Re: Map voices to channels in MIDI output

[Keith OHara]

On Tue, 15 Mar 2011 13:53:41 -0700, Jan Nieuwenhuizen <address@hidden> wrote:
> To create a new track for each voice as we do now,
> still seems a bit like a kludge to fix MIDI's brokenness.
It is, at least, the same kludge others (classicalmidiconnection.com) use when 
they have more than 16 simultaneous lines of music.  To have some sympathy for 
the brokenness, remember that MIDI is primarily a delivery protocol to playback 
hardware.


I tried to summarize what the relevant classes do, and indicated the desired 
extensions in [[ ]] below :

Objects of class Audio_staff correspond to MIDI tracks
Each Audio_Staff contains
   the list of audio_items that will go onto a midi_track

Objects of class Staff_performer correspond MIDI channels.
Each Staff_performer has
   a channel number,
   optionally a MidiInstrument, midiMinimumVolume, etc.,
   one [[or more]] objects of class Audio_Staff.
This class implements the LilyPond performer "Staff_performer"

Normally each Staff_performer gets a unique MIDI channel number,
[[ but if midiChannelMapping==#'instrument then Staff_performers with the same 
midiInstrument share a channel number.  Program-changes and midiVolume events 
from each Staff_performer will affect the shared MIDI channel.]]

Staff_performer is responsible for routing Audio_items to the appropriate 
Audio_staff.
Normally there is one Audio_staff per Staff_performer,
[[ but if midiTrackMapping==#'voice then each uniquely-named Voice has its own 
Audio_staff.]]

I still have the net change to midi output at 
http://codereview.appspot.com/4271043/ in case it is useful.
Should the Audio_staff be "promoted" to Track_performer, in Voice context by 
default, and collect its own Audio_items?
Do you still want all those maps ?