2 * Common code between the AC-3 and E-AC-3 decoders
3 * Copyright (c) 2007 Bartlomiej Wolowiec <bartek.wolowiec@gmail.com>
5 * This file is part of Libav.
7 * Libav is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
12 * Libav is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with Libav; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 * Common code between the AC-3 and E-AC-3 decoders.
26 * Summary of MDCT Coefficient Grouping:
27 * The individual MDCT coefficient indices are often referred to in the
28 * (E-)AC-3 specification as frequency bins. These bins are grouped together
29 * into subbands of 12 coefficients each. The subbands are grouped together
30 * into bands as defined in the bitstream by the band structures, which
31 * determine the number of bands and the size of each band. The full spectrum
32 * of 256 frequency bins is divided into 1 DC bin + 21 subbands = 253 bins.
33 * This system of grouping coefficients is used for channel bandwidth, stereo
34 * rematrixing, channel coupling, enhanced coupling, and spectral extension.
36 * +-+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+-+
37 * |1| |12| | [12|12|12|12] | | | | | | | | | | | | |3|
38 * +-+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+-+
39 * ~~~ ~~~~ ~~~~~~~~~~~~~ ~~~
41 * | | | 3 unused frequency bins--+
43 * | | +--1 band containing 4 subbands
45 * | +--1 subband of 12 frequency bins
50 #ifndef AVCODEC_AC3DEC_H
51 #define AVCODEC_AC3DEC_H
53 #include "libavutil/lfg.h"
59 #include "fmtconvert.h"
61 #define AC3_OUTPUT_LFEON 8
63 #define SPX_MAX_BANDS 17
66 AVCodecContext *avctx; ///< parent context
67 GetBitContext gbc; ///< bitstream reader
68 uint8_t *input_buffer; ///< temp buffer to prevent overread
70 ///@defgroup bsi bit stream information
72 int frame_type; ///< frame type (strmtyp)
73 int substreamid; ///< substream identification
74 int frame_size; ///< current frame size, in bytes
75 int bit_rate; ///< stream bit rate, in bits-per-second
76 int sample_rate; ///< sample frequency, in Hz
77 int num_blocks; ///< number of audio blocks
78 int bitstream_mode; ///< bitstream mode (bsmod)
79 int channel_mode; ///< channel mode (acmod)
80 int channel_layout; ///< channel layout
81 int lfe_on; ///< lfe channel in use
82 int channel_map; ///< custom channel map
83 int center_mix_level; ///< Center mix level index
84 int surround_mix_level; ///< Surround mix level index
85 int eac3; ///< indicates if current frame is E-AC-3
88 ///@defgroup audfrm frame syntax parameters
89 int snr_offset_strategy; ///< SNR offset strategy (snroffststr)
90 int block_switch_syntax; ///< block switch syntax enabled (blkswe)
91 int dither_flag_syntax; ///< dither flag syntax enabled (dithflage)
92 int bit_allocation_syntax; ///< bit allocation model syntax enabled (bamode)
93 int fast_gain_syntax; ///< fast gain codes enabled (frmfgaincode)
94 int dba_syntax; ///< delta bit allocation syntax enabled (dbaflde)
95 int skip_syntax; ///< skip field syntax enabled (skipflde)
98 ///@defgroup cpl standard coupling
99 int cpl_in_use[AC3_MAX_BLOCKS]; ///< coupling in use (cplinu)
100 int cpl_strategy_exists[AC3_MAX_BLOCKS];///< coupling strategy exists (cplstre)
101 int channel_in_cpl[AC3_MAX_CHANNELS]; ///< channel in coupling (chincpl)
102 int phase_flags_in_use; ///< phase flags in use (phsflginu)
103 int phase_flags[AC3_MAX_CPL_BANDS]; ///< phase flags (phsflg)
104 int num_cpl_bands; ///< number of coupling bands (ncplbnd)
105 uint8_t cpl_band_sizes[AC3_MAX_CPL_BANDS]; ///< number of coeffs in each coupling band
106 int firstchincpl; ///< first channel in coupling
107 int first_cpl_coords[AC3_MAX_CHANNELS]; ///< first coupling coordinates states (firstcplcos)
108 int cpl_coords[AC3_MAX_CHANNELS][AC3_MAX_CPL_BANDS]; ///< coupling coordinates (cplco)
111 ///@defgroup spx spectral extension
113 int spx_in_use; ///< spectral extension in use (spxinu)
114 uint8_t channel_uses_spx[AC3_MAX_CHANNELS]; ///< channel uses spectral extension (chinspx)
115 int8_t spx_atten_code[AC3_MAX_CHANNELS]; ///< spx attenuation code (spxattencod)
116 int spx_src_start_freq; ///< spx start frequency bin
117 int spx_dst_end_freq; ///< spx end frequency bin
118 int spx_dst_start_freq; ///< spx starting frequency bin for copying (copystartmant)
119 ///< the copy region ends at the start of the spx region.
