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| Matthias Gallé... |
 Posted: Mon Sep 14, 2009 8:23 am |
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I want to do some test with a(n adaptative) PPM coder (or context
arithmetic coder) but where the context is non-contiguos. Will say,
where the context of character at position i is a subsequence that
finishes at position i-k.
Is anybody aware of a simple implementation of such a coder? I tried M
Nelson's higher order AC
(http://www.dogma.net/markn/articles/arith/part2.htm), but there the
context is contiguos.
I would be thankful for any pointer you can give.
--
Matthias Gallé
Project Symbiose
Centre de Recherche INRIA Rennes - Bretagne Atlantique,
Campus de Beaulieu, 35042 Rennes cedex, France
tel: (33|0) 2 9984 7523
http://www.irisa.fr/symbiose/matthias_galle |
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| glen herrmannsfeldt... |
| Posted: Mon Sep 14, 2009 8:23 am |
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Matthias Gall? <mgalle at (no spam) irisa.fr> wrote:
< I want to do some test with a(n adaptative) PPM coder (or context
< arithmetic coder) but where the context is non-contiguos. Will say,
< where the context of character at position i is a subsequence that
< finishes at position i-k.
Not so long ago, I wrote an arithmetic coder pretty much from the
JBIG2 descriptions. The coder itself doesn't care where the context
comes from. It is up to you to supply the appropriate context each
time you call the coder routine. What is important is that the
context be the same as that used by the decoder. (In my case, I
was writing for an existing decoder.)
-- glen |
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