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Full Version: vsync vs a/v sync
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I've noticed the last couple nights that A/V does not stay in sync. It's not an immediate desync but a gradual drift where it can go several minutes just fine but eventually it gets too annoying. Sometimes pausing/resuming fixes it but usually that makes it worse. Using the "audio clock" and the 2 "video clock" sync options don't really help. It seems to build up to around 0.2s of desync (audio ahead of video) and then it gets too annoying for me. CPU usage never went above 35% (dual core atom 330 with 2GB ram).

While playing with the different settings I remembered that I had recently turned on vsync to get rid of tearing. I turned off vsync, rebooted, and now playback is reliably around 0.025s of desync and appears in sync.

Of course, turning off vsync allows tearing occasionally. If I then set the sync option to "video clock (resample audio)" that doesn't help with the tearing (I'm not sure if it should, seemed reasonable to try).

Any thoughts? I've read in other posts that this is kind of a known issue but what I've found didn't seem to fully match what I'm seeing.

With XBMC is it really a choice between A/V sync and tearing? Any other ideas to address the tearing?
does the A/V sync display in the codec info screen during playback show this error?
I assume by the codec info screen you mean the thing that comes up when you hit the context button on the remote during video playback (that also lets you set if a folder is tv or movies in the folder browser).

If so, yes with vsync on I can see the A/V desync grow to the numbers I mentioned in my initial post. Also, when I have any of the "sync to audio/video clock" options set I'll see an additional bit of info and eventually the "error" says 200-300%. But I've noticed the error that high with vsync off and the other A/V sync options on and the A/V was in sync.

Was there a specific field beyond what I've stated here and initially that you were interested in seeing info from?
What version are you using? 9.11 has some problems regarding framedropping which causes the player to never catch up when it's limited by vsync.
I'm using 9.11 on Ubuntu Lucid.
Are there any settings I can tweak to work around this or is it a fundamental code problem?
It's code.
Dharma branch doesn't have this issue.