[SRU] Light Locker blanks the screen when playing video

Bug #1309744 reported by Juan Montoya on 2014-04-18
This bug affects 11 people
Affects Status Importance Assigned to Milestone
xdg-utils (Ubuntu)
Unit 193

Bug Description

Problem description

Expected behaviour:
When playing back videos in fullscreen mode in Xubuntu's, the X11 screensaver should be inhibited. (Xubuntu previously used XScreensaver.)

The screensaver blanks the screen (after the timeout that the user defined in light-locker-settings, by default 10mins) despite the video playing in fullscreen.

[Test Case]
Play back a video file in Parole with screenblanking enabled (can be checked with "xset q | grep timeout").

[Regression potential]
None apparent, tested in Trusty.

[Other Info]
A little background: this problem became apparent only in Trusty with the switch from XScreensaver to light-locker. As light-locker doesn't handle screenblanking itself but instead relies on X11's builtin screensaver (aka MIT screensaver extension), it needs xdg-utils/screensaver's support for inhibiting the blanking. For some reason, xdg-screensaver doesn't support controlling X11's screensaver extension in Xfce, probably for historical reasons (e.g. most distros with Xfce use XScreensaver).

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: vlc 2.1.2-2build2
ProcVersionSignature: Ubuntu 3.13.0-20.42-generic 3.13.7
Uname: Linux 3.13.0-20-generic x86_64
NonfreeKernelModules: fglrx
ApportVersion: 2.14.1-0ubuntu3
Architecture: amd64
CurrentDesktop: XFCE
Date: Fri Apr 18 15:41:48 2014
InstallationDate: Installed on 2014-03-31 (18 days ago)
InstallationMedia: Xubuntu 14.04 LTS "Trusty Tahr" - Beta amd64 (20140326)
SourcePackage: vlc
UpgradeStatus: No upgrade log present (probably fresh install)

Related branches

Juan Montoya (th3pr0ph3t) wrote :
affects: vlc (Ubuntu) → ubuntu
affects: ubuntu → light-locker (Ubuntu)
Peter de Ridder (cavalier) wrote :

If "lock after screensaver" is enabled for light-locker the screen is locked after build-in X screensaver is activated.
The getting blanked is screensaver kicking in. That probably means that the build-in X screensaver isn't inhibitted.

This would mean that the same blanking happend even is light-locker is not used.

Launchpad Janitor (janitor) wrote :

Status changed to 'Confirmed' because the bug affects multiple users.

Changed in light-locker (Ubuntu):
status: New → Confirmed
Changed in light-locker (Ubuntu):
status: Confirmed → Invalid
hadrons123 (piruthiviraj) wrote :

@ simon
Why is it Invalid?

Simon Steinbeiß (ochosi) wrote :

@hadrons123: It is invalid against light-locker (as explained by Peter in #2) and valid against Parole.

hadrons123 (piruthiviraj) wrote :

Thanks for the answer. But I am not able to remove the built in x screensaver. I tried removing the xscreensaver but it was not installed in the first place. How to get rid of the built in x screensaver?

Simon Steinbeiß (ochosi) wrote :

This isn't really a support-thread, so please don't keep asking questions here.
In any case, you can use light-locker-settings to disable the timeout so there'll be no screen-blanking.

costales (costales) wrote :

@Simon: Awesome solution! ¬¬ FYI: The max time for disable the screensaver is 120', a movie can get that time.
Please, disable/Enable the screensaver isn't an option!

I think this could be a duplicate of #1193716

I can reproduce this with Totem & VLC.

Best regards.

Simon Steinbeiß (ochosi) wrote :

@costales: If you pull the respective slider in light-locker-settings to the very left, it disables the screensaver (the label says "Never").

claw (claw-111) wrote :

I upgraded Xubuntu from 12.04 LTS to 14.04 LTS and I removed xscreensaver based on the post-upgrade recommendation.

However, what I found was that the screen blanked while parole was playing a video. Here is what is happening:

Parole executes xdg-screensaver to inhibit the screen saver while video is being played and resume normal screen saver operations when the video has either stopped or is paused.

xdg-screensaver is a shell script which detects which screen saver is installed and then proceeds to perform the requested operation on the screen saver detected - note here, that light-locker is not supported, but xscreensaver is supported.

When no known screen saver is detected, xdg-screensaver defaults to manipulating xset. Light locker is not inhibited and its own timer will expire, thereby blanking the screen.

A cursor look at light-locker-command indicates that it supports immediately locking the screen only. i.e.: There is no way for xdg-screensaver to inhibit the light locker timer using light-locker-command.

So this issue is still VERY much valid for the light-locker package and its status ought to be changed from invalid. The developers for light-locker will need to work closely with the developers of xdg-utils to get this issue resolved.

For those of you interested in a work-around: Re-install xscreensaver and let light-locker pick up the dbus messages sent from the screen saver. Alternatively, uninstall light-locker and go back to xscreensaver.

IMHO, light-locker is immature and should not have been introduced into a LTS release, but its heading into a promising direction.

Simon Steinbeiß (ochosi) wrote :

@claw: light-locker doesn't have any timer of its own, it listens to X11's screensaver extension, so in a way what is happening is happening as planned. We have a working patch for Parole for that, so this issue will hopefully be resolved soon.

hawkerb (hawk) wrote :

Great to hear you got a patch ready. But I am also experiencing same issue with VLC 2.1.2 on pretty much clean install of xubuntu 14.04, so maybe the problem is not only in Parole?

