Audio / Video sync issue with a 30 minute 1080i capture at DVinfo.net

John Hewat · January 12th, 2006, 06:32 AM

Hi all,

I did a search for this problem and saw a few people have had it happen but I'm curious as to solutions.

Today I recorded 30 minutes of footage on my Z1 at 50i without pressing stop. I now want to capture all of that 30 minutes to my PC using Aspect & PPro at 25i.

So first I tried it with Scene Detect off - (given that there are no scene breaks anyway). And the result was a sync problem. In fact, the audio was clearly out of sync with the video from the very start of the clip.

After my research on the forums today I am currently trying it again with Scene Detect on but I doubt it will work, given that I did not press stop.

So I have a couple of questions here:

1. Why does the problem occur in the first place? (In my case the video was ahead of the audio - which seemed the opposite of what I'd have expected)
2. What is the maximum amount of footage I can capture before sync issues start to pop up?
3. Do I need to always be thinking of this problem when I'm capturing so that I make sure I press stop every few minutes on the camera so that when I capture with Scene Detect on I avoid the issue?
4. Or do I make more work for myself in Post by manually capturing 10 minutes (or whatever the maximum is) at a time?

This is quite an annoying problem and I forsee many problems in the future - I had planned to use my Z1 as an analogue->DV convertor and transfer all my home movies to my PC - but now I can see it may not be just as simple as plug it in, press record and go have a beer, come back in 2 hours and it's done...

David Newman · January 12th, 2006, 09:57 AM

If think you will find the re-capture will be fine. There will be not drift over time as the video and audio are locked together. If there is a fault with scene detection off that hasn't been reported, other than issues that can occur in MPEG that our scene detection code will handle. Try the recapture and report.

Matt Vanecek · January 17th, 2006, 01:48 PM

I would like to know if capturing long recording is an issue for Aspect HD. I just purchased an FX1, and am debating with myself the format in which to record. My typical recording scenario is 45 minutes to 1 1/2 hour, non-stop. Will capturing HDV with PPro/AspectHD in such a situation cause sync drift?

Thanks,
Matt

David Newman · January 17th, 2006, 02:02 PM

Matt,

It will work fine. If you have any doubts please use the free trail.

January 12th, 2006, 06:32 AM	#1
John Hewat Major Player Join Date: Dec 2005 Location: Melbourne, AUSTRALIA Posts: 735	Audio / Video sync issue with a 30 minute 1080i capture Hi all, I did a search for this problem and saw a few people have had it happen but I'm curious as to solutions. Today I recorded 30 minutes of footage on my Z1 at 50i without pressing stop. I now want to capture all of that 30 minutes to my PC using Aspect & PPro at 25i. So first I tried it with Scene Detect off - (given that there are no scene breaks anyway). And the result was a sync problem. In fact, the audio was clearly out of sync with the video from the very start of the clip. After my research on the forums today I am currently trying it again with Scene Detect on but I doubt it will work, given that I did not press stop. So I have a couple of questions here: 1. Why does the problem occur in the first place? (In my case the video was ahead of the audio - which seemed the opposite of what I'd have expected) 2. What is the maximum amount of footage I can capture before sync issues start to pop up? 3. Do I need to always be thinking of this problem when I'm capturing so that I make sure I press stop every few minutes on the camera so that when I capture with Scene Detect on I avoid the issue? 4. Or do I make more work for myself in Post by manually capturing 10 minutes (or whatever the maximum is) at a time? This is quite an annoying problem and I forsee many problems in the future - I had planned to use my Z1 as an analogue->DV convertor and transfer all my home movies to my PC - but now I can see it may not be just as simple as plug it in, press record and go have a beer, come back in 2 hours and it's done...

January 12th, 2006, 09:57 AM	#2
David Newman CTO, CineForm Inc. Join Date: Jul 2003 Location: Cardiff-by-the-Sea, California Posts: 8,095	If think you will find the re-capture will be fine. There will be not drift over time as the video and audio are locked together. If there is a fault with scene detection off that hasn't been reported, other than issues that can occur in MPEG that our scene detection code will handle. Try the recapture and report. __________________ David Newman -- web: www.gopro.com blog: cineform.blogspot.com -- twitter: twitter.com/David_Newman

January 17th, 2006, 01:48 PM	#3
Matt Vanecek Major Player Join Date: Jul 2005 Location: Denton, TX Posts: 334	Was there a resolution? I would like to know if capturing long recording is an issue for Aspect HD. I just purchased an FX1, and am debating with myself the format in which to record. My typical recording scenario is 45 minutes to 1 1/2 hour, non-stop. Will capturing HDV with PPro/AspectHD in such a situation cause sync drift? Thanks, Matt

January 17th, 2006, 02:02 PM	#4
David Newman CTO, CineForm Inc. Join Date: Jul 2003 Location: Cardiff-by-the-Sea, California Posts: 8,095	Matt, It will work fine. If you have any doubts please use the free trail. __________________ David Newman -- web: www.gopro.com blog: cineform.blogspot.com -- twitter: twitter.com/David_Newman