[XviD-devel] Transcode module

[Christoph Lampert]

On Wed, 2 Oct 2002, peter ross wrote:
> the video-object start code falls in the range [0x110,0x11f]
> the video-object-layer start code falls in the range [0x120,0x12f]
> 
> in both cases, the 4 lowest bits specify the object id.
> eg.
>         vo_id = vo_start & 0xf
>         vol_id = vol_start_code & 0xf
> 
> xvid does do anything with these ids, however they can be used to
> identiyu multiple objects (e.g. multiple videos or meshes) within the
> one bit stream.

Okay, sounds reasonable. So in theory more than one video_object startcode
per frame is possible, even if not used in XviD (or anyother MPEG-4 
codec I know of). It would therefore in general not be "clean" to simply
cut at VOP-start boundaries, but the timecode has to be taken into account
to see which VOPs belong in one chunk. Right? 

However, N-VOPs may not be combined with other VOPs even if they have the
same timecode, because they are just some kind of "stuffing" for us? 

Also, for bframes in packed mode, there are _more_ VOPs than there are 
frames and there would have to be a check that the combination 
P-VOP + B-VOP is written into one chunk. Also right? 

gruel