|
|
int nb_groups, i, k;
|
|
|
|
nb_groups = exponent_group_tab[exp_strategy-1][nb_exps] * 3;
|
|
|
|
/* for each group, compute the minimum exponent */
|
|
switch(exp_strategy) {
|
|
case EXP_D25:
|
|
for (i = 1, k = 1; i <= nb_groups; i++) {
|
|
uint8_t exp_min = exp[k];
|
|
if (exp[k+1] < exp_min)
|
|
exp_min = exp[k+1];
|
|
exp[i] = exp_min;
|
|
k += 2;
|
|
}
|
|
break;
|
|
case EXP_D45:
|
|
for (i = 1, k = 1; i <= nb_groups; i++) {
|
|
uint8_t exp_min = exp[k];
|
|
if (exp[k+1] < exp_min)
|
|
exp_min = exp[k+1];
|
|
if (exp[k+2] < exp_min)
|
|
exp_min = exp[k+2];
|
|
if (exp[k+3] < exp_min)
|
|
exp_min = exp[k+3];
|
|
exp[i] = exp_min;
|
|
k += 4;
|
|
}
|
|
break;
|
|
}
|
|
|
|
/* constraint for DC exponent */
|
|
if (exp[0] > 15)
|
|
exp[0] = 15;
|
|
|
|
/* decrease the delta between each groups to within 2 so that they can be
|
|
differentially encoded */
|
|
for (i = 1; i <= nb_groups; i++)
|
|
exp[i] = FFMIN(exp[i], exp[i-1] + 2);
|
|
i--;
|
|
while (--i >= 0)
|
|
exp[i] = FFMIN(exp[i], exp[i+1] + 2);
|
|
|
|
/* now we have the exponent values the decoder will see */
|
|
switch (exp_strategy) {
|
|
case EXP_D25:
|
|
for (i = nb_groups, k = nb_groups * 2; i > 0; i--) {
|
|
uint8_t exp1 = exp[i];
|
|
exp[k--] = exp1;
|
|
exp[k--] = exp1;
|
|
}
|
|
break;
|
|
case EXP_D45:
|
|
for (i = nb_groups, k = nb_groups * 4; i > 0; i--) {
|
|
exp[k] = exp[k-1] = exp[k-2] = exp[k-3] = exp[i];
|
|
k -= 4;
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
|
|
|
|
/**
|
|
* Encode exponents from original extracted form to what the decoder will see.
|
|
* This copies and groups exponents based on exponent strategy and reduces
|
|
* deltas between adjacent exponent groups so that they can be differentially
|
|
* encoded.
|
|
*/
|
|
static void encode_exponents(AC3EncodeContext *s)
|
|
{
|
|
int blk, blk1, blk2, ch;
|
|
AC3Block *block, *block1, *block2;
|
|
|
|
for (ch = 0; ch < s->channels; ch++) {
|
|
blk = 0;
|
|
block = &s->blocks[0];
|
|
while (blk < AC3_MAX_BLOCKS) {
|
|
blk1 = blk + 1;
|
|
block1 = block + 1;
|
|
/* for the EXP_REUSE case we select the min of the exponents */
|
|
while (blk1 < AC3_MAX_BLOCKS && block1->exp_strategy[ch] == EXP_REUSE) {
|
|
exponent_min(block->exp[ch], block1->exp[ch], s->nb_coefs[ch]);
|
|
blk1++;
|
|
block1++;
|
|
}
|
|
encode_exponents_blk_ch(block->exp[ch], s->nb_coefs[ch],
|
|
block->exp_strategy[ch]);
|
|
/* copy encoded exponents for reuse case */
|
|
block2 = block + 1;
|
|
for (blk2 = blk+1; blk2 < blk1; blk2++, block2++) {
|
|
memcpy(block2->exp[ch], block->exp[ch],
|
|
s->nb_coefs[ch] * sizeof(uint8_t));
|
|
}
|
|
blk = blk1;
|
|
block = block1;
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/**
|
|
* Group exponents.
|
|
* 3 delta-encoded exponents are in each 7-bit group. The number of groups
|
|
* varies depending on exponent strategy and bandwidth.
|
|
*/
|
|
static void group_exponents(AC3EncodeContext *s)
|
|
{
|
|
int blk, ch, i;
|
|
int group_size, nb_groups, bit_count;
|
|
uint8_t *p;
|
|
int delta0, delta1, delta2;
|
|
int exp0, exp1;
|
|
|
|
bit_count = 0;
|
|
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
|
|
AC3Block *block = &s->blocks[blk];
|
|
for (ch = 0; ch < s->channels; ch++) {
|
|
if (block->exp_strategy[ch] == EXP_REUSE) {
|
|
continue;
|
|
}
|
|
group_size = block->exp_strategy[ch] + (block->exp_strategy[ch] == EXP_D45);
|
|
nb_groups = exponent_group_tab[block->exp_strategy[ch]-1][s->nb_coefs[ch]];
|
|
bit_count += 4 + (nb_groups * 7);
|
|
p = block->exp[ch];
|
|
|
|
/* DC exponent */
|
|
exp1 = *p++;
|
|
block->grouped_exp[ch][0] = exp1;
|
|
|
|
/* remaining exponents are delta encoded */
|
|
for (i = 1; i <= nb_groups; i++) {
|
|
/* merge three delta in one code */
|
|
exp0 = exp1;
|
|
exp1 = p[0];
|
|
p += group_size;
|
|
delta0 = exp1 - exp0 + 2;
|
|
|
|
exp0 = exp1;
|
|
exp1 = p[0];
|
|
p += group_size;
|
|
delta1 = exp1 - exp0 + 2;
|
|
|
|
exp0 = exp1;
|
|
exp1 = p[0];
|
|
p += group_size;
|
|
delta2 = exp1 - exp0 + 2;
|
|
|
|
block->grouped_exp[ch][i] = ((delta0 * 5 + delta1) * 5) + delta2;
|
|
}
|
|
}
|
|
}
|
|
|
|
s->exponent_bits = bit_count;
|
|
}
|
|
|
|
|
|
/**
|
|
* Calculate final exponents from the supplied MDCT coefficients and exponent shift.
|
|
* Extract exponents from MDCT coefficients, calculate exponent strategies,
|
|
* and encode final exponents.
|
|
*/
|
|
static void process_exponents(AC3EncodeContext *s)
|
|
{
|
|
extract_exponents(s);
|
|
|
|
compute_exp_strategy(s);
|
|
|
|
encode_exponents(s);
|
|
|
|
group_exponents(s);
|
|
}
|
|
|
|
|
|
/**
|
|
* Count frame bits that are based solely on fixed parameters.
|
|
* This only has to be run once when the encoder is initialized.
