I, too, have a problem with choppy video/audio playback since upgrading to Snow Leopard.
The problem occurs only when an external display is attached.
It seems to occur when other programs access the network during playback. (E.g. MobileMe Sync, Safari updating webpage previews.)
It is worst when the video is a flash video streamed over Internet (in Safari or Zattoo) but also occurs in QT Player (X).
And it occasionally leads to crashes. (Grey screen of death or just a completely unresponsive computer.) Sometimes the crashed computer will continue to emit strange choppy sounds, it seems to repeat parts of the audio track.
Since I dropped my MacBook once, I figured it might be a hardware problem, but now that I hear of your problems I am not so sure anymore.
I run Snow Leopard 10.6.5, both Quicktime 10.0 and QuicktimePro 7.6.6 and I own a MacBook Pro (2.53 GHz with 4G RAM). And I have the same problem with choppy and out of sync HD playback. I am finding thread after thread complaining about the same issue with no solutions. It's been over a year since SL came out and I don't see anything about Apple addressing the issue. This is absolutely unacceptable and I feel cheated by Apple for buying a mac to be able to work on and playback HD media.
I am getting very choppy to the point of being unwatchable video playback in QuickTime.
H.264, 1280 x 720, Millions
AAC, 2 channels, 44100 Hz
Same videos from my Flip Ultra HD and Nikkon D90 play fine in VLC, but it is crappy because I have QuickTime Pro so I can trim them.
Nothing else eating up processor or memory either. Very frustrating.
Message was edited by: genesis2seven
I have this problem, too. I notice it especially when I watch videos online (Vimeo, YouTube, etc), which is about 25% of my work on the computer, so.... really really annoying.
Sound continues just fine, but video freezes every 10 seconds or so, then maybe 4 seconds later skips ahead and catches up. I started having this problem only a few weeks ago, and it's become much more frequent with time. I really hope they fix this as it's starting to creep into iTunes playback as well.
I had choppy playback under Leopard, and found complaints about it on forums but the problem was fairly intermittent so I lived with it.
Then I started getting a similar problem with audio, first embedded mp3 in web pages, then Garage Band, then even iTunes. At first I treated it as a separate problem to the above. Followed some forum suggestions (dump refs, make new profile) and they helped for a day or two then it was back.
Decided it might help to upgrade to Snow Leopard, which I did, and now both problems are worse than ever and as they have some common features (both contain audio, are worse when they are embedded or played through Flash) then it has struck me that the video problems may be caused by the audio track?
The audio glitching is not so bad when I listen to Soundcloud and is variable on iTunes.
I guess the only thing left is to do a full reinstall.
I found this solution yesterday. Maybe old? But it still worked for me. My computer is like it should have been in the first place - an awesome media center.
Open Terminal, enter the following command:
sudo mv /System/Library/Extensions/AppleGraphicsPowerManagement.kext/ /System/Library/Extensions/AppleGraphicsPowerManagement.disable
Enter your "root" password, this is usally the same as your account password
Let it run, close Terminal
Run Kext Utility found here
Run it until it says it is completed
Go into System Prefs, open Power Options and slide the second bar (screen) to 1 minute. Apply
Let your computer rest for 1 minute until screen goes black.
Done. You now have a Mac Mini without lag. This worked on my Snow Leopard setup, and now with Lion.
Awesome! Thanks to dok34! His/their website with a complete guide to this found here.
Video guide found here
I, too, had choppy video playback throughout the whole system: QuickTime, VLC, EyeTV on my MacMini (mid-2007) with 10.6.8. After much trial-and-error the culprit turned out to be an outdated Flash player. I updated to Flash player 11 directly from the Adobe site, rebooted the machine, and now all video playback is fine again!
What must have happened is that the previous Flash player worked with my older Mac OS X version. When I upgraded to 10.6.8 the now outdated Flash player started messing with the video playback of the entire system. Another poor piece of software by Adobe - can't get rid of it fast enough.
Hope this helps some folks out there. This issue should drove me nuts in the last two weeks!