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cpstmid

Get a MIDI note number (allows customized micro-tuning scales).

This unit is similar to cpsmidi, but allows fully customized micro-tuning scales.

Syntax

icps cpstmid ifn

Initialization

ifn -- function table containing the parameters (numgrades, interval, basefreq, basekeymidi) and the tuning ratios.

Performance

Init-rate only

cpsmid requires five parameters, the first, ifn, is the function table number of the tuning ratios, and the other parameters must be stored in the function table itself. The function table ifn should be generated by GEN02, with normalization inhibited. The first four values stored in this function are:

  1. numgrades -- the number of grades of the micro-tuning scale
  2. interval -- the frequency range covered before repeating the grade ratios, for example 2 for one octave, 1.5 for a fifth etc.
  3. basefreq -- the base frequency of the scale in Hz
  4. basekeymidi -- the MIDI note number to which basefreq is assigned unmodified

After these four values, the user can begin to insert the tuning ratios. For example, for a standard 12 note scale with the base frequency of 261 Hz assigned to the key number 60, the corresponding f-statement in the score to generate the table should be:

;          numgrades interval  basefreq basekeymidi tuning ratios (equal temp)
f1 0 64 -2   12       2        261        60         1  1.059463094359  1.122462048309  1.189207115003 ..etc...

Another example with a 24 note scale with a base frequency of 440 assigned to the key number 48, and a repetition interval of 1.5:

;           numgrades interval  basefreq basekeymidi tuning-ratios (equal temp)
f1 0 64 -2   24        1.5      440        48         1   1.01  1.02  1.03   ..etc...

Examples

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

Example of the cpstmid opcode.
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<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
-odac     -M0  ;;;RT audio I/O with MIDI in
;-iadc    ;;;uncomment -iadc if RT audio input is needed too
; For Non-realtime ouput leave only the line below:
; -o cpstmid.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>
; after an example from Kevin Conder
sr = 44100
ksmps = 32
nchnls = 2
0dbfs = 1

; Table #1, a normal 12-tone equal temperament scale.
; numgrades = 12 (twelve tones)
; interval = 2 (one octave)
; basefreq = 261.659 (Middle C)
; basekeymidi = 60 (Middle C)
gitemp ftgen 1, 0, 64, -2, 12, 2, 261.659, 60, 1.00, \
             1.059, 1.122, 1.189, 1.260, 1.335, 1.414, \
             1.498, 1.588, 1.682, 1.782, 1.888, 2.000

instr 1

ifn = 1
icps    cpstmid ifn
        print icps
asig    oscil 0.6, icps, 2
        outs  asig, asig

endin


</CsInstruments>
<CsScore>
f 0 20
;sine wave.
f 2 0 16384 10 1

e

</CsScore>
</CsoundSynthesizer>

See also

Midi Converters

Credits

Author: Gabriel Maldonado
Italy
1998

New in Csound version 3.492