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fluidsynth-dssi not playing; crashes when opening projects

1) fluidsynth-dssi not playing
As per the note on the Haziest Photon thread, I'm still having problems with fluidsynth-dssi. In the attached qtz I can't get sound out of it (Track 1), but LV2 Calf Fluidsynth (with the same sf2) and Monosynth play correctly on the same track. In Qtractor 0.7.6 (tarball from this site), fluidsynth-dssi in this same project works fine.

On the qtz:
1) Please use any sf2 you want (couldn't upload one due to 1MB limit here). It doesn't make any difference as far as I can tell
2) Ignore the "Sidechain" filename - that's just what I testing out at the time

I'm now not getting the "sf2 being un-loaded" issue encountered previously and haven't been able to reproduce the above on a completely clean session yet. The only major difference I can think of with the qtz and a clean file is that the qtz has many different busses from a template I use (though they're not used in the track in question).

FYI, I'm running fluidsynth-dssi 1.0.0-15.1.3, obtained as an RPM from the SUSE repos. It's from a while ago, but it seems it's not updated that much anymore anyway. I know DSSI is quite old, so maybe I should use Calf Fluidsynth from now on, but fluidsynth-dssi has been fine for years so I've had no reason to switch.

2) Crashes when opening projects
While I'm on I'd like to let you know about another issue that's been happening recently. Qtractor will frequently crash (around 75% repro rate) when switching from one session to another. That is:

1) Run Qtractor and open a session
2) With the session still active, use "Open session" icon (or File > Open Recent) and attempt to load another
3) Crash occurs at least 75% of the time

I've attached a backtrace of what occurs when I try to switch from a different project to the attached qtz. It's from 0.7.7 but this has been happening for at least the past few weeks.

rncbc's picture

i see you're using more than one instance of fluidsynth-dssi.

as a matter of fact the current latest released version (v1.0.0, since 2009) of the fluidsynth-dssi plugin has a crash bug that serious manifests when you instantiate more than one instance of it; this bug has been corrected upstream and should be silent now on git head (ca. 2012); unfortunately most if not all distros, including opensuse, still deliver the old bugged version.

i believe this is the root of your troubles with fluidsynth-dssi, there might be others but this is one i know for sure. and this might relate to both of your questions above.

you have some couple of options here then:

  1. avoid having more than one instance of fluidsynth-dssi plugin in any one time; if you're loading the same sf2 file on each MIDI track for instance, consider to make it a single instance inserted on an output MIDI bus instead;
  2. un-install current package, clone and build and install from upstream git repo and try and test whether the same troubles still prevail every so often.

take both and all will be even finer, i hope ;)


Thanks very much for the comprehensive analysis :-)

The multiple instance problem would certainly explain why I couldn't recreate this on a clean file earlier today, as it only had 1 track. However, the template I've been using for years has many fluidsynth-dssi instances and I've only seen these problems recently. Oh well, these things happen sometimes I suppose.

Have just cloned fluidsynth-dssi and tried to build it but was met with various errors and it saying I didn't have things installed which I do in fact appear to have. I'll need to look into this further before testing with Qtractor. In any case, will post back if I still encounter problems with the new version.

FYI, I tested switching between projects (2) above) using Calf Fluidsynth and had no crashes at all, so your suspicion about fluidsynth-dssi being the culprit looks to be correct. The sessions also load much faster - previously there was a lag of a second or two each time.

Thanks again for the info.

Thanks very much for this - seems to play fine now. Tested the qtz I uploaded plus various other projects, all of which use multiple instances, and everything worked.

FYI, am still getting the crashes (though not with Calf Fluidsynth) but the title of your post was "fluidsynth-dssi not playing", so I think that's what you were addressing (please correct me if I'm wrong).

Thanks again.

rncbc's picture

yes. your rationale is plain right. :)

the crashes should be now addressed to the old pre-2013 (iirc) fluidsynth-dssi release codebase.


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