|
|
*/
|
|
static void count_frame_bits_fixed(AC3EncodeContext *s)
|
|
{
|
|
static const int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
|
|
int blk;
|
|
int frame_bits;
|
|
|
|
/* assumptions:
|
|
* no dynamic range codes
|
|
* no channel coupling
|
|
* no rematrixing
|
|
* bit allocation parameters do not change between blocks
|
|
* SNR offsets do not change between blocks
|
|
* no delta bit allocation
|
|
* no skipped data
|
|
* no auxilliary data
|
|
*/
|
|
|
|
/* header size */
|
|
frame_bits = 65;
|
|
frame_bits += frame_bits_inc[s->channel_mode];
|
|
|
|
/* audio blocks */
|
|
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
|
|
frame_bits += s->fbw_channels * 2 + 2; /* blksw * c, dithflag * c, dynrnge, cplstre */
|
|
if (s->channel_mode == AC3_CHMODE_STEREO) {
|
|
frame_bits++; /* rematstr */
|
|
if (!blk)
|
|
frame_bits += 4;
|
|
}
|
|
frame_bits += 2 * s->fbw_channels; /* chexpstr[2] * c */
|
|
if (s->lfe_on)
|
|
frame_bits++; /* lfeexpstr */
|
|
frame_bits++; /* baie */
|
|
frame_bits++; /* snr */
|
|
frame_bits += 2; /* delta / skip */
|
|
}
|
|
frame_bits++; /* cplinu for block 0 */
|
|
/* bit alloc info */
|
|
/* sdcycod[2], fdcycod[2], sgaincod[2], dbpbcod[2], floorcod[3] */
|
|
/* csnroffset[6] */
|
|
/* (fsnoffset[4] + fgaincod[4]) * c */
|
|
frame_bits += 2*4 + 3 + 6 + s->channels * (4 + 3);
|
|
|
|
/* auxdatae, crcrsv */
|
|
frame_bits += 2;
|
|
|
|
/* CRC */
|
|
frame_bits += 16;
|
|
|
|
s->frame_bits_fixed = frame_bits;
|
|
}
|
|
|
|
|
|
/**
|
|
* Initialize bit allocation.
|
|
* Set default parameter codes and calculate parameter values.
|
|
*/
|
|
static void bit_alloc_init(AC3EncodeContext *s)
|
|
{
|
|
int ch;
|
|
|
|
/* init default parameters */
|
|
s->slow_decay_code = 2;
|
|
s->fast_decay_code = 1;
|
|
s->slow_gain_code = 1;
|
|
s->db_per_bit_code = 2;
|
|
s->floor_code = 4;
|
|
for (ch = 0; ch < s->channels; ch++)
|
|
s->fast_gain_code[ch] = 4;
|
|
|
|
/* initial snr offset */
|
|
s->coarse_snr_offset = 40;
|
|
|
|
/* compute real values */
|
|
/* currently none of these values change during encoding, so we can just
|
|
set them once at initialization */
|
|
s->bit_alloc.slow_decay = ff_ac3_slow_decay_tab[s->slow_decay_code] >> s->bit_alloc.sr_shift;
|
|
s->bit_alloc.fast_decay = ff_ac3_fast_decay_tab[s->fast_decay_code] >> s->bit_alloc.sr_shift;
|
|
s->bit_alloc.slow_gain = ff_ac3_slow_gain_tab[s->slow_gain_code];
|
|
s->bit_alloc.db_per_bit = ff_ac3_db_per_bit_tab[s->db_per_bit_code];
|
|
s->bit_alloc.floor = ff_ac3_floor_tab[s->floor_code];
|
|
|
|
count_frame_bits_fixed(s);
|
|
}
|
|
|
|
|
|
/**
|
|
* Count the bits used to encode the frame, minus exponents and mantissas.
|
|
* Bits based on fixed parameters have already been counted, so now we just
|
|
* have to add the bits based on parameters that change during encoding.
|
|
*/
|
|
static void count_frame_bits(AC3EncodeContext *s)
|
|
{
|
|
int blk, ch;
|
|
int frame_bits = 0;
|
|
|
|
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
|
|
uint8_t *exp_strategy = s->blocks[blk].exp_strategy;
|
|
for (ch = 0; ch < s->fbw_channels; ch++) {
|
|
if (exp_strategy[ch] != EXP_REUSE)
|
|
frame_bits += 6 + 2; /* chbwcod[6], gainrng[2] */
|
|
}
|
|
}
|
|
s->frame_bits = s->frame_bits_fixed + frame_bits;
|
|
}
|
|
|
|
|
|
/**
|
|
* Calculate the number of bits needed to encode a set of mantissas.
|
|
*/
|
|
static int compute_mantissa_size(int mant_cnt[5], uint8_t *bap, int nb_coefs)
|
|
{
|
|
int bits, b, i;
|
|
|
|
bits = 0;
|
|
for (i = 0; i < nb_coefs; i++) {
|
|
b = bap[i];
|
|
if (b <= 4) {
|
|
// bap=1 to bap=4 will be counted in compute_mantissa_size_final
|
|
mant_cnt[b]++;
|
|
} else if (b <= 13) {
|
|
// bap=5 to bap=13 use (bap-1) bits
|
|
bits += b - 1;
|
|
} else {
|
|
// bap=14 uses 14 bits and bap=15 uses 16 bits
|
|
bits += (b == 14) ? 14 : 16;
|
|
}
|
|
}
|
|
return bits;
|
|
}
|
|
|
|
|
|
/**
|
|
* Finalize the mantissa bit count by adding in the grouped mantissas.
|
|
*/
|
|
static int compute_mantissa_size_final(int mant_cnt[5])
|
|
{
|
|
// bap=1 : 3 mantissas in 5 bits
|
|
int bits = (mant_cnt[1] / 3) * 5;
|
|
// bap=2 : 3 mantissas in 7 bits
|
|
// bap=4 : 2 mantissas in 7 bits
|
|
bits += ((mant_cnt[2] / 3) + (mant_cnt[4] >> 1)) * 7;
|
|
// bap=3 : each mantissa is 3 bits
|
|
bits += mant_cnt[3] * 3;
|
|
return bits;
|
|
}
|
|
|
|
|
|
/**
|
|
* Calculate masking curve based on the final exponents.
|
|
* Also calculate the power spectral densities to use in future calculations.
|
|
*/
|
|
static void bit_alloc_masking(AC3EncodeContext *s)
|
|
{
|
|
int blk, ch;
|
|
|
|
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
|
|
AC3Block *block = &s->blocks[blk];
|
|
for (ch = 0; ch < s->channels; ch++) {
|
|
/* We only need psd and mask for calculating bap.
|
|
Since we currently do not calculate bap when exponent
|
|
strategy is EXP_REUSE we do not need to calculate psd or mask. */
|
|
if (block->exp_strategy[ch] != EXP_REUSE) {
|
|
ff_ac3_bit_alloc_calc_psd(block->exp[ch], 0,
|
|
s->nb_coefs[ch],
|
|
block->psd[ch], block->band_psd[ch]);
|
|
ff_ac3_bit_alloc_calc_mask(&s->bit_alloc, block->band_psd[ch],
|
|
0, s->nb_coefs[ch],
|
|
ff_ac3_fast_gain_tab[s->fast_gain_code[ch]],
|
|
ch == s->lfe_channel,
|
|
DBA_NONE, 0, NULL, NULL, NULL,
|
|
block->mask[ch]);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/**
|
|
* Ensure that bap for each block and channel point to the current bap_buffer.
|
|
* They may have been switched during the bit allocation search.
