[FFmpeg-devel] 4xm idct computation
michaelni at gmx.at
Wed Dec 28 17:30:24 CET 2011
On Wed, Dec 28, 2011 at 06:31:00AM +0100, yann.lepetitcorps at free.fr wrote:
> > > > > More precisely, I search an encoder/decoder that work like the DCT/iDCT
> > but
> > > > with
> > > > > the De Haar, Debauchies and/or others lifting schemes transforms
> > instead
> > > > the
> > > > > [Fast] Fourrier Transform
> > > >
> > > > look at dirac, snow, indeo4/5 and jpeg2000 they use things in that
> > > > direction. most are not block based though
> > > >
> > >
> > > This is my problem, I search something that is "only partially block based"
> > :)
> > > (cf. that work on fixed 8x8 blocs, but where the blocs are dynamically
> > > constructed from a "mipmapped" picture)
> > indeo4 uses block based haar transform amongth other things
> > see http://wiki.multimedia.cx/index.php?title=Indeo_4
> > the haar transform does not perform very well though.
> > and there are fraktal coders that work by downscaling a simple trivial
> > image and then using blocks from it to construct a new image repeatly
> > to build up the image one wants.
> > These are too slow for practical use though.
> This seem a good scheme, but what is the scale of the "too slow" ?
the problem with fraktal coders is the encoding step. It is VERY slow
so they are not used in practice anywhere AFAIK (someone will probably
reply and point out some real world useage if there is one)
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Observe your enemies, for they first find out your faults. -- Antisthenes
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