[XviD-devel] halfpel and maybe quarterpel interpolation questions

[Christoph Lampert]

On Sat, 11 Jan 2003, Marco "elcabesa" Belli wrote:

> 
> > We can't decide on these things ourselves, it's the MPEG-4 standard that
> > demands linear interpolation for halfpel-resolution. Btw. for Quarterpel
> > there is some FIR, also fixed by the standard.
> 
> ok i have understood.. and i have understood also why they decide for a linear 
> interpolation for it, using a FIR i went down to 6 fps, using your linear 
> interpolation i encode at 13 pfs forcing xvid to use only not assembler 
> optimized code=)
> 
> where can i find some MPEG-4 spec? i downloaded reference software..but i 
> cant' understand toomuch from it.. i'm also a student..so i have not much 
> money

No, unfortunately they are not available for free. You have to buy them 
from ISO 

http://www.iso.ch/iso/en/CatalogueDetailPage.CatalogueDetail?CSNUMBER=36081

at 44 CHF. 

There are some drafts available for free download from which you can get
much information, but details have changed since then.  And there is the
reference software, which is up to date, but rather difficult to read.

gruel