/*
- * Common code between AC3 and E-AC3 decoder
+ * 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.
+ * This file is part of Libav.
*
- * FFmpeg is free software; you can redistribute it and/or
+ * 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.
*
- * FFmpeg is distributed in the hope that it will be useful,
+ * 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 FFmpeg; if not, write to the Free Software
+ * License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
- * @file ac3.h
- * Common code between AC3 and E-AC3 decoder.
+ * @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 FFMPEG_AC3DEC_H
-#define FFMPEG_AC3DEC_H
+#ifndef AVCODEC_AC3DEC_H
+#define AVCODEC_AC3DEC_H
-#include "libavutil/random.h"
-#include "ac3tab.h"
+#include "libavutil/lfg.h"
#include "ac3.h"
-#include "bitstream.h"
+#include "ac3dsp.h"
+#include "get_bits.h"
#include "dsputil.h"
-
-/* override ac3.h to include coupling channel */
-#undef AC3_MAX_CHANNELS
-#define AC3_MAX_CHANNELS 7
-#define CPL_CH 0
+#include "fft.h"
+#include "fmtconvert.h"
#define AC3_OUTPUT_LFEON 8
-#define AC3_MAX_COEFS 256
-#define AC3_BLOCK_SIZE 256
-#define MAX_BLOCKS 6
+#define SPX_MAX_BANDS 17
-typedef struct {
+/** 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
+ AVFrame frame; ///< AVFrame for decoded output
GetBitContext gbc; ///< bitstream reader
- uint8_t *input_buffer; ///< temp buffer to prevent overread
-///@defgroup bsi bit stream information
+///@name Bit stream information
///@{
int frame_type; ///< frame type (strmtyp)
int substreamid; ///< substream identification
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 eac3; ///< indicates if current frame is E-AC-3
///@}
-///@defgroup audfrm frame syntax parameters
+///@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 skip_syntax; ///< skip field syntax enabled (skipflde)
///@}
-///@defgroup cpl standard coupling
- int cpl_in_use[MAX_BLOCKS]; ///< coupling in use (cplinu)
- int cpl_strategy_exists[MAX_BLOCKS]; ///< coupling strategy exists (cplstre)
+///@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[18]; ///< phase flags (phsflg)
- int num_cpl_subbands; ///< number of coupling sub bands (ncplsubnd)
+ int phase_flags[AC3_MAX_CPL_BANDS]; ///< phase flags (phsflg)
int num_cpl_bands; ///< number of coupling bands (ncplbnd)
- int cpl_band_struct[18]; ///< coupling band structure (cplbndstrc)
+ 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][18]; ///< coupling coordinates (cplco)
+ int cpl_coords[AC3_MAX_CHANNELS][AC3_MAX_CPL_BANDS]; ///< coupling coordinates (cplco)
///@}
-///@defgroup aht adaptive hybrid transform
- int channel_uses_aht[AC3_MAX_CHANNELS]; ///< channel AHT in use (chahtinu)
- int pre_mantissa[AC3_MAX_CHANNELS][AC3_MAX_COEFS][MAX_BLOCKS]; ///< pre-IDCT mantissas
+///@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)
///@}
-///@defgroup channel channel
+///@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
- float downmix_coeff_adjust[2]; ///< adjustment needed for each output channel when downmixing
int downmixed; ///< indicates if coeffs are currently downmixed
int output_mode; ///< output channel configuration
int out_channels; ///< number of output channels
///@}
-///@defgroup dynrng dynamic range
+///@name Dynamic range
float dynamic_range[2]; ///< dynamic range
+ float drc_scale; ///< percentage of dynamic range compression to be applied
///@}
-///@defgroup bandwidth bandwidth
+///@name Bandwidth
int start_freq[AC3_MAX_CHANNELS]; ///< start frequency bin (strtmant)
int end_freq[AC3_MAX_CHANNELS]; ///< end frequency bin (endmant)
///@}
-///@defgroup rematrixing rematrixing
+///@name Rematrixing
int num_rematrixing_bands; ///< number of rematrixing bands (nrematbnd)
int rematrixing_flags[4]; ///< rematrixing flags (rematflg)
///@}
-///@defgroup exponents exponents
+///@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[MAX_BLOCKS][AC3_MAX_CHANNELS]; ///< exponent strategies (expstr)
+ int exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS]; ///< exponent strategies (expstr)
///@}
-///@defgroup bitalloc bit allocation
+///@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][50]; ///< interpolated exponents
- int16_t mask[AC3_MAX_CHANNELS][50]; ///< masking curve values
+ 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_values[AC3_MAX_CHANNELS][8]; ///< delta values for each segment
///@}
-///@defgroup dithering zero-mantissa dithering
- int dither_all; ///< true if all channels are dithered
+///@name Zero-mantissa dithering
int dither_flag[AC3_MAX_CHANNELS]; ///< dither flags (dithflg)
- AVRandomState dith_state; ///< for dither generation
+ AVLFG dith_state; ///< for dither generation
///@}
-///@defgroup imdct IMDCT
+///@name IMDCT
int block_switch[AC3_MAX_CHANNELS]; ///< block switch flags (blksw)
- MDCTContext imdct_512; ///< for 512 sample IMDCT
- MDCTContext imdct_256; ///< for 256 sample IMDCT
+ FFTContext imdct_512; ///< for 512 sample IMDCT
+ FFTContext imdct_256; ///< for 256 sample IMDCT
///@}
-///@defgroup opt optimization
+///@name Optimization
DSPContext dsp; ///< for optimization
- float add_bias; ///< offset for float_to_int16 conversion
+ AC3DSPContext ac3dsp;
+ FmtConvertContext fmt_conv; ///< optimized conversion functions
float mul_bias; ///< scaling for float_to_int16 conversion
///@}
- int fixed_coeffs[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///> fixed-point transform coefficients
-
-///@defgroup arrays aligned arrays
- DECLARE_ALIGNED_16(float, transform_coeffs[AC3_MAX_CHANNELS][AC3_MAX_COEFS]); ///< transform coefficients
- DECLARE_ALIGNED_16(float, delay[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]); ///< delay - added to the next block
- DECLARE_ALIGNED_16(float, window[AC3_BLOCK_SIZE]); ///< window coefficients
- DECLARE_ALIGNED_16(float, tmp_output[AC3_BLOCK_SIZE*2]); ///< temporary storage for output before windowing
- DECLARE_ALIGNED_16(float, tmp_imdct[AC3_BLOCK_SIZE]); ///< temporary storage for imdct transform
- DECLARE_ALIGNED_16(float, output[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]); ///< output after imdct transform and windowing
- DECLARE_ALIGNED_16(short, int_output[AC3_MAX_CHANNELS-1][AC3_BLOCK_SIZE]); ///< final 16-bit integer output
+///@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
+ DECLARE_ALIGNED(32, uint8_t, input_buffer)[AC3_FRAME_BUFFER_SIZE + FF_INPUT_BUFFER_PADDING_SIZE]; ///< temp buffer to prevent overread
///@}
} AC3DecodeContext;
-#endif /* FFMPEG_AC3DEC_H */
+/**
+ * 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);
+
+/**
+ * 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 */
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