RE: Quarter-tone MIDI

[Nigel Warner]

-----Original Message-----
From: address@hidden
[mailto:address@hidden
Behalf Of Morteza Dehghani
Sent: 30 October 2003 07:19
To: address@hidden
Subject: Quarter-tone MIDI


>It appears to me that quarter-tone notes are not converted to the right
>frequency in the midi format of the file. Is there a patch for this, if
>not which source file needs to be modified in order to fix the
>frequencies?
>Thank you,
>Morteza

        I can't tell you which file needs to be modified but just in case
        you are not aware of how to do it you need to ensure that 
        at least three MIDI messages are used.

        The first, to be on the safe side, is a Registered Parameter number
        message which sets the pitch wheel sensitivity. Although the MIDI
        standard suggests that all MIDI devices default to 2 semitones 
        up and down from the central position it would be a good idea to
        ensure that in a file using quarter tones that this is set.

        Controller 101 sets the coarse value, semitones, and controller 
        100 the fine in hundreds of a semitone. Next for each quarter tone
        desired you need to prefix it with a pitch wheel message to 
        shift it's pitch in the desired direction and then send the note
        on event and then reset the pitch wheel back to the central position
        unless the next note on the channel is modified in pitch in which 
        case you need to move the pitch wheel to the desired position.

        For the gory details see:

        http://www.borg.com/~jglatt/tech/midispec.htm

        Hope this helps.

        Nigel.




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