[theora-dev] Re: Keyframe seeking in Ogg and spec

Niklas Höglund niklas at neuromancer.dnsalias.org
Tue Sep 17 07:36:01 PDT 2002

In article <001301c25dc4$f16e3520$0200a8c0 at athlonxp>, Tabuleiro wrote:
> On a related note, would it be possible/desireable for an application to
> write some sort of "comment" or "extended" info to the headers, which is
> optional and would contain information about the position of keyframes, etc?
> Higher layers could look for this information in the header, and if present
> they could use it to optimize seeks and buffering operations.

I personally would like to be able to record TV to .ogg, and view it
while it is being recorded.  While viewing I of course want to be able
to seek in the stream, so I can skip commercials, for example, or go
back and see a scene again.  I haven't been able to do this with AVI, as
it depends on having a seek index, and that index can't be written until
the recording has finished.  MPEG works, however, as it uses fixed-size
frames (I think).

I wouldn't mind an optional index, but the best would be if some method
could be found that eliminates the need for an index, or interleaves the
index in the stream.

I tried to find how ogg does this, but haven't, so maybe this is all
already nicely solved.  I suspect so.


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