Author Topic: Video tearing  (Read 1859 times)


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Video tearing
« on: October 27, 2007, 06:46:32 am »
If you want to know why I need to know this, read paragraphs two and three for an explanation, but if you just want to solve my problem, then skip to the last paragraph.

I have recently gained a little experience with video 'tearing' in LinuxMCE and MythTV.  I have a very decent NVIDIA graphics card that is capable of handling full UI2 (with alpha blending).  The problem was that if I enabled alpha blending, any video playback would have an observable amount of tearing in it.  This is nothing new, and is documented on other parts of this forum.  However, I have noticed something else that causes tearing in MythTV, and if I was a little smarter I could have a solution to it.  I know there are others out there (hopefully reading this) that are much smarter than I am, and could fix (or tell me how) in their sleep.

First of all, video playback never has any tearing when using LinuxMCE - and by that I mean xine.  I noticed some tearing during playback using MythTV.  Then I noticed that it was not all the time; I then proceeded to track it down to the following:  After I play something through Media->Video, MythTV starts to tear.  Before that (right after I reboot), MythTV plays just fine with no tearing.  I noticed that after I play something through Media->Video, it leaves pluto-xine-playback-window open.  If I do a 'sudo killall Xine_Player' then playback once again has no tearing in MythTV.  But if I watch something again through Media->video, MythTV begins tearing again, and on goes the cycle...

All of this to say, I need to know how to add a command that kills the Xine_Player process when you press stop, or select 'Off" from the LinuxMCE menu.  If anyone can help, this would be much appreciated.  Hopefully you can tell from my post that I am not too lazy to figure out the solution to this; I am simply not smart enough.  At any rate, this is an amazing piece of software, I am thoroughly impressed, and have very few problems with it.  Thanks in advance.


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Re: Video tearing
« Reply #1 on: October 27, 2007, 05:06:29 pm »
The best knowledge we have suggests the tearing (horizontal discontinuity's in the image) is from asynchronous rendering of the video image. Telling X to sync on vert (I think this is the control) causes the image to refresh only on vertical refresh. I don't think that is proberly managed in the default LMCE setup. I don't know where the Xine config files are. When I looked it seems there were two complete installs of Xine in the system. I would start with getting Xine properly configured first, before going deeper. Myth has several playback options and I don't know if Xine is used by Myth in LMCE or its using its own engine. Perhaps someone who knows more about this stuff can help.

Since LMCE is so complex killing Xine periodically may have some adverse unknown effects.