compiz team mailing list archive

[Daniel van Vugt <vanvugt@xxxxxxxxx>]

** Description changed:

  You might expect that with "Sync To VBlank" enabled in compiz that video
  tearing doesn't happen. But it does, just less often.
  
  This is normal, expected behaviour. The cause is that compiz (up to
  0.9.6 at least) uses GLX_SGI_video_sync, which provides a rough way of
  synchronizing with the video frame rate of the monitor. But it's not
  reliable in most cases because if you take a little too long to render
  the frame, then you can miss the frame deadline and tearing can still be
  seen.
  
  The solution to this bug is to modify compiz to use GLX_SGI_swap_control
  instead, which provides a more reliable and more efficient way of
- synchronizing with the refresh rate.
+ synchronizing with the refresh rate. However to use GLX_SGI_swap_control
+ means your code must use glXSwapBuffers for every frame. Compiz
+ presently does not use it for every frame.
  
- Speaking with smspillaz, he says a move to glXSwapBuffers is planned for
- a future version of compiz, not least because it is required in order to
- port compiz to OpenGLES. Once compiz uses glXSwapBuffers for every
- frame, it will be possible to then use GLX_SGI_swap_control for reliable
- synchronization.
+ Speaking with smspillaz, he says a move to 100% glXSwapBuffers is
+ planned for a future version of compiz, not least because it is required
+ in order to port compiz to OpenGLES. Once compiz uses glXSwapBuffers for
+ every frame, it will be possible to then use GLX_SGI_swap_control for
+ reliable synchronization.
  
  More info: http://www.opengl.org/wiki/Swap_Interval
  
  ProblemType: Bug
  DistroRelease: Ubuntu 11.10
  Package: compiz 1:0.9.6+bzr20110929-0ubuntu5
  ProcVersionSignature: Ubuntu 3.0.0-12.20-generic 3.0.4
  Uname: Linux 3.0.0-12-generic x86_64
  .tmp.unity.support.test.0:
-  
+ 
  ApportVersion: 1.23-0ubuntu3
  Architecture: amd64
  CompizPlugins: [core,bailer,detection,composite,opengl,compiztoolbox,decor,mousepoll,place,gnomecompat,resize,imgpng,move,wall,regex,grid,vpswitch,animation,session,resizeinfo,unitymtgrabhandles,expo,workarounds,fade,scale,ezoom,unityshell]
  CompositorRunning: compiz
  Date: Mon Oct 24 16:01:07 2011
  DistUpgraded: Fresh install
  DistroCodename: oneiric
  DistroVariant: ubuntu
  GraphicsCard:
-  Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller [8086:0102] (rev 09) (prog-if 00 [VGA controller])
-    Subsystem: Dell Device [1028:047e]
+  Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller [8086:0102] (rev 09) (prog-if 00 [VGA controller])
+    Subsystem: Dell Device [1028:047e]
  InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012)
  MachineType: Dell Inc. OptiPlex 990
  PackageArchitecture: all
  ProcEnviron:
-  LANGUAGE=en_AU:en
-  PATH=(custom, no user)
-  LANG=en_AU.UTF-8
-  SHELL=/bin/bash
+  LANGUAGE=en_AU:en
+  PATH=(custom, no user)
+  LANG=en_AU.UTF-8
+  SHELL=/bin/bash
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.0.0-12-generic root=UUID=c9a0c042-2d94-4c4b-bb7f-756faf723ada ro quiet splash intel_iommu=on vt.handoff=7
  SourcePackage: compiz
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 05/28/2011
  dmi.bios.vendor: Dell Inc.
  dmi.bios.version: A05
  dmi.board.name: 0D6H9T
  dmi.board.vendor: Dell Inc.
  dmi.board.version: A00
  dmi.chassis.type: 15
  dmi.chassis.vendor: Dell Inc.
  dmi.modalias: dmi:bvnDellInc.:bvrA05:bd05/28/2011:svnDellInc.:pnOptiPlex990:pvr01:rvnDellInc.:rn0D6H9T:rvrA00:cvnDellInc.:ct15:cvr:
  dmi.product.name: OptiPlex 990
  dmi.product.version: 01
  dmi.sys.vendor: Dell Inc.
  version.compiz: compiz 1:0.9.6+bzr20110929-0ubuntu5
  version.ia32-libs: ia32-libs N/A
  version.libdrm2: libdrm2 2.4.26-1ubuntu1
  version.libgl1-mesa-dri: libgl1-mesa-dri 7.11-0ubuntu3
  version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
  version.libgl1-mesa-glx: libgl1-mesa-glx 7.11-0ubuntu3
  version.xserver-xorg: xserver-xorg 1:7.6+7ubuntu7
  version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.6.0-1ubuntu13
  version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:6.14.99~git20110811.g93fc084-0ubuntu1
  version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.15.901-1ubuntu2
  version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:0.0.16+git20110411+8378443-1

-- 
You received this bug notification because you are a member of compiz
packagers, which is subscribed to compiz in Ubuntu.
https://bugs.launchpad.net/bugs/880707

Title:
  Video tearing still occurs in compiz (less so) when "Sync To VBlank"
  is enabled.

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