mirror of https://github.com/FFmpeg/FFmpeg.git
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
273 lines
14 KiB
273 lines
14 KiB
/* |
|
* Common code between the AC-3 and E-AC-3 decoders |
|
* Copyright (c) 2007 Bartlomiej Wolowiec <bartek.wolowiec@gmail.com> |
|
* |
|
* This file is part of FFmpeg. |
|
* |
|
* FFmpeg is free software; you can redistribute it and/or |
|
* modify it under the terms of the GNU Lesser General Public |
|
* License as published by the Free Software Foundation; either |
|
* version 2.1 of the License, or (at your option) any later version. |
|
* |
|
* FFmpeg is distributed in the hope that it will be useful, |
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of |
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
|
* Lesser General Public License for more details. |
|
* |
|
* You should have received a copy of the GNU Lesser General Public |
|
* License along with FFmpeg; if not, write to the Free Software |
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
|
*/ |
|
|
|
/** |
|
* @file |
|
* Common code between the AC-3 and E-AC-3 decoders. |
|
* |
|
* Summary of MDCT Coefficient Grouping: |
|
* The individual MDCT coefficient indices are often referred to in the |
|
* (E-)AC-3 specification as frequency bins. These bins are grouped together |
|
* into subbands of 12 coefficients each. The subbands are grouped together |
|
* into bands as defined in the bitstream by the band structures, which |
|
* determine the number of bands and the size of each band. The full spectrum |
|
* of 256 frequency bins is divided into 1 DC bin + 21 subbands = 253 bins. |
|
* This system of grouping coefficients is used for channel bandwidth, stereo |
|
* rematrixing, channel coupling, enhanced coupling, and spectral extension. |
|
* |
|
* +-+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+-+ |
|
* |1| |12| | [12|12|12|12] | | | | | | | | | | | | |3| |
|
* +-+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+-+ |
|
* ~~~ ~~~~ ~~~~~~~~~~~~~ ~~~ |
|
* | | | | |
|
* | | | 3 unused frequency bins--+ |
|
* | | | |
|
* | | +--1 band containing 4 subbands |
|
* | | |
|
* | +--1 subband of 12 frequency bins |
|
* | |
|
* +--DC frequency bin |
|
*/ |
|
|
|
#ifndef AVCODEC_AC3DEC_H |
|
#define AVCODEC_AC3DEC_H |
|
|
|
#include "libavutil/float_dsp.h" |
|
#include "libavutil/fixed_dsp.h" |
|
#include "libavutil/lfg.h" |
|
#include "ac3.h" |
|
#include "ac3dsp.h" |
|
#include "bswapdsp.h" |
|
#include "get_bits.h" |
|
#include "fft.h" |
|
#include "fmtconvert.h" |
|
|
|
#define AC3_OUTPUT_LFEON 8 |
|
|
|
#define SPX_MAX_BANDS 17 |
|
|
|
/** Large enough for maximum possible frame size when the specification limit is ignored */ |
|
#define AC3_FRAME_BUFFER_SIZE 32768 |
|
|
|
typedef struct AC3DecodeContext { |
|
AVClass *class; ///< class for AVOptions |
|
AVCodecContext *avctx; ///< parent context |
|
GetBitContext gbc; ///< bitstream reader |
|
|
|
///@name Bit stream information |
|
///@{ |
|
int frame_type; ///< frame type (strmtyp) |
|
int substreamid; ///< substream identification |
|
int frame_size; ///< current frame size, in bytes |
|
int bit_rate; ///< stream bit rate, in bits-per-second |
|
