The Alternative Csound Reference Manual
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# midinoteonpch

midinoteonpch -- Gets a MIDI note number as a pitch-class value.

## Description

midinoteonpch is designed to simplify writing instruments that can be used interchangeably for either score or MIDI input, and to make it easier to adapt instruments originally written for score input to work with MIDI input.

In general, it should be possible to write instrument definitions that work identically with both scores and MIDI, including both MIDI files and real-time MIDI input, without using any conditional statements, and that take full advantage of MIDI voice messages.

Note that correlating Csound instruments with MIDI channel numbers is done using the massign opcode for real-time performance,. For file-driven performance, instrument numbers default to MIDI channel number + 1, but the defaults are overridden by any MIDI program change messages in the file.

## Syntax

midinoteonpch xpch, xvelocity

## Performance

xpch -- returns MIDI key translated to octave.pch during MIDI activation, remains unchanged otherwise.

xvelocity -- returns MIDI velocity during MIDI activation, remains unchanged otherwise.

If the instrument was activated by MIDI input, the opcode overwrites the values of xpch and xvelocity with the corresponding value from MIDI input. If the instrument was NOT activated by MIDI input, the values of xpch and xvelocity remain unchanged.

This enables score p-fields to receive MIDI input data during MIDI activation, and score values otherwise.

| Adapting a score-activated Csound instrument.

To adapt an ordinary Csound instrument designed for score activation for score/MIDI interoperability:

- Change all linen, linseg, and expseg opcodes to linenr, linsegr, and expsegr, respectively, except for a de-clicking or damping envelope. This will not materially change score-driven performance.

- Add the following lines at the beginning of the instrument definition:

      ; Ensures that a MIDI-activated instrument
      ; will have a positive p3 field.
      mididefault 60, p3
      ; Puts MIDI key translated to cycles per
      ; second into p4, and MIDI velocity into p5
      midinoteoncps p4, p5

  Obviously, midinoteoncps could be changed to midinoteonoct or any of the other options, and the choice of p-fields is arbitrary.

## Examples

Here is an example of the midinoteonpch opcode. It uses the files midinoteonpch.orc and midinoteonpch.sco.

Example 1. Example of the midinoteonpch opcode.

    /* midinoteonpch.orc */
    ; Initialize the global variables.
    sr = 44100
    kr = 4410
    ksmps = 10
    nchnls = 1

    ; Instrument #1.
    instr 1
      kpch init 0
      kvelocity init 0

      midinoteonpch kpch, kvelocity

      ; Display the pitch-class value when it changes.
      printk2 kpch
    endin
    /* midinoteonpch.orc */

    /* midinoteonpch.sco */
    ; Play Instrument #1 for ten seconds.
    i 1 0 10
    e
    /* midinoteonpch.sco */

Its output should include lines like:

     i1     8.09000
     i1     9.05000

## See Also

midichannelaftertouch, midicontrolchange, mididefault, midinoteoff, midinoteoncps, midinoteonkey, midinoteonoct, midipitchbend, midipolyaftertouch, midiprogramchange

## Credits

Author: Michael Gogins

Example written by Kevin Conder.

New in version 4.20

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