ampmidicurve

Maps an input MIDI velocity number to an output gain factor with a maximum value of 1, modifying the output gain by a dynamic range and a shaping exponent.

Plugin opcode in ampmidid.

The minimum output gain is 1 minus the dynamic range. A shaping exponent of 1 gives a linear response; increasing the exponent produces an increasingly depressed knee in the gain response curve.

Syntax

igain ampmidicurve ivelocity, idynamicrange, iexponent
kgain ampmidicurve kvelocity, kdynamicrange, kexponent

Initialization

_imidivelocity _ -- MIDI velocity number, ranging from 0 through 127.

idynamicrange -- Intended dynamic range of gain, from 0 through 1.

iexponent -- Exponent applied to shape the gain response curve, 1 or greater.

Performance

_kmidivelocity _ -- MIDI velocity number, ranging from 0 through 127.

kdynamicrange -- Intended dynamic range of gain, from 0 through 1.

kexponent -- Exponent applied to shape the gain response curve, 1 or greater.

Maps an input MIDI velocity number to an output gain factor with a maximum value of 1, modifying the output gain by a dynamic range and a shaping exponent. The minimum output gain is 1 minus the dynamic range. A shaping exponent of 1 gives a linear response; increasing the exponent produces an increasingly depressed knee in the gain response curve, according to the equation: \(y = d \; (x/127)^h + 1 - d\), where \(y\) = the gain, \(x\) = the input MIDI velocity (from 0 through 127), \(d\) = the dynamic range (from p through 1), and \(h\) = the shaping exponent (1 or greater). This opcode was suggested by Mauro Giubileo.

Examples

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

<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
;;;RT audio out, note=p4 and velocity=p5
-odac --midi-key=4 --midi-velocity-amp=5
;-iadc    ;;;uncomment -iadc if RT audio input is needed too
; For Non-realtime ouput leave only the line below:
; -o ampmidid.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

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

massign 0, 1    ;assign all midi to instr. 1

instr 1

isine ftgenonce 0, 0, 4096, 10, 1 ;sine wave

  ihz = cpsmidinn(p4)
  ivelocity = p5
  ; MIDI velocity to signal amplitude.
  iamplitude = ampdb(ivelocity)
  ; Gain with compressed dynamic range, soft knee.
  igain ampmidicurve ivelocity, .92, 3
  print ivelocity, iamplitude, igain
  a1   oscili 1, ihz, isine
  aenv madsr 0.05, 0.1, 0.5, 0.2
  asig = a1 * aenv * igain
  outs asig, asig

endin

</CsInstruments>
<CsScore>
;       note velocity
i 1 0 2  61  100
i 1 + 2  65  10
e
</CsScore>
</CsoundSynthesizer>

See also

Midi Converters

Credits

Author: Michael Gogins
2019