FFT functions

Files
file	avfft.h
	FFT functions.

Data Structures
struct	FFTComplex

Typedefs
typedef float	FFTSample
typedef struct FFTContext	FFTContext
typedef struct RDFTContext	RDFTContext
typedef struct DCTContext	DCTContext

Enumerations
enum	RDFTransformType { DFT_R2C, IDFT_C2R, IDFT_R2C, DFT_C2R }
enum	DCTTransformType { DCT_II = 0, DCT_III, DCT_I, DST_I }

Functions
FFTContext *	av_fft_init (int nbits, int inverse)
	Set up a complex FFT. More...
void	av_fft_permute (FFTContext *s, FFTComplex *z)
	Do the permutation needed BEFORE calling ff_fft_calc(). More...
void	av_fft_calc (FFTContext *s, FFTComplex *z)
	Do a complex FFT with the parameters defined in av_fft_init(). More...
void	av_fft_end (FFTContext *s)
FFTContext *	av_mdct_init (int nbits, int inverse, double scale)
void	av_imdct_calc (FFTContext *s, FFTSample *output, const FFTSample *input)
void	av_imdct_half (FFTContext *s, FFTSample *output, const FFTSample *input)
void	av_mdct_calc (FFTContext *s, FFTSample *output, const FFTSample *input)
void	av_mdct_end (FFTContext *s)
RDFTContext *	av_rdft_init (int nbits, enum RDFTransformType trans)
	Set up a real FFT. More...
void	av_rdft_calc (RDFTContext *s, FFTSample *data)
void	av_rdft_end (RDFTContext *s)
DCTContext *	av_dct_init (int nbits, enum DCTTransformType type)
	Set up DCT. More...
void	av_dct_calc (DCTContext *s, FFTSample *data)
void	av_dct_end (DCTContext *s)

Detailed Description

Typedef Documentation

FFTSample

typedef float FFTSample

Definition at line 35 of file avfft.h.

FFTContext

typedef struct FFTContext FFTContext

Definition at line 41 of file avfft.h.

RDFTContext

typedef struct RDFTContext RDFTContext

Definition at line 78 of file avfft.h.

DCTContext

typedef struct DCTContext DCTContext

Definition at line 91 of file avfft.h.

Enumeration Type Documentation

RDFTransformType

enum RDFTransformType

Enumerator
DFT_R2C
IDFT_C2R
IDFT_R2C
DFT_C2R

Definition at line 71 of file avfft.h.

DCTTransformType

enum DCTTransformType

Enumerator
DCT_II
DCT_III
DCT_I
DST_I

Definition at line 93 of file avfft.h.

Function Documentation

av_fft_init()

FFTContext* av_fft_init	(	int	nbits,
		int	inverse
	)

Set up a complex FFT.

Parameters

nbits	log2 of the length of the input array
inverse	if 0 perform the forward transform, if 1 perform the inverse

av_fft_permute()

void av_fft_permute	(	FFTContext *	s,
		FFTComplex *	z
	)

Do the permutation needed BEFORE calling ff_fft_calc().

av_fft_calc()

void av_fft_calc	(	FFTContext *	s,
		FFTComplex *	z
	)

Do a complex FFT with the parameters defined in av_fft_init().

The input data must be permuted before. No 1.0/sqrt(n) normalization is done.

av_fft_end()

void av_fft_end

(

FFTContext *

s

)

av_mdct_init()

FFTContext* av_mdct_init	(	int	nbits,
		int	inverse,
		double	scale
	)

av_imdct_calc()

void av_imdct_calc	(	FFTContext *	s,
		FFTSample *	output,
		const FFTSample *	input
	)

av_imdct_half()

void av_imdct_half	(	FFTContext *	s,
		FFTSample *	output,
		const FFTSample *	input
	)

av_mdct_calc()

void av_mdct_calc	(	FFTContext *	s,
		FFTSample *	output,
		const FFTSample *	input
	)

av_mdct_end()

void av_mdct_end

(

FFTContext *

s

)

av_rdft_init()

RDFTContext* av_rdft_init	(	int	nbits,
		enum RDFTransformType	trans
	)

Set up a real FFT.

Parameters

nbits	log2 of the length of the input array
trans	the type of transform

av_rdft_calc()

void av_rdft_calc	(	RDFTContext *	s,
		FFTSample *	data
	)

av_rdft_end()

void av_rdft_end

(

RDFTContext *

s

)

av_dct_init()

DCTContext* av_dct_init	(	int	nbits,
		enum DCTTransformType	type
	)

Set up DCT.

Parameters

nbits	size of the input array: (1 << nbits) for DCT-II, DCT-III and DST-I (1 << nbits) + 1 for DCT-I
type	the type of transform

Note

the first element of the input of DST-I is ignored

av_dct_calc()

void av_dct_calc	(	DCTContext *	s,
		FFTSample *	data
	)

av_dct_end()

void av_dct_end

(

DCTContext *

s

)