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LHe Audio Sync on Capture on many systems with many variables

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Francois Stark
LHe Audio Sync on Capture on many systems with many variables
on Jan 8, 2010 at 4:36:25 am


Is there anybody out there that has his LHe system so stable that it NEVER captures a clip with audio out of sync? Please describe such a system...

When we capture to our AJA Kona LHe cards we find that about one in twenty to one in fifty clips are out of sync - audio sync. Generally the other clips are perfectly in sync, but these faulty clips' audio are about 200ms or about 1 second early. It stays constant. It seems there is a delay in starting video capture, while the audio starts on cue.

We have a lot of variables but this exact issue stays with us across all these variables:

We used FCP to capture from component Beta SP to DV clips (PAL);
We also used AJA Deck Control to capture a HDSDI 1080i50 or a SDI PAL live feed to Apple Prores;
Hardware varied from G5 2GHz to New mac pro quad 2.66GHz;
Storage varied from internal single IDE or fibre channel SAN with the G5's, as well as internal Raid 1 on the new mac pro's and also even capturing over ethernet to a very fast server;
FCP version 6 - from 6.02 to 6.05 or AJA Kona Deck Control;
We used three different LHe cards, from three year old to brand new;
We used house sync or free running sync;

None of these changes made any difference. Some clips are just out of sync. We used to be able to live with it by just pulling the occasional clips' sync in post, but now we are capturing a live studio feed and need to look back at these clips immediately after capture. What else can we try to get the LHe card to capture every clip in sync?


This points to a LHe problem - either hardware or drivers.


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