PPM 8-bit?

Giganews Newsgroups
Subject: PPM 8-bit?
Posted by:  Harry Potter (rose.joseph…@yahoo.com)
Date: Mon, 25 May 2020

Hi!  I just looked at the Wikipedia article "Prediction by partial matching=
" and like what I hear.  I believe I get the gist of it: shorten each chara=
cter to the likelihood that it will occur after the previous character.  No=
w, I have an idea to shorten the code:

1.  Scan the input for all strings and count the number of occurrences of e=
ach character after the last.
2.  Scan the occurrences and write, for each preceding character, the 16 mo=
st-often-occurring following characters. 16 could be any useful number.
3.  Scan the input again and, for each character stored as likely-occurring=
, write 1 then the shortened count.  Otherwise, write 0 then a fraction of =
the entry skipping the stored values over the total non-stored values.  I h=
ave a way to shorten these values in bit streams.

Now, this requires a lot of memory: the counts alone would require 256k and=
, therefore, I deem it a 32-bit technique.  I am currently working on 8- an=
d 16-bit compression technique.  I plan to do 32- and 64-bit compression at=
a later date.  Unless, of course, I can shorten the buffer to include only=
the often-occurring values.  :)

What do you think?

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