[FFmpeg-devel] 4xm idct computation

[Michael Niedermayer]

On Wed, Dec 28, 2011 at 05:40:57AM +0100, yann.lepetitcorps at free.fr wrote:
> Selon Michael Niedermayer <michaelni at gmx.at>:
> 
> > On Wed, Dec 28, 2011 at 05:07:43AM +0100, yann.lepetitcorps at free.fr wrote:
> > > Selon yann.lepetitcorps at free.fr:
> > >
> > > > Hi,
> > > >
> > > > I have take a look into the libavcodec/4xm.c
> > > > => can the IDCT to be remplaced by something more simpler like Haar
> > wavelets
> > > > ?
> > > > (for to can be accellerated by MMX instructions for example)
> > > >
> > > >
> > > > @+
> > > > Yannoo
> > > > _______________________________________________
> > > > ffmpeg-devel mailing list
> > > > ffmpeg-devel at ffmpeg.org
> > > > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> > > >
> > >
> > > 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
> >
> > [...]
> > --
> > Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
> >
> > Let us carefully observe those good qualities wherein our enemies excel us
> > and endeavor to excel them, by avoiding what is faulty, and imitating what
> > is excellent in them. -- Plutarch
> >
> 
> 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.

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Its not that you shouldnt use gotos but rather that you should write
readable code and code with gotos often but not always is less readable
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