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Re: [fluid-dev] [Rosegarden-devel] Problems With Rosegarden Using Qsynth
Re: [fluid-dev] [Rosegarden-devel] Problems With Rosegarden Using Qsynth or Fluidsynth When Using PulseAudio Instead Of JACK
Tue, 29 Jan 2013 14:59:31 -0700
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On 01/29/2013 01:55 PM, D. Michael McIntyre wrote:
I don't have a clue why Rosegarden is causing this and MusE isn't. Upon
a superficial and quick comparison, they both appear to work the same
way in the case where QSynth is already running, and it's configured to
use pulseaudio: they both start with audio support disabled, due to
being unable to start jackd, because pulseaudio has control of the hardware.
Michael, and all:
Perhaps that is a significant clue to the problem.
JACK seems to have made great strides lately. Where it used to not
co-exist with anything, it now seems to get along with most everything.
You can now play Internet videos with sound while JACK (QjackCtl) is
running, and can run all sorts of things together with it. On the other
hand, Audacity doesn't get-along with it at all.
If you look in the QjackCtl "Connections" dialog, in the "Audio" tab,
you now see a "PulseAudio JACK Sink" and a "PulseAudio JACK Source"
device. And the ubiquitous hangs seem much harder to cause.
I had concluded, based on my testing on several desktop computers in my
test-bed, that they had finally solved all of the problems, and that
JACK nicely gets along with everything. They seem to have even put
those fixes in the Long-Term-Support release, 12.04, because it behaves
just as well.
But then I tried the same test on my Acer Aspire laptop, and my new MIDI
device initially trying to use the (PulseAudio) Java Sound synthesizer
(with QjackCtl already running), hung it tighter than a drum, and I had
to power the machine down.
So I guess all is not yet well on the JACK audio front.
The significant clue in what you said, was that Rosegarden would fail to
start jackd, and would thus start up without audio support.
In doing the test, there was no warning about audio support being
disabled (that I in the past always used to see in such situations).
Where they now co-exist better, it probably succeeded in starting
jackd. But perhaps, they don't successfully co-exist in other ways.
As you pointed out, running with JACK is much more efficient. Where
processor usage was around 75% using PulseAudio, the same piece played
using JACK had a processor utilization of around 25%, which is no
insignificant difference. To even get it to work without cutting-out on
PulseAudio, I had to disable both the Reverb and the Chorus. I can use
them when I use JACK in place of PulseAudio.
By the way, most of my testing was done on an Intel Celeron CPU 2.53 GHz
desktop machine, running Lubuntu 12.10.