[theora] Theora processing at server side : Removing non-needed frames

[ogg.k.ogg.k at googlemail.com]

> Finally I we be able to compress ogg video by removing frames from ogg/ogv
> video

Assuming you aren't selecting only keyframes, those images you select will have
to be reencoded as keyframes as they're built from earlier frames in
the original.
You can't just delete arbitrary frames and have the remaining ones
show properly.
That might not be a problem, since even encoding at a high quality should give
you a low bitrate stream due to the low number of frames, but I
thought I'd point it
out anyway.