Description

Converts a control signal to an audio signal using linear interpolation.

Syntax

ares interp ksig [, iskip] [, imode]
    [, ivalue]

Initialization

iskip (optional, default=0) -- if non zero skips initialisation of internal save space (see reson).

imode (optional, default=0) -- sets the initial output value to the first k-rate input instead of zero. The following graphs show the output of interp with a constant input value, in the original, when skipping init, and in the new mode:

ivalue (optional, default=0) -- initial value if both imode and iskip are zero.

Performance

ksig -- input k-rate signal.

interp converts a control signal to an audio signal. It uses linear interpolation between successive kvals.

Examples

Here is an example of the interp opcode. Play interp.csd

<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
; Audio out   Audio in
-odac      ;;;RT audio out
; For Non-realtime ouput leave only the line below:
; -o interp.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

sr     = 44100
ksmps  = 1024    ; very high, for demonstration purpose
nchnls = 2
0dbfs  = 1

instr 1
  
kamp linseg 0, p3/2, .5, p3/2, 0        ; Create an amplitude envelope.
a1   oscil kamp, 440                    ; The amplitude envelope will sound rough because it
outs a1, a1                             ; jumps every ksmps period (1024)
endin


instr 2     ; a smoother sounding instrument.

kamp linseg 0, p3/2, .5, p3/2, 0        ; Create an amplitude envelope
aamp interp kamp                        ; The amplitude envelope will sound smoother due to
a1 oscil aamp, 440                      ; linear interpolation at the higher a-rate
outs a1, a1
endin

</CsInstruments>
<CsScore>
i 1 0 2     ; sounds raw

i 2 3 2     ; sounds smooth
e
</CsScore>
</CsoundSynthesizer>

See Also

diff, downsamp, integ, samphold, upsamp

More information on this opcode: Csound Journal, issue10 - An Overview of Csound Variable Types , written by Andrés Cabrera

Credits

Updated November 2002, thanks to a note from both Rasmus Ekman and Istvan Varga.