[fluid-dev] Re: An evil screeching noise when playing

[Kimmo Sundqvist]

Toby wrote:

> If you can use CVS you could narrow it down to a single CVS checkin.

I don't know about how to use CVS, but if it is not hard, then I might try it 
out and get somewhere.

> Kimmo Sundqvist wrote:

>> Tried playing sabre_dance.mid.  It was ok for 10 seconds, then I
>> noticed a clicking that got faster and faster, and suddenly the noise
...
>> after the Sabre dance starts playing, Fluidsynth's CPU usage slowly
>> (in about 10 seconds) climbs to 99% and stays there.

> Wait a minute, does the screeching sound only appear after Fluidsynth
> has been at 99% CPU for some time?  

I think I saw with 1.0.5 that the CPU usage of Fluidsynth was low until I 
started playing, and the problem appeared at the same time the CPU usage 
wento to 100%.

With 1.0.3 the CPU usage goes to 99% immediately after I start Fluidsynth.  
That is, before any SoundFont is loaded and before anything is being played.  
This is not a big problem with a dual CPU machine, but a bug nevertheless.

I never have problems with actual skipping.  I have problems with the relative 
loudness of instruments totally messed up with 1.0.3 and Merlin 22MB 
soundfont, but other than that, 1.0.3 would work perfectly if not for the 99% 
of CPU time.

> From what you say it seems like something is making Fluidsynth
> gradually comsume more and more CPU until it reaches 99%, at which point
> clicks appear (this is normal.)

Not clicks as in skipping, but clicks as in a positive feedback loop.

> This is quite plausible behaviour and quite a different matter than
> 'something' in the MIDI file triggering evil screeches at random.

I will look more into the randomness.

> If this were the case, we'd be looking for a sort of 'CPU leak'
> somewhere in Fluidsynth or maybe in your system's libraries or kernel.
> Can you investigate further?

My system is Gentoo linux with gcc-3.3.6, glibc-2.3.5-r2

I will try installing 1.0.5 and do comparisons.  1.0.4 is not available in 
Portage, but I will see if I can make a 1.0.4 ebuild myself.

-Kimmo S.