On 11/28/18 7:01 PM, [email protected] wrote:
On Sunday, November 25, 2018 at 7:38:24 AM UTC-5, awokd wrote:
[email protected] wrote on 11/24/18 7:45 PM:
Hi all.
I've put enough time into this one where I'm finally willing to reach out for
some help. I wanted to see if I could create an AppVm dedicated to music
creation, using QJackCtl and other open source software.
However, I'm having a terrible time at even getting Jack Audio off of the floor.
System: Base Qubes 4.0 installation, Fedora 28 template, Thinkpad T480 w/32Gb
RAM.
Expected results: Pressing "Start" on the QJackCtl GUI starts the server, per
the online manuals and Fedora's Musician documentation.
Actual results: Receive the "Could not connect to JACK server as client. - Overall
operation failed. - Unable to connect to server." error.
Tried so far: Following online documentation (treating the AppVM as a standard
Fedora installation), assigning the Audio PCI of the computer to that VM via
the Qubes Manager.
I'm totally willing to have this be something simple and embarrassing as I
learn the OS. Any help that you can provide would be much appreciated!
If I understand Qubes' audio right, Pulseaudio inside AppVMs gets
redirected to dom0's Pulseaudio which normally controls the sound
hardware. So if you want to override that, maybe try setting up an HVM
with the audio device assigned and without Qubes Pulseaudio redirection.
Think there's a Qubes package that does it so don't install that one in
the HVM.
Thanks, awokd. I tried passing through the audio PCI, but didn't get any
farther than the 'Settings' tab in Qjackctl. I could get Jack to recognize the
sound card, but couldn't get the server to actually start.
If anyone else has success in implementing Jack Audio (or configuring an audio
creation VM in Qubes/Xen), please don't hesitate to contact me!
Not meaning to discourage you but latency sensitive stuff will be a
hit-or-miss with virtualization (and by experience misses unfortunately
far outweigh hits). That's because of inaccuracies with the guest OS'
virtualized timer and/or how host resources are prioritized and
allocated to the guests.
With Qubes: my quality USB DAC constantly outputs audible clicks despite
being fed a data stream directly from sys-usb (ie. it's not
"pass-through'ed" to another VM). The same DAC works perfectly well on
other laptops (including a 10+ year old one) without virtualization.
It's USB though, and USB audio sucks so YMMV :)
I do hope you'll manage to have your setup working properly. If not I'd
advise that you buy/use an old laptop dedicated to your audio creation
tasks. That way you could install an audio focused distribution (like
Ubuntu Studio [1], AV Linux [2] - and probably others), as those
distributions package all the popular apps and may provide so-called
realtime kernels that help with latency and jitter.
You could also try to install such a distribution as a HVM in Qubes and
see how it works.
[1] https://ubuntustudio.org/
[2] http://www.bandshed.net/avlinux/
If this is the intended sound set up for Qubes, it makes sense and I'll instead
try the HVM approach to create my audio VM. I'll address the issues that I've
found so far in that attempt in another thread.
Excellent community, thank you!
- Max
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