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Sound Out Useless in F17 under VMware Fusion due to Underruns

Fedora 17 on a VMware Fusion virtual machine is great for lightweight use (editing, silent apps), but audio apps unfortunately do not keep up with real time (getting continuous underruns, called ``xruns'' in the JACK messages window). This is likely just a bug of some kind, since the hardware should be able to do it. Plain ALSA sound-out comes closer to working than JACK sound-out. I tried making huge buffers in JACK (4096 frames/period, the largest setting in qjackctl) and dropping the sampling rate to 22 kHz, but this had no audible effect. There is much more silence than sound when there should be a steady sound. (In the ALSA case, the sound is nearly continuous, but noisy.) Tests run included the Pd tone generator (menu item Media / Test Audio and MIDI) and a qtractor lv2 synth plugin (simple sawtooth oscillator). I am allocating one CPU core and 1GB of memory to the Linux virtual machine, which should be enough. Going to 2 cores and 4GB of memory affected it, yielding a steady stream of short beeps about two per second, but still of course unuseable. Also, something prevents locking of 100MB of memory by JACK. This is probably a permissions problem, but I see no point in worrying about it. Virtual Linux for audio development is presently a dead issue because VMware Fusion v5.0.3 (last tested 6/29/13) has unworkable sound support for it.


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``My Computers'', by Julius O. Smith III, Web document.
Copyright © 2015-03-02 by Julius O. Smith III
Center for Computer Research in Music and Acoustics (CCRMA),   Stanford University
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