[XviD-devel] 1.0 bug

Christoph Lampert chl at math.uni-bonn.de
Wed Mar 31 10:08:59 CEST 2004

On Wed, 31 Mar 2004, Andrew Voznytsa wrote:
> May I ask you what N-VOP is? I know I/P/B/S, but N is really something 
> new for me.
> If it is not so hard - point me to some resource where I can read about.

N-VOPs are "not coded VOPs" (I guess even "not coded P-VOPs").

In VideoObjectPlane header there's a bit "vop_coded". If that is set to 
'0', there is no new image data in this frame, and the VOPs bitstream ends 
here. So the whole frame's bitstream is just a few bytes long. 

It can be used if e.g. you do object shape coding and no part of the
object is visible, or, to just tell the decoder "nothing changed".

Btw. according to 3ivx, Quicktime doesn't handle them but crashes. 


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