Okay, what I did was change Ubuntu 10.04 32-bit -> 64-bit sometime
this year (to be clear, I'm speaking about VirtualBox VMs, none of my
Ubuntus are/were on host machine). I tried to render the midi file in
1.1.1 and it had piano bug. I updated to 1.1.2 from your unofficial
ppa on launchpad and notes for some instruments started to be off-key.
Just to be sure I booted the clean Ubuntu 10.04 32-bit VM, updated to
1.1.2 from your ppa (1.1.1 has piano bug, too) and what do you know,
it works fine.
Ah cool, so that PPA was useful then :) Note that my PPA has since been superseded by a native 1.1.2 package in Ubuntu 10.10.
So I'm assuming the problem lies somewhere in 64-bit
compiled code.
Ah, then that does sound like a bug in the 64-bit version. I haven't got a 64-bit OS set up to test it on.
On 32-bit VM it plays fine, on 64-bit gives off-key notes. There's a
very slight chance it's somehow VirtualBox bug but I wouldn't bet on
it, the wave rendering goes before outputting the sound stream and
rhythm/drums sound fine in both cases.
I doubt it's a virtualisation problem, since you are (or at least in your last email, were) rendering to a file, which means it's unrelated to the virtual hardware or timing (the faster-than-realtime mode of FluidSynth doesn't use the system timer, as far as I know, it just computes the final wave file and outputs it). In the most recent email, you used -a alsa to test, which would be more susceptible to virtual hardware issues. I assume you also tried it with -F in 1.1.3.
(Btw I am not a FluidSynth developer, I'm just interested.)