[Theora-dev] Re: [ogg-dev] OggYUV
arc at Xiph.org
Mon Nov 7 23:30:08 PST 2005
On Mon, Nov 07, 2005 at 11:11:16PM -0800, Ralph Giles wrote:
> On Mon, Nov 07, 2005 at 10:22:50PM -0800, Arc wrote:
> > In response to (and with the help of) John Koleszar I put together an early
> > draft of OggYUV.. or rather, a list of header fields for it.
> Why not just wrap yuv4mpeg, one frame per packet?
Honestly, that's what it'll probobally end up being functionally. Practically,
we need something a bit more flexible, as yuv4mpeg is 4:2:0 only, and we need a
wider variety of colorspaces.
> It does suffer from not being clear on colourspace or sampling issues,
It's not a lack of clarity, it's a lack of flexibility. AFAIK, based on all
I've read and seen in implementation, it's *ONLY* 4:2:0, and while you could use
any colorspace theoretically, it makes sense to put this in the stream header.
I may be wrong, but even if it's more flexible than that, it certainly doesn't
support the myriad of different formats we need, or will need in the future.
> but it is dead simple.
Well, it could be more simple.. ie, instead of using space-delimited ascii
numbers, we'll use binary numbers which the Ogg bitpacker can easily extract.
Personally, I think that http://wiki.xiph.org/index.php/OggPCM#Format is pretty
damned simple - several orders of magnitude more so than RIFF .wav files.
I think that, giving OggYUV a similar format to OggPCM, a Python script using
pyogg2 could be written to convert yuv4mpeg2 to OggYUV in under 100 lines.
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