Description

Smooth the amplitude and frequency time functions of a pv stream using a 1st order lowpass IIR with time-varying cutoff frequency. This opcode uses the same filter as the 'tone' opcode, but this time acting separately on the amplitude and frequency time functions that make up a pv stream. The cutoff frequency parameter runs at the control-rate, but unlike tone and tonek, it is not specified in Hz, but as fractions of 1/2 frame-rate (actually the pv stream sampling rate), which is easier to understand. This means that the highest cutoff frequency is 1 and the lowest 0; the lower the frequency the smoother the functions and more pronounced the effect will be. This opcode produces effects that are more or less similar to pvsblur, but with two important differences: 1.smoothing of amplitudes and frequencies use separate sets of filters; and 2. there is no increase in computational cost when higher amounts of 'blurring' (smoothing) are desired.

Syntax

fsig pvsmooth fsigin, kacf, kfcf

Performance

fsig -- output pv stream

fsigin -- input pv stream.

kacf -- amount of cutoff frequency for amplitude function filtering, between 0 and 1, in fractions of 1/2 frame-rate.

kfcf -- amount of cutoff frequency for frequency function filtering, between 0 and 1, in fractions of 1/2 frame-rate.

	Warning
	It is unsafe to use the same f-variable for both input and output of pvs opcodes. Using the same one might lead to undefined behavior on some opcodes. Use a different one on the left and right sides of the opcode.

Examples

asig1  in                             ; input
fim   pvsanal  asig1,1024,256,1024,0  ; pvoc analysis 
fou   pvsmooth fim, 0.01, 0.01        ; smooth with cf at 1% of 1/2 frame-rate (ca 8.6 Hz)
aout  pvsynth fou                     ; pvoc synthesis
        

In the example above the input signal will be smoothed/blurred by pvsmooth with a cutoff frequency of 1% of 1/2 frame-rate (which is about 172Hz, so the cf is about 8.6Hz) .

Credits

New plugin in version 5

May 2006.