[XviD-devel] B frame help

[Radek Czyz]

Hello Zoltan,

> only forward/backward vectors

You can skip B-frames if you don't intend to use direct mode... they
will always be inferior compared to P-frames.
B-frames are only better because of direct mode.

>  > * motion vectors stored differently (thus compensation performed
>  > differently)

> I use the exact same encoder (and predictor) what I use for the
> P frames and that might be the heart of the problem.

It sure is :) Predictor is 'last encoded vector for this MB type' and
it's set to zero at left boundary. It's very similar to p-frame
predictor in mpeg1/2.

Also remeber that if in future P-frame macroblock is not coded, it's
completely ignored in b-frames for which it would be future reference.
It is decoded as forward with 0,0 vector then.

Best regards,
Radek