[Matroska-devel] MPEG2 in MKV!

spyder spyder at matroska.org
Thu Oct 30 06:15:57 CET 2003

On Wednesday 29 October 2003 23:07, Christian HJ Wiesner wrote:
> John,
> congrats !!! It took you some time to make it, i know understanding the
> MPEG bitstream specs is not easy, but you always believed in that you
> can make it, and here you are !
> About your questions :
> spyder wrote:
> >The problem is how to mux this.  I think the GOP header should go with the
> >I-frame in a single block.
> What are the alternatives ? Introducing a GOP element ? Could this maybe
> help for advanced editing ?

I don't think that's necessary.  The GOP header is only needed for the few 
frames that follow.  And it always comes before an I-frame by my 
understanding.  So basicly it's part of the I-frame IMO.

> >  Also, there are repeated sequence headers before
> >most GOPs.  We can stick these with the I frame as well.
> As above .... a sequence header element ? Do these have 'read-only'
> character or do they have to be modified on editing ?

The sequence header can have a few changed properties I think but nothing 
should be changed unless the actual encoding is.

> >  The decoders should
> >have no problem with this.  The frames are in coding order.  And the
> > problem comes here:  Some frames in MPEG2 video actually decode to 2
> > frames on playback to produce a 3:2 pulldown.  I can detect these frames
> > with my code but how do we timestamp them.
> Timeslice ? What was the name of the feature again we introduced for
> handling of h.264 NALU's ?

I don't know :P  This is where I am lost.  Mosu says he doesn't know either 


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