[fluid-dev] Questions about fluidsynth router commands

[Lutz Morelater]

Hi,

when run from the command line some router commands can be used with 
fluidsynth.

I would like to use these router commands to play several sounds on one MIDI 
channel, which is not possible with MIDI standard commands.

Let's say, I do this:

fluidsynth -a alsa --midi-channels=48

This will run fluidsynth once and create ONE single instance of fluidsynth. It 
will create THREE MIDI IN ports of fluidsynth which will show up in tools 
like ALSA sequencer etc.

In ALSA sequencer, for testing purposes, I create a connection from vkbd 
(virtual keyboard) to the first (lowest port number) of the 3 MIDI inputs of 
fluidsynth.

I load my favourite soundfont file into fluidsynth.

Now I can enter router commands in fluidsynth:

router_clear
router_begin note
router_chan 0 0 0 20
router_chan 0 0 0 21
...
router_end

This will clear the default router settings, install a new router rule which 
will track incoming MIDI note on messages of channel 0 and send the MIDI note 
on message on channel 20 and 21 (which are actually located in port 2 of the 
three virtual instances of MIDI in ports). So this means I am now playing two 
sounds on one MIDI channel at the same time.

BUT:
How do I change the sounds of channel 20 and 21 from within fluidsynth? Do I 
have to to this by connecting a tool to all of the three MIDI IN ports of 
fluidsynth and send the preset change commands from there (this would mean I 
send a preset change command to the second port of fluidsynth, channel 5 and 
6)?

Or is there another way? I hope it is not too complicated to understand what I 
am attempting to do...

Thanks for any hint and regards,
Lutz.