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OpenMusic DocumentationOM 6.6 User Manual > MIDI > Rendering and Playback > Microintervals
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Playing Microintervals with MIDI

The MIDI pitch unit correspond to 1 semi-tone, so microintervals, in principle, are not handled by this format.

In OM however, pitches are expressed in midicents, which corresponds to MIDI pitch * 100.

Writing Microintervals

Two possibilities exist to play microintervals in OM :

Using MidiShare (The Default MIDI Player)

When playing microintervals, OpebnMusic uses a "trick" consisting in dispatching the notes on different MIDI channels depending on their micro-intervallic pitch.

  • 1/8 tones are sent to channel #2

  • 1/4 tones are sent to channel #3

  • 3/8 tones are sent to channel #4

As a consequence, you just need to "depitch" the corresponding channels to the right values in order to obtain the right microintervalling rendering.

Modifying Pitches in MIDI : PitchBend
Limitations of the Microintervals Playback

1) This techniques works ONLY for 1/4 and 1/8th tones (other or smaller microintervals are not considered)

2) MIDI channels must not be set or used for other purposes : they will be changed automatically by the OM player, so all the notes should initially be on channel 1.

Setting the MIDI Channels for Microintervals

In order to play 1/ or 1/8th tones in OM, channels 1, 2 and 3 must be depitched :

  • Channel 2 of 1/8 tone

  • Channel 3 of 2/8 tones (or 1/4 tone)

  • Channel 4 of 3/8 tones

Channel 1

Channel 1 does not need to be modified since 1/2 tones only will be kept on this channel.


The pitchbend and pitchwheel functions can be use to set the pitch of the "microintervallic channels".

PitchBend/PitchWheel : MIDI-Send boxes
Depitching with PitchWheel

The pitchweel function has more precision than pitchbend (this is the main difference between the two functions).

The value range for the pitchwheel are 0 - 8192, which usually correspond to 1 tone pitch deviation.

As a consequence, 1/8th tone corresponds to pitchwheel = 1024, 2/8th tones = 2048, and 3/8th tones = 3072.

These values must be assigned respectively to channels 2, 3 and 4.

At evaluating the pitchwheel box, the MIDI channels will be modified and subsequent MIDI playback will render miucrotones accordingly.


To reset the pitchbend values pitchweel again with values = 0 for every channel:

Using Another Player

The MicroPlayer allows to play MIDI objects with no microintervallic restriction.

Changing the Player / About MicroPlayer
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