MIDI channel assignments

[David Santamauro]

Hi,

it's been a while since I had time to work with LilyPond but coming
back to it I'm trying to make one tiny adjustment to MIDI output:
specify exact channel (staff/voice contexts).

I need this because, like was mentioned here:

http://lists.gnu.org/archive/html/lilypond-user/2011-05/msg00165.html

... I use sound libraries inside my sequencer and the templates I have
setup there have orchestra families on different MIDI ports

port-1
ch-1 => woodwinds/flute-general
ch-2 => woodwinds/flute-legato

port-2
ch-1 => strings/violin-1-legator
ch-2 => strings/violin-1-pizz

etc ...

What I did was simply allow: \set midiChannel = 1

I haven't done extensive testing but behavior should default to
midiChannelMapping if midiChannel is not set.

I should proababy add a warning message if channel is out of range, but
it was just a proof-of-concept.

Any interest in this from anyone else?



git diff
diff --git a/lily/staff-performer.cc b/lily/staff-performer.cc
index bab8ae0..d649292 100644
--- a/lily/staff-performer.cc
+++ b/lily/staff-performer.cc
@@ -213,6 +213,16 @@ int
 Staff_performer::get_channel (string instrument)
 {
   SCM channel_mapping = get_property ("midiChannelMapping");
+
+  /* allow specific designation of MIDI channel */
+  SCM ch = get_property ("midiChannel");
+  if (scm_is_number(ch))
+    {
+      int c = scm_to_int(ch);
+      if (c > 0 && c < 17)
+        return c - 1;
+    }
+
   map<string, int>& channel_map
     = (channel_mapping != ly_symbol2scm ("instrument"))
     ? channel_map_
diff --git a/scm/define-context-properties.scm
b/scm/define-context-properties.scm index dab5211..90b97d8 100644
--- a/scm/define-context-properties.scm
+++ b/scm/define-context-properties.scm
@@ -364,6 +364,7 @@ event when notes with the same pitch, in the same
MIDI-file track, overlap.") @code{midiMinimumVolume}.")
      (midiMinimumVolume ,number? "Set the minimum loudness for MIDI.
 Ranges from 0 address@hidden")
+     (midiChannel ,number? "MIDI channel (1-16) for Staff or Voice.
  Default behavior is the default for @code{midiChannelMapping}")
(midiChannelMapping ,symbol? "How to map MIDI channels: per
@code{instrument} (default), @code{staff} or @code{voice}.")
(minimumFret ,number? "The tablature auto string-selecting mechanism
selects the highest string with a fret at least


thanks,

David