|
|
*/
|
|
static void reset_block_bap(AC3EncodeContext *s)
|
|
{
|
|
int blk, ch;
|
|
if (s->blocks[0].bap[0] == s->bap_buffer)
|
|
return;
|
|
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
|
|
for (ch = 0; ch < s->channels; ch++) {
|
|
s->blocks[blk].bap[ch] = &s->bap_buffer[AC3_MAX_COEFS * (blk * s->channels + ch)];
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/**
|
|
* Run the bit allocation with a given SNR offset.
|
|
* This calculates the bit allocation pointers that will be used to determine
|
|
* the quantization of each mantissa.
|
|
* @return the number of bits needed for mantissas if the given SNR offset is
|
|
* is used.
|
|
*/
|
|
static int bit_alloc(AC3EncodeContext *s,
|
|
int snr_offset)
|
|
{
|
|
int blk, ch;
|
|
int mantissa_bits;
|
|
int mant_cnt[5];
|
|
|
|
snr_offset = (snr_offset - 240) << 2;
|
|
|
|
reset_block_bap(s);
|
|
mantissa_bits = 0;
|
|
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
|
|
AC3Block *block = &s->blocks[blk];
|
|
// initialize grouped mantissa counts. these are set so that they are
|
|
// padded to the next whole group size when bits are counted in
|
|
// compute_mantissa_size_final
|
|
mant_cnt[0] = mant_cnt[3] = 0;
|
|
mant_cnt[1] = mant_cnt[2] = 2;
|
|
mant_cnt[4] = 1;
|
|
for (ch = 0; ch < s->channels; ch++) {
|
|
/* Currently the only bit allocation parameters which vary across
|
|
blocks within a frame are the exponent values. We can take
|
|
advantage of that by reusing the bit allocation pointers
|
|
whenever we reuse exponents. */
|
|
if (block->exp_strategy[ch] == EXP_REUSE) {
|
|
memcpy(block->bap[ch], s->blocks[blk-1].bap[ch], AC3_MAX_COEFS);
|
|
} else {
|
|
ff_ac3_bit_alloc_calc_bap(block->mask[ch], block->psd[ch], 0,
|
|
s->nb_coefs[ch], snr_offset,
|
|
s->bit_alloc.floor, ff_ac3_bap_tab,
|
|
block->bap[ch]);
|
|
}
|
|
mantissa_bits += compute_mantissa_size(mant_cnt, block->bap[ch], s->nb_coefs[ch]);
|
|
}
|
|
mantissa_bits += compute_mantissa_size_final(mant_cnt);
|
|
}
|
|
return mantissa_bits;
|
|
}
|
|
|
|
|
|
/**
|
|
* Constant bitrate bit allocation search.
|
|
* Find the largest SNR offset that will allow data to fit in the frame.
|
|
*/
|
|
static int cbr_bit_allocation(AC3EncodeContext *s)
|
|
{
|
|
int ch;
|
|
int bits_left;
|
|
int snr_offset, snr_incr;
|
|
|
|
bits_left = 8 * s->frame_size - (s->frame_bits + s->exponent_bits);
|
|
|
|
snr_offset = s->coarse_snr_offset << 4;
|
|
|
|
while (snr_offset >= 0 &&
|
|
bit_alloc(s, snr_offset) > bits_left) {
|
|
snr_offset -= 64;
|
|
}
|
|
if (snr_offset < 0)
|
|
return AVERROR(EINVAL);
|
|
|
|
FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
|
|
for (snr_incr = 64; snr_incr > 0; snr_incr >>= 2) {
|
|
while (snr_offset + 64 <= 1023 &&
|
|
bit_alloc(s, snr_offset + snr_incr) <= bits_left) {
|
|
snr_offset += snr_incr;
|
|
FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
|
|
}
|
|
}
|
|
FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
|
|
reset_block_bap(s);
|
|
|
|
s->coarse_snr_offset = snr_offset >> 4;
|
|
for (ch = 0; ch < s->channels; ch++)
|
|
s->fine_snr_offset[ch] = snr_offset & 0xF;
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
/**
|
|
* Downgrade exponent strategies to reduce the bits used by the exponents.
|
|
* This is a fallback for when bit allocation fails with the normal exponent
|
|
* strategies. Each time this function is run it only downgrades the
|
|
* strategy in 1 channel of 1 block.
|
|
* @return non-zero if downgrade was unsuccessful
|
|
*/
|
|
static int downgrade_exponents(AC3EncodeContext *s)
|
|
{
|
|
int ch, blk;
|
|
|
|
for (ch = 0; ch < s->fbw_channels; ch++) {
|
|
for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
|
|
if (s->blocks[blk].exp_strategy[ch] == EXP_D15) {
|
|
s->blocks[blk].exp_strategy[ch] = EXP_D25;
|
|
return 0;
|
|
}
|
|
}
|
|
}
|
|
for (ch = 0; ch < s->fbw_channels; ch++) {
|
|
for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
|
|
if (s->blocks[blk].exp_strategy[ch] == EXP_D25) {
|
|
s->blocks[blk].exp_strategy[ch] = EXP_D45;
|
|
return 0;
|
|
}
|
|
}
|
|
}
|
|
for (ch = 0; ch < s->fbw_channels; ch++) {
|
|
/* block 0 cannot reuse exponents, so only downgrade D45 to REUSE if
|
|
the block number > 0 */
|
|
for (blk = AC3_MAX_BLOCKS-1; blk > 0; blk--) {
|
|
if (s->blocks[blk].exp_strategy[ch] > EXP_REUSE) {
|
|
s->blocks[blk].exp_strategy[ch] = EXP_REUSE;
|
|
return 0;
|
|
}
|
|
}
|
|
}
|
|
return -1;
|
|
}
|
|
|
|
|
|
/**
|
|
* Reduce the bandwidth to reduce the number of bits used for a given SNR offset.
|
|
* This is a second fallback for when bit allocation still fails after exponents
|
|
* have been downgraded.
|
|
* @return non-zero if bandwidth reduction was unsuccessful
|
|
*/
|
|
static int reduce_bandwidth(AC3EncodeContext *s, int min_bw_code)
|
|
{
|
|
int ch;
|
|
|
|
if (s->bandwidth_code[0] > min_bw_code) {
|
|
for (ch = 0; ch < s->fbw_channels; ch++) {
|
|
s->bandwidth_code[ch]--;
|
|
s->nb_coefs[ch] = s->bandwidth_code[ch] * 3 + 73;
|
|
}
|
|
return 0;
|
|
}
|
|
return -1;
|
|
}
|
|
|
|
|
|
/**
|
|
* Perform bit allocation search.
|
|
* Finds the SNR offset value that maximizes quality and fits in the specified
|
|
* frame size. Output is the SNR offset and a set of bit allocation pointers
|
|
* used to quantize the mantissas.
