[theora-dev] Updated VP3 Document
melanson at pcisys.net
Fri Oct 10 10:36:34 PDT 2003
On Fri, 10 Oct 2003, Timothy B. Terriberry wrote:
> Didn't read too deeply yet, but a few comments on the Theora differences
Neat. This is the kind of feedback I was hoping for. I haven't
gone too deep into the Theora stuff yet but I wanted to get a placeholder
in the document for it.
> 1) We plan to fix the frame orientation to conform to that used with VP3
> before the beta (most likely in an alpha3). We want to preserve the
> ability to transcode from VP3 losslessly, and there's no real reason to
> keep two different orientations around.
No real reason other than it makes more sense to render from top
-> bottom. I won't dwell on the issue, though. I thought Dan Miller was
proposing a header bit to specify frame orientation; what happened to that
> 2) Theora stores the prefix-free codes directly, in the form of a full
> binary tree (this is a change from alpha 1, where the histograms used to
> generate the prefix-free codes were stored).
[should I be paranoid about the absense of item 3? :)]
> 4) Theora removes some of the unused bits in the VP3 frame header. There
> are still 3 0 bits in keyframe headers (keyframe type, which is always
> 0, and 2 unused bits), but the others are gone.
Thanks for the feedback...
<p><p>--- >8 ----
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