tunemidi.c: microtune a MIDI file.

Author: Kees van den Doel
        kvdoel@cs.ubc.ca

This   program  reads a MIDI  file   and creates a   new MIDI  file with
customized tuning, specified on the command  line.  You tell it how many
cents (1/100 of a semitone) it should change  the 12 pitches, relative to
equal temperament.

source: tunemidi.c

platform: UNIX (trivially portable, only unlink() seems nonportable)

compile: cc -o tunemidi tunemidi.c

usage: tunemidi c1 c2 c3 c4 c5 c6 c7 c8 c9 c10 c11 c12 [infile [outfile]]

c1,..,c12 are  the fine tunings  of pitches starting  from  C, in cents.
Maximal  +-200 cent. If no  outfile specified writes on standard output.
If no  input  file specified reads  from  standard  input and writes  on
standard output.  Will  change tuning of input  MIDI file infile.

For example, if song.mid contains a MIDI file in shur in E, the F should
be 40 cent sharp.

tunemidi 0 0 0 0 40 0 0 0 0 0 0 song.mid song2.mid

will create file song2.mid in the correct tuning. You probably also want
to flatten the G and the C by 15 cent or so, with

tunemidi -15 0 0 0 40 0 -15 0 0 0 0 song.mid song2.mid

BUGS and limitations: 

Assumes that your sytnhesizer has pitch bend range set to 2 semitones up
and  down. You can  change this  in the  code  trivially. I should clean
this up.

The input  file must contain ONLY  MONOPHONIC TRACKS (no chords inside a
track).  You can have as many  tracks as you  want, but they must all be
on  different MIDI channels.  This  is a fundamental limitation of MIDI,
since pitchbend is channelwide. I see no way around this.

The input file should not contain any  pitchbend commands already before
processing.  They will   interfere  with the pitchbends  inserted.  This
should be fixed by an extra pass, removing the pitchbends already in the
file. If that's important to anyone, I may fix that.

You must have write permission  in the directory  you run tunemidi from.
This is because a temporary file is created. I am definitely too lazy to
worry about that.


Kees