/* * Common code between the AC-3 and E-AC-3 decoders * Copyright (c) 2007 Bartlomiej Wolowiec * * This file is part of Libav. * * Libav 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. * * Libav 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 Libav; 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/lfg.h" #include "ac3.h" #include "ac3dsp.h" #include "get_bits.h" #include "dsputil.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 AVFrame frame; ///< AVFrame for decoded output 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_mode; ///< bitstream mode (bsmod) int channel_mode; ///< channel mode (acmod) int channel_layout; ///< channel layout int lfe_on; ///< lfe channel in use int channel_map; ///< custom channel map int center_mix_level; ///< Center mix level index int surround_mix_level; ///< Surround mix level index int eac3; ///< indicates if current frame is E-AC-3 ///@} ///@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_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_sizes[SPX_MAX_BANDS]; ///< number of bins in each spx band uint8_t first_spx_coords[AC3_MAX_CHANNELS]; ///< first spx coordinates states (firstspxcos) float spx_noise_blend[AC3_MAX_CHANNELS][SPX_MAX_BANDS]; ///< spx noise blending factor (nblendfact) float 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 float downmix_coeffs[AC3_MAX_CHANNELS][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 float dynamic_range[2]; ///< dynamic range float drc_scale; ///< percentage of dynamic range compression to be applied ///@} ///@name Bandwidth int start_freq[AC3_MAX_CHANNELS]; ///< start frequency bin (strtmant) int end_freq[AC3_MAX_CHANNELS]; ///< end frequency bin (endmant) ///@} ///@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 DSPContext dsp; ///< for optimization AC3DSPContext ac3dsp; FmtConvertContext fmt_conv; ///< optimized conversion functions ///@} ///@name Aligned arrays DECLARE_ALIGNED(16, int, fixed_coeffs)[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< fixed-point transform coefficients DECLARE_ALIGNED(32, float, transform_coeffs)[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< transform coefficients DECLARE_ALIGNED(32, float, delay)[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]; ///< delay - added to the next block DECLARE_ALIGNED(32, float, window)[AC3_BLOCK_SIZE]; ///< window coefficients DECLARE_ALIGNED(32, float, tmp_output)[AC3_BLOCK_SIZE]; ///< temporary storage for output before windowing DECLARE_ALIGNED(32, float, output)[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]; ///< output after imdct transform and windowing DECLARE_ALIGNED(32, uint8_t, input_buffer)[AC3_FRAME_BUFFER_SIZE + FF_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. */ 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. */ 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. */ void ff_eac3_apply_spectral_extension(AC3DecodeContext *s); #endif /* AVCODEC_AC3DEC_H */