int sample_rate; ///< sample frequency, in Hz |
|
int num_blocks; ///< number of audio blocks |
|
int bitstream_id; ///< bitstream id (bsid) |
|
int bitstream_mode; ///< bitstream mode (bsmod) |
|
int channel_mode; ///< channel mode (acmod) |
|
int lfe_on; ///< lfe channel in use |
|
int dialog_normalization[2]; ///< dialog level in dBFS (dialnorm) |
|
int compression_exists[2]; ///< compression field is valid for frame (compre) |
|
int compression_gain[2]; ///< gain to apply for heavy compression (compr) |
|
int channel_map; ///< custom channel map |
|
int preferred_downmix; ///< Preferred 2-channel downmix mode (dmixmod) |
|
int center_mix_level; ///< Center mix level index |
|
int center_mix_level_ltrt; ///< Center mix level index for Lt/Rt (ltrtcmixlev) |
|
int surround_mix_level; ///< Surround mix level index |
|
int surround_mix_level_ltrt; ///< Surround mix level index for Lt/Rt (ltrtsurmixlev) |
|
int lfe_mix_level_exists; ///< indicates if lfemixlevcod is specified (lfemixlevcode) |
|
int lfe_mix_level; ///< LFE mix level index (lfemixlevcod) |
|
int eac3; ///< indicates if current frame is E-AC-3 |
|
int eac3_frame_dependent_found; ///< bitstream has E-AC-3 dependent frame(s) |
|
int eac3_subsbtreamid_found; ///< bitstream has E-AC-3 additional substream(s) |
|
int dolby_surround_mode; ///< dolby surround mode (dsurmod) |
|
int dolby_surround_ex_mode; ///< dolby surround ex mode (dsurexmod) |
|
int dolby_headphone_mode; ///< dolby headphone mode (dheadphonmod) |
|
///@} |
|
|
|
int preferred_stereo_downmix; |
|
float ltrt_center_mix_level; |
|
float ltrt_surround_mix_level; |
|
float loro_center_mix_level; |
|
float loro_surround_mix_level; |
|
int target_level; ///< target level in dBFS |
|
float level_gain[2]; |
|
|
|
///@name Frame syntax parameters |
|
int snr_offset_strategy; ///< SNR offset strategy (snroffststr) |
|
int block_switch_syntax; ///< block switch syntax enabled (blkswe) |
|
int dither_flag_syntax; ///< dither flag syntax enabled (dithflage) |
|
int bit_allocation_syntax; ///< bit allocation model syntax enabled (bamode) |
|
int fast_gain_syntax; ///< fast gain codes enabled (frmfgaincode) |
|
int dba_syntax; ///< delta bit allocation syntax enabled (dbaflde) |
|
int skip_syntax; ///< skip field syntax enabled (skipflde) |
|
///@} |
|
|
|
///@name Standard coupling |
|
int cpl_in_use[AC3_MAX_BLOCKS]; ///< coupling in use (cplinu) |
|
int cpl_strategy_exists[AC3_MAX_BLOCKS];///< coupling strategy exists (cplstre) |
|
int channel_in_cpl[AC3_MAX_CHANNELS]; ///< channel in coupling (chincpl) |
|
int phase_flags_in_use; ///< phase flags in use (phsflginu) |
|
int phase_flags[AC3_MAX_CPL_BANDS]; ///< phase flags (phsflg) |
|
int num_cpl_bands; ///< number of coupling bands (ncplbnd) |
|
uint8_t cpl_band_struct[AC3_MAX_CPL_BANDS]; |
|
uint8_t cpl_band_sizes[AC3_MAX_CPL_BANDS]; ///< number of coeffs in each coupling band |
|
int firstchincpl; ///< first channel in coupling |
|
int first_cpl_coords[AC3_MAX_CHANNELS]; ///< first coupling coordinates states (firstcplcos) |
|
int cpl_coords[AC3_MAX_CHANNELS][AC3_MAX_CPL_BANDS]; ///< coupling coordinates (cplco) |
|
///@} |
|
|
|
///@name Spectral extension |
|
///@{ |
