dct.c File Reference

(Inverse) Discrete Cosine Transforms. More...

#include <math.h>
#include <string.h>
#include "libavutil/mathematics.h"
#include "dct.h"
#include "dct32.h"

Macros
#define	SIN(s, n, x)   (s->costab[(n) - (x)])
#define	COS(s, n, x)   (s->costab[x])

Functions
av_cold int	ff_dct_init (DCTContext *s, int nbits, enum DCTTransformType inverse)
	Set up DCT. More...
av_cold void	ff_dct_end (DCTContext *s)

Detailed Description

(Inverse) Discrete Cosine Transforms.

These are also known as the type II and type III DCTs respectively.

Function Documentation

ff_dct_init()

av_cold int ff_dct_init	(	DCTContext *	s,
		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