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 FFmpeg.
7 * FFmpeg 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 * FFmpeg 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 FFmpeg; 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"
58 #include "fmtconvert.h"
60 /* override ac3.h to include coupling channel */
61 #undef AC3_MAX_CHANNELS
62 #define AC3_MAX_CHANNELS 7
65 #define AC3_OUTPUT_LFEON 8
67 #define SPX_MAX_BANDS 17
70 AVCodecContext *avctx; ///< parent context
71 GetBitContext gbc; ///< bitstream reader
72 uint8_t *input_buffer; ///< temp buffer to prevent overread
74 ///@defgroup bsi bit stream information
76 int frame_type; ///< frame type (strmtyp)
77 int substreamid; ///< substream identification
78 int frame_size; ///< current frame size, in bytes
79 int bit_rate; ///< stream bit rate, in bits-per-second
80 int sample_rate; ///< sample frequency, in Hz
81 int num_blocks; ///< number of audio blocks
82 int channel_mode; ///< channel mode (acmod)
83 int channel_layout; ///< channel layout
84 int lfe_on; ///< lfe channel in use
85 int channel_map; ///< custom channel map
86 int center_mix_level; ///< Center mix level index
87 int surround_mix_level; ///< Surround mix level index
88 int eac3; ///< indicates if current frame is E-AC-3
91 ///@defgroup audfrm frame syntax parameters
92 int snr_offset_strategy; ///< SNR offset strategy (snroffststr)
93 int block_switch_syntax; ///< block switch syntax enabled (blkswe)
94 int dither_flag_syntax; ///< dither flag syntax enabled (dithflage)
95 int bit_allocation_syntax; ///< bit allocation model syntax enabled (bamode)
96 int fast_gain_syntax; ///< fast gain codes enabled (frmfgaincode)
97 int dba_syntax; ///< delta bit allocation syntax enabled (dbaflde)
98 int skip_syntax; ///< skip field syntax enabled (skipflde)
101 ///@defgroup cpl standard coupling
102 int cpl_in_use[AC3_MAX_BLOCKS]; ///< coupling in use (cplinu)
103 int cpl_strategy_exists[AC3_MAX_BLOCKS];///< coupling strategy exists (cplstre)
104 int channel_in_cpl[AC3_MAX_CHANNELS]; ///< channel in coupling (chincpl)
105 int phase_flags_in_use; ///< phase flags in use (phsflginu)
106 int phase_flags[AC3_MAX_CPL_BANDS]; ///< phase flags (phsflg)
107 int num_cpl_bands; ///< number of coupling bands (ncplbnd)
108 uint8_t cpl_band_sizes[AC3_MAX_CPL_BANDS]; ///< number of coeffs in each coupling band
109 int firstchincpl; ///< first channel in coupling
110 int first_cpl_coords[AC3_MAX_CHANNELS]; ///< first coupling coordinates states (firstcplcos)
111 int cpl_coords[AC3_MAX_CHANNELS][AC3_MAX_CPL_BANDS]; ///< coupling coordinates (cplco)
114 ///@defgroup spx spectral extension
116 int spx_in_use; ///< spectral extension in use (spxinu)
117 uint8_t channel_uses_spx[AC3_MAX_CHANNELS]; ///< channel uses spectral extension (chinspx)
118 int8_t spx_atten_code[AC3_MAX_CHANNELS]; ///< spx attenuation code (spxattencod)
119 int spx_src_start_freq; ///< spx start frequency bin
120 int spx_dst_end_freq; ///< spx end frequency bin
121 int spx_dst_start_freq; ///< spx starting frequency bin for copying (copystartmant)
122 ///< the copy region ends at the start of the spx region.
