[theora-codecs] setting things right (side up)

[dan miller]

thanks Mau --

in response to the previous post, the reason I think it's important is that VP3 is pretty well
supported under Quicktime and Windows, in terms of plugging into typical apps such as Premiere,
AfterFX, MediaCleaner, etc.  This represents quite a few years of development and debugging with a
large userbase on multiple platform versions.

A lossless transcode creates an easy path to Theora media creation without waiting for all the
Theora/OGG-native plug-ins to be built, optimized, and debugged on every platform variant.  That's
about the only reason, but I think it's a pretty good one.

-dan

--- Mauricio Piacentini <mauricio at xiph.org> wrote:
> Dan, apparently the flip is done on input and reversed on output depending
> on the fomat,  in the vfwcodec.cpp layer code. See
> 
> vfwCodec::dx
> vfwCodec::cx
> 
> I talked with Ralph and derf at irc, and apparently no one is really sure
> the internal vp3 format is reversed, but I guess it is by looking at this
> code snippet. Is there a reason for this? I know DIBs are upside down on
> Windows, maybe that's the reason. I guess we should try to code the
> transcoder to see what are the issues, but it is not a trivial task. I am
> currently kind of busy, but will try to find some free time to hack an
> avifile parser.
> 
> Regards,
> Mauricio
> 
> ----- Original Message ----- 
> From: "dan miller" <danbmil99 at yahoo.com>
> To: <theora-codecs at xiph.org>
> Sent: Monday, June 23, 2003 2:26 PM
> Subject: [theora-codecs] setting things right (side up)
> 
> 
> > since no one has responded on theora-dev, I'm posting this here
> >
> > Theora apparently does not invert the image like VP3.  This is bad because
> we will not be able to
> > losslessly transcode stuff from VP3 to Theora or vice-versa.  Can anyone
> pinpoint where in the VP3
> > logic the decision is made to scan the image from the bottom-up, so we can
> diff it against the
> > Theora code?
> >
> > thanks - dan
> >
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