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I have the same issue (also with the svn build from yesterday). I've only just started playing with XBMC linux, so I can't say whether the same issue occurred previously. But I have the same symptoms: audio ahead of the video (by a few seconds) when running in a high resolution. CPU usage is low (~20-40% on each core). It occurs when watching DVDs and also downloaded movies (mpeg4 format). Happens whether I use analog audio or digital passthrough. Happens both with and without "UseEvents" enabled in xorg.conf (I tried that since it had once fixed some issues I had with MythTV and high-res playback).
As ldt0 reported, the issues go away if I run at, say, 480p. Hardware is an Abit AN-M2HD motherboard with integrated GeForce 7 Series graphics. CPU is AMD Athlon 64 X2 4000+. 1 GB RAM. I can post debug logs if more logs would help.
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Just to add to my experiences with this issue. The 20 FPS comment is right on. This seems to be the maximum fps, even when I explicitly set it to 1080p @ 60 Hz. Even sitting in the interface, the fps caps out at 20. Whereas with 480p, it caps at 60. Interestingly, at 720p, it caps at 30 fps (so I don't have sync issues with 24fps DVDs at 720p, but do at 1080p).
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ldt0
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Well, i'm glad i'm not the only one with this problem :-) Hopefully there will be a sollution soon. In case any of the devs are interested i'll post my complete system specs. It's a Dell 8300 with Nvidia FX 5200 AGP 1,5GB RAM, P4HT 3Ghz running Ubuntu 7.10 with the drivers installed from the restricted drivers manager.
To StuLove: Are you having problems with all movies or just some and what video driver are you using? I seem to be able to play some files fine, i think most DivXs play fine and i have for example Casino Royale and Beowulf in 720p/mkv and they seem to work fine and reporting round 25fps.
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ldt0
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I just applied you "fix" and it seems to work! THANK YOU! Hope it fixes your issues as well StuLove.
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I tried it as well and it has improved things a lot. Still get out-of-sync but much better. Still, mplayer worked fine even without this "fix" playing the same files..
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Enabling triple buffering did help. With triple buffering, 24 fps DVDs play fine, but I still see problems with 30fps recorded TV shows (mpeg2 format). These start off synced, but then the video slowly gets farther and farther behind the audio. And it's not a CPU performance issue because it happens on SD recordings as well as HD (cpu usage on each core is < 25%).
Since you suggested it, I did try playing the same file in mplayer with OpenGL output (-vo gl). There were no audio sync issues there.
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Did some more experimenting. Installed xbmc on two other machines. One with an ATI x1950pro and one with an NVIDIA 7600GT. Worked great on both (although I couldn't find a way to get vsync to work on the ATI).
It seems that all of us who have experienced this problem either have on-board GPUs or AGP GPUs. It would be interesting to know if anyone has an on-board NVIDIA card that doesn't exhibit this problem. Or, conversely, if anyone has a PCI Express card that DOES have the problem.
I'd be happy to take a look at the code and see if I can track down the problem. But I would need one of the developers to point me in the right direction.