[PlanetCCRMA] Rosegarden + Fluidsynth-DSSI + Jack = problem

Peter Howard pjh at coastal.net.au
Tue Apr 7 04:46:10 PDT 2009

(I have a vague memory of something like this appearing on the list
before: unfortunately I can't find it in the archives.  Apologies if
I've missed it)

Further apology for ordering - I made the discovery that starting
everything as root "fixes" things as I was typing this up.

After a break of a month or two, I loaded up some ideas I had sketched
in Rosegarden.  It's all MIDI - with multiple instances of
Fluidsynth-DSSI and some extra effects.  While pushing my laptop close
to the limit (Thinkpad T42p) in terms of CPU usage, it was working fine.

Now when I try to play the same file, it dies very quickly. (Sometimes
the moment I hit "play", sometimes it runs a few seconds then dies).  I
get the following two dialogues popping up:

        Error - Rosegarden
        The JACK Audio subsystem has failed or it has stopped Rosegarden
        from processing audio.
        Please restart Rosegarden to continue working with audio.
        Quitting other running applications may improve Rosegarden's

        Informational - artsmessage
        Sound server informational message:
        Error while initializing the sound driver:
        device: default can't be opened for playback (Device or resource
        The sound server will continue, using the null output device.

There's also the following line in the jack log:

        cannot create new client; rosegarden already exists
        cannot complete client connection process

The problem occurs using both standard Fedora kernels and CCRMA rt
kernels.  The presence of absence of pulseaudio-module-jack makes no

Another message from Jack got me thinking - real time failures

        cannot use real-time scheduling (FIFO at priority 55) [for
        thread -1235522672, from thread -1235522672] (1: Operation not

These messages appear for all kernels - both rt and non-rt

So on a hunch I started both qjackctl and rosegarden as root.  And that
works - running as root makes the rt failure disappear and rosegarden
works fine. Except that in January I didn't need to run anything as
root :-)

So can somebody suggest what broke during yum updates? 

Peter Howard <pjh at coastal.net.au>

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