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239 lines
12 KiB
239 lines
12 KiB
/* |
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* Common code between the AC-3 and E-AC-3 decoders |
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* Copyright (c) 2007 Bartlomiej Wolowiec <bartek.wolowiec@gmail.com> |
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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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* Common code between the AC-3 and E-AC-3 decoders. |
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* |
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* Summary of MDCT Coefficient Grouping: |
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* The individual MDCT coefficient indices are often referred to in the |
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* (E-)AC-3 specification as frequency bins. These bins are grouped together |
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* into subbands of 12 coefficients each. The subbands are grouped together |
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* into bands as defined in the bitstream by the band structures, which |
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* determine the number of bands and the size of each band. The full spectrum |
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* of 256 frequency bins is divided into 1 DC bin + 21 subbands = 253 bins. |
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* This system of grouping coefficients is used for channel bandwidth, stereo |
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* rematrixing, channel coupling, enhanced coupling, and spectral extension. |
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* |
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* +-+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+-+ |
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* |1| |12| | [12|12|12|12] | | | | | | | | | | | | |3| |
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* +-+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+-+ |
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* ~~~ ~~~~ ~~~~~~~~~~~~~ ~~~ |
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* | | | | |
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* | | | 3 unused frequency bins--+ |
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* | | | |
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* | | +--1 band containing 4 subbands |
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* | | |
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* | +--1 subband of 12 frequency bins |
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* | |
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* +--DC frequency bin |
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*/ |
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#ifndef AVCODEC_AC3DEC_H |
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#define AVCODEC_AC3DEC_H |
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#include "libavutil/lfg.h" |
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#include "ac3.h" |
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#include "ac3dsp.h" |
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#include "get_bits.h" |
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#include "dsputil.h" |
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#include "fft.h" |
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#include "fmtconvert.h" |
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#define AC3_OUTPUT_LFEON 8 |
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#define SPX_MAX_BANDS 17 |
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/** Large enough for maximum possible frame size when the specification limit is ignored */ |
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#define AC3_FRAME_BUFFER_SIZE 32768 |
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typedef struct { |
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AVClass *class; ///< class for AVOptions |
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AVCodecContext *avctx; ///< parent context |
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GetBitContext gbc; ///< bitstream reader |
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///@name Bit stream information |
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///@{ |
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int frame_type; ///< frame type (strmtyp) |
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int substreamid; ///< substream identification |
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int frame_size; ///< current frame size, in bytes |
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int bit_rate; ///< stream bit rate, in bits-per-second |
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int sample_rate; ///< sample frequency, in Hz |
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int num_blocks; ///< number of audio blocks |
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int bitstream_mode; ///< bitstream mode (bsmod) |
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int channel_mode; ///< channel mode (acmod) |
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int channel_layout; ///< channel layout |
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int lfe_on; ///< lfe channel in use |
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int channel_map; ///< custom channel map |
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int center_mix_level; ///< Center mix level index |
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int surround_mix_level; ///< Surround mix level index |
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int eac3; ///< indicates if current frame is E-AC-3 |
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///@} |
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int preferred_stereo_downmix; |
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float ltrt_center_mix_level; |
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float ltrt_surround_mix_level; |
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float loro_center_mix_level; |
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float loro_surround_mix_level; |
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///@name Frame syntax parameters |
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int snr_offset_strategy; ///< SNR offset strategy (snroffststr) |
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int block_switch_syntax; ///< block switch syntax enabled (blkswe) |
