OVERVIEW

AGF is a sample pre-processor. It transofrms the data into a form having very
little information content. This makes it easier for compression programs to
pack it down to a small size. AGF combined with GZIP gives an average
compression of 50% and it is always better than any other compression method on
its own. It is similar to ADPCM, but better :)

HISTORY

05-09-1999 : Released a version that works properly (more or less)

SUMMARY

AGF - Adaptive Gradient-descent FIR filter.

This is a neural-network-like adaptive FIR filter. The adaptation is
deterministic, which means that the sample can be recovered from the processed
file without needing to save an FIR coefficients to it as well. Adaptation is
done on-line, on a sample-by-sample basis.

USAGE

AGF MODE sample processed_sample

The processed sample can then be efficiently packed with any kind of packer.
I recommend xpk (xGZIP or xSQSH). lha/lzx will also do :)
The results are always MUCH better.

Modes:
   x  :  extract (decode) using a linear ANN
   c  :  compress (encode) using a linear ANN
   xd :  extract (decode) using a static filter
   cd :  compress (encode) using a static filter

TODO

Make an xpksublib out of it.
Add options for adjusting the number of coefficients and adaptation rate.



BUGS

Might have problems with samples that clip a lot..

Bugs Reports to olethros@geocities.com with "AGF BUG" as the subject message please

SEE ALSO

see also dev/basic/gasp.lha for a similar pre-processor where the adaptive
process is controlled by a Genetic Algorithm

 PERMSSN    UID  GID    PACKED    SIZE  RATIO     CRC       STAMP          NAME
---------- ----------- ------- ------- ------ ---------- ------------ -------------
[generic]                  942    1778  53.0% -lh5- 4dd0 Sep  6  1999 agf/agf.readme
[generic]                 8242   17020  48.4% -lh5- fd93 Sep  6  1999 agf/bin/agf
[generic]                  672    1820  36.9% -lh5- 8640 Sep  6  1999 agf/src/agf.c
[generic]                  129     233  55.4% -lh5- a7c4 Sep  6  1999 agf/src/agf.h
[generic]                  546    1164  46.9% -lh5- fcaa Sep  6  1999 agf/src/fir.c
[generic]                  163     291  56.0% -lh5- 6b53 Sep  6  1999 agf/src/fir.h
[generic]                  544    1534  35.5% -lh5- 2f9f Sep  6  1999 agf/src/main.c
---------- ----------- ------- ------- ------ ---------- ------------ -------------
 Total         7 files   11238   23840  47.1%            Sep  6  1999