|
|
*/
|
|
static int compute_bit_allocation(AC3EncodeContext *s)
|
|
{
|
|
int ret;
|
|
|
|
count_frame_bits(s);
|
|
|
|
bit_alloc_masking(s);
|
|
|
|
ret = cbr_bit_allocation(s);
|
|
while (ret) {
|
|
/* fallback 1: downgrade exponents */
|
|
if (!downgrade_exponents(s)) {
|
|
extract_exponents(s);
|
|
encode_exponents(s);
|
|
group_exponents(s);
|
|
ret = compute_bit_allocation(s);
|
|
continue;
|
|
}
|
|
|
|
/* fallback 2: reduce bandwidth */
|
|
/* only do this if the user has not specified a specific cutoff
|
|
frequency */
|
|
if (!s->cutoff && !reduce_bandwidth(s, 0)) {
|
|
process_exponents(s);
|
|
ret = compute_bit_allocation(s);
|
|
continue;
|
|
}
|
|
|
|
/* fallbacks were not enough... */
|
|
break;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
|
|
/**
|
|
* Symmetric quantization on 'levels' levels.
|
|
*/
|
|
static inline int sym_quant(int c, int e, int levels)
|
|
{
|
|
int v;
|
|
|
|
if (c >= 0) {
|
|
v = (levels * (c << e)) >> 24;
|
|
v = (v + 1) >> 1;
|
|
v = (levels >> 1) + v;
|
|
} else {
|
|
v = (levels * ((-c) << e)) >> 24;
|
|
v = (v + 1) >> 1;
|
|
v = (levels >> 1) - v;
|
|
}
|
|
assert(v >= 0 && v < levels);
|
|
return v;
|
|
}
|
|
|
|
|
|
/**
|
|
* Asymmetric quantization on 2^qbits levels.
|
|
*/
|
|
static inline int asym_quant(int c, int e, int qbits)
|
|
{
|
|
int lshift, m, v;
|
|
|
|
lshift = e + qbits - 24;
|
|
if (lshift >= 0)
|
|
v = c << lshift;
|
|
else
|
|
v = c >> (-lshift);
|
|
/* rounding */
|
|
v = (v + 1) >> 1;
|
|
m = (1 << (qbits-1));
|
|
if (v >= m)
|
|
v = m - 1;
|
|
assert(v >= -m);
|
|
return v & ((1 << qbits)-1);
|
|
}
|
|
|
|
|
|
/**
|
|
* Quantize a set of mantissas for a single channel in a single block.
|
|
*/
|
|
static void quantize_mantissas_blk_ch(AC3EncodeContext *s,
|
|
int32_t *mdct_coef, int8_t exp_shift,
|
|
uint8_t *exp, uint8_t *bap,
|
|
uint16_t *qmant, int n)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < n; i++) {
|
|
int v;
|
|
int c = mdct_coef[i];
|
|
int e = exp[i] - exp_shift;
|
|
int b = bap[i];
|
|
switch (b) {
|
|
case 0:
|
|
v = 0;
|
|
break;
|
|
case 1:
|
|
v = sym_quant(c, e, 3);
|
|
switch (s->mant1_cnt) {
|
|
case 0:
|
|
s->qmant1_ptr = &qmant[i];
|
|
v = 9 * v;
|
|
s->mant1_cnt = 1;
|
|
break;
|
|
case 1:
|
|
*s->qmant1_ptr += 3 * v;
|
|
s->mant1_cnt = 2;
|
|
v = 128;
|
|
break;
|
|
default:
|
|
*s->qmant1_ptr += v;
|
|
s->mant1_cnt = 0;
|
|
v = 128;
|
|
break;
|
|
}
|
|
break;
|
|
case 2:
|
|
v = sym_quant(c, e, 5);
|
|
switch (s->mant2_cnt) {
|
|
case 0:
|
|
s->qmant2_ptr = &qmant[i];
|
|
v = 25 * v;
|
|
s->mant2_cnt = 1;
|
|
break;
|
|
case 1:
|
|
*s->qmant2_ptr += 5 * v;
|
|
s->mant2_cnt = 2;
|
|
v = 128;
|
|
break;
|
|
default:
|
|
*s->qmant2_ptr += v;
|
|
s->mant2_cnt = 0;
|
|
v = 128;
|
|
break;
|
|
}
|
|
break;
|
|
case 3:
|
|
v = sym_quant(c, e, 7);
|
|
break;
|
|
case 4:
|
|
v = sym_quant(c, e, 11);
|
|
switch (s->mant4_cnt) {
|
|
case 0:
|
|
s->qmant4_ptr = &qmant[i];
|
|
v = 11 * v;
|
|
s->mant4_cnt = 1;
|
|
break;
|
|
default:
|
|
*s->qmant4_ptr += v;
|
|
s->mant4_cnt = 0;
|
|
v = 128;
|
|
break;
|
|
}
|
|
break;
|
|
case 5:
|
|
v = sym_quant(c, e, 15);
|
|
break;
|
|
case 14:
|
|
v = asym_quant(c, e, 14);
|
|
break;
|
|
case 15:
|
|
v = asym_quant(c, e, 16);
|
|
break;
|
|
default:
|
|
v = asym_quant(c, e, b - 1);
|
|
break;
|
|
}
|
|
qmant[i] = v;
|
|
}
|
|
}
|
|
|
|
|
|
/**
|
|
* Quantize mantissas using coefficients, exponents, and bit allocation pointers.
|
|
*/
|
|
static void quantize_mantissas(AC3EncodeContext *s)
|
|
{
|
|
int blk, ch;
|
|
|
|
|
|
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
|
|
AC3Block *block = &s->blocks[blk];
|
|
s->mant1_cnt = s->mant2_cnt = s->mant4_cnt = 0;
|
|
s->qmant1_ptr = s->qmant2_ptr = s->qmant4_ptr = NULL;
|
|
|
|
for (ch = 0; ch < s->channels; ch++) {
|
|
quantize_mantissas_blk_ch(s, block->mdct_coef[ch], block->exp_shift[ch],
|
|
block->exp[ch], block->bap[ch],
|
|
block->qmant[ch], s->nb_coefs[ch]);
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/**
|
|
* Write the AC-3 frame header to the output bitstream.
|
|
*/
|
|
static void output_frame_header(AC3EncodeContext *s)
|
|
{
|
|
put_bits(&s->pb, 16, 0x0b77); /* frame header */
|
|
put_bits(&s->pb, 16, 0); /* crc1: will be filled later */
|
|
put_bits(&s->pb, 2, s->bit_alloc.sr_code);
|
|
put_bits(&s->pb, 6, s->frame_size_code + (s->frame_size - s->frame_size_min) / 2);
|
|
put_bits(&s->pb, 5, s->bitstream_id);
|
|
put_bits(&s->pb, 3, s->bitstream_mode);
|
|
put_bits(&s->pb, 3, s->channel_mode);
|
|
if ((s->channel_mode & 0x01) && s->channel_mode != AC3_CHMODE_MONO)
|
|
put_bits(&s->pb, 2, 1); /* XXX -4.5 dB */
|
|
if (s->channel_mode & 0x04)
|
|
put_bits(&s->pb, 2, 1); /* XXX -6 dB */
|
|
if (s->channel_mode == AC3_CHMODE_STEREO)
|
|
put_bits(&s->pb, 2, 0); /* surround not indicated */
|
|
put_bits(&s->pb, 1, s->lfe_on); /* LFE */
|
|
put_bits(&s->pb, 5, 31); /* dialog norm: -31 db */
|
|
put_bits(&s->pb, 1, 0); /* no compression control word */
|
|
put_bits(&s->pb, 1, 0); /* no lang code */
|
|
put_bits(&s->pb, 1, 0); /* no audio production info */
|
|
put_bits(&s->pb, 1, 0); /* no copyright */
|
|
put_bits(&s->pb, 1, 1); /* original bitstream */
|
|
put_bits(&s->pb, 1, 0); /* no time code 1 */
|
|
put_bits(&s->pb, 1, 0); /* no time code 2 */
|
|
put_bits(&s->pb, 1, 0); /* no additional bit stream info */
|
|
}
|
|
|
|
|
|
/**
|
|
* Write one audio block to the output bitstream.