123 int num_spx_bands; ///< number of spx bands (nspxbnds)
124 uint8_t spx_band_sizes[SPX_MAX_BANDS]; ///< number of bins in each spx band
125 uint8_t first_spx_coords[AC3_MAX_CHANNELS]; ///< first spx coordinates states (firstspxcos)
126 float spx_noise_blend[AC3_MAX_CHANNELS][SPX_MAX_BANDS]; ///< spx noise blending factor (nblendfact)
127 float spx_signal_blend[AC3_MAX_CHANNELS][SPX_MAX_BANDS];///< spx signal blending factor (sblendfact)
130 ///@defgroup aht adaptive hybrid transform
131 int channel_uses_aht[AC3_MAX_CHANNELS]; ///< channel AHT in use (chahtinu)
132 int pre_mantissa[AC3_MAX_CHANNELS][AC3_MAX_COEFS][AC3_MAX_BLOCKS]; ///< pre-IDCT mantissas
135 ///@defgroup channel channel
136 int fbw_channels; ///< number of full-bandwidth channels
137 int channels; ///< number of total channels
138 int lfe_ch; ///< index of LFE channel
139 float downmix_coeffs[AC3_MAX_CHANNELS][2]; ///< stereo downmix coefficients
140 int downmixed; ///< indicates if coeffs are currently downmixed
141 int output_mode; ///< output channel configuration
142 int out_channels; ///< number of output channels
145 ///@defgroup dynrng dynamic range
146 float dynamic_range[2]; ///< dynamic range
149 ///@defgroup bandwidth bandwidth
150 int start_freq[AC3_MAX_CHANNELS]; ///< start frequency bin (strtmant)
151 int end_freq[AC3_MAX_CHANNELS]; ///< end frequency bin (endmant)
154 ///@defgroup rematrixing rematrixing
155 int num_rematrixing_bands; ///< number of rematrixing bands (nrematbnd)
156 int rematrixing_flags[4]; ///< rematrixing flags (rematflg)
159 ///@defgroup exponents exponents
160 int num_exp_groups[AC3_MAX_CHANNELS]; ///< Number of exponent groups (nexpgrp)
161 int8_t dexps[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< decoded exponents
162 int exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS]; ///< exponent strategies (expstr)
165 ///@defgroup bitalloc bit allocation
166 AC3BitAllocParameters bit_alloc_params; ///< bit allocation parameters
167 int first_cpl_leak; ///< first coupling leak state (firstcplleak)
168 int snr_offset[AC3_MAX_CHANNELS]; ///< signal-to-noise ratio offsets (snroffst)
169 int fast_gain[AC3_MAX_CHANNELS]; ///< fast gain values/SMR's (fgain)
170 uint8_t bap[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< bit allocation pointers
171 int16_t psd[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< scaled exponents
172 int16_t band_psd[AC3_MAX_CHANNELS][AC3_CRITICAL_BANDS]; ///< interpolated exponents
173 int16_t mask[AC3_MAX_CHANNELS][AC3_CRITICAL_BANDS]; ///< masking curve values
174 int dba_mode[AC3_MAX_CHANNELS]; ///< delta bit allocation mode
175 int dba_nsegs[AC3_MAX_CHANNELS]; ///< number of delta segments
176 uint8_t dba_offsets[AC3_MAX_CHANNELS][8]; ///< delta segment offsets
177 uint8_t dba_lengths[AC3_MAX_CHANNELS][8]; ///< delta segment lengths
178 uint8_t dba_values[AC3_MAX_CHANNELS][8]; ///< delta values for each segment
181 ///@defgroup dithering zero-mantissa dithering
182 int dither_flag[AC3_MAX_CHANNELS]; ///< dither flags (dithflg)
183 AVLFG dith_state; ///< for dither generation
186 ///@defgroup imdct IMDCT
187 int block_switch[AC3_MAX_CHANNELS]; ///< block switch flags (blksw)
188 FFTContext imdct_512; ///< for 512 sample IMDCT
189 FFTContext imdct_256; ///< for 256 sample IMDCT
192 ///@defgroup opt optimization
193 DSPContext dsp; ///< for optimization
194 FmtConvertContext fmt_conv; ///< optimized conversion functions
195 float mul_bias; ///< scaling for float_to_int16 conversion
198 ///@defgroup arrays aligned arrays
199 DECLARE_ALIGNED(16, int, fixed_coeffs)[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///> fixed-point transform coefficients
200 DECLARE_ALIGNED(16, float, transform_coeffs)[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< transform coefficients
201 DECLARE_ALIGNED(16, float, delay)[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]; ///< delay - added to the next block
202 DECLARE_ALIGNED(16, float, window)[AC3_BLOCK_SIZE]; ///< window coefficients
203 DECLARE_ALIGNED(16, float, tmp_output)[AC3_BLOCK_SIZE]; ///< temporary storage for output before windowing
204 DECLARE_ALIGNED(16, float, output)[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]; ///< output after imdct transform and windowing
209 * Parse the E-AC-3 frame header.
210 * This parses both the bit stream info and audio frame header.
212 int ff_eac3_parse_header(AC3DecodeContext *s);
215 * Decode mantissas in a single channel for the entire frame.
216 * This is used when AHT mode is enabled.
218 void ff_eac3_decode_transform_coeffs_aht_ch(AC3DecodeContext *s, int ch);
220 void ff_ac3_downmix_c(float (*samples)[256], float (*matrix)[2],
221 int out_ch, int in_ch, int len);
224 * Apply spectral extension to each channel by copying lower frequency
225 * coefficients to higher frequency bins and applying side information to
226 * approximate the original high frequency signal.
228 void ff_eac3_apply_spectral_extension(AC3DecodeContext *s);
230 #endif /* AVCODEC_AC3DEC_H */