[theora] Many improvements and a few problems

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

> .OGV produced now are not recognized by MPC-HC's internal OGG splitter,
> which worked well for all files previously. If Haali splitter is
> installed, it can handle most files, but in some of them duration is
> incorrectly detected and the stop after a few seconds.
>
> Has something changed in the OGG stream or in libogg or something?

Nothing has changed in the Ogg bitstream or the Theora format.
However, the new encoders make use of more freedom allowed by the
format, so code that just handled the subset used by previous versions
of the libtheora encoder might be confused by newer streams.

This should not affect duration determination though, as the container
layer (which you get time from) hasn't changed, but MPC-HC might have
custom code that decodes at the same time.

(I assume that by splitter, you mean demuxer ?)