[XviD-devel] Transcode module

[Christoph Lampert]

On Wed, 2 Oct 2002, peter ross wrote:

> >P.S. Would it be possible to write a import_xvidraw.c module that
> >reads finished output from export_xvidraw.c module and put that
> >e.g. into an AVI file?
> 
> iam no transcode wiz, but, the problem with raw files is:
> 
> a) the width/height dimensions must be either specified on the cmd
>    line, or you need to modifiy xvid to auto detect width/height.

Not a big problem. Transcode (and I guess all other encoding application)
have parameters for width/height. And I thought the feature to read
from stream was added to XVID a while ago, or "almost" added? 

> b) there is no framing, and therefore you have to be careful about
>    reading the file, such that the there is no buffer underflow.
>    the solutions to this are:
>    * naive: read the whole file into memory

Bad for large files or streaming material. 

>    * always read in width*height*3/2 bytes (an individual mpeg-4 frame
>      should not be larger than this, "but it could be").

I thought of 2*framesize (=width*height*3), I read somewhere that this is
an upper bound. Don't ask me where... 

>    * modify xvid to support some kind of buffer underflow callback.
> 
> api3 does not currently address decoding buffer underflows.

Is there still need for this if our buffer is large enough? 

Most important for me for the moment: 
     * It should be possible to detect where the next VOP starts 
       without decoding the whole frame to enable some kind of
       "pass-through". Is this simple? 

gruel