Re: [Denemo-devel] midi channel allocation

[Nils]

On Sat, 7 Nov 2009 14:39:21 -0600
Jeremiah Benham <address@hidden> wrote:

This is a general problem and maybe Muse solves it this way, but other software 
solves it differently.
The good thing first: This is only the default behaviour, luckily you can enter 
channel and such changes at any time and in the end you can make it like you 
want it. Its important that we never lose sight that it should be possible to 
assign each midi port to any staff, even multiple staffs to only one port (a 
common usage).

I talked with Richard about this several times in IRC. The important point here 
is: Whats the lowest (or highest?) level? With normal midi, which is 
fluidsynth, you have one port (which is the virtual equivalent to the physical 
midi-port) and that is fluidsynth. This port has 16 channels so the channel is 
the level where the action happens with bank- and programchanges.

Jackmidi takes this to a new level: Now the port is the container, you can have 
unlimited ports, for example for any staff a new one. The 16 channels per port 
now are a limitation that does no harm.

What does this mean for Denemo?

For Jackmidi it is like you said, Jeremiah. Each staff is a different jack-port 
by default (with the option to change that later) and since the channel doesn't 
matter it can be channel 1 all the time.

But for Fluidsynth (and Midi-Export!!) its different. We have only one port 
there (and I recommend not to think of multiple fluid-instances) so we must use 
the channels. This means each staff a new channel.

The problem is: How to control this? I don't know this, but its a reason more 
to work on independent sets of midi-settings for each staff. 

Maybe just take the existing preferences tab for each staff and use it 
exclusivly for Fluidsynth. And with Richards new Dynamic Directives we could 
script the Channelchange (and Bank and Program if needed) to only work for 
Jackmidi out.

Nils



> I created functions in midi.c. There are called 
> 
> get_midi_channel() 
> get_midi_prognum()
> 
> They return an int representing the channel or prognum of the the
> currently selected staff. It was copied and moved from away from
> exportmidi.c to be used by other files. I noticed that denemo allocates
> a new channel for each staff. Other programs don't do this. Muse for
> example assigns channel 1 to each newly created staff. I think this
> should be our default also. The problem with making the channel number
> the same as the staff number is that you can only have 16 different
> tracks then. I don't know what this will do to midi playback because
> the channel can only be a number between 0-15. This needs to be
> changed. I will change it but I wanted to issue a warning.
> 
> Jeremiah
> 
> 
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> 


-- 
Nils Gey
http://www.nilsgey.de