[Ffmpeg-devel] Snow?

Keenan Pepper keenanpepper
Wed May 11 18:54:36 CEST 2005


Michael Niedermayer wrote:
> tarkin is so dead that not even a necromancer would dare to touch it

I rather suspected that. Oh well.

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

I have a vague idea of what "biorthogonal" means - basically that it's 
not actually orthogonal and that you need different sets of vectors for 
analysis and synthesis, right?
Does "9/7" mean the low pass filter has 9 taps and the high pass filter 
has 7 taps? Or vice versa?
(I guess I should just read the code and find this stuff out for myself, 
huh? =P)

Is this the same wavelet used in JPEG2000?

> 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

Makes sense.

> 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

So basically it's in the same legal category as Theora?





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