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Groups > comp.compression > #1642

Re: Fixed-length coding trick

From Phil Carmody <thefatphil_demunged@yahoo.co.uk>
Newsgroups comp.compression
Subject Re: Fixed-length coding trick
Date 2012-12-05 23:25 +0200
Organization A noiseless patient Spider
Message-ID <87obi8kx7d.fsf@bazspaz.fatphil.org> (permalink)
References <5e0d49e8-44dd-412f-81f4-483162f17932@googlegroups.com> <9c2b1cb1-294e-4832-962c-5975ca72c847@googlegroups.com>

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JoeK <joek06@gmail.com> writes:
> On Saturday, September 22, 2012 3:50:00 PM UTC-4, Casper Bang wrote:
> > Reading up on some basic information theory, I came by some notes by David S.Touretzky, regarding fixed-length codes, where he hints of a certain trick when a few items are outside the upper-bound of the fixed length
> 
> Probably he means expanding a few codes to one more bit.
> 
> Say you have the codes:
> 
> ..00..
> ..01..
> ..10..
> ..11..
> 
> The "simple" method of expanding the number of codes is to just keep going lexicographically while extending the shortest codes:
> 
> adding one more symbol:
> 
> .000..
> ..01..
> ..10..
> ..11..
> .100..

10 and 100 share the same prefix - you cannot know whether a '10' is the whole 
symbol or just part of it.

However, you could expand the symbols at the other end:

..000..
..001..
..01..
..10..
..11..

Phil
-- 
I'm not saying that google groups censors my posts, but there's a strong link
between me saying "google groups sucks" in articles, and them disappearing.

Oh - I guess I might be saying that google groups censors my posts.

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Thread

Fixed-length coding trick Casper Bang <casper.bang@gmail.com> - 2012-09-22 12:50 -0700
  Re: Fixed-length coding trick Thomas Richter <thor@math.tu-berlin.de> - 2012-09-23 11:20 +0200
  Re: Fixed-length coding trick JoeK <joek06@gmail.com> - 2012-12-04 11:02 -0800
    Re: Fixed-length coding trick Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2012-12-05 23:25 +0200
  Re: Fixed-length coding trick James Dow Allen <gmail@jamesdowallen.nospam> - 2012-12-06 10:25 +0000
    Re: Fixed-length coding trick James Dow Allen <jdallen2000@yahoo.com> - 2012-12-06 02:47 -0800
  Re: Fixed-length coding trick Ernst <Ernst_Berg@sbcglobal.net> - 2013-04-05 17:38 -0700

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