video tearing in Unity, Gnome Shell is fine

[Tomek Bury]

Video playback shows plenty of tearing. I'm using Dell XPS M1530 laptop running Ubuntu 11.10 and nvidia-current driver.

The best way to verify the bug is to download this video:

$ youtube-dl http://www.youtube.com/watch?v=IRe9ykSfXyQ

and than play it back with totem in full screen:

$ totem IRe9ykSfXyQ.mp4

I've tried Unity, Gnome Shell and Gnome 2 sessions. Apparently and all but Unity work fine. I've tried all known workarounds including ccsm settings (sync to vblank, unredirect full-screen, forced refresh rate, legacy fullscreen, force bufer swap) and nvidia-settings (vblank sync in GL and XVideo, load at startup) but no luck.

[Tomek Bury (tomek-bury)]

I've just noticed that xrandr reports 50Hz refresh rate of laptop's panel but glxgears runs at 60 FPS but claims it's synchronised with the panel. Also moving glxgears window is very laggy. The window freezes when I start dragging it and appears in the new place about a second after I stop moving the mouse (touchpad).

I'm happy to provide any additional information you may need or run some tests with various settings or source code modifications if that helps to pinpoint the source of the tearing issue and get rid of it once and for all.

[Tomek Bury (tomek-bury)]

Hello Sebastian,

Are you sure it's low? There are many video tearing bugs reported by various people on many different HW configurations and over quite some years now. It seems to me that there must be some fundamental problem in the SW stack.

Is it possible to create a "generic video tearing bug report"? I'm not sure the duplicate feature is the right way to go but I don't know of any other way of doing it in launchpad....

As long as there are tens or hundreds of unrelated tearing bugs each of them seems small and insignificant. I believe that combining them into one "superbug" would draw very different picture.

[Sebastien Bacher (seb128)]

settings can change but since that bug has only 1 affected users and no duplicate it's "low" for now, that doesn't seem a so common issues, can you point to some other bugs you spotted? Does it happen in a GNOME session with compiz or is that only specific to unity?

[Tomek Bury (tomek-bury)]

Sure:

Intel example: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/755841
NV example: https://bugs.launchpad.net/ubuntu-release-notes/+bug/600178
ATI example: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-ati/+bug/514245

You can also google for "ubuntu fix tearing" and you'll get quite a long list containing various Ubuntu releases and various video cards.

My point is that those bugs keep coming back. Each new release fixes some tearing bugs and introduces some new tearing problems or causes regressions.

[Tomek Bury (tomek-bury)]

On the side note, none of the Gnome GUIs available in 11.10 is capable of tear-free video playback in dual-screen configuration, with laptop being primary screen and TV over HDMI being the secondary screen at least on my XPS M1530 laptop. The NVidia settings app has a radio-buttons to select which display to synchronise to but this doesn't seem to work any more.

[Sebastien Bacher (seb128)]

The bugs you pointed, 2 are video drivers issue, the other one was reported before unity existed in Ubuntu, nothing there seems to confirm that the issue is with unity? did you try in a GNOME classic session with compiz to see if that makes any difference?

[Tomek Bury (tomek-bury)]

This are my results

GNOME:
* window movement - OK
* video window - ocaasional tearing
* full-screen video - occasional tearing

GNOME Classic (*):
* window movement - OK
* video window - ocaasional tearing
* full-screen video - occasional tearing

GNOME Classic (no effects):
* window movement - tearing
* video window - OK
* full-screen video - OK

Ubuntu:
* window movement - occasional tearing
* video window - tearing
* full-screen video - tearing

Ubuntu 2D:
* window movement - occasional tearing
* video window - tearing
* full-screen video - tearing

(*) GNOME Classic started with Metacity in both cases. I had to run "compiz --replace" and wait approx 15-20 seconds before it switched to compiz.

Gnome 2 with compiz and Gnome 3 behave in identical way. The window movement is fine but video playback shows occasional tearing in irregular intervals.

Gnome 2 with Metacity is quite slow when it comes to window movement and shows very heavy tearing, but video playback is perfectly fine.

Unity tears in all cases. The window movement is considerably faster and smoother than in Gnome2+Metacity case but tearing is visible. The video playback in Unity is worst of all. Pretty much every frame is wrong in windowed and in full screen modes. Unity 2D has no translucent backgrounds and no blur effects but in terms of tearing it behaves equally wrong.

To summarize, there is definitely some problem in Unity that doesn't exist in Gnome Shell or Gnome 2, but the tearing bug is much bigger and much older than Unity.

[Michael Kriegel (7v-dev-gw)]

Still unconfirmed. It might be a misconfiguration of your X-Server. Can you attach the Xorg Log file, if the problem is still present?

At the report is getting old I tagged it incomplete. Please add the log information and retag it.

[Tomek Bury (tomek-bury)]

Here's my video card. Please let me know if you need any other data.

$ lspci -s 01:00.0 -vv
01:00.0 VGA compatible controller: nVidia Corporation G86 [GeForce 8400M GS] (rev a1) (prog-if 00 [VGA controller])
 Subsystem: Dell Device 022e
 Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
 Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
 Latency: 0
 Interrupt: pin A routed to IRQ 16
 Region 0: Memory at fd000000 (32-bit, non-prefetchable) [size=16M]
 Region 1: Memory at e0000000 (64-bit, prefetchable) [size=256M]
 Region 3: Memory at fa000000 (64-bit, non-prefetchable) [size=32M]
 Region 5: I/O ports at ef00 [size=128]
 [virtual] Expansion ROM at fc000000 [disabled] [size=128K]
 Capabilities: <access denied>
 Kernel driver in use: nvidia
 Kernel modules: nvidia_current, nvidia_173_updates, nvidia_current_updates, nvidia_173, nouveau, nvidiafb

[Tomek Bury (tomek-bury)]

I can confirm that the bug is still easily reproducible on Dell XPS M1530.
Retagged "confirmed" as per Michael Kriegel's request (#8) .

[Daniel van Vugt (vanvugt)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug 880707, so it is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Feel free to continue to report any other bugs you may find.

[Daniel van Vugt (vanvugt)]

Tomek, regarding you other comments...

"I've just noticed that xrandr reports 50Hz refresh rate of laptop's panel but glxgears runs at 60 FPS but claims it's synchronised with the panel."
--> bug 92599

"Also moving glxgears window is very laggy. The window freezes when I start dragging it and appears in the new place about a second after I stop moving the mouse (touchpad)."
--> bug 773861

Tearing on multi-monitor configurations:
--> bug 201342

Other tearing issues:
--> bug 798868
--> bug 755841