Jittery Video Playback

[Baloonoise]

I have seen similar threads regarding this problem on other forums, but thought I would post something more specifically
related to my problem here as I'm running on an LE system.
I recently upgraded from the last generation PPC iMac G5 running PT 7 to a new Intel iMac. (27" 2.93GHz i7, 8Gb RAM, ATI Radeon HD 5750 video card)
This computer came with OS 10.6.4 installed on it. I am running Pro Tools 8.0.4 on an Mbox2 with all the latest updates available.
The sessions and files are on a LaCie D2 Quadra 1Tb External HD.

The video playback in Pro Tools is jittery. Looks as though it is skipping frames.
It is doing this with both DV and H.264 (the only formats I currently have in sessions on hand).
Most other problems I've seen posted regarding this refer to playback on a second monitor, but in my case it is jittery when playing on the computer monitor as well.
The video files on their own play back without issue in quicktime player.
These same PT sessions and video files play fine on my older system, and on other systems running 8.0.3 and OS 10.6.3.

Has anyone had any similar experiences or got any suggestions?
I'm wondering if doing a clean install of 10.6.3 and PT 8.0.3 would fix the problem, but I'm not sure if going backwards on the system software is a good idea. I don't even know if it's compatible with an i7 machine.

[Slim Shady]

I'm wondering if doing a clean install of 10.6.3 and PT 8.0.3 would fix the problem

I doubt it. I have no issues with 10.6.4 and 8.0.4 on 2 different LE systems playing H.264 and DV video inside PT.

Where is the video being stored/streamed from? Internal or firewire drive? Is there a lot of audio coming from that same drive simultaneously?

[Baloonoise]

I have tried it with the video playing from the internal drive and the audio from the external, as well as with both video and audio coming from the same external drive with no difference. There's not an excessive amount of audio being played in my opinion.

[Slim Shady]

Do you have a spare SATA drive that you could use for some testing? Use the restore DVDs that came with your Mac Pro and create a new boot drive and install Mac OS and PT only on it and see if you get any different results.

[Baloonoise]

Originally Posted by Slim Shady

Do you have a spare SATA drive that you could use for some testing? Use the restore DVDs that came with your Mac Pro and create a new boot drive and install Mac OS and PT only on it and see if you get any different results.

I'm running on a brand new iMac with one firewire 800 port. The only software I've installed on it is Pro Tools, anything else that's there would be on the install disks so, while I'm open any suggestions, I'm not exactly sure what such a test would reveal.

[440Hz]

I have experienced similar issues in the past.
Is there any audio on the QT (video) file you are trying to play? I found that I needed to export separate audio and video files using QT Pro. Then import those separate files into my PT session.

Hope this is of assistance

[Baloonoise]

Originally Posted by 440Hz

I have experienced similar issues in the past.
Is there any audio on the QT (video) file you are trying to play? I found that I needed to export separate audio and video files using QT Pro. Then import those separate files into my PT session.

Hope this is of assistance

There is currently both video and audio tracks in the QT files. I'll try your suggestion. Thanks.

[Baloonoise]

Originally Posted by 440Hz

I have experienced similar issues in the past.
Is there any audio on the QT (video) file you are trying to play? I found that I needed to export separate audio and video files using QT Pro. Then import those separate files into my PT session.

Hope this is of assistance

No luck with that unfortunately. Thanks anyway.

[Baloonoise]

Should anyone else find themselves in a similar situation, I have traced the problem to a faulty mini display port adapter. Once that was removed, the jittery playback problem was corrected.