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/float_dsp.h"
54 #include "libavutil/fixed_dsp.h"
55 #include "libavutil/lfg.h"
61 #include "fmtconvert.h"
63 #define AC3_OUTPUT_LFEON 8
65 #define SPX_MAX_BANDS 17
67 /** Large enough for maximum possible frame size when the specification limit is ignored */
68 #define AC3_FRAME_BUFFER_SIZE 32768
70 typedef struct AC3DecodeContext
{
71 AVClass
*class; ///< class for AVOptions
72 AVCodecContext
*avctx
; ///< parent context
73 GetBitContext gbc
; ///< bitstream reader
75 ///@name Bit stream information
77 int frame_type
; ///< frame type (strmtyp)
78 int substreamid
; ///< substream identification
79 int frame_size
; ///< current frame size, in bytes
80 int bit_rate
; ///< stream bit rate, in bits-per-second
81 int sample_rate
; ///< sample frequency, in Hz
82 int num_blocks
; ///< number of audio blocks
83 int bitstream_id
; ///< bitstream id (bsid)
84 int bitstream_mode
; ///< bitstream mode (bsmod)
85 int channel_mode
; ///< channel mode (acmod)
86 int lfe_on
; ///< lfe channel in use
87 int dialog_normalization
[2]; ///< dialog level in dBFS (dialnorm)
88 int compression_exists
[2]; ///< compression field is valid for frame (compre)
89 int compression_gain
[2]; ///< gain to apply for heavy compression (compr)
90 int channel_map
; ///< custom channel map
91 int preferred_downmix
; ///< Preferred 2-channel downmix mode (dmixmod)
92 int center_mix_level
; ///< Center mix level index
93 int center_mix_level_ltrt
; ///< Center mix level index for Lt/Rt (ltrtcmixlev)
94 int surround_mix_level
; ///< Surround mix level index
95 int surround_mix_level_ltrt
; ///< Surround mix level index for Lt/Rt (ltrtsurmixlev)
96 int lfe_mix_level_exists
; ///< indicates if lfemixlevcod is specified (lfemixlevcode)
97 int lfe_mix_level
; ///< LFE mix level index (lfemixlevcod)
98 int eac3
; ///< indicates if current frame is E-AC-3
99 int dolby_surround_mode
; ///< dolby surround mode (dsurmod)
100 int dolby_surround_ex_mode
; ///< dolby surround ex mode (dsurexmod)
101 int dolby_headphone_mode
; ///< dolby headphone mode (dheadphonmod)
104 int preferred_stereo_downmix
;
105 float ltrt_center_mix_level
;
106 float ltrt_surround_mix_level
;
107 float loro_center_mix_level
;
108 float loro_surround_mix_level
;
109 int target_level
; ///< target level in dBFS
112 ///@name Frame syntax parameters
113 int snr_offset_strategy
; ///< SNR offset strategy (snroffststr)
114 int block_switch_syntax
; ///< block switch syntax enabled (blkswe)
115 int dither_flag_syntax
; ///< dither flag syntax enabled (dithflage)
116 int bit_allocation_syntax
; ///< bit allocation model syntax enabled (bamode)
117 int fast_gain_syntax
; ///< fast gain codes enabled (frmfgaincode)
118 int dba_syntax
; ///< delta bit allocation syntax enabled (dbaflde)
119 int skip_syntax
; ///< skip field syntax enabled (skipflde)
122 ///@name Standard coupling
123 int cpl_in_use
[AC3_MAX_BLOCKS
]; ///< coupling in use (cplinu)
124 int cpl_strategy_exists
[AC3_MAX_BLOCKS
];///< coupling strategy exists (cplstre)
125 int channel_in_cpl
[AC3_MAX_CHANNELS
]; ///< channel in coupling (chincpl)
126 int phase_flags_in_use
; ///< phase flags in use (phsflginu)
127 int phase_flags
[AC3_MAX_CPL_BANDS
]; ///< phase flags (phsflg)
128 int num_cpl_bands
; ///< number of coupling bands (ncplbnd)
129 uint8_t cpl_band_sizes
[AC3_MAX_CPL_BANDS
]; ///< number of coeffs in each coupling band
130 int firstchincpl
; ///< first channel in coupling
131 int first_cpl_coords
[AC3_MAX_CHANNELS
]; ///< first coupling coordinates states (firstcplcos)
132 int cpl_coords
[AC3_MAX_CHANNELS
][AC3_MAX_CPL_BANDS
]; ///< coupling coordinates (cplco)
135 ///@name Spectral extension
137 int spx_in_use
; ///< spectral extension in use (spxinu)
138 uint8_t channel_uses_spx
[AC3_MAX_CHANNELS
]; ///< channel uses spectral extension (chinspx)
139 int8_t spx_atten_code
[AC3_MAX_CHANNELS
]; ///< spx attenuation code (spxattencod)
140 int spx_src_start_freq
; ///< spx start frequency bin
141 int spx_dst_end_freq
; ///< spx end frequency bin
142 int spx_dst_start_freq
; ///< spx starting frequency bin for copying (copystartmant)
143 ///< the copy region ends at the start of the spx region.
