[Theora] Playback too slow?!

Ivan Popov pin at medic.chalmers.se
Wed Mar 30 05:59:18 PST 2005

On Wed, Mar 30, 2005 at 02:45:28PM -0000, Alen Ladavac wrote:
> > improve performance on multicore processors.
> Interesting idea. How could that be done? I always thought that next frame
> is dependent on the previous one. Or should the operations inside one frame
> be paralellized?

I mean inside a frame. It is hardly feasible to buffer the whole chunks
between keyframes (unless you encode with guaranteed small max keyframe

> > you would spare quite a bit of cpu by decompressing 5 frames instead of 6.
> I am still not sure why, but on consoles with TV output, frame-tearing
> (swapping in the middle of refresh) just doesn't look good. It may be that

You don't have to. Just telecine (repeat each 5-th frame) after decoding.
It will look worse than otherwise - but it is the way a whole lot of movies
are damaged due to the American TV standard... Still that is treated
as acceptable (though I detelecine always when I can).

> but we have to tune for the worst case scenario, which is NTSC. 20 fps would
> work for NTSC as well (sync each 3 fields), but it is not smooth enough.

Telecining may be unacceptable as well, but may be better than nothing.
It should look more natural, if it is prepared not from a real 25 fps movie,
but from a decimated 30 fps one.
Well, of course it is just an ugly workaround...


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