I'm experiencing a similar problem, except that the videos usually just freeze when the ac3 audio track is selected. This problem happens on my mac pro using itunes 10.2.1 and osx 10.6.7, but not on my older macbook pro that is running itunes 10.2.1 and osx 10.6.6, so it is reasonable to assume that there is something in 10.6.7 causing the problem.
OSX 10.6.7 update has broken any video content with
Dolby tracks that are imported. This is only a problem
with iTunes. Other third party players (Plex,etc,) don't have any issues.
I have no surround sound issues in iTunes with iTunes purchased
The OSX 10.6.7 update did however fix a issue of video pausing
with iTunes purchased HD material that seemed to have been
caused by 10.6.5.
Just curious, but do you have and HDMI connection as well
as optical? I found that when I was watching a movie on
my HDMI connection to the system and I had an optical
connection (doesn't matter to what) iTunes purchased
video audio content would "skip". Switch to the optical
input and it would be fine. If I removed the optical connection,
the HDMI audio would be fine. Something weird goes on
if both connections are made. Also, this odd behavior was
only manifested in iTunes not any other software,
I have the same problem with iTunes since upgrading to 10.2.1 and OS 10.6.7.
To get the AC3 passthrough working again I downgraded back to iTunes 10.1 (not actually solving the problem in 10.2.1). Was not using Time Machine on the Mac Mini so I followed the steps (step 1 and 2 in my case, plus recreating the iTunes library) on this page:
iTunes 10.1 installer found here:
Does not solve the actual problem in iTunes 10.2.1 but will give you 5.1 surround back. AC3 Passthrough works fine again. Will stay with this version until the AC3 passthrough issue issolved in iTunes.
Hope this message is not waste of space.
I'm experiencing this today.. I didn't know anything about this issue with the upgrade.
I have just ripped some of my DVDs with Handbrake with AC3 audio setting and it seems some video files in Quicktime player will play with audio digital noise or the audio will play strangely in the one channel on a stereo system. I tested the files and they check out fine playing correctly on my PS3. So what gives?
Is there a fix in the works? Anyone know?
Well, again works here...
I noticed and update for Perian that might have affected the setup.
I also notice that it is a good idea not to change soundtracks while playing back, but stop
the movie, change the track and then hit play again.
Works here at the moment with this workaround of sorts...
hope this helps