atrac3plusdsp.c File Reference

DSP functions for ATRAC3+ decoder. More...

#include <math.h>
#include "libavutil/float_dsp.h"
#include "libavutil/libm.h"
#include "avcodec.h"
#include "sinewin.h"
#include "fft.h"
#include "atrac3plus.h"

Macros
#define	ATRAC3P_MDCT_SIZE   (ATRAC3P_SUBBAND_SAMPLES * 2)
#define	TWOPI   (2 * M_PI)
#define	DEQUANT_PHASE(ph)   (((ph) & 0x1F) << 6)

Functions
av_cold void	ff_atrac3p_init_imdct (AVCodecContext *avctx, FFTContext *mdct_ctx)
	Initialize IMDCT transform. More...
av_cold void	ff_atrac3p_init_wave_synth (void)
	Initialize sine waves synthesizer.
void	ff_atrac3p_generate_tones (Atrac3pChanUnitCtx *ch_unit, AVFloatDSPContext *fdsp, int ch_num, int sb, float *out)
	Synthesize sine waves for a particular subband. More...
void	ff_atrac3p_power_compensation (Atrac3pChanUnitCtx *ctx, AVFloatDSPContext *fdsp, int ch_index, float *sp, int rng_index, int sb)
	Perform power compensation aka noise dithering. More...
void	ff_atrac3p_imdct (AVFloatDSPContext *fdsp, FFTContext *mdct_ctx, float *pIn, float *pOut, int wind_id, int sb)
	Regular IMDCT and windowing without overlapping, with spectrum reversal in the odd subbands. More...
void	ff_atrac3p_ipqf (FFTContext *dct_ctx, Atrac3pIPQFChannelCtx *hist, const float *in, float *out)
	Subband synthesis filter based on the polyphase quadrature (pseudo-QMF) filter bank. More...

Variables
const uint16_t	ff_atrac3p_qu_to_spec_pos [33]
	Map quant unit number to its position in the spectrum. More...
const float	ff_atrac3p_sf_tab [64]
const float	ff_atrac3p_mant_tab [8]

Detailed Description

DSP functions for ATRAC3+ decoder.

Function Documentation

ff_atrac3p_generate_tones()

void ff_atrac3p_generate_tones	(	Atrac3pChanUnitCtx *	ch_unit,
		AVFloatDSPContext *	fdsp,
		int	ch_num,
		int	sb,
		float *	out
	)

Synthesize sine waves for a particular subband.

Parameters

[in]	ch_unit	pointer to the channel unit context
[in]	fdsp	pointer to float DSP context
[in]	ch_num	which channel to process
[in]	sb	which subband to process
[out]	out	receives processed data

ff_atrac3p_imdct()

void ff_atrac3p_imdct	(	AVFloatDSPContext *	fdsp,
		FFTContext *	mdct_ctx,
		float *	pIn,
		float *	pOut,
		int	wind_id,
		int	sb
	)

Regular IMDCT and windowing without overlapping, with spectrum reversal in the odd subbands.

Parameters

[in]	fdsp	pointer to float DSP context
[in]	mdct_ctx	pointer to MDCT transform context
[in]	pIn	float input
[out]	pOut	float output
[in]	wind_id	which MDCT window to apply
[in]	sb	subband number

ff_atrac3p_init_imdct()

av_cold void ff_atrac3p_init_imdct	(	AVCodecContext *	avctx,
		FFTContext *	mdct_ctx
	)

Initialize IMDCT transform.

Parameters

[in]	avctx	ptr to the AVCodecContext
[in]	mdct_ctx	pointer to MDCT transform context

ff_atrac3p_ipqf()

void ff_atrac3p_ipqf	(	FFTContext *	dct_ctx,
		Atrac3pIPQFChannelCtx *	hist,
		const float *	in,
		float *	out
	)

Subband synthesis filter based on the polyphase quadrature (pseudo-QMF) filter bank.

Parameters

[in]	dct_ctx	ptr to the pre-initialized IDCT context
[in,out]	hist	ptr to the filter history
[in]	in	input data to process
[out]	out	receives processed data

ff_atrac3p_power_compensation()

void ff_atrac3p_power_compensation	(	Atrac3pChanUnitCtx *	ctx,
		AVFloatDSPContext *	fdsp,
		int	ch_index,
		float *	sp,
		int	rng_index,
		int	sb_num
	)

Perform power compensation aka noise dithering.

Parameters

[in]	ctx	ptr to the channel context
[in]	fdsp	pointer to float DSP context
[in]	ch_index	which channel to process
[in,out]	sp	ptr to channel spectrum to process
[in]	rng_index	indicates which RNG table to use
[in]	sb_num	which subband to process

Variable Documentation

ff_atrac3p_mant_tab

const float ff_atrac3p_mant_tab[8]

Initial value:

= {
    0.0,
    0.74801636,
    0.44882202,
    0.32058716,
    0.20400238,
    0.1496048,
    0.07239151,
    0.035619736
}

ff_atrac3p_qu_to_spec_pos

const uint16_t ff_atrac3p_qu_to_spec_pos[33]

Initial value:

= {
      0,    16,   32,   48,   64,   80,   96,  112,
    128,   160,  192,  224,  256,  288,  320,  352,
    384,   448,  512,  576,  640,  704,  768,  896,
    1024, 1152, 1280, 1408, 1536, 1664, 1792, 1920,
    2048
}

Map quant unit number to its position in the spectrum.

To get the number of spectral lines in each quant unit do the following: num_specs = qu_to_spec_pos[i+1] - qu_to_spec_pos[i]

ff_atrac3p_sf_tab

const float ff_atrac3p_sf_tab[64]

Initial value:

= {
    0.027852058,  0.0350914, 0.044212341, 0.055704117,  0.0701828,
    0.088424683, 0.11140823,   0.1403656,  0.17684937, 0.22281647, 0.2807312, 0.35369873,
    0.44563293,   0.5614624,  0.70739746,  0.89126587,  1.1229248, 1.4147949,  1.7825317,
    2.2458496,    2.8295898,   3.5650635,   4.4916992,  5.6591797,  7.130127,  8.9833984,
    11.318359,    14.260254,   17.966797,   22.636719,  28.520508, 35.933594,  45.273438,
    57.041016,    71.867188,   90.546875,   114.08203,  143.73438, 181.09375,  228.16406,
    287.46875,     362.1875,   456.32812,    574.9375,    724.375, 912.65625,   1149.875,
    1448.75,      1825.3125,     2299.75,      2897.5,   3650.625,    4599.5,     5795.0,
    7301.25,         9199.0,     11590.0,     14602.5,    18398.0,   23180.0,    29205.0,
    36796.0,        46360.0,     58410.0
}