|
|
*/
|
|
static void output_audio_block(AC3EncodeContext *s,
|
|
int block_num)
|
|
{
|
|
int ch, i, baie, rbnd;
|
|
AC3Block *block = &s->blocks[block_num];
|
|
|
|
/* block switching */
|
|
for (ch = 0; ch < s->fbw_channels; ch++)
|
|
put_bits(&s->pb, 1, 0);
|
|
|
|
/* dither flags */
|
|
for (ch = 0; ch < s->fbw_channels; ch++)
|
|
put_bits(&s->pb, 1, 1);
|
|
|
|
/* dynamic range codes */
|
|
put_bits(&s->pb, 1, 0);
|
|
|
|
/* channel coupling */
|
|
if (!block_num) {
|
|
put_bits(&s->pb, 1, 1); /* coupling strategy present */
|
|
put_bits(&s->pb, 1, 0); /* no coupling strategy */
|
|
} else {
|
|
put_bits(&s->pb, 1, 0); /* no new coupling strategy */
|
|
}
|
|
|
|
/* stereo rematrixing */
|
|
if (s->channel_mode == AC3_CHMODE_STEREO) {
|
|
if (!block_num) {
|
|
/* first block must define rematrixing (rematstr) */
|
|
put_bits(&s->pb, 1, 1);
|
|
|
|
/* dummy rematrixing rematflg(1:4)=0 */
|
|
for (rbnd = 0; rbnd < 4; rbnd++)
|
|
put_bits(&s->pb, 1, 0);
|
|
} else {
|
|
/* no matrixing (but should be used in the future) */
|
|
put_bits(&s->pb, 1, 0);
|
|
}
|
|
}
|
|
|
|
/* exponent strategy */
|
|
for (ch = 0; ch < s->fbw_channels; ch++)
|
|
put_bits(&s->pb, 2, block->exp_strategy[ch]);
|
|
if (s->lfe_on)
|
|
put_bits(&s->pb, 1, block->exp_strategy[s->lfe_channel]);
|
|
|
|
/* bandwidth */
|
|
for (ch = 0; ch < s->fbw_channels; ch++) {
|
|
if (block->exp_strategy[ch] != EXP_REUSE)
|
|
put_bits(&s->pb, 6, s->bandwidth_code[ch]);
|
|
}
|
|
|
|
/* exponents */
|
|
for (ch = 0; ch < s->channels; ch++) {
|
|
int nb_groups;
|
|
|
|
if (block->exp_strategy[ch] == EXP_REUSE)
|
|
continue;
|
|
|
|
/* DC exponent */
|
|
put_bits(&s->pb, 4, block->grouped_exp[ch][0]);
|
|
|
|
/* exponent groups */
|
|
nb_groups = exponent_group_tab[block->exp_strategy[ch]-1][s->nb_coefs[ch]];
|
|
for (i = 1; i <= nb_groups; i++)
|
|
put_bits(&s->pb, 7, block->grouped_exp[ch][i]);
|
|
|
|
/* gain range info */
|
|
if (ch != s->lfe_channel)
|
|
put_bits(&s->pb, 2, 0);
|
|
}
|
|
|
|
/* bit allocation info */
|
|
baie = (block_num == 0);
|
|
put_bits(&s->pb, 1, baie);
|
|
if (baie) {
|
|
put_bits(&s->pb, 2, s->slow_decay_code);
|
|
put_bits(&s->pb, 2, s->fast_decay_code);
|
|
put_bits(&s->pb, 2, s->slow_gain_code);
|
|
put_bits(&s->pb, 2, s->db_per_bit_code);
|
|
put_bits(&s->pb, 3, s->floor_code);
|
|
}
|
|
|
|
/* snr offset */
|
|
put_bits(&s->pb, 1, baie);
|
|
if (baie) {
|
|
put_bits(&s->pb, 6, s->coarse_snr_offset);
|
|
for (ch = 0; ch < s->channels; ch++) {
|
|
put_bits(&s->pb, 4, s->fine_snr_offset[ch]);
|
|
put_bits(&s->pb, 3, s->fast_gain_code[ch]);
|
|
}
|
|
}
|
|
|
|
put_bits(&s->pb, 1, 0); /* no delta bit allocation */
|
|
put_bits(&s->pb, 1, 0); /* no data to skip */
|
|
|
|
/* mantissas */
|
|
for (ch = 0; ch < s->channels; ch++) {
|
|
int b, q;
|
|
for (i = 0; i < s->nb_coefs[ch]; i++) {
|
|
q = block->qmant[ch][i];
|
|
b = block->bap[ch][i];
|
|
switch (b) {
|
|
case 0: break;
|
|
case 1: if (q != 128) put_bits(&s->pb, 5, q); break;
|
|
case 2: if (q != 128) put_bits(&s->pb, 7, q); break;
|
|
case 3: put_bits(&s->pb, 3, q); break;
|
|
case 4: if (q != 128) put_bits(&s->pb, 7, q); break;
|
|
case 14: put_bits(&s->pb, 14, q); break;
|
|
case 15: put_bits(&s->pb, 16, q); break;
|
|
default: put_bits(&s->pb, b-1, q); break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/** CRC-16 Polynomial */
|
|
#define CRC16_POLY ((1 << 0) | (1 << 2) | (1 << 15) | (1 << 16))
|
|
|
|
|
|
static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly)
|
|
{
|
|
unsigned int c;
|
|
|
|
c = 0;
|
|
while (a) {
|
|
if (a & 1)
|
|
c ^= b;
|
|
a = a >> 1;
|
|
b = b << 1;
|
|
if (b & (1 << 16))
|
|
b ^= poly;
|
|
}
|
|
return c;
|
|
}
|
|
|
|
|
|
static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly)
|
|
{
|
|
unsigned int r;
|
|
r = 1;
|
|
while (n) {
|
|
if (n & 1)
|
|
r = mul_poly(r, a, poly);
|
|
a = mul_poly(a, a, poly);
|
|
n >>= 1;
|
|
}
|
|
return r;
|
|
}
|
|
|
|
|
|
/**
|
|
* Fill the end of the frame with 0's and compute the two CRCs.
