FFT functions

Files
file	avfft.h
	FFT functions.

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.
void	av_fft_permute (FFTContext *s, FFTComplex *z)
	Do the permutation needed BEFORE calling ff_fft_calc().
void	av_fft_calc (FFTContext *s, FFTComplex *z)
	Do a complex FFT with the parameters defined in av_fft_init().
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.
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.
void	av_dct_calc (DCTContext *s, FFTSample *data)
void	av_dct_end (DCTContext *s)

Detailed Description

Typedef Documentation

typedef float FFTSample

Definition at line 35 of file avfft.h.

Enumeration Type Documentation

enum RDFTransformType

Enumerator:

DFT_R2C
IDFT_C2R
IDFT_R2C
DFT_C2R

Definition at line 71 of file avfft.h.

enum DCTTransformType

Enumerator:

DCT_II
DCT_III
DCT_I
DST_I

Definition at line 93 of file avfft.h.

Function Documentation

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.

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.

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.

void av_fft_end

(

FFTContext *

s

)

Definition at line 48 of file avfft.c.

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.

Parameters

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

Referenced by config_output(), video_audio_display(), and yae_reset().

void av_rdft_calc	(	RDFTContext *	s,
		FFTSample *	data
	)

Referenced by plot_spectrum_column(), video_audio_display(), yae_apply(), yae_flush(), and yae_xcorr_via_rdft().

void av_rdft_end

(

RDFTContext *

s

)

Referenced by config_output(), stream_component_close(), uninit(), video_audio_display(), yae_release_buffers(), and yae_reset().

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

Note

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

Referenced by init().

void av_dct_calc	(	DCTContext *	s,
		FFTSample *	data
	)

Referenced by dct_block(), and idct_block().

void av_dct_end

(

DCTContext *

s

)

Referenced by uninit().