[Theora] trying to encode from dvd using mplayer

Ralph Giles giles at xiph.org
Tue Dec 14 11:13:06 PST 2004

On Tue, Dec 14, 2004 at 10:21:48AM +0100, David Kuehling wrote:

> Don't know.  Just used those values since they are closer to the default
> keyframe distances used by mencoder for encoding to MPEG4/DivX.  In
> theory it should give some improvements.  Too large keyframe distance
> might cause certain artefacts, but since I was never able to spot one of
> these, I assume that Theora is designed for this kind of use...

It's just a tradeoff. Larger distances aren't as good for seek 
or webcasting, but can save some on the bitrate. I understand
a number of DivX encoders use huge keyframe spacings, obsessed
with bitrate over functionality, one might say.

> If you have particularly noisy input data you might also try to play
> around with `ti.noise_sensitivity'...  but using mplayer's denoise
> filter (for example: `-vf hqdn3d=2:2:2') might give better quality.

Yes. I would expect a denoise prefilter to work better as well.

> Try:  (not sure about that)
>   svn co http://svn.xiph.org/trunk/theora-mmx   

http://svn.xiph.org/branches/theora-mmx/ actually.


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