|
|
*/
|
|
static void output_frame_end(AC3EncodeContext *s)
|
|
{
|
|
const AVCRC *crc_ctx = av_crc_get_table(AV_CRC_16_ANSI);
|
|
int frame_size_58, pad_bytes, crc1, crc2, crc_inv;
|
|
uint8_t *frame;
|
|
|
|
frame_size_58 = ((s->frame_size >> 2) + (s->frame_size >> 4)) << 1;
|
|
|
|
/* pad the remainder of the frame with zeros */
|
|
flush_put_bits(&s->pb);
|
|
frame = s->pb.buf;
|
|
pad_bytes = s->frame_size - (put_bits_ptr(&s->pb) - frame) - 2;
|
|
assert(pad_bytes >= 0);
|
|
if (pad_bytes > 0)
|
|
memset(put_bits_ptr(&s->pb), 0, pad_bytes);
|
|
|
|
/* compute crc1 */
|
|
/* this is not so easy because it is at the beginning of the data... */
|
|
crc1 = av_bswap16(av_crc(crc_ctx, 0,
|
|
frame + 4, frame_size_58 - 4));
|
|
crc_inv = s->crc_inv[s->frame_size > s->frame_size_min];
|
|
crc1 = mul_poly(crc_inv, crc1, CRC16_POLY);
|
|
AV_WB16(frame + 2, crc1);
|
|
|
|
/* compute crc2 */
|
|
crc2 = av_bswap16(av_crc(crc_ctx, 0,
|
|
frame + frame_size_58,
|
|
s->frame_size - frame_size_58 - 2));
|
|
AV_WB16(frame + s->frame_size - 2, crc2);
|
|
}
|
|
|
|
|
|
/**
|
|
* Write the frame to the output bitstream.
|
|
*/
|
|
static void output_frame(AC3EncodeContext *s,
|
|
unsigned char *frame)
|
|
{
|
|
int blk;
|
|
|
|
init_put_bits(&s->pb, frame, AC3_MAX_CODED_FRAME_SIZE);
|
|
|
|
output_frame_header(s);
|
|
|
|
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++)
|
|
output_audio_block(s, blk);
|
|
|
|
output_frame_end(s);
|
|
}
|
|
|
|
|
|
/**
|
|
* Encode a single AC-3 frame.
|
|
*/
|
|
static int ac3_encode_frame(AVCodecContext *avctx,
|
|
unsigned char *frame, int buf_size, void *data)
|
|
{
|
|
AC3EncodeContext *s = avctx->priv_data;
|
|
const int16_t *samples = data;
|
|
int ret;
|
|
|
|
if (s->bit_alloc.sr_code == 1)
|
|
adjust_frame_size(s);
|
|
|
|
deinterleave_input_samples(s, samples);
|
|
|
|
apply_mdct(s);
|
|
|
|
process_exponents(s);
|
|
|
|
ret = compute_bit_allocation(s);
|
|
if (ret) {
|
|
av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
|
|
return ret;
|
|
}
|
|
|
|
quantize_mantissas(s);
|
|
|
|
output_frame(s, frame);
|
|
|
|
return s->frame_size;
|
|
}
|
|
|
|
|
|
/**
|
|
* Finalize encoding and free any memory allocated by the encoder.
|
|
*/
|
|
static av_cold int ac3_encode_close(AVCodecContext *avctx)
|
|
{
|
|
int blk, ch;
|
|
AC3EncodeContext *s = avctx->priv_data;
|
|
|
|
for (ch = 0; ch < s->channels; ch++)
|
|
av_freep(&s->planar_samples[ch]);
|
|
av_freep(&s->planar_samples);
|
|
av_freep(&s->bap_buffer);
|
|
av_freep(&s->bap1_buffer);
|
|
av_freep(&s->mdct_coef_buffer);
|
|
av_freep(&s->exp_buffer);
|
|
av_freep(&s->grouped_exp_buffer);
|
|
av_freep(&s->psd_buffer);
|
|
av_freep(&s->band_psd_buffer);
|
|
av_freep(&s->mask_buffer);
|
|
av_freep(&s->qmant_buffer);
|
|
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
|
|
AC3Block *block = &s->blocks[blk];
|
|
av_freep(&block->bap);
|
|
av_freep(&block->mdct_coef);
|
|
av_freep(&block->exp);
|
|
av_freep(&block->grouped_exp);
|
|
av_freep(&block->psd);
|
|
av_freep(&block->band_psd);
|
|
av_freep(&block->mask);
|
|
av_freep(&block->qmant);
|
|
}
|
|
|
|
mdct_end(&s->mdct);
|
|
|
|
av_freep(&avctx->coded_frame);
|
|
return 0;
|
|
}
|
|
|
|
|
|
/**
|
|
* Set channel information during initialization.
|
|
*/
|
|
static av_cold int set_channel_info(AC3EncodeContext *s, int channels,
|
|
int64_t *channel_layout)
|
|
{
|
|
int ch_layout;
|
|
|
|
if (channels < 1 || channels > AC3_MAX_CHANNELS)
|
|
return AVERROR(EINVAL);
|
|
if ((uint64_t)*channel_layout > 0x7FF)
|
|
return AVERROR(EINVAL);
|
|
ch_layout = *channel_layout;
|
|
if (!ch_layout)
|
|
ch_layout = avcodec_guess_channel_layout(channels, CODEC_ID_AC3, NULL);
|
|
if (av_get_channel_layout_nb_channels(ch_layout) != channels)
|
|
return AVERROR(EINVAL);
|
|
|
|
s->lfe_on = !!(ch_layout & AV_CH_LOW_FREQUENCY);
|
|
s->channels = channels;
|
|
s->fbw_channels = channels - s->lfe_on;
|
|
s->lfe_channel = s->lfe_on ? s->fbw_channels : -1;
|
|
if (s->lfe_on)
|
|
ch_layout -= AV_CH_LOW_FREQUENCY;
|
|
|
|
switch (ch_layout) {
|
|
case AV_CH_LAYOUT_MONO: s->channel_mode = AC3_CHMODE_MONO; break;
|
|
case AV_CH_LAYOUT_STEREO: s->channel_mode = AC3_CHMODE_STEREO; break;
|
|
case AV_CH_LAYOUT_SURROUND: s->channel_mode = AC3_CHMODE_3F; break;
|
|
case AV_CH_LAYOUT_2_1: s->channel_mode = AC3_CHMODE_2F1R; break;
|
|
case AV_CH_LAYOUT_4POINT0: s->channel_mode = AC3_CHMODE_3F1R; break;
|
|
case AV_CH_LAYOUT_QUAD:
|
|
case AV_CH_LAYOUT_2_2: s->channel_mode = AC3_CHMODE_2F2R; break;
|
|
case AV_CH_LAYOUT_5POINT0:
|
|
case AV_CH_LAYOUT_5POINT0_BACK: s->channel_mode = AC3_CHMODE_3F2R; break;
|
|
default:
|
|
return AVERROR(EINVAL);
|
|
}
|
|
|
|
s->channel_map = ff_ac3_enc_channel_map[s->channel_mode][s->lfe_on];
|
|
*channel_layout = ch_layout;
|
|
if (s->lfe_on)
|
|
*channel_layout |= AV_CH_LOW_FREQUENCY;
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
static av_cold int validate_options(AVCodecContext *avctx, AC3EncodeContext *s)
|
|
{
|
|
int i, ret;
|
|
|
|
/* validate channel layout */
|
|
if (!avctx->channel_layout) {
|
|
av_log(avctx, AV_LOG_WARNING, "No channel layout specified. The "
|
|
"encoder will guess the layout, but it "
|
|
"might be incorrect.\n");
|
|
}
|
|
ret = set_channel_info(s, avctx->channels, &avctx->channel_layout);
|
|
if (ret) {
|
|
av_log(avctx, AV_LOG_ERROR, "invalid channel layout\n");
|
|
return ret;
|
|
}
|
|
|
|
/* validate sample rate */
|
|
for (i = 0; i < 9; i++) {
|
|
if ((ff_ac3_sample_rate_tab[i / 3] >> (i % 3)) == avctx->sample_rate)
|
|
break;
|
|
}
|
|
if (i == 9) {
|
|
av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
|
|
return AVERROR(EINVAL);
|
|
}
|
|
s->sample_rate = avctx->sample_rate;
|
|
s->bit_alloc.sr_shift = i % 3;
|
|
s->bit_alloc.sr_code = i / 3;
|
|
|
|
/* validate bit rate */
|
|
for (i = 0; i < 19; i++) {
|
|
if ((ff_ac3_bitrate_tab[i] >> s->bit_alloc.sr_shift)*1000 == avctx->bit_rate)
|
|
break;
|
|
}
|
|
if (i == 19) {
|
|
av_log(avctx, AV_LOG_ERROR, "invalid bit rate\n");
|
|
return AVERROR(EINVAL);
|
|
}
|
|
s->bit_rate = avctx->bit_rate;
|
|
s->frame_size_code = i << 1;
|
|
|
|
/* validate cutoff */
|
|
if (avctx->cutoff < 0) {
|
|
av_log(avctx, AV_LOG_ERROR, "invalid cutoff frequency\n");
|
|
return AVERROR(EINVAL);
|
|
}
|
|
s->cutoff = avctx->cutoff;
|
|
if (s->cutoff > (s->sample_rate >> 1))
|
|
s->cutoff = s->sample_rate >> 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
/**
|
|
* Set bandwidth for all channels.
