[Ffmpeg-devel] Snow?

[Michael Niedermayer]

Hi

On Wednesday 11 May 2005 00:40, Keenan Pepper wrote:
> Wavelets are really cool. I have nothing to do this summer (actually I
> have to go to this stupid math camp in Nebraska but hopefully I'll have
> internet access), so I'm going to learn more about wavelets, and hack on
> a wavelet codec, either Dirac or trying to bring Tarkin back from the
> dead, or this "snow" codec I just heard about.

tarkin is so dead that not even a necromancer would dare to touch it


> It seems a little mysterious though. 

good :)


> From google all I've found out is 
> that it's an experimental wavelet codec written by the ffmpeg team. What
> kind of wavelet transform does it use? Daubechies? Symmetric? Does it

a symmetric biorthoginal integer approxmation of the 9/7 daubechies wavelet


> use motion vectors? 

yes


> 3D wavelets? 

no, normal 3d wavelets are simply a very bad choice for video compression, 
there are other lifting based temporal transforms which do work well, but 
they add some delay, higher memory requirment and they would slow snow down 
further


> Are there any license/patent issues?  

iam not aware of any patents which cover it except one from IBM which IIRC 
will expire in a few month if it didnt already
if you want a certainly patent free codec you have no choice except using one 
which is older then the expiration timespan for patents
anyone who claims that a codec which is less old to be patent free is lying 
the number of patents is so huge that checking them all is simply not 
possible

[...]
-- 
Michael