120 int num_spx_bands; ///< number of spx bands (nspxbnds)
121 uint8_t spx_band_sizes[SPX_MAX_BANDS]; ///< number of bins in each spx band
122 uint8_t first_spx_coords[AC3_MAX_CHANNELS]; ///< first spx coordinates states (firstspxcos)
123 float spx_noise_blend[AC3_MAX_CHANNELS][SPX_MAX_BANDS]; ///< spx noise blending factor (nblendfact)
124 float spx_signal_blend[AC3_MAX_CHANNELS][SPX_MAX_BANDS];///< spx signal blending factor (sblendfact)
127 ///@defgroup aht adaptive hybrid transform
128 int channel_uses_aht[AC3_MAX_CHANNELS]; ///< channel AHT in use (chahtinu)
129 int pre_mantissa[AC3_MAX_CHANNELS][AC3_MAX_COEFS][AC3_MAX_BLOCKS]; ///< pre-IDCT mantissas
132 ///@defgroup channel channel
133 int fbw_channels; ///< number of full-bandwidth channels
134 int channels; ///< number of total channels
135 int lfe_ch; ///< index of LFE channel
136 float downmix_coeffs[AC3_MAX_CHANNELS][2]; ///< stereo downmix coefficients
137 int downmixed; ///< indicates if coeffs are currently downmixed
138 int output_mode; ///< output channel configuration
139 int out_channels; ///< number of output channels
142 ///@defgroup dynrng dynamic range
143 float dynamic_range[2]; ///< dynamic range
146 ///@defgroup bandwidth bandwidth
147 int start_freq[AC3_MAX_CHANNELS]; ///< start frequency bin (strtmant)
148 int end_freq[AC3_MAX_CHANNELS]; ///< end frequency bin (endmant)
151 ///@defgroup rematrixing rematrixing
152 int num_rematrixing_bands; ///< number of rematrixing bands (nrematbnd)
153 int rematrixing_flags[4]; ///< rematrixing flags (rematflg)
156 ///@defgroup exponents exponents
157 int num_exp_groups[AC3_MAX_CHANNELS]; ///< Number of exponent groups (nexpgrp)
158 int8_t dexps[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< decoded exponents
159 int exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS]; ///< exponent strategies (expstr)
162 ///@defgroup bitalloc bit allocation
163 AC3BitAllocParameters bit_alloc_params; ///< bit allocation parameters
164 int first_cpl_leak; ///< first coupling leak state (firstcplleak)
165 int snr_offset[AC3_MAX_CHANNELS]; ///< signal-to-noise ratio offsets (snroffst)
166 int fast_gain[AC3_MAX_CHANNELS]; ///< fast gain values/SMR's (fgain)
167 uint8_t bap[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< bit allocation pointers
168 int16_t psd[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< scaled exponents
169 int16_t band_psd[AC3_MAX_CHANNELS][AC3_CRITICAL_BANDS]; ///< interpolated exponents
170 int16_t mask[AC3_MAX_CHANNELS][AC3_CRITICAL_BANDS]; ///< masking curve values
171 int dba_mode[AC3_MAX_CHANNELS]; ///< delta bit allocation mode
172 int dba_nsegs[AC3_MAX_CHANNELS]; ///< number of delta segments
173 uint8_t dba_offsets[AC3_MAX_CHANNELS][8]; ///< delta segment offsets
174 uint8_t dba_lengths[AC3_MAX_CHANNELS][8]; ///< delta segment lengths
175 uint8_t dba_values[AC3_MAX_CHANNELS][8]; ///< delta values for each segment
178 ///@defgroup dithering zero-mantissa dithering
179 int dither_flag[AC3_MAX_CHANNELS]; ///< dither flags (dithflg)
180 AVLFG dith_state; ///< for dither generation
183 ///@defgroup imdct IMDCT
184 int block_switch[AC3_MAX_CHANNELS]; ///< block switch flags (blksw)
185 FFTContext imdct_512; ///< for 512 sample IMDCT
186 FFTContext imdct_256; ///< for 256 sample IMDCT
189 ///@defgroup opt optimization
190 DSPContext dsp; ///< for optimization
191 AC3DSPContext ac3dsp;
192 FmtConvertContext fmt_conv; ///< optimized conversion functions
193 float mul_bias; ///< scaling for float_to_int16 conversion
196 ///@defgroup arrays aligned arrays
197 DECLARE_ALIGNED(16, int, fixed_coeffs)[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< fixed-point transform coefficients
198 DECLARE_ALIGNED(32, float, transform_coeffs)[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< transform coefficients
199 DECLARE_ALIGNED(32, float, delay)[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]; ///< delay - added to the next block
200 DECLARE_ALIGNED(32, float, window)[AC3_BLOCK_SIZE]; ///< window coefficients
201 DECLARE_ALIGNED(32, float, tmp_output)[AC3_BLOCK_SIZE]; ///< temporary storage for output before windowing
202 DECLARE_ALIGNED(32, float, output)[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]; ///< output after imdct transform and windowing
207 * Parse the E-AC-3 frame header.
208 * This parses both the bit stream info and audio frame header.
210 int ff_eac3_parse_header(AC3DecodeContext *s);
213 * Decode mantissas in a single channel for the entire frame.
214 * This is used when AHT mode is enabled.
216 void ff_eac3_decode_transform_coeffs_aht_ch(AC3DecodeContext *s, int ch);
218 void ff_ac3_downmix_c(float (*samples)[256], float (*matrix)[2],
219 int out_ch, int in_ch, int len);
222 * Apply spectral extension to each channel by copying lower frequency
223 * coefficients to higher frequency bins and applying side information to
224 * approximate the original high frequency signal.
226 void ff_eac3_apply_spectral_extension(AC3DecodeContext *s);
228 #endif /* AVCODEC_AC3DEC_H */