| /* |
| * 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 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_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) |
| 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[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 |
| 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 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); |
| |
| #endif /* AVCODEC_AC3DEC_H */ |