144 int num_spx_bands
; ///< number of spx bands (nspxbnds)
145 uint8_t spx_band_sizes
[SPX_MAX_BANDS
]; ///< number of bins in each spx band
146 uint8_t first_spx_coords
[AC3_MAX_CHANNELS
]; ///< first spx coordinates states (firstspxcos)
147 INTFLOAT spx_noise_blend
[AC3_MAX_CHANNELS
][SPX_MAX_BANDS
]; ///< spx noise blending factor (nblendfact)
148 INTFLOAT spx_signal_blend
[AC3_MAX_CHANNELS
][SPX_MAX_BANDS
];///< spx signal blending factor (sblendfact)
151 ///@name Adaptive hybrid transform
152 int channel_uses_aht
[AC3_MAX_CHANNELS
]; ///< channel AHT in use (chahtinu)
153 int pre_mantissa
[AC3_MAX_CHANNELS
][AC3_MAX_COEFS
][AC3_MAX_BLOCKS
]; ///< pre-IDCT mantissas
157 int fbw_channels
; ///< number of full-bandwidth channels
158 int channels
; ///< number of total channels
159 int lfe_ch
; ///< index of LFE channel
160 SHORTFLOAT downmix_coeffs
[AC3_MAX_CHANNELS
][2]; ///< stereo downmix coefficients
161 int downmixed
; ///< indicates if coeffs are currently downmixed
162 int output_mode
; ///< output channel configuration
163 int out_channels
; ///< number of output channels
166 ///@name Dynamic range
167 INTFLOAT dynamic_range
[2]; ///< dynamic range
168 INTFLOAT drc_scale
; ///< percentage of dynamic range compression to be applied
169 int heavy_compression
; ///< apply heavy compression
170 INTFLOAT heavy_dynamic_range
[2]; ///< heavy dynamic range compression
174 int start_freq
[AC3_MAX_CHANNELS
]; ///< start frequency bin (strtmant)
175 int end_freq
[AC3_MAX_CHANNELS
]; ///< end frequency bin (endmant)
179 int num_rematrixing_bands
; ///< number of rematrixing bands (nrematbnd)
180 int rematrixing_flags
[4]; ///< rematrixing flags (rematflg)
184 int num_exp_groups
[AC3_MAX_CHANNELS
]; ///< Number of exponent groups (nexpgrp)
185 int8_t dexps
[AC3_MAX_CHANNELS
][AC3_MAX_COEFS
]; ///< decoded exponents
186 int exp_strategy
[AC3_MAX_BLOCKS
][AC3_MAX_CHANNELS
]; ///< exponent strategies (expstr)
189 ///@name Bit allocation
190 AC3BitAllocParameters bit_alloc_params
; ///< bit allocation parameters
191 int first_cpl_leak
; ///< first coupling leak state (firstcplleak)
192 int snr_offset
[AC3_MAX_CHANNELS
]; ///< signal-to-noise ratio offsets (snroffst)
193 int fast_gain
[AC3_MAX_CHANNELS
]; ///< fast gain values/SMR's (fgain)
194 uint8_t bap
[AC3_MAX_CHANNELS
][AC3_MAX_COEFS
]; ///< bit allocation pointers
195 int16_t psd
[AC3_MAX_CHANNELS
][AC3_MAX_COEFS
]; ///< scaled exponents
196 int16_t band_psd
[AC3_MAX_CHANNELS
][AC3_CRITICAL_BANDS
]; ///< interpolated exponents
197 int16_t mask
[AC3_MAX_CHANNELS
][AC3_CRITICAL_BANDS
