|
- /*
- * 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 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
-
- typedef struct {
- AVClass *class; ///< class for AVOptions
- AVCodecContext *avctx; ///< parent context
- GetBitContext gbc; ///< bitstream reader
- uint8_t *input_buffer; ///< temp buffer to prevent overread
-
- ///@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
- float mul_bias; ///< scaling for float_to_int16 conversion
- ///@}
-
- ///@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
- ///@}
- } 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);
-
- void ff_ac3_downmix_c(float (*samples)[256], float (*matrix)[2],
- int out_ch, int in_ch, int len);
-
- /**
- * 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 */
|
