File README_VCF of Package ladspa and implement plugins for audio EQ biquad filters
based on the cookbook formulae by Robert Bristow-Johnson: has audio rate ports for signal i/o. has additional audio rate inputs for time dependent control of 
filter parameters. The Frequency Input is linear between 0..1, where 1
corresponds to 20000 Hz. The input signal is added to the Frequency Offset

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