|
int spx_in_use; ///< spectral extension in use (spxinu) |
|
uint8_t channel_uses_spx[AC3_MAX_CHANNELS]; ///< channel uses spectral extension (chinspx) |
|
int8_t spx_atten_code[AC3_MAX_CHANNELS]; ///< spx attenuation code (spxattencod) |
|
int spx_src_start_freq; ///< spx start frequency bin |
|
int spx_dst_end_freq; ///< spx end frequency bin |
|
int spx_dst_start_freq; ///< spx starting frequency bin for copying (copystartmant) |
|
///< the copy region ends at the start of the spx region. |
|
int num_spx_bands; ///< number of spx bands (nspxbnds) |
|
uint8_t spx_band_struct[SPX_MAX_BANDS]; |
|
uint8_t spx_band_sizes[SPX_MAX_BANDS]; ///< number of bins in each spx band |
|
uint8_t first_spx_coords[AC3_MAX_CHANNELS]; ///< first spx coordinates states (firstspxcos) |
|
INTFLOAT spx_noise_blend[AC3_MAX_CHANNELS][SPX_MAX_BANDS]; ///< spx noise blending factor (nblendfact) |
|
INTFLOAT spx_signal_blend[AC3_MAX_CHANNELS][SPX_MAX_BANDS];///< spx signal blending factor (sblendfact) |
|
///@} |
|
|
|
///@name Adaptive hybrid transform |
|
int channel_uses_aht[AC3_MAX_CHANNELS]; ///< channel AHT in use (chahtinu) |
|
int pre_mantissa[AC3_MAX_CHANNELS][AC3_MAX_COEFS][AC3_MAX_BLOCKS]; ///< pre-IDCT mantissas |
|
///@} |
|
|
|
///@name Channel |
|
int fbw_channels; ///< number of full-bandwidth channels |
|
int channels; ///< number of total channels |
|
int lfe_ch; ///< index of LFE channel |
|
SHORTFLOAT *downmix_coeffs[2]; ///< stereo downmix coefficients |
|
int downmixed; ///< indicates if coeffs are currently downmixed |
|
int output_mode; ///< output channel configuration |
|
int out_channels; ///< number of output channels |
|
///@} |
|
|
|
///@name Dynamic range |
|
INTFLOAT dynamic_range[2]; ///< dynamic range |
|
INTFLOAT drc_scale; ///< percentage of dynamic range compression to be applied |
|
int heavy_compression; ///< apply heavy compression |
|
INTFLOAT heavy_dynamic_range[2]; ///< heavy dynamic range compression |
|
///@} |
|
|
|
///@name Bandwidth |
|
int start_freq[AC3_MAX_CHANNELS]; ///< start frequency bin (strtmant) |
|
int end_freq[AC3_MAX_CHANNELS]; ///< end frequency bin (endmant) |
|
///@} |
|
|
|
///@name Consistent noise generation |
|
int consistent_noise_generation; ///< seed noise generation with AC-3 frame on decode |
|
///@} |
|
|
|
///@name Rematrixing |
|
int num_rematrixing_bands; ///< number of rematrixing bands (nrematbnd) |
|
int rematrixing_flags[4]; ///< rematrixing flags (rematflg) |
|
///@} |
|
|
|
///@name Exponents |
|
int num_exp_groups[AC3_MAX_CHANNELS]; ///< Number of exponent groups (nexpgrp) |
|
int8_t dexps[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< decoded exponents |
|
int exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS]; ///< exponent strategies (expstr) |
|
///@} |
|
|
|
///@name Bit allocation |
|
AC3BitAllocParameters bit_alloc_params; ///< bit allocation parameters |
|
int first_cpl_leak; ///< first coupling leak state (firstcplleak) |
|
int snr_offset[AC3_MAX_CHANNELS]; ///< signal-to-noise ratio offsets (snroffst) |
|
int fast_gain[AC3_MAX_CHANNELS]; ///< fast gain values/SMR's (fgain) |
|
uint8_t bap[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< bit allocation pointers |
