interp

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

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:

Example 485. iskip=0, imode=0


 |    ________
 |   /        
 |  /         
 | /          
 |/           
-+------------
 |            
        


Example 486. iskip=1, imode=0


(prev)
 |  __________
 | /          
 |/           
 |            
 |            
-+------------
 |            
        


Example 487. iskip=0, imode=1


 |____________
 |
 |
 |
 |
-+------------
 |
        


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. It uses the file interp.csd.

Example 488. Example of the interp opcode.

See the sections Real-time Audio and Command Line Flags for more information on using command line flags.

<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

Sample Level Operators

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.