[Matroska-devel] CodecState and CueCodecState

Steve Lhomme steve.lhomme at free.fr
Mon Jan 15 19:32:57 CET 2007


Moritz Bunkus wrote:
> Hey,
> 
> Mike (Haali) pointed out to me that keeping the sequence headers in the
> bitstream for MPEG-1/-2 video poses a problem when seeking. He proposed
> that we switch to using CodecState which has been created for just such
> a case.
> 
> Now I started working on it and noticed a couple of things.
> 
> 1. KaxCodecState does not exist yet in libmatroska. I've added it and
>    will commit the code soon.
> 
> 2. CodecState is a child of BlockGroup. However, the specs don't say
>    clearly when exactly CodecState is supposed to take effect. I propose
>    that it must be processed by the codec _before_ the data in the same
>    BlockGroup is processed, even if the Block element is located before
>    the CodecState element in the same BlockGroup.
> 
> Comments?

I'm OK with all that, but doesn't it raise compatibility issues with the 
older files ? Since we expect something in CodecPrivate that is not 
there anymore ?

Steve



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