Skip to content

distort1

Modified hyperbolic tangent distortion.

distort1 can be used to generate wave shaping distortion based on a modification of the tanh function.

       exp(asig * (shape1 + pregain)) - exp(asig * (shape2 - pregain))
aout = ---------------------------------------------------------------
       exp(asig * pregain)            + exp(-asig * pregain)

Syntax

ares distort1 asig, kpregain, kpostgain, kshape1, kshape2[, imode]

Initialization

imode (Csound version 5.00 and later only; optional, defaults to 0) -- scales kpregain, kpostgain, kshape1, and kshape2 for use with audio signals in the range -32768 to 32768 (imode=0), -0dbfs to 0dbfs (imode=1), or disables scaling of kpregain and kpostgain and scales kshape1 by kpregain and kshape2 by -kpregain (imode=2).

Performance

asig -- is the input signal.

kpregain -- determines the amount of gain applied to the signal before waveshaping. A value of 1 gives slight distortion.

kpostgain -- determines the amount of gain applied to the signal after waveshaping.

kshape1 -- determines the shape of the positive part of the curve. A value of 0 gives a flat clip, small positive values give sloped shaping.

kshape2 -- determines the shape of the negative part of the curve.

Examples

Here is an example of the distort1 opcode. It uses the file distort1.csd.

Example of the distort1 opcode.
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
-odac     ;;;RT audio out
;-iadc    ;;;uncomment -iadc if RT audio input is needed too
; For Non-realtime ouput leave only the line below:
; -o distort1.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

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


gadist init 0

instr 1
  iamp = p4
  ifqc = cpspch(p5)
  asig pluck iamp, ifqc, ifqc, 0, 1
  gadist = gadist + asig
endin

instr 50
  kpre init p4
  kpost init p5
  kshap1 init p6
  kshap2 init p7
  aout distort1 gadist, kpre, kpost, kshap1, kshap2, 1

  outs aout, aout

  gadist = 0
endin


</CsInstruments>
<CsScore>

;   Sta  Dur  Amp    Pitch
i1  0.0  3.0  0.5  6.00
i1  0.5  2.5  0.5  7.00
i1  1.0  2.0  0.5  7.07
i1  1.5  1.5  0.5  8.00

;   Sta  Dur  PreGain PostGain Shape1 Shape2
i50 0    4      2       .5       0      0
e

</CsScore>
</CsoundSynthesizer>

See also

Special Effects

Waveshaping

Credits

Author: Hans Mikelson
December 1998

New in Csound version 3.50