Drifting audio with FCP and AJA Kona LHi

Apple Final Cut Pro Legacy

Drifting audio with FCP and AJA Kona LHi

Posted by Cass Barbour on April 7, 2011 at 10:18 pm

Hi, all!

I’ve got one troublesome issue that’s been plaguing me for weeks. So, I hope someone can help me out. I’ve read many other threads and so far, nothing has helped me.

I’m using a AJA Kona LHi to input a 1920×1080 @ 29.97fps HD-SDI signal with audio embedded on 1&2. I’m capturing to Apple ProRes 422 (HQ) in Final Cut Pro 7.0.3 on a ~January 2011 Mac Pro 2.8 Quad-core Xeon (OSX 10.6.7).

When I’m monitoring the HD-SDI input, the audio and video line up just fine. While capturing, the audio and video monitoring line up as well. However, after capturing for an hour or more, I’m getting some really bad audio drift. Fifty minutes into the capture, the audio is about 1.5 seconds ahead of the video. I even tried inputting analog audio instead of the HD-SDI embedded audio and I’m still getting the same amount of audio drift.

I’ve tried slot 4, 3, and 2. No change. I’m currently in Slot 2.

I’ve spoken with AJA at length over the phone, they said my setup and all my settings check out—-they told me my hard drives were probably too slow…uh.

So, just for fun, I’ve tried RAID 1 over both eSATA and FW800, RAID 5 over eSATA and FW800, RAID 0 (internal), RAID 1 (internal), and just a straight up internal harddrive, no RAID.

However, nothing seems to affect the audio drifting. Any suggestions?

Thanks!

Cass Barbour replied 15 years, 5 months ago 4 Members · 6 Replies
6 Replies

Chris Tompkins
April 7, 2011 at 11:17 pm

Capture in 20 min. chunks?
At least until you can get this issue fixed.

Chris Tompkins
Video Atlanta LLC
Cass Barbour
April 7, 2011 at 11:26 pm

Unfortunately, we can’t. This is a performance hall at a college School of Music so it’s live capture from first curtain till the end of the concert.
Chris Tompkins
April 7, 2011 at 11:34 pm

Didn’t realize the live capture.
Tried trashing prefs?
You’d think AJA would have solved it.

Chris Tompkins
Video Atlanta LLC
Neil Sadwelkar
April 8, 2011 at 11:03 am

If it’s a live capture do you have a common ref fed to cameras and the LHi?

———————————–
Neil Sadwelkar
neilsadwelkar.blogspot.com
twitter: fcpguru
FCP Editor, Edit systems consultant
Mumbai India
Andreas Kiel
April 9, 2011 at 4:25 pm

As Neil said – you should have a common ref.

Another option which might be worth to try is to record video and audio to separate files onto different disks.
This normally doesn’t make sense with embedded audio, but it take off quite a burden from the system when handling really long clips.

Andreas

Spherico
https://www.spherico.com/filmtools
Cass Barbour
April 9, 2011 at 11:18 pm

Sorry for the delay; yes, I do have a common reference. I’m actually running all cameras through an HD-SDI video mixer for doing live to-air and to-“tape” recording. I have the board referenced via Tri-sync, and also the Kona LHi from the same tri-sync source.

I ended up installing a fresh OS with a brand new main harddrive. I think our IT department here screwed up the install (darn them and their iMac images on Mac Pros).

So, with that and a funky tri-sync source now fixed, capture seems to be working okay. I’m going to have to run a few more tests during some afternoon rehearsals, but I am hopeful.

Thanks for your help thus far. I’ll let you know if I find anything else out.

Reply to this Discussion! Login or Sign Up

Creative Communities of the World Forums