port

Applies portamento to a step-valued control signal.

Syntax

kres port ksig, ihtim [, isig]

Initialization

ihtim -- half-time of the function, in seconds.

isig (optional, default=0) -- initial (i.e. previous) value for internal feedback. The default value is 0. Negative value will cause initialization to be skipped and last value from previous instance to be used as initial value for note.

Performance

kres -- the output signal at control-rate.

ksig -- the input signal at control-rate.

port applies portamento to a step-valued control signal. At each new step value, ksig is low-pass filtered to move towards that value at a rate determined by ihtim. ihtim is the “half-time” of the function (in seconds), during which the curve will traverse half the distance towards the new value, then half as much again, etc., theoretically never reaching its asymptote. With portk, the half-time can be varied at the control rate.

Examples

Here is an example of the port opcode. It uses the file port.csd.

<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
-odac   ;;;realtime audio out
;-iadc    ;;;uncomment -iadc if realtime audio input is needed too
; For Non-realtime ouput leave only the line below:
; -o port.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

sr = 44100 
ksmps = 32 
0dbfs  = 1 
nchnls = 2

instr 1

aout  diskin2 "fox.wav",1, 0, 1
kf,ka ptrack aout, 512  ; pitch track with winsize=1024
kcps  port kf, 0.01     ; smooth freq
kamp  port ka, 0.01     ; smooth amp
; drive an oscillator
asig  poscil ampdb(kamp)*0dbfs, kcps, 1
      outs  asig, asig

endin
</CsInstruments>
<CsScore>
; simple sine wave
f 1 0 4096 10 1

i 1 0  5
e
</CsScore>
</CsoundSynthesizer>

See also

Standard Filters: Control signal filters