|
|
* The user can optionally supply a cutoff frequency. Otherwise an appropriate
|
|
* default value will be used.
|
|
*/
|
|
static av_cold void set_bandwidth(AC3EncodeContext *s)
|
|
{
|
|
int ch, bw_code;
|
|
|
|
if (s->cutoff) {
|
|
/* calculate bandwidth based on user-specified cutoff frequency */
|
|
int fbw_coeffs;
|
|
fbw_coeffs = s->cutoff * 2 * AC3_MAX_COEFS / s->sample_rate;
|
|
bw_code = av_clip((fbw_coeffs - 73) / 3, 0, 60);
|
|
} else {
|
|
/* use default bandwidth setting */
|
|
/* XXX: should compute the bandwidth according to the frame
|
|
size, so that we avoid annoying high frequency artifacts */
|
|
bw_code = 50;
|
|
}
|
|
|
|
/* set number of coefficients for each channel */
|
|
for (ch = 0; ch < s->fbw_channels; ch++) {
|
|
s->bandwidth_code[ch] = bw_code;
|
|
s->nb_coefs[ch] = bw_code * 3 + 73;
|
|
}
|
|
if (s->lfe_on)
|
|
s->nb_coefs[s->lfe_channel] = 7; /* LFE channel always has 7 coefs */
|
|
}
|
|
|
|
|
|
static av_cold int allocate_buffers(AVCodecContext *avctx)
|
|
{
|
|
int blk, ch;
|
|
AC3EncodeContext *s = avctx->priv_data;
|
|
|
|
FF_ALLOC_OR_GOTO(avctx, s->planar_samples, s->channels * sizeof(*s->planar_samples),
|
|
alloc_fail);
|
|
for (ch = 0; ch < s->channels; ch++) {
|
|
FF_ALLOCZ_OR_GOTO(avctx, s->planar_samples[ch],
|
|
(AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),
|
|
alloc_fail);
|
|
}
|
|
FF_ALLOC_OR_GOTO(avctx, s->bap_buffer, AC3_MAX_BLOCKS * s->channels *
|
|
AC3_MAX_COEFS * sizeof(*s->bap_buffer), alloc_fail);
|
|
FF_ALLOC_OR_GOTO(avctx, s->bap1_buffer, AC3_MAX_BLOCKS * s->channels *
|
|
AC3_MAX_COEFS * sizeof(*s->bap1_buffer), alloc_fail);
|
|
FF_ALLOC_OR_GOTO(avctx, s->mdct_coef_buffer, AC3_MAX_BLOCKS * s->channels *
|
|
AC3_MAX_COEFS * sizeof(*s->mdct_coef_buffer), alloc_fail);
|
|
FF_ALLOC_OR_GOTO(avctx, s->exp_buffer, AC3_MAX_BLOCKS * s->channels *
|
|
AC3_MAX_COEFS * sizeof(*s->exp_buffer), alloc_fail);
|
|
FF_ALLOC_OR_GOTO(avctx, s->grouped_exp_buffer, AC3_MAX_BLOCKS * s->channels *
|
|
128 * sizeof(*s->grouped_exp_buffer), alloc_fail);
|
|
FF_ALLOC_OR_GOTO(avctx, s->psd_buffer, AC3_MAX_BLOCKS * s->channels *
|
|
AC3_MAX_COEFS * sizeof(*s->psd_buffer), alloc_fail);
|
|
FF_ALLOC_OR_GOTO(avctx, s->band_psd_buffer, AC3_MAX_BLOCKS * s->channels *
|
|
64 * sizeof(*s->band_psd_buffer), alloc_fail);
|
|
FF_ALLOC_OR_GOTO(avctx, s->mask_buffer, AC3_MAX_BLOCKS * s->channels *
|
|
64 * sizeof(*s->mask_buffer), alloc_fail);
|
|
FF_ALLOC_OR_GOTO(avctx, s->qmant_buffer, AC3_MAX_BLOCKS * s->channels *
|
|
AC3_MAX_COEFS * sizeof(*s->qmant_buffer), alloc_fail);
|
|
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
|
|
AC3Block *block = &s->blocks[blk];
|
|
FF_ALLOC_OR_GOTO(avctx, block->bap, s->channels * sizeof(*block->bap),
|
|
alloc_fail);
|
|
FF_ALLOCZ_OR_GOTO(avctx, block->mdct_coef, s->channels * sizeof(*block->mdct_coef),
|
|
alloc_fail);
|
|
FF_ALLOCZ_OR_GOTO(avctx, block->exp, s->channels * sizeof(*block->exp),
|
|
alloc_fail);
|
|
FF_ALLOCZ_OR_GOTO(avctx, block->grouped_exp, s->channels * sizeof(*block->grouped_exp),
|
|
alloc_fail);
|
|
FF_ALLOCZ_OR_GOTO(avctx, block->psd, s->channels * sizeof(*block->psd),
|
|
alloc_fail);
|
|
FF_ALLOCZ_OR_GOTO(avctx, block->band_psd, s->channels * sizeof(*block->band_psd),
|
|
alloc_fail);
|
|
FF_ALLOCZ_OR_GOTO(avctx, block->mask, s->channels * sizeof(*block->mask),
|
|
alloc_fail);
|
|
FF_ALLOCZ_OR_GOTO(avctx, block->qmant, s->channels * sizeof(*block->qmant),
|
|
alloc_fail);
|
|
|
|
for (ch = 0; ch < s->channels; ch++) {
|
|
block->bap[ch] = &s->bap_buffer [AC3_MAX_COEFS * (blk * s->channels + ch)];
|
|
block->mdct_coef[ch] = &s->mdct_coef_buffer [AC3_MAX_COEFS * (blk * s->channels + ch)];
|
|
block->exp[ch] = &s->exp_buffer [AC3_MAX_COEFS * (blk * s->channels + ch)];
|
|
block->grouped_exp[ch] = &s->grouped_exp_buffer[128 * (blk * s->channels + ch)];
|
|
block->psd[ch] = &s->psd_buffer [AC3_MAX_COEFS * (blk * s->channels + ch)];
|
|
block->band_psd[ch] = &s->band_psd_buffer [64 * (blk * s->channels + ch)];
|
|
block->mask[ch] = &s->mask_buffer [64 * (blk * s->channels + ch)];
|
|
block->qmant[ch] = &s->qmant_buffer [AC3_MAX_COEFS * (blk * s->channels + ch)];
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
alloc_fail:
|
|
return AVERROR(ENOMEM);
|
|
}
|
|
|
|
|
|
/**
|
|
* Initialize the encoder.
