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Render Glitch/Time code shift when overlaying GFX

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Jonathan Briggs
Render Glitch/Time code shift when overlaying GFX
on May 4, 2009 at 12:27:47 am

Hi there -

I'm really, really hoping someone out there can help me as I'm about to lose my mind and destroy the mac suite I'm working in.

Background info :

Feature film delivery. I graded and finished the film in ASSIMILATE Scratch. It was played out to HDCAM SR @ 24psf. The whole film was then captured into FCP in reels from this SR.
Then the director wanted to adjust some shots on the original grade. Some changes were made to some shots at the beginning of the film within SCRATCH - these shots were then played out from Scratch to another HDCAM SR, and then these were digitized into FCP. I then placed these clips into the timeline at correct points replacing the original capture. I play back the timeline and everything is fine... shots are in synch and cut points are clean. I then need to overlay some title GFX on top of these shots. These GFX are After Effects renders - Animation Codec wit a straight alpha. Now here comes the problem!

When these GFX elements are placed on top of the re-dig'd shots obviously they need to be rendered. BUT as soon as I place the GFX into the timeline it does something WEIRD to the shots on the vid track below. Basically it nudges the whole clip backwards by two frames, so the cut to the next shot is all f@cked up. There are 6 of these cilps and each one is effected in exactly the same way when the AFX renders are placed on top...

I tried re-rendering the shots from AFX as PNG seqs and bringing them in with the still length set to 1 frame. This kinda works - the render bar turns green for preview. I hit play and the shot plays back fine - the GFX animate over the top of the clip perfectly and the clip remains the same and
un-shifted BUT obviously as its preview mode the GFX are low quality. As soon as I hit render the same problem occurs. Exporting the clips (with or without the GFX on top) causes the clips to time shift in the same weird way.

I've tried opening the project in everyone of our suites. I've tried dumping the preferences. I've tried copy pasting onto another sequence. I've tried re-saving.

Anyone who has managed to follow that and thinks they can help please get back to me ASAP? Before I do something I'll regret :-)

Cheers.

Jonny.


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Andrew Kimery
Re: Render Glitch/Time code shift when overlaying GFX
on May 4, 2009 at 1:16:35 am

Whenever I've run into this type of problem it has been corrupt/bad media in some form or another. What card and codec did you capture the HDCAM-SR with? Try either recapturing a clip from the tape or take a clip you already have an transcode it and drop the transcoded clip into the timeline to see if you get the same problem or not. You can also open up a clip in QT, hit command+i and make sure the frame rate is accurate. For example, last week I had some DVCPro HD 720p60 clips that were acting this way and when I opened them up in QT the frame rate was 59.97 or 59.91 instead of 59.94 (the footage was captured w/a MOTU V4HD). From QT I exported the clips as DVCPro HD 720p60 and the new clips had the proper frame rate in QT and worked flawlessly in FCP.


-A

3.2GHz 8-core, FCP 6.0.4, 10.5.5
Blackmagic Multibridge Eclipse (6.8.1)



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Jared Lorenz
Re: Render Glitch/Time code shift when overlaying GFX
on May 4, 2009 at 3:29:47 am

We are experiencing the exact same render glitch here specific to one sequence. Other sequences appear to be rendering OK. The difference with this one was a recapture.

I am chasing frame offset as the potential culprit except that when un-rendered the clips preview OK, which leads me now to chase a Quicktime/FCP problem. We have tried on multiple workstations & projects, trashed the render files. Now deleting FCP prefs.

In our case there is no interaction with SCRATCH or anything outside of FCP itself, just a recapture of a 24PsF HDCam textless master. Sequence settings are ProRes 422 1080p23.98.

Will be watching this thread and reporting if we come up with anything.


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Jared Lorenz
Re: Render Glitch/Time code shift when overlaying GFX
on May 4, 2009 at 4:43:42 am

So far I can eliminate the following as causes or solutions:
- render files zapped, no change
- prefs zapped, no change
- machines restarted, no change
- external video reset, no change
- updated QT on one workstation, no change
- re-exporting from the quicktime as suggested does not fix the problem but makes it worse, suggesting maybe a corrupt capture file.

