cha_filter 1.1

Short:        OctaMED nsm plugin - better filter effect
Author:       cheilandallen@yahoo.co.uk (Claude Heiland-Allen)
Version:      1.1
Requires:     nsm patched OctaMED SoundStudio
Architecture: m68k-amigaos


$VER: cha_filter.readme 1.3 (2000.02.26) © Claude Heiland-Allen

BUGFIX: could divide by 0 if instrument default pitch >= C-4


A better filter effect for processing samples using OctaMED
SoundStudio with the nsm patch system.


Features:
 -  reasonably fast (speed depends on filter settings)
 -  sounds good (much better than OSS)
 -  easy(ish) to use command line interface
 -  parameters use standard units (eg. Hz instead of a
    number of samples)
 -  professional quality algorithms mean you can do more
    than guess what averaging and distance should be
 -  highly modular object oriented design allows code to be
    reused easily in other plugins
 -  4 filter types (Butterworth, Chebyshev, Bessel,
    resonator)
 -  6 filter shapes (lowpass, highpass, bandstop, bandpass,
    allpass, notch)


Example usage:

cha_filter from 1 to 2 butterworth bilinear lowpass
                                      frequency 250 order 4
cha_filter 1 2 bw blt lp f 250 o 4
    - simple lowpass filter, second command line shows the
      many abbreviations


Tips:
 -  control-C interrupts processing, for emergencies
 -  centralize the sample before filtering otherwise the
    offset error may increase


Future:
 -  cha_autofilter: using note data in the tracker editor,
    different parts of the sample can be filtered at
    different frequencies

Source:
 -  in cha_source.lha
 -  this program is based on
        mkfilter/mkshape/mkaverage/gencode/genplot
        A. J. Fisher
        fisher@minster.york.ac.uk


Claude