[LAU] Fluidsynth, soundfonts, jack, and latency

Guru Prasad B. R. prasadbrg at gmail.com
Mon Nov 2 08:42:43 EST 2009

Jonathan E. Brickman wrote:

> Guru, do you know what was/is the CPU load during the episode? 
> J.E.B.

No, Jonathan, unfortunately I didn't check... was running behind 
schedule before the gig, and haven't been near my system since. It may 
take a while for me to get back to my system, and checking CPU load will 
be the first thing I intend to do.

Couple of other things that I missed out in previous posts. Firstly, 
before the gig I wanted to check whether it was a qsynth-specific or 
general fluidsynth issue, so I installed ghostess, which can run 
multiple instances simultaneously. I loaded the same soundfonts, and 
experienced exactly the same issue - so if there's a bug in the app, 
then it must be in the fluidsynth libraries.

Second issue of note: few weeks ago, while still running Ubuntu, I 
wanted to find out what exactly caused the jack crash that I reported on 
this list at the time (perhaps unrelated to the current issue) . I found 
a "stress test" to replicate the problem: hitting a lot of notes while 
keeping my sustain pedal down. Initially, the crash would happen within 
20-30 seconds of banging the controller (!). When I changed the 
polyphony settings from 256 to 64, it would be much more stable - for 
more than 10-15 mins of banging! Again, I was able to replicate the same 
thing with ghostess.

This incident has left me with a lurking suspicion about a possible bug 
in the fluidsynth libraries. I'm curious, though... has anyone else 
experienced similar issues?
Looking forward to pointers/feedback/suggestions.


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