[XviD-devel] FDCT constants

[skal]

	Hi,

On Mon, 2004-11-29 at 07:46, lakshmikanth r wrote:
> HI,
> 
> I am a new to the field of MPEG4 encodeing and I was
> going through your xvid reference code and in specfic
> DCT calculation. The following line of code is found
> in dct.c
> "
> #define FIX_0_298631336  ((int)  2446)	/*
> FIX(0.298631336) */

	[...]

> #define FIX_3_072711026  ((int) 25172)	/*
> FIX(3.072711026) */


	these constants are mostly tan[k.pi/16].
	Have a look there:

http://skal.planet-d.net/coding/dct.html

	in particular the part where 2d-rotations
	with 3 mults are described.

Skal