xvididct.c File Reference

Walken IDCT Alternative IDCT implementation for decoding compatibility. More...

#include "config.h"
#include "libavutil/attributes.h"
#include "avcodec.h"
#include "idctdsp.h"
#include "xvididct.h"

Macros
#define	ROW_SHIFT   11
#define	COL_SHIFT   6
#define	RND0   65536
#define	RND1   3597
#define	RND2   2260
#define	RND3   1203
#define	RND4   0
#define	RND5   120
#define	RND6   512
#define	RND7   512
#define	TAN1   0x32EC
#define	TAN2   0x6A0A
#define	TAN3   0xAB0E
#define	SQRT2   0x5A82
#define	MULT(c, x, n)   (((c) * (x)) >> (n))
#define	BUTTERFLY(a, b, tmp)
#define	LOAD_BUTTERFLY(m1, m2, a, b, tmp, s)

Functions
void	ff_xvid_idct (int16_t *const in)
av_cold void	ff_xvid_idct_init (IDCTDSPContext *c, AVCodecContext *avctx)

Detailed Description

Walken IDCT Alternative IDCT implementation for decoding compatibility.

Author

Skal

Note

This C version is not the original IDCT, but a modified one that yields the same error profile as the MMX/MMXEXT/SSE2 versions.

Macro Definition Documentation

BUTTERFLY

#define BUTTERFLY	(		a,
			b,
			tmp
	)

Value:

(tmp) = (a) + (b);           \
    (b)   = (a) - (b);           \
    (a)   = (tmp)

LOAD_BUTTERFLY

#define LOAD_BUTTERFLY	(		m1,
			m2,
			a,
			b,
			tmp,
			s
	)

Value:

(m1) = (s)[(a)] + (s)[(b)];                \
    (m2) = (s)[(a)] - (s)[(b)]