Loss of synchronization during render

MikeB_Bellevue wrote on 12/31/2009, 11:05 AM

I'm a newbie so bare with me. My current problem involves loss of synchronization (audio gets ahead of video by 5 seconds (+/-) in 4 min) but only in the rendered version. When I preview, the synchronization is fine. Early in the sequence the synchronization is fine even in the rendered version. The decoupling of the rendered version seems to happen after a few clips are cross faded. I am testing now to determine if removal of the cross fade fixes the synchronization.
Is there a button I need to push somewhere to make this work right?

Also, is it normal for rendering of 20 min of 1920x1080 video to take 90 minutes?
Running VegasPro9c 64bit on Win7 Dell with a i7 920 processor.

Comments

xberk wrote on 12/31/2009, 12:13 PM

Use the link below to download John Cline's rendertest-hdv.veg which I found is a good gauge for render speeds (thanks again John! ) .. Do a further search within the rendertest thread to get render times for an i7-920 CPU so you can see how your system compares.

rendertest-hdv

All I know about sync is to right click an event and at the bottom of that pulldown is Synchronize. You can sync any given clip this way by "moving" or "slipping" -- this I believe works using timecodes. If no timecode is present then you must sync things by hand (moving either audio track or video track) and this can drift over time in a long event so you have to re-sync now and then as needed. I have not heard that a render can throw things out of sync if preview has been ok.

What type of footage? What type of camera? Can you render the unedited original clips without any sync issue?

MikeB_Bellevue wrote on 12/31/2009, 3:16 PM

Thanks,
I tried the rendertest and I came out right on target (1:12).

When I right click on the Synchronize, it is greyed out, which I interpret as meaning it is already synchronized. It looks OK and previews OK, but the rendered version is off by 5 seconds for some clips. I am going to rebuild the whole thing from scratch and see if that helps.
Camera is Canon HF100. I have several small pieces where everything works fine (no sync issues).

musicvid10 wrote on 12/31/2009, 3:19 PM

What are you rendering to? (Post your render settings)
What are you playing back on? (Have you tried more than one player?)

I ask this because playback sync problems are usually a combination of those factors.

MikeB_Bellevue wrote on 12/31/2009, 4:12 PM

Hmmm good questions:
Sony AVC .mt2s
AVCHD 1920x1080-60i

I have always used Windows Media Player to view the rendered product.
But based on your question, I imported the rendered video into Vegas and !!! the sync problems are gone.
I don't know what to make of this.

BudWzr wrote on 12/31/2009, 4:45 PM

Does the sync go out at a constant rate? Or gets worse with time?

Are you sure it's not the video that's out of sync?

MikeB_Bellevue wrote on 12/31/2009, 4:55 PM

The clips I am using are not the best for testing this issue because there are long periods with no way to gauge the synch. However it does appear to occur suddenly. Two clips are fine, then 3 clips (2min total) of beach walking (no lips to read), then a series of clips of talking that are all out of sync by a constant amount.
I did discover that both Vegas and Windows movie editor will play the rendered video without sync problems. It is only WMP11 that produces the sync problem. I am looking for another viewer now.
I never dreamed it could be a bug in WMP.
Mike

musicvid10 wrote on 12/31/2009, 5:36 PM

It is awfully hard for any player to keep up with full-frame playback of AVCHD material. WMP is bad, QT is worse. Out of sync playback is usually the first sign of a struggle.

Two players that generally get high marks are VLC and MPlayer.

YMMV

BudWzr wrote on 12/31/2009, 5:53 PM

YES, Smplayer is very smooth with AVC, don't know about 1080 though. Why can't you just use 720p?

MikeB_Bellevue wrote on 1/1/2010, 3:52 PM

I still haven't found a player that works on the 20 min render I am working with but it really doesn't matter at this point. I burned a BD-RE disc and it all looks (and sounds) great. No sync problems. Since this is my main and final product the rest it just an inconvenience.
Thanks all for the info.
I'll be back with my next problem, which will likely be soon.
Mike

Rob Franks wrote on 1/1/2010, 9:04 PM

"It is awfully hard for any player to keep up with full-frame playback of AVCHD material. "

Power DVD, Nero Showtime, Total media Theater... lots of them out there. What you need is a machine capable of playing the player properly.