Rodion (dulicek) wrote :

Got the same problem (VLC, Parole) on clean install of Xubuntu 14.04.

Launchpad Janitor (janitor) wrote :

Status changed to 'Confirmed' because the bug affects multiple users.

Changed in xdg-utils (Ubuntu):
status: New → Confirmed
affects: xfce4-power-manager → xdg-utils (Ubuntu)

Could anyone affected by this please run the terminal command "xset -q" while a movie is playing and attach the output to this report?


Simon Steinbeiß (ochosi) wrote :

Just to give you guys an update, I suspect that the xdg-screensaver script is actually the source of the problem. This is a common way for media players to interact with screensavers, as there is on default/standard that all screensavers stick to.
For that I haven't found a cure yet.

Fixing this issue solely in Parole isn't enough and actually not a desirable solution.

Simon Steinbeiß (ochosi) wrote :

Ok, so I think I've figured this one out.

The problem is that the /usr/bin/xdg-screensaver script does detect the desktop-environment (in our case: "xfce"), but when checking for it in "perform_action" there's actually no case that matches xfce, so it never does anything if it detects xfce.
This was previously not noted because we used xscreensaver, which has a special case built in.

There is one easy workaround: replace the '' in line 435 with 'xfce' and it should work.

The desired patch is probably adding a special case for light-locker just as there's one for xscreensaver and gnome-screensaver, cause it could also be used in other DEs.

However, there is one big caveat: the script in its current form always sets the screensaver timeout to the system default value of "600" (i.e. 10minutes). So the feature of remembering the timeout and re-setting it correctly on "resume" would have to be added in a second step.

no longer affects: parole
Launchpad Janitor (janitor) wrote :

Status changed to 'Confirmed' because the bug affects multiple users.

Changed in xdg-utils (Ubuntu):
status: New → Confirmed
Ubuntu QA Website (ubuntuqa) wrote :

This bug has been reported on the Ubuntu Package testing tracker.

A list of all reports related to this bug can be found here:

tags: added: package-qa-testing
description: updated
summary: - Light Locker blanks the screen when playing video
+ [SRU] Light Locker blanks the screen when playing video
Jackson Doak (noskcaj) on 2014-07-16
Changed in xdg-utils (Ubuntu):
status: Confirmed → Triaged
Unit 193 (unit193) wrote :
Unit 193 (unit193) wrote :

Attaching a debdiff for Trusty

Jackson Doak (noskcaj) on 2014-07-16
no longer affects: light-locker (Ubuntu)
Brian Murray (brian-murray) wrote :

The Launchpad bug number was not referenced in the changelog entry for the utopic upload fixing this, so I am manually setting it to Fix Released.

xdg-utils (1.1.0~rc1-2ubuntu8) utopic; urgency=medium

  * Add patch xfce-blanking.diff to prevent screenblanking in Xfce when
    XScreensaver isn't installed/used
 -- Simon Steinbeiss <email address hidden> Wed, 16 Jul 2014 11:19:43 +0200

Changed in xdg-utils (Ubuntu):
status: Triaged → Fix Released
Changed in xdg-utils (Ubuntu Trusty):
status: New → Triaged
importance: Undecided → Medium
Iain Lane (laney) wrote :

Uploaded to t-proposed

Changed in xdg-utils (Ubuntu Trusty):
status: Triaged → In Progress
assignee: nobody → Unit 193 (unit193)

Hello Th3Pr0ph3t, or anyone else affected,

Accepted xdg-utils into trusty-proposed. The package will build now and be available at http://launchpad.net/ubuntu/+source/xdg-utils/1.1.0~rc1-2ubuntu7.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, and change the tag from verification-needed to verification-done. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

Changed in xdg-utils (Ubuntu Trusty):
status: In Progress → Fix Committed
tags: added: verification-needed
Jack Fromm (jjfrv8) wrote :

Verified fix.
- Did a fresh install of Trusty on hardware and confirmed I could reproduce the bug.
- Enabled -proposed, updated, verified I got xdg-utils 1.1.0~rc1_2ubuntu7.1 and re-ran testcase.
- Did not get the screen blanking during fullscreen video playback in Parole.

tags: added: verification-done
removed: verification-needed
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package xdg-utils - 1.1.0~rc1-2ubuntu7.1

xdg-utils (1.1.0~rc1-2ubuntu7.1) trusty; urgency=medium

  * Add patch xfce-blanking.diff to prevent screenblanking in Xfce when
    XScreensaver isn't installed/used. (LP: #1309744)
 -- Unit 193 <email address hidden> Wed, 16 Jul 2014 17:49:42 -0400

Changed in xdg-utils (Ubuntu Trusty):
status: Fix Committed → Fix Released

The verification of the Stable Release Update for xdg-utils has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

Sergio Benjamim (sergio-br2) wrote :

The fix worked here, tested with retroarch.

John Hupp (john.hupp) wrote :

With a fully patched Lubuntu Trusty, streaming Flash video through Firefox results in the screen blanking and locking after 10 minutes.

I have the recommended/most-recent version of xdg-utils.

Does this mean that media players in general use xdg-screensaver to inhibit the screensaver while playing video, but that Firefox does not?

If so, is there a workaround?

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