[matroska-devel] Re: AVI compatibility mode?

Moritz Bunkus moritz at bunkus.org
Mon Feb 17 15:36:47 CET 2003


> >  - These structures are Windows specific. Neither Unix/Linux nor MacOS
> > knows about them.
> As long as they don't deal with AVI. Otherwise it is handled somewhere.

Sure, but not necessarily the complete structures. E.g. the only fields
that are used e.g. in mplayer or my ogmtools are width, height, fps,
fourcc, bits per pixel, channels, sample rate... There are a lot of
fields that I don't know what I should put into them at all. So if I
write a Matroska file and have to create such structures which fields
do I set to which values?

> Correct, but since it's a Microsoft compatibility mode, we can assume the
> structure is little endian. It should also be aligned on 1 octet. (uint8 = 1
> octet, not 4)


What my primary question is - why is there a MS compatibility mode at
all? Is there a real need for such a mode? (Apart from being lazy and
able to reuse those structures, and apart from being able to tell that
the 'dummy frames for B frames' are still present)

> Normally most of them should already be in matroska and general to any
> (audio/video) codec. For the rest, they probably have no meaning at the
> container level.

Then why are those structures still used?

> > Another point: I now know that there are dummy frames in AVIs if B
> > frames are being used. I understand that you want to store that fact
> > in Matroska in some way. But there's alreadly KaxCodecID...
> ?

Well forget that paragraph, I don't know either what I wanted to say
anymore ;)

 ==> Ciao, Mosu (Moritz Bunkus)

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