Strange sync slippage when I export movie files

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My first thought is to suspect that this is related to the files in the Capture Scratch folder.

If you want to experiment, “make off-line/trash” the files which contain the problem “slipping” clips and then Batch Capture them again.

Then, see how they behave with a new export.

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Double Double Post Post

[Daniel Haythorn]

Thanks, I’d like to try that but unfortunately I don’t have the tapes to hand. I will give it a go when I do. I think you may be right, though… when I captured it, it seemed to capture it as lots and lots of different clips; it’s possible that this was due to broken timecode and, consequently, some of the media start/end times are inconsistent or faulty… does this make sense?

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[Dan H] ” some of the media start/end times are inconsistent or faulty… does this make sense? “

Yes.

[Bill Bilowit]

In FCP 5.1.4 this happens sometimes when previous audio renders are referenced instead of the most current.
If FCP 6 menu is the same in this regard, then: trash your audio renders, select all the clips on your timeline and from the menu bar: Sequence>Render Only> Mixdown. Try exporting a problem area to test if it worked.

[Shan Sanford]

Please let us know if the above fixed it for you.

It seems to me that the problem is in the software and how it references the video material in the scratch drive. You said that edits had been rolled. As if your “ins and outs” have been shifted. I’ve seen this before with HDV timelines being exported via FCP’s Batch export to H.264. I haven’t been able to find an explanation for it, but I speculate that it has to do with HDV’s long GOP structure and FCP finding the wrong frames within that GOP to export.

If any one can please shed some light on this subject it would be handy and I think I’ll create a fresh post regarding the issue that I’ve experienced.

OSX 10.4.1
FCP 5.1.2/ 2 x 2.66 Ghz Dual-Core Inter Xeon
4GB RAM
internal media Hard drive + GRAID

[Daniel Haythorn]

Hi there,

I don’t think faulty audio had anything to do with the problem – this was a music video, and there was no audio in the timeline other than one 48khz AIFF (ie, the song of the vid). The “sync slippage” wasn’t actual sync with picture; as Shan Sanford clarified, it was as if the ins and outs had been shifted (ie, as if I’d done a “roll edit” on various shots).

I think Shan Sanford’s diagnosis may be near to the problem – this was shot on HDV, and it’s the first time I’ve edited in this format… it’s also the first time I’ve had this rather peculiar problem!

Thanks again

Dan

[Graeme Duane]

I’ve been tearing my hair out with a single HDV shot that I export to any “Quicktime conversion” format in FCP that becomes very out of sync in the compressed file.

I’ve trashed prefs, reshot,recaptured, tried numerous different export codecs (h264, Streambox, even back to HDV) and it still happens.

Camera is a V1 (PAL), FCP versions 5 and 6, two different machines, and the weirdest thing is that if I use Quicktime itself to export, the sound & video is in sync.

Infuriating.

f900/HVX

[Daniel Haythorn]

Yup, this sounds familiar. I had a similar problem and I’m afraid to say I never really got to the bottom of it. It’s something to do with the GOP structures of HDV material, but beyond that it gets pretty complicated. Suffice to say that I’ve worked on another HDV-shot piece recently and the problem doesn’t seem to have recurred. In this instance I have captured using the Final Cut Pro HDV interface (therefore capturing HDV material), edited the film, and exported using the “Current Settings” export choice in FCP (ie, exporting to an HDV quicktime, and then converting to my final format / codec from there). It seemed to work fine. If you haven’t tried the above procedure, give that a go… if you have, good luck fixing the problem!

[Bill Bilowit]

My dual-2.5 G5 had quirks when processing anything much more than playback for the small bit of HDV we did. Rendering from a timeline to another compressed codec is certainly a workout. Better also to export as Current Settings, then quit Final Cut, and use Compressor to convert the native settings Quicktime you created.

My recent MBPro handles HDV much better, but I always try to get HDV projects out of GOP workflows.

For HDV work, better to capture as an intra-frame codec which is far less taxing on the system for subsequent editing and rendering out to other codecs.