quicktime video in and out of sync

[inky]

running protools 6.4 on Mac OS 10.3.4. the source of my audio and video are final cut pro. in this specific session, the video is 2 frames out (early) in some places, and in sync in others. it is not drifting, it is in and out of sync in the same places consistently. i have a 30 minute session with a quicktime video imported into it. the audio (imported from an OMF) is in sync with the imported guide track from the movie. the sample rate settings are all correct (same as we normally use when we don't have this problem). the picture is playing out firewire through a sony DVMC-DA2 box.

could this problem be due to a fragmented audio drive? or is it inherent in firewire video to have inconsistent drifting? please advise.

thanks,
inky

[tonicjeff]

Try doing an offset bt 22 qtr frames. That helped me when playing the QT vid out a canopus box.. That was digi's advice.

J

[marty lester]

FCP is very tricky when doing OMF. sounds like your problem lies w/ how FCP does OMF.
i've been told when one exports OMFs from FCP, you should NOT check "use crossfade
transitions" or whatever the one check-box in the OMF export dialog box is.

also, if your editor used audio tracks but didn't re-digitize them...ie., left them as 44.1K
in a 48K video session (i'm assuming it's 48K), then FCP does samplerate convert
on the fly but this hoses you at the OMF export step.

i'm making many assumptions about your session, but your symptoms sound very
familiar and i believe that's what has screwed me before.

hope this helps, and isn't inaccurate...i'm no FCP wiz,

marty

[inky]

Thanks, we are set at 21 quarter frame offset normally, which is working for most of the session. The sync issues only occurs in a couple of places. Thanks! I must keep searching for the solution...

[inky]

Thanks re FCP advice. This facility runs at 48k all the time, so the 44.1 conversion wouldn't be an issue. We are looking into the check box unchecked option..... hopefully this will help.
thanks!

[Fokke van Saane]

Why do we talk about the OMF issues? ... if i read your post well...you say that the guide track from FCP is in sync with the OMF. So, that means that the problem is not in the OMF, nor in the audio at all. Is that true?

I have issues with DV video playback here as well although i run all in a supported system. I notice drift after 20 mins. If i stop and continue at that place all is back in sync. I started a thread about this long time ago and noone had the definitive answer. Some suggested not to include audio in the movie file, some suggested to strip and repaste the audio in the QT movie.. it all didn't help. The problem is that it is a vague problem. The off sync is just a few fields, just enough to make you wonder why it is offsync but not enough to clearly see where to problem is. It happens after 20 mins here if i view in a long run. Yeah, that is when director and producer are watching my work....

I also think that sometimes i see my movie jump to get back into sync. Can anyone confirm this?

I still think that it is a quicktime problem. Quicktime is running on the internal clock of the CPU where PT is running on another clock.

Canopus ADVC-100 on a MIXplus system on a G4 dual 1.25 1GB RAM DVPAL usually made by FCP.

Fokke van Saane

[JKD99]

You didn't say this specifically, so I'll go ahead and mention it: You said the OMF is in sync w/ the guide track, but......is the guide track in sync with the video at the specific spots you mention? It's always possible, especially if it's a film-based project, that the telecine is out of sync....Happened to me. If this is possibly the problem, ask your picture editor to check that the clapper's in sync at the top of the shot.
Anyway, hope this helps and does not annoy

[inky]

Thanks for your response. Fokke van Saane. Yes, the Quicktime guide track from FCP is in sync with the OMF. I don't believe we are drifting as you do, but we are out of sync in the same locations in the session, and off by up to 3 or more frames - yikes! I thought it may be a fragmented drive or something, but I tried a different less-full drive, and had the same problems. We are checking to see if my stems (that look out of sync in places) are in sync with the original FCP picture. So far, it seems they are.... Hmmmmm....

[inky]

Yep, the OMF is in sync w/ the guide track, but......the guide track is NOT in sync with the video at the specific spots. The audio matches throughout. This is a video based project, no telecine involved. Any other thoughts? Thanks much, Inky

[brinaddison]

Have you tried to layback the audio mixdown to the sequence in FCP? Try it, I have noticed that when laying it back onto the FCP timeline for output that all the sync issues go away. It makes it a little harder to sinc while in PT but if you just trust that it will sync up again in FCP then work like that.

I'm not sure why it only happens on certain frames only but if it isn't drifting, you should in theory be ok. Do you have TC BURN on the Quicktime movie? If so you'll be able to see how some frames are sometimes off by a frame or two in PT.

Not much but I hope this helps.