]; ///< masking curve values
198 int dba_mode
[AC3_MAX_CHANNELS
]; ///< delta bit allocation mode
199 int dba_nsegs
[AC3_MAX_CHANNELS
]; ///< number of delta segments
200 uint8_t dba_offsets
[AC3_MAX_CHANNELS
][8]; ///< delta segment offsets
201 uint8_t dba_lengths
[AC3_MAX_CHANNELS
][8]; ///< delta segment lengths
202 uint8_t dba_values
[AC3_MAX_CHANNELS
][8]; ///< delta values for each segment
205 ///@name Zero-mantissa dithering
206 int dither_flag
[AC3_MAX_CHANNELS
]; ///< dither flags (dithflg)
207 AVLFG dith_state
; ///< for dither generation
211 int block_switch
[AC3_MAX_CHANNELS
]; ///< block switch flags (blksw)
212 FFTContext imdct_512
; ///< for 512 sample IMDCT
213 FFTContext imdct_256
; ///< for 256 sample IMDCT
216 ///@name Optimization
217 BswapDSPContext bdsp
;
219 AVFixedDSPContext
*fdsp
;
221 AVFloatDSPContext
*fdsp
;
223 AC3DSPContext ac3dsp
;
224 FmtConvertContext fmt_conv
; ///< optimized conversion functions
227 SHORTFLOAT
*outptr
[AC3_MAX_CHANNELS
];
228 INTFLOAT
*xcfptr
[AC3_MAX_CHANNELS
];
229 INTFLOAT
*dlyptr
[AC3_MAX_CHANNELS
];
231 ///@name Aligned arrays
232 DECLARE_ALIGNED(16, int, fixed_coeffs
)[AC3_MAX_CHANNELS
][AC3_MAX_COEFS
]; ///< fixed-point transform coefficients
233 DECLARE_ALIGNED(32, INTFLOAT
, transform_coeffs
)[AC3_MAX_CHANNELS
][AC3_MAX_COEFS
]; ///< transform coefficients
234 DECLARE_ALIGNED(32, INTFLOAT
, delay
)[AC3_MAX_CHANNELS
][AC3_BLOCK_SIZE
]; ///< delay - added to the next block
235 DECLARE_ALIGNED(32, INTFLOAT
, window
)[AC3_BLOCK_SIZE
]; ///< window coefficients
236 DECLARE_ALIGNED(32, INTFLOAT
, tmp_output
)[AC3_BLOCK_SIZE
]; ///< temporary storage for output before windowing
237 DECLARE_ALIGNED(32, SHORTFLOAT
, output
)[AC3_MAX_CHANNELS
][AC3_BLOCK_SIZE
]; ///< output after imdct transform and windowing
238 DECLARE_ALIGNED(32, uint8_t, input_buffer
)[AC3_FRAME_BUFFER_SIZE
+ FF_INPUT_BUFFER_PADDING_SIZE
]; ///< temp buffer to prevent overread
243 * Parse the E-AC-3 frame header.
244 * This parses both the bit stream info and audio frame header.
246 int ff_eac3_parse_header(AC3DecodeContext
*s
);
249 * Decode mantissas in a single channel for the entire frame.
250 * This is used when AHT mode is enabled.
252 void ff_eac3_decode_transform_coeffs_aht_ch(AC3DecodeContext
*s
, int ch
);
255 * Apply spectral extension to each channel by copying lower frequency
256 * coefficients to higher frequency bins and applying side information to
257 * approximate the original high frequency signal.
259 void ff_eac3_apply_spectral_extension(AC3DecodeContext
*s
);
261 #endif /* AVCODEC_AC3DEC_H */