I'm just coming to terms with how to send commands to FluidSynth to control things like reverb (specifically, I want to control reverb).
I'm under the impression that while a few things can be controlled from the command-line (such as gain), most things (such as reverb) cannot be. There are a few other ways to control these things:
- Using the interactive shell, you can type in commands manually. - You can also use Unix pipes to send the same shell commands (e.g., 'echo "rev_setlevel 10" | fluidsynth' or 'fluidsynth < commands.txt').*
- Using -s, FluidSynth listens for TCP connections and accepts the same shell commands via network input. - Using the API, you can programmatically change the settings. - Graphically using QSynth (which I imagine uses the API).
The problem is that none of these methods seem to work in conjunction with the -F fast renderer feature. -F is a way to tell FluidSynth "forget about TCP servers, MIDI servers, output devices, command shells, etc -- just convert a MIDI input into a digital audio file as fast as you can and quit." Which is a fantastic feature -- I have makefiles set up so that I can just go "make" and FluidSynth renders all of my music (it's one thing I love about FluidSynth as it lets me export all of my music with a single command).
The problem is that as far as I can tell, ALL of the above options for changing settings require that you are running FluidSynth either in server mode or via the API, which means they are incompatible with -F. In fact, I can't find a way to change reverb when using the fast renderer at all. Note that I have tried using -F and not -i, and piping a text file in to stdin, but FluidSynth seems to ignore stdin when -F is supplied. Is there a way?
The only way I can think of is only available to me because I've hacked on FluidSynth in the past:
- Edit include/fluidsynth/synth.h FLUID_REVERB_DEFAULT_LEVEL and friends and recompile the program.
Obviously not the cleanest solution :) As I am coming up on a deadline, if there is no simple solution, I'll do that for now. But in the future, I would like to propose a feature (which I'm willing to work on) where you can specify on the command-line:
This would read in <settings-file> and execute it as if it was supplied to stdin, but it would always work (even when FS refuses to read from stdin, such as with -F). This should be pretty trivial to implement, I would imagine.