[linux-audio-user] RE: midi automation and scripting tools?

[Stuart Allie]

> From: Mark Constable <markc at renta.net>
> 
> A crude but extremely simple option is to use midicomp and tweak the
ascii
> output anywhich way you care to with any scripting language on the
planet.
> Sure, there is no GUI and it's only a one shot process but there is
> nothing you could not do to a MIDI file with some persistence. What is
a
> total bonus is that once a technique is perfected then it can be
easily
> batched, ie; to normalize the volume settings of any MIDI file, to
always
> put the kick drum dead center, change any kick1 to kick2... and so on.
I
> used to have a bunch of macros and scripts for Kate (KDE editor) that
made
> working with the intermediate ascii output quite easy... I could make
> changes and one menu option would pipe the changes thru midicomp -c
and
> then into timidity so I could preview changes directly from Kate.
> 
> midicomp some.mid | somefilter arg1 arg2 | midicomp -c some2.mid
> 
> http://midicomp.opensrc.org/
> 
> --markc

Hi Mark,

Thanks for that. I have used midicomp plus awk/python to do some of
these things, (and midicsv which does a very similar job to midicomp)
but there are some limitations to do with midi itself that makes some of
the transformations I'd like to do very difficult.

For example, midi has no idea about bars/beats, but with the time
signature info in type 1 midi files you can map ticks to
bars/beats/ticks and so on, but it's not trivial.

The main problem is that midi files are streams of event data, not
musical information, and extracting the musical information sensibly is
tricky. For example, in a midi drum track, there might be a pan
controller before every note_on event to set the pan individually for
each drum. So if you are going to move the note_on event backwards or
forwards in time, you need to make sure that the pan event moves with
it. You also need to make sure that you don't get overlaps between notes
and mess up the note_on/note_off order. 

It looks like a scripting based solution is my best bet, with some sort
of awk-like language for specifying transformations. I think I'll have
to get stuck into my python code and see what happens.

Cheers,

Stuart