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Full Version: ATI card and [email protected] jerky playback help
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Hi have had xbmc linux set up for a few weeks now and i recently bought a new tv, lg lcd 1080p 120 htz. So i got it set to 1920x1080 no problem and fixed the overscan issue (black boarders) now the only thing is if i set it to sync playback to display i get extremely jerky video like unwatchable. i notice there are some fixes for nivida cards by editing the xorg.conf file, would the fix for me be the same? or does ati just not play nice with this mode. I'd really appreciate some feedback. thanks
just disable sync to playback.
The problem is most likely related to the xvba-video backend for vaapi. I don't understand why there is that much open gl rendering done in a backend driver, which I think interferes with XBMC rendering.
I am working on direct support for xvba.
FernetMenta Wrote:The problem is most likely related to the xvba-video backend for vaapi. I don't understand why there is that much open gl rendering done in a backend driver, which I think interferes with XBMC rendering.
I am working on direct support for xvba.

Nice, this is great news Smile

btw, are you planning to submit your vaapi changes to mainline? I've been running git with your patches for nearly 2 months now and its solves/works around most of the 24p and audio out of sync issues.
Using VAAPI on ATI without your patches is a pain, so it would be great to have them merged.
wsnipex Wrote:Nice, this is great news Smile

btw, are you planning to submit your vaapi changes to mainline? I've been running git with your patches for nearly 2 months now and its solves/works around most of the 24p and audio out of sync issues.
Using VAAPI on ATI without your patches is a pain, so it would be great to have them merged.

I'm not using these patches could someone link meeting to them and,what's the command to patch the git
http://forum.xbmc.org/showthread.php?tid=99154&page=50

how to compile from GIT is left as an exercise to the reader, there are plenty of tutorials/info on this.
ok i'm starting to figure it out. i found your patches i think and i got it somewhat working. basically i can get it to work if i go into system and set it to 23.98 fps globally but then the gui is laggy, if i set it to just switch in video settings i get some tearing. thats it though so if i can fix the tearing i'll bee good. i think its selecting 24 ftps instead of 23.98 when i have it set to set display to match video in video settings, you see what i'm saying? how do i disabld 24 all together so it has to choose the other one

edit if i also enable sync video to display enabled then its not tearing but if i have vsync set to always enabled the gui lags. i can set it to only use for video playback but then i get tearing in the gui. i think one of your patches caused this but not sure which one. do you know?

edit 2: if i close xbmc run startx and then amdcccle to open the catalyst control panel if i turn "tear free deaskop" on which basically is their own vsync enabled and then set xbmc to only enable during video playback everything is good but it doesnt seem ideal. this must mean one of your patches is borking vsync for 60htz. but this is a good work around but it should still be addressed if we ever want these patched to mainline
also what is the benefit to 24htz is it worth the hastle to get it working? what will be different about PQ
The problem might be timing/locking related, if xvba synchronized to the vertical blank, and sync playback to display does the same, and there's no locking between xvba and opengl, you'll end up rendering some frames too long and others not at all or too late.

We had the same problem with VDPAU at one point, we had to use a workaround.
Quote:i think one of your patches caused this but not sure which one. do you know?

https://github.com/FernetMenta/xbmc/comm...16257e2a97

Note that this is not a real patch because it does not fix the problem. It cures the symptoms a bit but may introduce GUI lag.

@wsnipex
the patch addressing a/v sync is already in mainline.
Yeah I noticed, thanks for that.
But what about the other patches that change the vsync mode and increase the render buffers?

I understand that they are not real fixes, but the difference between using them or not is night and day @24p

For me its not a problem applying them in my own compile, but there a lots of novice users around that are having problems with that. Obviously enabling vaapi in the nightlies would be needed too.
So is my workaround to GUI lag sufficient basically vsync setting is controlled by catalyst not xbmc and the GUI lag goes away, what are patches 2 e and 4. 1 finally what are the advantages of 24 p why is it desired so much
I suggest you set vsync to "let application decide" in catalyst and to "on during video playback" in xbmc.

24p(or often 23,976) is the native refresh rate of most HD material, specially movies.
This means 24 full frames/sec = progressive.
Generally playing any video material in its native refresh rate gives the best visual quality since there is no conversion needed. This is only true if you have a TV that actually accepts 24p as input and displays it as such.
Hack_kid Wrote:So is my workaround to GUI lag sufficient basically vsync setting is controlled by catalyst not xbmc and the GUI lag goes away, what are patches 2 e and 4. 1 finally what are the advantages of 24 p why is it desired so much



bump more opinions please?
Because if your video is 24 fps, you want every frame shown exactly 1/24th of a second apart, the refreshrate needs to be 24 or a multiple of 24 for that to be possible.
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