From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Wilson Subject: Re: Video tearing on Sandybridge Date: Mon, 02 Apr 2012 11:03:50 +0100 Message-ID: <1333361053_198990@CP5-2952> References: <4F774449.5080906@vtnd.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from fireflyinternet.com (smtp.fireflyinternet.com [109.228.6.236]) by gabe.freedesktop.org (Postfix) with ESMTP id E57849E802 for ; Mon, 2 Apr 2012 03:04:17 -0700 (PDT) In-Reply-To: <4F774449.5080906@vtnd.de> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org To: Oliver Seitz , Intel Graphics Development List-Id: intel-gfx@lists.freedesktop.org On Sat, 31 Mar 2012 19:52:09 +0200, Oliver Seitz wrote: [snip] > If, however, two screens are next to or on top of each other, playing > video on one of the screens can show some tearing. It is not always seen > with normal video, a special test pattern is helpful. Also, it does only > tear in one out of ten tries, you can hit pause again and again, sooner > or later the tearing will appear, and disappear again after the next > pause/unpause cycle. While the tearing is there, it stays at about the > same height of the video until the next pause/unpause cycle. Most times > it is seen in the top third of the video. It does not matter if the > video is fullscreen or not. > > Is it likely that this is a bug, or am I doing something wrong? Video tearing in windows is a known issue on SandyBridge as they removed the commands to perform vsync'ed updates and hid the logic behind a baffling sequence of registers that we have not yet got working. The only workaround is to force pageflipping (ie exchange the whole scanout for each frame) either by using a compositing WM (and hoping for the best) or to only use fullscreen DRI video applications (OpenGL or libva decoders) that use SwapBuffers. -Chris -- Chris Wilson, Intel Open Source Technology Centre