command line lilypond, midi to stdout

[Bob Harris]

Howdy,

I'm wondering if there is a way to have command-line
lilypond produce midi on stdout.

My typical use is to feed a .ly file into lilypond to create
a .midi output, then take thatinto garage band (a mac
program which I would describe as a midi recorder and track
editor).  Unfortunately lilypond sets the velocity of every
note to the max, 127, and for instruments like a bass or a
guitar garage band plays vel=127 as sort of a temporary
pitch shift (like a very hard string pluck and maybe some
motion on the fret).  To work around this, I wrote a simple
command-line program to receive a midi file on stdin, change
all the note-on velocities to a specified value, and spit
the result out on stdout.

I was hoping to combine lilypond with this on the command
line like this:
   cat mysong.ly | lilypond - | velchanger | mysong.midi

Unfortunatley, it appears lilypond provides no way to output
on stdout.  Instead it creates -.midi, requiring a second
command line to process the result.

Anybody have any ideas how I can accomplish that in a single
command?  My cycle is
edit,convert-to-midi,listen-in-garage-band, and I'm trying
to get it down to as few steps as possible to go from the
edit to hearing it.

Thanks,
Bob H