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int dither_flag_syntax; ///< dither flag syntax enabled (dithflage) |
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int bit_allocation_syntax; ///< bit allocation model syntax enabled (bamode) |
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int fast_gain_syntax; ///< fast gain codes enabled (frmfgaincode) |
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int dba_syntax; ///< delta bit allocation syntax enabled (dbaflde) |
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int skip_syntax; ///< skip field syntax enabled (skipflde) |
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///@} |
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///@name Standard coupling |
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int cpl_in_use[AC3_MAX_BLOCKS]; ///< coupling in use (cplinu) |
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int cpl_strategy_exists[AC3_MAX_BLOCKS];///< coupling strategy exists (cplstre) |
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int channel_in_cpl[AC3_MAX_CHANNELS]; ///< channel in coupling (chincpl) |
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int phase_flags_in_use; ///< phase flags in use (phsflginu) |
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int phase_flags[AC3_MAX_CPL_BANDS]; ///< phase flags (phsflg) |
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int num_cpl_bands; ///< number of coupling bands (ncplbnd) |
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uint8_t cpl_band_sizes[AC3_MAX_CPL_BANDS]; ///< number of coeffs in each coupling band |
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int firstchincpl; ///< first channel in coupling |
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int first_cpl_coords[AC3_MAX_CHANNELS]; ///< first coupling coordinates states (firstcplcos) |
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int cpl_coords[AC3_MAX_CHANNELS][AC3_MAX_CPL_BANDS]; ///< coupling coordinates (cplco) |
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///@} |
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///@name Spectral extension |
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///@{ |
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int spx_in_use; ///< spectral extension in use (spxinu) |
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uint8_t channel_uses_spx[AC3_MAX_CHANNELS]; ///< channel uses spectral extension (chinspx) |
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int8_t spx_atten_code[AC3_MAX_CHANNELS]; ///< spx attenuation code (spxattencod) |
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int spx_src_start_freq; ///< spx start frequency bin |
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int spx_dst_end_freq; ///< spx end frequency bin |
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int spx_dst_start_freq; ///< spx starting frequency bin for copying (copystartmant) |
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///< the copy region ends at the start of the spx region. |
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int num_spx_bands; ///< number of spx bands (nspxbnds) |
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uint8_t spx_band_sizes[SPX_MAX_BANDS]; ///< number of bins in each spx band |
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uint8_t first_spx_coords[AC3_MAX_CHANNELS]; ///< first spx coordinates states (firstspxcos) |
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float spx_noise_blend[AC3_MAX_CHANNELS][SPX_MAX_BANDS]; ///< spx noise blending factor (nblendfact) |
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float spx_signal_blend[AC3_MAX_CHANNELS][SPX_MAX_BANDS];///< spx signal blending factor (sblendfact) |
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///@} |
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///@name Adaptive hybrid transform |
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int channel_uses_aht[AC3_MAX_CHANNELS]; ///< channel AHT in use (chahtinu) |
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int pre_mantissa[AC3_MAX_CHANNELS][AC3_MAX_COEFS][AC3_MAX_BLOCKS]; ///< pre-IDCT mantissas |
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///@} |
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///@name Channel |
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int fbw_channels; ///< number of full-bandwidth channels |
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int channels; ///< number of total channels |
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int lfe_ch; ///< index of LFE channel |
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float downmix_coeffs[AC3_MAX_CHANNELS][2]; ///< stereo downmix coefficients |
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int downmixed; ///< indicates if coeffs are currently downmixed |
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int output_mode; ///< output channel configuration |
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int out_channels; ///< number of output channels |
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///@} |
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///@name Dynamic range |
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float dynamic_range[2]; ///< dynamic range |
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float drc_scale; ///< percentage of dynamic range compression to be applied |
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///@} |
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///@name Bandwidth |
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int start_freq[AC3_MAX_CHANNELS]; ///< start frequency bin (strtmant) |
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int end_freq[AC3_MAX_CHANNELS]; ///< end frequency bin (endmant) |
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///@} |
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///@name Rematrixing |
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int num_rematrixing_bands; ///< number of rematrixing bands (nrematbnd) |
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int rematrixing_flags[4]; ///< rematrixing flags (rematflg) |
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///@} |
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///@name Exponents |
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int num_exp_groups[AC3_MAX_CHANNELS]; ///< Number of exponent groups (nexpgrp) |
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int8_t dexps[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< decoded exponents |
