libavcodec/mdct.c File Reference

MDCT/IMDCT transforms. More...

#include "dsputil.h"

Go to the source code of this file.

Defines
#define	BESSEL_I0_ITER   50
#define	CMUL(pre, pim, are, aim, bre, bim)
Functions
av_cold void	ff_kbd_window_init (float *window, float alpha, int n)
	Generate a Kaiser-Bessel Derived Window.
	DECLARE_ALIGNED (16, float, ff_sine_128[128])
	DECLARE_ALIGNED (16, float, ff_sine_256[256])
	DECLARE_ALIGNED (16, float, ff_sine_512[512])
	DECLARE_ALIGNED (16, float, ff_sine_1024[1024])
	DECLARE_ALIGNED (16, float, ff_sine_2048[2048])
	DECLARE_ALIGNED (16, float, ff_sine_4096[4096])
av_cold void	ff_sine_window_init (float *window, int n)
	Generate a sine window.
av_cold int	ff_mdct_init (MDCTContext *s, int nbits, int inverse)
	init MDCT or IMDCT computation.
void	ff_imdct_half_c (MDCTContext *s, FFTSample *output, const FFTSample *input)
	Compute the middle half of the inverse MDCT of size N = 2^nbits, thus excluding the parts that can be derived by symmetry.
void	ff_imdct_calc_c (MDCTContext *s, FFTSample *output, const FFTSample *input)
	Compute inverse MDCT of size N = 2^nbits.
void	ff_mdct_calc_c (MDCTContext *s, FFTSample *out, const FFTSample *input)
	Compute MDCT of size N = 2^nbits.
av_cold void	ff_mdct_end (MDCTContext *s)
Variables
float *	ff_sine_windows [6]

---

Detailed Description

MDCT/IMDCT transforms.

Definition in file mdct.c.

---

Define Documentation

#define BESSEL_I0_ITER   50

Definition at line 29 of file mdct.c.

Referenced by ff_kbd_window_init().

#define CMUL	(		pre,
			pim,
			are,
			aim,
			bre,
			bim
	)

Value:

{\
    FFTSample _are = (are);\
    FFTSample _aim = (aim);\
    FFTSample _bre = (bre);\
    FFTSample _bim = (bim);\
    (pre) = _are * _bre - _aim * _bim;\
    (pim) = _are * _bim + _aim * _bre;\
}

Definition at line 103 of file mdct.c.

Referenced by ff_imdct_half_c(), and ff_mdct_calc_c().

---

Function Documentation

DECLARE_ALIGNED	(	16	,
		float	,
		ff_sine_128	[128]
	)

DECLARE_ALIGNED	(	16	,
		float	,
		ff_sine_512	[512]
	)

DECLARE_ALIGNED	(	16	,
		float	,
		ff_sine_1024	[1024]
	)

DECLARE_ALIGNED	(	16	,
		float	,
		ff_sine_256	[256]
	)

DECLARE_ALIGNED	(	16	,
		float	,
		ff_sine_2048	[2048]
	)

DECLARE_ALIGNED	(	16	,
		float	,
		ff_sine_4096	[4096]
	)

void ff_imdct_calc_c	(	MDCTContext *	s,
		FFTSample *	output,
		const FFTSample *	input
	)

Compute inverse MDCT of size N = 2^nbits.

Parameters:

	output	N samples
	input	N/2 samples

Definition at line 162 of file mdct.c.

void ff_imdct_half_c	(	MDCTContext *	s,
		FFTSample *	output,
		const FFTSample *	input
	)

Compute the middle half of the inverse MDCT of size N = 2^nbits, thus excluding the parts that can be derived by symmetry.

Parameters:

	output	N/2 samples
	input	N/2 samples

Definition at line 119 of file mdct.c.

Referenced by ff_imdct_calc_c().

av_cold void ff_kbd_window_init	(	float *	window,
		float	alpha,
		int	n
	)

Generate a Kaiser-Bessel Derived Window.

Parameters:

	window	pointer to half window
	alpha	determines window shape
	n	size of half window

Definition at line 30 of file mdct.c.

Referenced by aac_decode_init(), aac_encode_init(), and ac3_decode_init().

void ff_mdct_calc_c	(	MDCTContext *	s,
		FFTSample *	out,
		const FFTSample *	input
	)

Compute MDCT of size N = 2^nbits.

Parameters:

	input	N samples
	out	N/2 samples

Definition at line 182 of file mdct.c.

av_cold void ff_mdct_end

(

MDCTContext *

s

)

Definition at line 224 of file mdct.c.

Referenced by aac_decode_close(), aac_encode_end(), ac3_decode_end(), cook_decode_close(), dca_decode_end(), decode_end(), encode_end(), ff_wma_end(), main(), vorbis_encode_close(), and vorbis_free().

av_cold int ff_mdct_init	(	MDCTContext *	s,
		int	nbits,
		int	inverse
	)

init MDCT or IMDCT computation.

Definition at line 71 of file mdct.c.

Referenced by aac_decode_init(), aac_encode_init(), ac3_decode_init(), create_vorbis_context(), dca_decode_init(), decode_init(), encode_init(), init_atrac3_transforms(), init_cook_mlt(), main(), vorbis_parse_id_hdr(), and wma_decode_init().

av_cold void ff_sine_window_init	(	float *	window,
		int	n
	)

Generate a sine window.

Parameters:

	window	pointer to half window
	n	size of half window

Definition at line 62 of file mdct.c.

Referenced by aac_decode_init(), aac_encode_init(), decode_init(), encode_init(), ff_wma_init(), imc_decode_init(), and init_cook_mlt().

---

Variable Documentation

float* ff_sine_windows[6]

Initial value:

 {
    ff_sine_128, ff_sine_256, ff_sine_512, ff_sine_1024, ff_sine_2048, ff_sine_4096
}

Definition at line 57 of file mdct.c.

Referenced by ff_wma_init().