FFT functions
[Utility functions]

Data Structures
struct	FFTComplex
Files
file	avfft.h
	FFT functions.
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.
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)

---

Typedef Documentation

typedef struct DCTContext DCTContext

Definition at line 91 of file avfft.h.

typedef struct FFTContext FFTContext

Definition at line 41 of file avfft.h.

typedef float FFTSample

Definition at line 35 of file avfft.h.

typedef struct RDFTContext RDFTContext

Definition at line 78 of file avfft.h.

---

Enumeration Type Documentation

enum DCTTransformType

Enumerator:

DCT_II
DCT_III
DCT_I
DST_I

Definition at line 93 of file avfft.h.

enum RDFTransformType

Enumerator:

DFT_R2C
IDFT_C2R
IDFT_R2C
DFT_C2R

Definition at line 71 of file avfft.h.

---

Function Documentation

void av_dct_calc	(	DCTContext *	s,
		FFTSample *	data
	)

void av_dct_end

(

DCTContext *

s

)

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

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 42 of file avfft.c.

void av_fft_end

(

FFTContext *

s

)

Definition at line 47 of file avfft.c.

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 27 of file avfft.c.

void av_fft_permute	(	FFTContext *	s,
		FFTComplex *	z
	)

Do the permutation needed BEFORE calling ff_fft_calc().

Definition at line 37 of file avfft.c.

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

)

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

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().

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().