[Ffmpeg-devel] [RFC, Request for testing, PATCH] snow wavelet fliping

Michael Niedermayer michaelni
Tue Jan 2 21:59:34 CET 2007


On Tue, Jan 02, 2007 at 07:47:38PM +0100, Stefan de Konink wrote:
> On Tue, 2 Jan 2007, Michael Niedermayer wrote:
> > -> some signals simply can be represented much more compactly in the
> >    wavelet domain if they are shifted a little
> >
> > if we now always encode images with the same shift then there is a much
> > higher chance that some signals will be always hard to store, if OTOH
> > we flip the wavelet after each frame then what cannot easily be stored
> > (= gets quantized to 0) in the even frames can with some luck more easily
> > be stored in the odd frames
> So if I get this right; if this is tied to a local motion predictor which
> results a local direction. It could find the optimal local shift?
> Or wouldn't this be possible because the wavelet will be rotated and
> cannot be applied to the image in decoding. I'm surprised a fixed 180
> degree turn 'just' works better.

i dont see how this could be done easily locally, at least not without
sideeffects like blocking artefacts ...

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Breaking DRM is a little like attempting to break through a door even
though the window is wide open and the only thing in the house is a bunch
of things you dont want and which you would get tomorrow for free anyway
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