/*
- * 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.
*/
/**
- * @file ac3.h
- * Common code between AC3 and E-AC3 decoder.
+ * @file libavcodec/ac3.h
+ * 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 "get_bits.h"
#include "dsputil.h"
+#include "fft.h"
/* override ac3.h to include coupling channel */
#undef AC3_MAX_CHANNELS
#define AC3_MAX_COEFS 256
#define AC3_BLOCK_SIZE 256
#define MAX_BLOCKS 6
+#define SPX_MAX_BANDS 17
typedef struct {
AVCodecContext *avctx; ///< parent context
int sample_rate; ///< sample frequency, in Hz
int num_blocks; ///< number of audio blocks
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 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 num_cpl_bands; ///< number of coupling bands (ncplbnd)
- int cpl_band_struct[18]; ///< coupling band structure (cplbndstrc)
+ uint8_t cpl_band_sizes[18]; ///< 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)
///@}
+///@defgroup spx 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 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][6]; ///< pre-IDCT mantissas
+ 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
///@}
///@defgroup channel channel
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 dithering zero-mantissa dithering
- int dither_all; ///< true if all channels are dithered
int dither_flag[AC3_MAX_CHANNELS]; ///< dither flags (dithflg)
- AVRandomState dith_state; ///< for dither generation
+ AVLFG dith_state; ///< for dither generation
///@}
///@defgroup imdct 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
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
+ DECLARE_ALIGNED(16, int, fixed_coeffs)[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///> fixed-point transform coefficients
+ 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]; ///< temporary storage for output before windowing
+ DECLARE_ALIGNED(16, float, output)[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]; ///< output after imdct transform and windowing
///@}
} 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);
+
+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 */
projects / ffmpeg / blobdiff