Now trying a recapture to see if that fixes it.


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Jared Lorenz
Re: Render Glitch/Time code shift when overlaying GFX
on May 4, 2009 at 5:26:45 am

... And recapturing the media didn't work here either... still the same problem.


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Andrew Kimery
Re: Render Glitch/Time code shift when overlaying GFX
on May 4, 2009 at 5:36:16 am

What capture card are you using? Maybe something w/it is the cause? Do you have another machine you could try capturing on? If not maybe try completely uninstalling the capture card (including all software/drivers) and reinstalling it? Also, are you capturing ProRes or ProRes HQ? Some people have reported rare problems using HQ but no problems w/non-HQ.


-A

3.2GHz 8-core, FCP 6.0.4, 10.5.5
Blackmagic Multibridge Eclipse (6.8.1)



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Jonathan Briggs
Re: Render Glitch/Time code shift when overlaying GFX
on May 5, 2009 at 8:49:34 am

Hey Guys

Sorry for delayed response -

When I originally posted it was around 2am on a Saturday Holiday weekend in the UK so I left work shortly after.

I'm using a Kona 3 Card to capture through SDI using the Kona UNCOMPRESSED 10bit 24sf capture settings within FCP.

I've tried other 24 settings but no others will allow me to capture.

My sequence settings are :

Time base : 24

1920x1080

Square Pixel Non Anamorphic

No fields

Uncompressed 10bit 442 24sf Codec

High precision YUV 10bit rendering

At the risk of repating what other users have posted here I've tried the following -

Exporting the clips and reimporting - didn't work.
Recapturing - didn't work.

Trashing prefs, thumbnail cahe, restart and reinstall etc

Am going to try opening the original capture file from the capture scratch as suggested by the first post and either exporting from QT Pro OR Opening in Cinema Tools and manually setting FrameRate to 24.

Will report back.

Cheers

Jonny


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Jonathan Briggs
Re: Render Glitch/Time code shift when overlaying GFX
on May 5, 2009 at 11:32:15 am

Problem solved by the following :

Reveal original captured file in finder

Duplicate this file

open in cinema tools and manually set framerate to 24

reimport into FCP and replace defective clips on timeline.

Thanks for all the feed back/suggestions and help guys!




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Jared Lorenz
Re: Render Glitch/Time code shift when overlaying GFX
on Oct 19, 2009 at 11:18:03 pm

This continues to be a problem in our facility even after uninstalling and reinstalling drivers and final cut on the offending workstations. It has gone from being an intermittent issue to one that plagues nearly every capture performed on one machine.

I have narrowed it down (in our case) quite specifically to clips captured at ProRes 422 1080psF23.98 via SDI into the Matrox MXO2. Re-Re-Re-Recapturing doesn't fix it. Taking the source movie, exporting a new quicktime and reconnecting to that copy sometimes fixes it, but not reliably. Upgrading software/firmware/drivers to latest versions hasn't fixed it either.

At one point I thought it could be a driver or compatibility issue between different machines, since there is only one Matrox here. We move projects around from machine to machine and some have Blackmagic cards. The online machines have an Aja IO, Aja IO HD and a Matrox MXO2. However the glitch also shows up on the Matrox machine, so I don't think that's the issue.

The issue manifests itself as follows:
- clips play back fine in real-time playback
- when we render or export, dissolves, motion effects, or time effects cause unpredictable shifts of 2-3 frames (typical)
- I then scream into the air and bang my fists against the table

As of today, I am still hunting for a way to fix it. Given the amount of fruitless effort to date, I think I'm going to fix it by recabling everything so that the Matrox captures SD, and the IO captures HD. Too bad. I like the fact I can leave the Matrox looped-through. Thus any insight into the real source of the problem would be greatly appreciated.

Mac Pro 8-core 2.8ghz
XSan 1.4 / XServe Quad / XServe RAID
OS 10.5.8
FCP 6.06
Matrox MXO2 1.6

FCP


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