Subject: [ecasound] filter testing
From: Kai Vehmanen (kaiv@wakkanet.fi)
Date: Thu Sep 16 1999 - 23:33:19 EEST
Ok, I took a sample of random noise and tested all ecasound's
filters. I used snd for the fft analysis.
-ef1 Resonant bandpass. Not a good start. This is definately
broken.
-ef3 Resonant lowpass. This is one the most complex effects of
ecasound... and also among the working ones.
-efb Bandpass. Appears to work as expected.
-efh Highpass. Seems to work. -efh:22050 produces silence as it
should.
-efi Inverse comb. Works as expected.
-efl Lowpass. Works, but isn't as aggressive as ef3. -efl:0
produces silence.
-efr Bandreject. -efr:11025,22050 results in a empty fft as
it should.
-efs Resonator (=resonant bandpass). Seems to work fine.
Not very accurate though.
So most of them work as expected. I'll try to fix -ef1.
Btw; efb, efh, efl and efr are all based on the same
filter equation (2nd order butterworth filters). Due to
this, they're also equally accurate. Anyway, there will probably
be a few new filters in ecasound 1.6.x. For more info about
planned features of 1.6.x and 1.7.x, see
http://www.wakkanet.fi/~kaiv/ecasound/plans.html
-- Kai Vehmanen <kaiv@wakkanet.fi> -------- CS, University of Turku, Finland . http://www.wakkanet.fi/ecasound/ - linux audio processing . http://www.wakkanet.fi/sculpscape/ - ambient-idm-rock-... mp3/ra/wav
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