[x264-devel] Re: about motion compensation

[Loren Merritt]

On Fri, 15 Dec 2006, ÕÅî£ wrote:

> in x264, the 3 half-pel planes are interpolated after encoding each frame,
> which is implemented in x264_frame_filter().
> but I don't understand why more 8 pixels are interpolated than origin image
> width, and I want to know if the 3 half-pel planes could be just
> inpterpolated without dealing with the 8 pixels.
> thanks!

Because the interpolation is a 6-tap filter, 5 extra pixels are needed (3 
on the top & left, 2 on the bottom & right). The number is then rounded up 
to the size of an MMX register.

--Loren Merritt