[theora-dev] Keyframe seeking in Ogg and spec

jbradford at dial.pipex.com jbradford at dial.pipex.com
Sat Sep 14 14:02:17 PDT 2002

> please do pipe up if it appears I missed a salient point.

I might be missing something obvious here, (probably am :-) ), but here goes:

Shouldn't we include metadata that indicates which packets can be ignored to create a lower bandwidth version of the stream?  How does Vorbis do this?  What I'm refering to is the ability to take an, e.g. 128 Kbps stream and create the 64 Kbps stream that *would* have been created, had the material been encoded at 64 Kbps to begin with, not just re-lossy-compressing an existing compressed stream.

The reason I'm mentioning this is because whilst with Vorbis the idea was primarily, I think, to allow people to encode at a high bit rate, and then create low bit rate streams from that, with video, isn't it possible that a server might be configured to drop packets gracefully, if bandwidth was short?  So, low bandwidth would not result in jumpy, skippy video, but just lower quality video.  The problem is, substream priority identification would really have to be implemented at the Ogg container file level, so that the sever didn't have to actually parse the Theora stream to intellegently drop packets.

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