[XviD-devel] B frame help

[suxen_drol]

On Fri,  7 Feb 2003 12:08:26 +1100 (EST) Zoltan Kocsi <zoltan at bendor.com.au> wrote:

hi
> 
> I have to write a bitstream encoder. I use the XviD decoder for
____^^^^^^^

who is forcing you?
and what do you mean by bitstream encoder? ie. are you implementing your
own bistream routines (putbits,etc.), or writing a mpeg video encoder
from scratch.

> testing the bitstream. I and P frames are working nice but with
> B frames I have severe problems. The bitstream looks syntactically
> correct, at least XviD reads exactly as many bits for the frame
> as I write but what it generates as a decoded image is very 
> strange. I created very simple test images to see what happens 
> and the results are just weird.

b-vops are very similar to p-vops; the major differences:
* macroblock mode/cbp vlcs
* motion vectors stored differently (thus compensation performed
differently)
* co-located block skipping semantics

> I would really appreciate if someone would be willing to help me 
> to figure out what do I do wrong (possibly in private mail, so that
> the list doesn't get cluttered with this).

the list wont mind getting cluttered.

-- pete; life is like a box of ammo