[fluid-dev] Unloading unused patch between MIDI playbacks + force bank

[Christian Casteyde]

Hello,

First of all, thanks for fluidsynth which is... fluid! It's fast and works 
reliably on any machine I used it, without latency and without CPU hog. Seems 
too to have less noise in the output sound thand Timidity:-)

I'm thinking however to small things, that IMHO prevent fluid from being a 
good candidate for default soft synth on low end machines (at least on 
linux), till having high sound quality.

Sound quality is really fine with good SF2, but good SF2 are huge. So I'm 
wondering if fluidsynth could have an option to tell it to unload instruments 
when it is not playing any MIDI file (as timidity option "-U"). So fluid 
would reduce its RAM requirements when it's not used (OK, that could be 
swapped out by the system, but then it would be prone to latencies). Or maybe 
mlock RAM only before playing the file?

Better: I'm also wondering if it would be possible to add an option for 
loading only instruments used by a MIDI file? (It could be tricky if the MIDI 
file uses program changes of course: that would imply preparsing it. 
Moreover, that could not work with generic MIDI clients connected). So, 
instead of having, say 64MB of sound samples in memory, only having 2-4MB 
while playing a file...

Another question: I tried to play a file I played on a yamaha piano, that uses 
XG. Precisely, it uses a MSB/LSB 128 to select its own bank. fluidsynth does 
not recognise it, and the file is not played. However, apart from the bank, 
the instrument number is the same (1 for Grand Piano), so would it be 
possible to simply ignore bank change if the bank is not present in the SF2, 
just to be able to still play everything with GM instruments? (timidity 
indeed seems to do that... at least with is option "--force-bank". Meanwhile 
I'm compelled to edit the MIDI file with RoseGarden, or select standard piano 
on my piano before playing).

Thanks for all
Regards