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int exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS]; ///< exponent strategies (expstr) |
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///@} |
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///@name Bit allocation |
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AC3BitAllocParameters bit_alloc_params; ///< bit allocation parameters |
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int first_cpl_leak; ///< first coupling leak state (firstcplleak) |
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int snr_offset[AC3_MAX_CHANNELS]; ///< signal-to-noise ratio offsets (snroffst) |
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int fast_gain[AC3_MAX_CHANNELS]; ///< fast gain values/SMR's (fgain) |
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uint8_t bap[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< bit allocation pointers |
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int16_t psd[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< scaled exponents |
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int16_t band_psd[AC3_MAX_CHANNELS][AC3_CRITICAL_BANDS]; ///< interpolated exponents |
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int16_t mask[AC3_MAX_CHANNELS][AC3_CRITICAL_BANDS]; ///< masking curve values |
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int dba_mode[AC3_MAX_CHANNELS]; ///< delta bit allocation mode |
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int dba_nsegs[AC3_MAX_CHANNELS]; ///< number of delta segments |
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uint8_t dba_offsets[AC3_MAX_CHANNELS][8]; ///< delta segment offsets |
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uint8_t dba_lengths[AC3_MAX_CHANNELS][8]; ///< delta segment lengths |
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uint8_t dba_values[AC3_MAX_CHANNELS][8]; ///< delta values for each segment |
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///@} |
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///@name Zero-mantissa dithering |
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int dither_flag[AC3_MAX_CHANNELS]; ///< dither flags (dithflg) |
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AVLFG dith_state; ///< for dither generation |
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///@} |
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///@name IMDCT |
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int block_switch[AC3_MAX_CHANNELS]; ///< block switch flags (blksw) |
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FFTContext imdct_512; ///< for 512 sample IMDCT |
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FFTContext imdct_256; ///< for 256 sample IMDCT |
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///@} |
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///@name Optimization |
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DSPContext dsp; ///< for optimization |
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AC3DSPContext ac3dsp; |
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FmtConvertContext fmt_conv; ///< optimized conversion functions |
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float mul_bias; ///< scaling for float_to_int16 conversion |
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///@} |
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///@name Aligned arrays |
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DECLARE_ALIGNED(16, int, fixed_coeffs)[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< fixed-point transform coefficients |
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DECLARE_ALIGNED(32, float, transform_coeffs)[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< transform coefficients |
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DECLARE_ALIGNED(32, float, delay)[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]; ///< delay - added to the next block |
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DECLARE_ALIGNED(32, float, window)[AC3_BLOCK_SIZE]; ///< window coefficients |
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DECLARE_ALIGNED(32, float, tmp_output)[AC3_BLOCK_SIZE]; ///< temporary storage for output before windowing |
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DECLARE_ALIGNED(32, float, output)[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]; ///< output after imdct transform and windowing |
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DECLARE_ALIGNED(32, uint8_t, input_buffer)[AC3_FRAME_BUFFER_SIZE + FF_INPUT_BUFFER_PADDING_SIZE]; ///< temp buffer to prevent overread |
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///@} |
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} AC3DecodeContext; |
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/** |
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* Parse the E-AC-3 frame header. |
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* This parses both the bit stream info and audio frame header. |
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*/ |
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int ff_eac3_parse_header(AC3DecodeContext *s); |
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/** |
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* Decode mantissas in a single channel for the entire frame. |
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* This is used when AHT mode is enabled. |
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*/ |
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void ff_eac3_decode_transform_coeffs_aht_ch(AC3DecodeContext *s, int ch); |
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void ff_ac3_downmix_c(float (*samples)[256], float (*matrix)[2], |
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int out_ch, int in_ch, int len); |
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/** |
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* Apply spectral extension to each channel by copying lower frequency |
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* coefficients to higher frequency bins and applying side information to |
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* approximate the original high frequency signal. |
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*/ |
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void ff_eac3_apply_spectral_extension(AC3DecodeContext *s); |
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#endif /* AVCODEC_AC3DEC_H */
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