[fluid-dev] Feature Request for fluidsynth PRESET CHANGE

[Lutz Morelater]

Hi,

some time ago I wrote about a feature I would have liked to be implemented in 
fluidsynth. Because I never had enough time to look after that I had 
forgotten about it. Now it is time to let it live up again ;-)

The feature I would like fluidsynth to have is about the Preset Change 
command.

Normally, it works like this:

Fluidsynth receives "preset change XXX on channel YYY". It then switches off 
the sound currently playing on that channel YYY and turns on sound XXX for 
this channel. This is the standard behaviour of this MIDI command.

BUT:
even on today's fast computers this means, we can select one sound at a time 
only. We can combine several channels to play simultanously but we can never 
have two or more instruments on the very same channel and change between 
them. We also might need additional software that merges several MIDI 
channels into one channel.

This is where my request enters the stage.

Why not have a second mode for the PRESET CHANGE command that does not switch 
sounds for a channel but toggle them? So, when receiving "preset change XXX 
on channel YYY" what happens is that if XXX is already playing on that 
channel YYY the sound will be switched off, and if ABC is playing on that 
channel YYY then both sounds are now playing, i.e. XXX and at the same time 
ABC.

This feature would be really nice to have. It is like pulling and pushing the 
stops of a church organ with the PRESET CHANGE command. There are several 
nice sound fonts that contain interesting synth sounds well worth combining 
like stops, and we could then combine just about any sound with another sound 
very easyly. Setting more than 128 sounds could be possible by using the bank 
change command.

Another request which is an extension of the above request.
Looking at hardware synths, keyboards etc. we might find an option for the 
PRESET CHANGE command that does not switch sounds but complete presets.
When receiving a PRESET CHANGE command in this mode the synth does not only 
set/switch sounds for one channel, it also sets the sounds for all channels, 
their chorus and hall values, footswitch settings, volume settings etc. The 
channel parameter of this command is ignored while in that mode.  wonder if 
fluidsynth could have this mode too, so that a simple PRESET CHANGE command 
sent by any MIDI device would let fluidsynth load one/several soundfont 
files, set the sounds for all channel, set volume, chorus and hall values. I 
think that would be great.

So, this would mean there are three different modes for the PRESET CHANGE 
command, and if fluidsynth knew all of them it could even switch itself from 
one mode to another, depending on its settings.

What do You think?

Kind regards,
Crypto.