Latency in Unity?

[elbaro]

We have an HD3 on Unity, audio and video are both playing back off of Unity. An OMF export out of an Avid/Symphony seems off sync-wise. The video is delayed by 1/2 to 1 frame. Seems like a Unity-playback only thing b/c the layback to digibeta always looks fine when I'm done with the mix. Not a time-code or drop/nondrop issue, everything lines up. Anyone else experience anything like this? This happens both with an OMF'd video from Avid (single stream) as well as me digitizing it in myself off of tape. (20:1)
-LB

[DigiTechSupt]

No, I have not seen this and there should be no delay with AV/XL video in Pro Tools on Unity or local drives. Not sure which ones off the top of my head (don't want to point the finger incorrectly) but some video decks have a 1/2 to 1 frame offset that needs to be compensated for. If you are digitizing into the Avid or Pro Tools with one of these decks you may need to nudge by a frame to align things correctly.

Any latency you might experience in Pro Tools from Unity or local drives would be limited to the amount of time it takes to start and stop playback and there should be none of this either. Once playback is started, assuming your system is correctly resolved and in good shape, you should have near sample accurate video to audio relationship. If for any reason, the audio and Avid video in Pro Tools drift (such as in an incorrectly resolved system) Pro Tools will stop playback and throw an error dialouge saying so.

Hope this helps,
Jon Connolly
Digidesign Product Specialist

[elbaro]

Jon,
Thanks for the info. This certainly makes more sense than a latency explanation. Can you email me directly about which decks might have this delay, this will definately help in tracking down the problem. As a side issue is running both audio and video off Unity acceptable? We have removable scsi drives that are not currently being utilized.
-LB

[DigiTechSupt]

Yes, it is recommended when using Unity. However, audio and video must be on separate allocation groups. Not just separate workspaces, but allocation groups (separate groups of drives). In most configurations, the video group is also shared by Avid clients.

-Jordan

[elbaro]

bump

[Clash310]

Hey is there any documentation for Pro Tools and Unity? i cant any anywhere, i'd love to read up on it