FFT functions

Files
file	avfft.h

Data Structures
struct	FFTComplex

Typedefs
typedef float	FFTSample

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.

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

Definition at line 28 of file avfft.c.

Referenced by fft_init().

av_fft_permute()

void av_fft_permute	(	FFTContext *	s,
		FFTComplex *	z
	)

Do the permutation needed BEFORE calling ff_fft_calc().

Definition at line 38 of file avfft.c.

Referenced by fft_permute().

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.

Definition at line 43 of file avfft.c.

Referenced by fft_calc().

av_fft_end()

void av_fft_end

(

FFTContext *

s

)

Definition at line 48 of file avfft.c.

Referenced by fft_end().

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

)

Referenced by mdct_end().

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

Referenced by video_audio_display().

av_rdft_calc()

void av_rdft_calc	(	RDFTContext *	s,
		FFTSample *	data
	)

Referenced by video_audio_display().

av_rdft_end()

void av_rdft_end

(

RDFTContext *

s

)

Referenced by stream_component_close(), and video_audio_display().

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

)