Video/Audio Choppiness Every 4-6 Minutes When Playing High-Definition Video & Using USB Audio

[aQubesUser]

Qubes OS version (e.g., R3.2):

R.3.2

Affected TemplateVMs (e.g., fedora-23, if applicable):

StandaloneVM, fedora-24 upgraded from fedora-23 from base install

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Expected behavior:

Hi-definition video (720p & above; encoded using h264 standard) should play smoothly throughout duration of video. Video may be online (e.g. YouTube.com) or stored locally (e.g. *.mkv file). Audio is sent over a USB device that is connected to the sys-usb VM and attached to the StandaloneVM with qvm-usb -a ...

Actual behavior:

Video plays smoothly for 4 to 6 minutes, audio & video are in-sync. For a few seconds, video will be choppy as well as audio before returning to smooth playback. Issue repeats every 4-6 minutes. I have checked /etc/crontab for dom0 and the StandaloneVM in case there was a cronjob running that would cause load on the system, both are empty.

Steps to reproduce the behavior:

1. Create a StandaloneVM from fedora-23 template
2. Upgrade StandaloneVM to fedora-24
   1. Add, enable rpmfusion sources & install ffmpeg-libs to allow playback of h264 videos in Firefox
   2. Install mpv/vlc/etc for playback of video files
3. Play a high-definition video from YouTube.com or locally
4. Allow playback to conitinue for 4-6 minutes

General notes:

Some messages seen in dmesg:

[ 4667.143981] vhci_hcd: dequeue a urb ffff8800788b5200
[ 4667.144012] vhci_hcd: device ffff880078fd8298 seems to be still connected
[ 4667.144042] vhci_hcd: dequeue a urb ffff8800788b5600
[ 4667.144056] vhci_hcd: device ffff880078fd8298 seems to be still connected
[ 4667.144070] vhci_hcd: dequeue a urb ffff8800788b4a00
[ 4667.144083] vhci_hcd: device ffff880078fd8298 seems to be still connected
[ 4667.147250] vhci_hcd: unlink->seqnum 434847
[ 4667.147274] vhci_hcd: unlink->seqnum 434848
[ 4667.147290] vhci_hcd: urb->status -104
[ 4667.153414] vhci_hcd: unlink->seqnum 434847
[ 4667.153437] vhci_hcd: unlink->seqnum 434849
[ 4667.153453] vhci_hcd: urb->status -104
[ 4667.159357] vhci_hcd: unlink->seqnum 434847
[ 4667.159385] vhci_hcd: urb->status -104

Relevant video hardware:

00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09)
01:00.0 3D controller: NVIDIA Corporation GF117M [GeForce 610M/710M/810M/820M / GT 620M/625M/630M/720M] (rev a1)

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Related issues:

[aQubesUser]

I just wanted to add that playing similar videos in Firefox or mpv worked without any issues when this system was running Debian.

[aQubesUser]

I just wanted to add that playing similar videos in Firefox or mpv worked without any issues when this system was running Debian.

[marmarek]

Actually, there is a dom0 cron job running every 6 minutes - /etc/cron.d/qubes-sync-clock.cron

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-- Best Regards, Marek Marczykowski-Górecki Invisible Things Lab A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing?

[marmarek]

Actually, there is a dom0 cron job running every 6 minutes - /etc/cron.d/qubes-sync-clock.cron

…

-- Best Regards, Marek Marczykowski-Górecki Invisible Things Lab A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing?

[aQubesUser]

@marmarek

Ah. I hadn't looked in the directories, thanks for pointing this out.
Do you recommend making the following change?

*/6 * * * * root /usr/bin/nice 19 /usr/bin/qvm-sync-clock > /dev/null 2>&1 || true

[aQubesUser]

@marmarek

Ah. I hadn't looked in the directories, thanks for pointing this out.
Do you recommend making the following change?

*/6 * * * * root /usr/bin/nice 19 /usr/bin/qvm-sync-clock > /dev/null 2>&1 || true

[marmarek]

I'd first comment it out completely to check if that's the cause.

…

-- Best Regards, Marek Marczykowski-Górecki Invisible Things Lab A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing?

[marmarek]

I'd first comment it out completely to check if that's the cause.

…

-- Best Regards, Marek Marczykowski-Górecki Invisible Things Lab A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing?

[aQubesUser]

I made that change and played a video to test before seeing your response. The change seems to have fixed the periodic choppiness, but I will continue to test this.

mpv falls back to using the x11 video output driver, playback with opengl results in choppy audio even though video playback is fine (not sure about this either).
x11 makes sense given the description of the GUI on this page: https://www.qubes-os.org/doc/gui/

[aQubesUser]

I made that change and played a video to test before seeing your response. The change seems to have fixed the periodic choppiness, but I will continue to test this.

mpv falls back to using the x11 video output driver, playback with opengl results in choppy audio even though video playback is fine (not sure about this either).
x11 makes sense given the description of the GUI on this page: https://www.qubes-os.org/doc/gui/

[aQubesUser]

Description of video drivers for mpv: https://mpv.io/manual/master/#video-output-drivers

[aQubesUser]

Description of video drivers for mpv: https://mpv.io/manual/master/#video-output-drivers

[andrewdavidwong]

I made that change and played a video to test before seeing your response. The change seems to have fixed the periodic choppiness, but I will continue to test this.

Closing as notanissue based on this comment. If the problem recurs, or if you think that this merits further action (e.g., disabling that cron job by default, which would cause other problems), let us know.

[andrewdavidwong]

I made that change and played a video to test before seeing your response. The change seems to have fixed the periodic choppiness, but I will continue to test this.

Closing as notanissue based on this comment. If the problem recurs, or if you think that this merits further action (e.g., disabling that cron job by default, which would cause other problems), let us know.