|
int16_t psd[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< scaled exponents |
|
int16_t band_psd[AC3_MAX_CHANNELS][AC3_CRITICAL_BANDS]; ///< interpolated exponents |
|
int16_t mask[AC3_MAX_CHANNELS][AC3_CRITICAL_BANDS]; ///< masking curve values |
|
int dba_mode[AC3_MAX_CHANNELS]; ///< delta bit allocation mode |
|
int dba_nsegs[AC3_MAX_CHANNELS]; ///< number of delta segments |
|
uint8_t dba_offsets[AC3_MAX_CHANNELS][8]; ///< delta segment offsets |
|
uint8_t dba_lengths[AC3_MAX_CHANNELS][8]; ///< delta segment lengths |
|
uint8_t dba_values[AC3_MAX_CHANNELS][8]; ///< delta values for each segment |
|
///@} |
|
|
|
///@name Zero-mantissa dithering |
|
int dither_flag[AC3_MAX_CHANNELS]; ///< dither flags (dithflg) |
|
AVLFG dith_state; ///< for dither generation |
|
///@} |
|
|
|
///@name IMDCT |
|
int block_switch[AC3_MAX_CHANNELS]; ///< block switch flags (blksw) |
|
FFTContext imdct_512; ///< for 512 sample IMDCT |
|
FFTContext imdct_256; ///< for 256 sample IMDCT |
|
///@} |
|
|
|
///@name Optimization |
|
BswapDSPContext bdsp; |
|
#if USE_FIXED |
|
AVFixedDSPContext *fdsp; |
|
#else |
|
AVFloatDSPContext *fdsp; |
|
#endif |
|
AC3DSPContext ac3dsp; |
|
FmtConvertContext fmt_conv; ///< optimized conversion functions |
|
///@} |
|
|
|
SHORTFLOAT *outptr[AC3_MAX_CHANNELS]; |
|
INTFLOAT *xcfptr[AC3_MAX_CHANNELS]; |
|
INTFLOAT *dlyptr[AC3_MAX_CHANNELS]; |
|
|
|
///@name Aligned arrays |
|
DECLARE_ALIGNED(16, int, fixed_coeffs)[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< fixed-point transform coefficients |
|
DECLARE_ALIGNED(32, INTFLOAT, transform_coeffs)[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< transform coefficients |
|
DECLARE_ALIGNED(32, INTFLOAT, delay)[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]; ///< delay - added to the next block |
|
DECLARE_ALIGNED(32, INTFLOAT, window)[AC3_BLOCK_SIZE]; ///< window coefficients |
|
DECLARE_ALIGNED(32, INTFLOAT, tmp_output)[AC3_BLOCK_SIZE]; ///< temporary storage for output before windowing |
|
DECLARE_ALIGNED(32, SHORTFLOAT, output)[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]; ///< output after imdct transform and windowing |
|
DECLARE_ALIGNED(32, uint8_t, input_buffer)[AC3_FRAME_BUFFER_SIZE + AV_INPUT_BUFFER_PADDING_SIZE]; ///< temp buffer to prevent overread |
|
///@} |
|
} AC3DecodeContext; |
|
|
|
/** |
|
* Parse the E-AC-3 frame header. |
|
* This parses both the bit stream info and audio frame header. |
|
*/ |
|
static int ff_eac3_parse_header(AC3DecodeContext *s); |
|
|
|
/** |
|
* Decode mantissas in a single channel for the entire frame. |
|
* This is used when AHT mode is enabled. |
|
*/ |
|
static void ff_eac3_decode_transform_coeffs_aht_ch(AC3DecodeContext *s, int ch); |
|
|
|
/** |
|
* Apply spectral extension to each channel by copying lower frequency |
|
* coefficients to higher frequency bins and applying side information to |
|
* approximate the original high frequency signal. |
|
*/ |
|
static void ff_eac3_apply_spectral_extension(AC3DecodeContext *s); |
|
|
|
#if (!USE_FIXED) |
|
extern float ff_ac3_heavy_dynamic_range_tab[256]; |
|
#endif |
|
|
|
#endif /* AVCODEC_AC3DEC_H */
|
|
|