Weird and Intermittent Sync Problem

Posted by rdedits 
Weird and Intermittent Sync Problem
April 05, 2011 07:40PM
Hopefully I can explain this clearly. Working on a SD 30 minute show. All sequences where copied over to the master project and assembled into the 30 minute timeline. I dragged the copied sequences into my viewer and assemble edited them into the 30 minute timeline thus creating several nested sequence's. I needed to edit in a bug for the show on V2 plus some show bumpers. Sometimes, not every time, when playing the timeline down as these bugs and dissolves from the show bumper come up, the nested sequences will jump back a couple frames and go out of sync. If I go back say 30 seconds and reply it will run smooth, go back and try it again and it may or may not jump back a few frames. I've rendered everything out as well. I've also trashed FCP preferences and still get this bizarre jump in my timeline. Working to get this figured out so I apologize if I left something crucial out in my post. Very frustrating!

Re: Weird and Intermittent Sync Problem
April 05, 2011 07:59PM
It sounds like your machine isn't powerful enough to cope with playing it back correctly, since it can do it with a run up, that means there's not anything actually wrong with the program, just that it's not displaying correctly.

If you're really worried, export just one of the problem sections and play it out of QT. Like, export ten seconds of an area that gives you problems and see if the problem actually exists outside of live playback in FCP.

If you want to do more troubleshooting, tell us

your machine specs
what kind of media you're cutting
what conversions, filters etc you have going on, if any
what your RT settings are
what peripherals you have attached
what drive you are running the media off, and how full ALL your drives are

Re: Weird and Intermittent Sync Problem
April 05, 2011 08:44PM
Thanks Jude. I actually did just that, exported a QT Ref of the entire show and it played fine. I needed to make some DVD approvals and they worked just fine. I just don't get it, yesterday the entire 30 minute show played out fine without any problems, today all these weird hiccups. This isn't the first time this has happened, usually rendering everything in the timeline solves the problem. Also, if I step into the nested sequence and add whatever bug or lower third that is needed, jump back out the sequence will play fine. Still new to FCP (Media Composer has been my home for the last 18 years) so I'm working my way through all the basics at the moment.

The system I'm working on is a MacPro 3GHz Dual Core OSX 10.6.7, 8 GB's RAM, 6TB mini SAS RAID 5 storage. The media is all XDCAM EXp24 although the project is SD. Unlimited RT and my sequences are set to the following,

frame size: 720x486 CCIR 601 NTSC (40:27)
Pixel Aspect: Square
Field Dominance: Lower (Even)
FR 29.97

QT Compressor: Apple ProRes
Re: Weird and Intermittent Sync Problem
April 05, 2011 09:33PM
So are you using the sequence to downconvert the media, or did you convert it before import? Those long gop formats are hell on playback, when things get busy.

Also, do you have a lot of audio going on? Try increasing your audio allowance, and maybe even try an audio mixdown (which just give you a simpler playback for audio that takes pressure off the system - it doesn't change your number of tracks or actual output at all)

And are your drives filling up? Any of them? Performance routinely decreases as your drives get fuller, and any attached drive can cause issues, even if you're not actually using it.

Re: Weird and Intermittent Sync Problem
April 05, 2011 09:41PM
Is the source 23.98 fps or 29.97?
Re: Weird and Intermittent Sync Problem
April 05, 2011 10:31PM
All of the footage was already ingested by the producer of the show and as far as I can tell FCP is telling me it's Apple ProRes 29.97. He did bring a G Raid 4 TB drive with him that has one of the shows sequences already edited. I would normally transfer all the media to my RAID set-up but things got a bit crazy and I had to run with it. Not much audio on the timeline, 4 tracks at best. Just can't figure out how the timeline plays great one day and hiccups the next.

strypes, as far as I know the actual source footage was 23.98 but the ingested footage is 29.97.
Re: Weird and Intermittent Sync Problem
April 05, 2011 10:41PM
> as far as I know the actual source footage was 23.98 but the ingested footage is 29.97.

??? Why is that?

Okay, I think you need to stop and get on the same page with your producer. You should not be an editor plunging into a project without knowing the settings of what they shot, and why they captured a certain way. For all you know, the producer ingested or edited the footage incorrectly...and it's your job to catch that. Any work you do on incorrectly set-up projects will just increase the amount of time you'll spend fixing unnecessary problems. I also don't understand why you'd edit an SD show in square pixels. If it's going straight to the web, why aren't you editing in HD (unless you shot tapeless at SD quality...bizarre, but not unheard-of, I suppose) and at the original 23.98fps? And if it's going out to SD tape for broadcast, why are you using square pixels?
Re: Weird and Intermittent Sync Problem
April 05, 2011 11:15PM
Use the default sequence presets. And check the framerate. Better, get a source clip from the producer.
Re: Weird and Intermittent Sync Problem
April 06, 2011 12:57AM
Totally agree Derek and under my normal workflow I would have more control of this situation from the start. This project came to me at the last minute. All the off-lines were completed by the producer and some of the finishing by a different editor. Things happen and I was asked to finish the project. I took the word of this client and figured it was pretty much assembling the show and outputting to tape. Obviously not the case and there is no time to start re-ingesting footage (or is there?).

No matter how may times I tell the producers who like to off-line their stuff what format they should set their project to, I'm always re-adjusting their sequence settings when it gets to me. It gets old but the solution for me is that they simply get billed an extra hour for me to redo their screw up.

My problem right now, right this second is to figure out why I'm getting these hiccups one minute and none the next.
Re: Weird and Intermittent Sync Problem
April 06, 2011 01:31AM
Isn't it more that you didn't used to get them and now you do? If the project is that much of a mess and your QT exports are fine, you might be better off just living with the weird playback and getting the hell out of there. Stopping now to make it play back OK, when it's exporting at a level you can accept, is possibly a waste of time.

Of course, if you had the time and the dollars and the need, I would say go right back to the beginning, figure out what they have done and fix it.

Re: Weird and Intermittent Sync Problem
April 06, 2011 04:37AM
These guys know their stuff, but I have this with properly captured material. FCP is telling a bunch of files to 'play' at a certain point. Gaps in your video track seem to affect audio sync playback. Also any sample rate conversions and effects that are occuring 'on the fly' tax the system.

Some settings seem to improve things sometimes:

'audio playback quality': 'high'

render 'audio mixdown'

turn off 'unlimited RT' and render as needed to watch full speed / sync playback

Re: Weird and Intermittent Sync Problem
April 06, 2011 08:20AM
I wish I could turn down business Jude! Hopefully next time around I will be in control from the start.

Trevora: Thanks for the tips. I'll give them a whirl this morning.
Re: Weird and Intermittent Sync Problem
April 06, 2011 09:30AM
Oh, sorry, I didn't mean dump the job, I meant just live with the weirdness on this one, get it done and then get out, with the idea of starting afresh next time.

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