|
|
*/
|
|
static av_cold int ac3_encode_init(AVCodecContext *avctx)
|
|
{
|
|
AC3EncodeContext *s = avctx->priv_data;
|
|
int ret, frame_size_58;
|
|
|
|
avctx->frame_size = AC3_FRAME_SIZE;
|
|
|
|
ac3_common_init();
|
|
|
|
ret = validate_options(avctx, s);
|
|
if (ret)
|
|
return ret;
|
|
|
|
s->bitstream_id = 8 + s->bit_alloc.sr_shift;
|
|
s->bitstream_mode = 0; /* complete main audio service */
|
|
|
|
s->frame_size_min = 2 * ff_ac3_frame_size_tab[s->frame_size_code][s->bit_alloc.sr_code];
|
|
s->bits_written = 0;
|
|
s->samples_written = 0;
|
|
s->frame_size = s->frame_size_min;
|
|
|
|
/* calculate crc_inv for both possible frame sizes */
|
|
frame_size_58 = (( s->frame_size >> 2) + ( s->frame_size >> 4)) << 1;
|
|
s->crc_inv[0] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
|
|
if (s->bit_alloc.sr_code == 1) {
|
|
frame_size_58 = (((s->frame_size+2) >> 2) + ((s->frame_size+2) >> 4)) << 1;
|
|
s->crc_inv[1] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
|
|
}
|
|
|
|
set_bandwidth(s);
|
|
|
|
exponent_init(s);
|
|
|
|
bit_alloc_init(s);
|
|
|
|
s->mdct.avctx = avctx;
|
|
ret = mdct_init(&s->mdct, 9);
|
|
if (ret)
|
|
goto init_fail;
|
|
|
|
ret = allocate_buffers(avctx);
|
|
if (ret)
|
|
goto init_fail;
|
|
|
|
avctx->coded_frame= avcodec_alloc_frame();
|
|
|
|
dsputil_init(&s->dsp, avctx);
|
|
|
|
return 0;
|
|
init_fail:
|
|
ac3_encode_close(avctx);
|
|
return ret;
|
|
}
|
|
|
|
|
|
#ifdef TEST
|
|
/*************************************************************************/
|
|
/* TEST */
|
|
|
|
#include "libavutil/lfg.h"
|
|
|
|
#define MDCT_NBITS 9
|
|
#define MDCT_SAMPLES (1 << MDCT_NBITS)
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#define FN (MDCT_SAMPLES/4)
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static void fft_test(AC3MDCTContext *mdct, AVLFG *lfg)
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{
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IComplex in[FN], in1[FN];
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int k, n, i;
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float sum_re, sum_im, a;
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for (i = 0; i < FN; i++) {
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in[i].re = av_lfg_get(lfg) % 65535 - 32767;
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in[i].im = av_lfg_get(lfg) % 65535 - 32767;
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in1[i] = in[i];
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}
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fft(mdct, in, 7);
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/* do it by hand */
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for (k = 0; k < FN; k++) {
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sum_re = 0;
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sum_im = 0;
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for (n = 0; n < FN; n++) {
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a = -2 * M_PI * (n * k) / FN;
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sum_re += in1[n].re * cos(a) - in1[n].im * sin(a);
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sum_im += in1[n].re * sin(a) + in1[n].im * cos(a);
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}
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av_log(NULL, AV_LOG_DEBUG, "%3d: %6d,%6d %6.0f,%6.0f\n",
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k, in[k].re, in[k].im, sum_re / FN, sum_im / FN);
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}
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}
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static void mdct_test(AC3MDCTContext *mdct, AVLFG *lfg)
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{
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int16_t input[MDCT_SAMPLES];
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int32_t output[AC3_MAX_COEFS];
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float input1[MDCT_SAMPLES];
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float output1[AC3_MAX_COEFS];
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float s, a, err, e, emax;
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int i, k, n;
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for (i = 0; i < MDCT_SAMPLES; i++) {
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input[i] = (av_lfg_get(lfg) % 65535 - 32767) * 9 / 10;
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input1[i] = input[i];
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}
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mdct512(mdct, output, input);
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/* do it by hand */
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for (k = 0; k < AC3_MAX_COEFS; k++) {
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s = 0;
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for (n = 0; n < MDCT_SAMPLES; n++) {
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a = (2*M_PI*(2*n+1+MDCT_SAMPLES/2)*(2*k+1) / (4 * MDCT_SAMPLES));
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s += input1[n] * cos(a);
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}
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output1[k] = -2 * s / MDCT_SAMPLES;
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}
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err = 0;
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emax = 0;
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for (i = 0; i < AC3_MAX_COEFS; i++) {
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av_log(NULL, AV_LOG_DEBUG, "%3d: %7d %7.0f\n", i, output[i], output1[i]);
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e = output[i] - output1[i];
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if (e > emax)
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emax = e;
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err += e * e;
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}
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av_log(NULL, AV_LOG_DEBUG, "err2=%f emax=%f\n", err / AC3_MAX_COEFS, emax);
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}
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int main(void)
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{
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AVLFG lfg;
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AC3MDCTContext mdct;
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mdct.avctx = NULL;
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av_log_set_level(AV_LOG_DEBUG);
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mdct_init(&mdct, 9);
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fft_test(&mdct, &lfg);
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mdct_test(&mdct, &lfg);
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return 0;
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}
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#endif /* TEST */
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AVCodec ac3_encoder = {
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"ac3",
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AVMEDIA_TYPE_AUDIO,
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CODEC_ID_AC3,
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sizeof(AC3EncodeContext),
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ac3_encode_init,
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ac3_encode_frame,
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ac3_encode_close,
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NULL,
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.sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_S16,AV_SAMPLE_FMT_NONE},
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.long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
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.channel_layouts = (const int64_t[]){
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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),
|
|
(AV_CH_LAYOUT_4POINT0 | AV_CH_LOW_FREQUENCY),
|
|
AV_CH_LAYOUT_5POINT1,
|
|
AV_CH_LAYOUT_5POINT1_BACK,
|
|
0 },
|
|
};
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