Hi, As suggested by Paul Davis in the Moog VCF thread, I implemented the biquad filters found in
http://www.harmony-central.com/Computer/Programming/Audio-EQ-Cookbook.txt and a simple resonant lowpass by Paul Kellett as LADSPA plugins: ftp://ftp.suse.com/pub/people/mana/kalsatools-current/vcf-0.0.3.tar.bz2 Two .so files will be built: vcf.so has single audio input and output. vcf_cv_in.so has additional audio rate inputs for frequency-, resonance- and dBgain control. These ports need not be used by the host. In this case the host should init them with NULL. The plugin will interpret a NULL pointer as unused audio port. I updated my host AlsaModularSynth and added an example for the new filters (example_ladspa_vcf_cv_in.ams) ftp://ftp.suse.com/pub/people/mana/kalsatools-current/ams-1.2.0_pre5.tar.bz2 The lower and upper bounds of some control parameters may still need some refinement. Suggestions ? When playing with the filters, the spectrum analyzer KWaveView might be helpful. BTW KWaveView does not require KDE... Have fun ! Matthias -- Dr. Matthias Nagorni SuSE GmbH Deutschherrnstr. 15-19 phone: +49 911 74053375 D - 90429 Nuernberg fax : +49 911 74053483
