Maybe this is something that everybody already knows, but I'd been trying to figure out what was causing the nasty tearing issues when playing back fullscreen video on my home theater Mini, regardless of the app.
Turns out that if you boot the mini with no display attached (which, in this case, means that my HT receiver and TV are powered off so the HDMI sees nothing attached) then the MacOS disables Quartz Extreme, claiming that there isn't a compatible video card available. (I guess this is because if it's truly headless then it's not able to pass output processing to the graphics chip?)
End result, no coalesced video writes, and tearing. Probably also substantially poorer video upscaling in at least some players (I'm almost positive at least QT Player X).
Solution is to make sure you turn on the device on the other end of the HDMI cable before powering on the Mac; just detecting displays after boot didn't seem to fix it (though turning stuff off after boot then on again later doesn't seem to be an issue).
This definitely is an issue through 10.6.1, and in hindsight it was actually happening under 10.5 as well, I just hadn't done a "headless" boot to realize it. Wish I'd figured it out sooner, instead of chasing my tail trying to troubleshoot my video players for poor performance and tearing.
Turns out that if you boot the mini with no display attached (which, in this case, means that my HT receiver and TV are powered off so the HDMI sees nothing attached) then the MacOS disables Quartz Extreme, claiming that there isn't a compatible video card available. (I guess this is because if it's truly headless then it's not able to pass output processing to the graphics chip?)
End result, no coalesced video writes, and tearing. Probably also substantially poorer video upscaling in at least some players (I'm almost positive at least QT Player X).
Solution is to make sure you turn on the device on the other end of the HDMI cable before powering on the Mac; just detecting displays after boot didn't seem to fix it (though turning stuff off after boot then on again later doesn't seem to be an issue).
This definitely is an issue through 10.6.1, and in hindsight it was actually happening under 10.5 as well, I just hadn't done a "headless" boot to realize it. Wish I'd figured it out sooner, instead of chasing my tail trying to troubleshoot my video players for poor performance and tearing.