clip
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## clip

clip — Clips a signal to a predefined limit.

## Description

Clips an a-rate signal to a predefined limit, in a “soft” manner, using one of three methods.

## Syntax

    ares clip asig, imeth, ilimit [, iarg]

## Initialization

imeth -- selects the clipping method. The default is 0. The methods are:

- 0 = Bram de Jong method (default)

- 1 = sine clipping

- 2 = tanh clipping

ilimit -- limiting value

iarg (optional, default=0.5) -- when imeth = 0, indicates the point at which clipping starts, in the range 0 - 1. Not used when imeth = 1 or imeth = 2. Default is 0.5.

## Performance

asig -- a-rate input signal

The Bram de Jong method (imeth = 0) applies the algorithm (denoting ilimit as limit and iarg as a):

    |x| >= 0 and |x| <= (limit*a):  f(x) = f(x)
    |x| > (limit*a) and |x| <= limit:  f(x) = sign(x) * (limit*a+(x-limit*a)/(1+((x-limit*a)/(limit*(1-a)))2))
    |x| > limit:  f(x) = sign(x) * (limit*(1+a))/2

The second method (imeth = 1) is the sine clip:

    |x| < limit:  f(x) = limit * sin(π*x/(2*limit)),   |x| >= limit:  f(x) = limit * sign(x)

The third method (imeth = 2) is the tanh clip:

    |x| < limit:  f(x) = limit * tanh(x/limit)/tanh(1),   |x| >= limit:  f(x) = limit * sign(x)

| Note
Method 1 appears to be non-functional at release of Csound version 4.07.

## Examples

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

Example 142. Example of the clip 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
    -odac     ;;;RT audio out
    ;-iadc    ;;;uncomment -iadc if RT audio input is needed too
    ; For Non-realtime ouput leave only the line below:
    ; -o clip.wav -W ;;; for file output any platform
    </CsOptions>
    <CsInstruments>

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

    instr 1	; white noise

    arnd rand 1	; full amlitude
    ; Clip the noisy waveform's amplitude to 0.5
    a1 clip arnd, p4, 0.5
       outs a1, a1

    endin

    instr 2	; white noise

    arnd rand 1	; full amlitude
    ; Clip the noisy waveform's amplitude to 0.1
    a1 clip arnd, p4, 0.1
       outs a1, a1

    endin

    </CsInstruments>
    <CsScore>

    ; Play Instrument #1 for one second.
    i 1 0 1 2
    ; Play Instrument #2 for one second.
    i 2 1 1 2
    s 3
    ; Play Instrument #1 for one second.
    i 1 0 1 0
    ; Play Instrument #2 for one second.
    i 2 1 1 0
    s 3
    ; Play Instrument #1 for one second.
    i 1 0 1 1
    ; Play Instrument #2 for one second.
    i 2 1 1 1
    e

    </CsScore>
    </CsoundSynthesizer>

## Credits

Author: John ffitch
University of Bath, Codemist Ltd.
Bath, UK
August, 2000

New in Csound version 4.07

September 2009: Thanks to a note from Paolo Dell'Osso, corrected the formula.

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