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video goes out of sync on render

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Mitchell Hart
video goes out of sync on render
on Sep 21, 2010 at 5:50:27 pm

I have a long timeline (hour and a half) of prores footage. when i export, the video is incorrect. The video looks to be taken from earlier in the timeline. Perhaps it's a frame rate issue, but the timeline is 24 fps and so is the footage. If anyone has any ideas I would be grateful.

Allow me to elaborate more in case the details help. When the timeline status bar (if that's what it's called) is green (playable, but unrendered) the video lines up correctly. When i do an unlimited render (status bar turns blue-ish) the video goes out of sync.

I'm on FCP 7.0.2

Thanks!!


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Shane Ross
Re: video goes out of sync on render
on Sep 21, 2010 at 6:41:40 pm

24fps? or 23.98fps? Don't mix the two. If the footage is 23.98 (23.976 rounded up), then your sequence needs to be 23.98.

What codec?

Shane



GETTING ORGANIZED WITH FINAL CUT PRO DVD...don't miss it.
Read my blog, Little Frog in High Def


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Mitchell Hart
Re: video goes out of sync on render
on Sep 21, 2010 at 6:52:18 pm

Not 23.976, it's actually 24. It's been converted from a quicktime screen recording, which was originally around 5 fps. The timeline is set at 24 and the sync is WAY off, like it converted the footage, but still plays it at 5fps.

Also, it's prores in and out.


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Mitchell Hart
Re: video goes out of sync on render
on Sep 21, 2010 at 6:57:34 pm

Shane,

Thanks for your response, but it's not 23.976, it's actually 24. It's been converted from a quicktime screen recording, which was originally around 5 fps. The timeline is set at 24 and the sync is WAY off, like it converted, yet still plays at 5 fps.

Also, it's ProRes.


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Dave LaRonde
Re: video goes out of sync on render
on Sep 21, 2010 at 7:37:54 pm

[Mitchell Hart] "It's been converted from a quicktime screen recording, which was originally around 5 fps... Also, it's ProRes. "

How do you know the screen capture was originally 5 fps?
What's the horizontal and vertical resolution of the screen capture?
What was the codec used when the screen was captured?
What form did the audio take when the screen was captured?
What was used to convert thefile from 5 to 24fps?

And what's the big deal about using 24fps -- are you doing a film-out or something?

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Mitchell Hart
Re: video goes out of sync on render
on Sep 21, 2010 at 7:47:37 pm

Hi Dave, here are the answers:

How do you know the screen capture was originally 5 fps?
> I checked the info in quicktime 7. It was actually more like 4.24

What's the horizontal and vertical resolution of the screen capture?
> 1920 × 1080

What was the codec used when the screen was captured?
> H.264

What form did the audio take when the screen was captured?
> 24 bit 48KHz

What was used to convert thefile from 5 to 24fps?

>Quicktime pro 7

Thanks for your help!


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Dave LaRonde
Re: video goes out of sync on render
on Sep 21, 2010 at 9:07:34 pm

[Mitchell Hart] "I checked the info in quicktime 7. It was actually more like 4.24.... 1920 × 1080... H.264.... 24 bit 48KHz"

Hmmmmm. For future reference, you can't really trust the QT info window to ahow an accurate frame rate. It's better to check it in FCP, even if the codec's bad... which in your case, it is! I'd bet it's 5fps.

I'd treat this stuff like it was footage from a DSLR: use Compressor to convert the footage to ProRes 422. The converted file should also be 5fps, which you should double-check before proceeding to the next step. To get the frame rate to 24, take a COPY of the converted file into Cinema Tools and conform it to 24.

I still haven't figured out why you need 24. Personally, I'd conform it to 23.976, which is the NTSC film frame rate. FCP misleads people by calling it 23.98.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Mitchell Hart
Re: video goes out of sync on render
on Sep 21, 2010 at 10:55:28 pm

Thanks again for the helpful info. I repeated the steps you outlined: converting in compressor and conforming in cinema tools (rather than converting and conforming simultaneously in quicktime, but I still ended up with the same outcome: a video file of identical length (audio is the same) but the video is crunched up (read: goes by 4 times the speed). That's where I changed the speed in FCP to ~ 25% to get my original speed. Although it seems like it would work fine, here is where I get my render or export problem and the video not syncing.

ALAS! I used After Effects as a replacement for the speed change step in FCP, thus solving the problem. I hope that wasn't too confusing.

As for the 24 fps, there wasn't a reason for it, just had other footage on the timeline already at 24, so I was trying to avoid problems. I ended up finishing in 23.98 (23.976).

Cheers!


Hmmmmm. For future reference, you can't really trust the QT info window to ahow an accurate frame rate. It's better to check it in FCP, even if the codec's bad... which in your case, it is! I'd bet it's 5fps.

I'd treat this stuff like it was footage from a DSLR: use Compressor to convert the footage to ProRes 422. The converted file should also be 5fps, which you should double-check before proceeding to the next step. To get the frame rate to 24, take a COPY of the converted file into Cinema Tools and conform it to 24.

I still haven't figured out why you need 24. Personally, I'd conform it to 23.976, which is the NTSC film frame rate. FCP misleads people by calling it 23.98.


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Neil Sadwelkar
Re: video goes out of sync on render
on Sep 22, 2010 at 1:40:57 am

You must have done the MacOSX screen capture? That makes these funny 4.24 fps kind of movies.
I\'ve done this before and converted the capture movie to Apple ProRes at 25 fps before using in FCP. My use didn\'t involve audio sync in a any critical way though.

But for a critical audio sync screen capture I used Voila 3.0 and it worked better. Some say Screen Flow or Camtasia is good too.

About the 24fps, if you need 24fps, you need 24fps. I too make it 24fps when needed. In PAL countries we have no use for the odd 23.976 fps. Our film is 24, our TV is 25.
Cinema Tools easily conforms one to the other.

23.976, 29.97, 59.94. All these are numbers that I see in settings in FCP that I've very rarely had to use.

-----------------------------------
Neil Sadwelkar
neilsadwelkar.blogspot.com
twitter: fcpguru
FCP Editor, Edit systems consultant
Mumbai India


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Mitchell Hart
Re: video goes out of sync on render
on Sep 23, 2010 at 2:50:03 am

Neil,

You are exactly right, it was a Quicktime screen recording. And what a nightmare it was. It won't play natively in FCP or iMovie (tried that as a last hope) I ended up switching to Screenium, which worked wonderfully.

Thanks for your comments.

- Mitch


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Dave LaRonde
Re: video goes out of sync on render
on Sep 22, 2010 at 3:00:35 pm

[Mitchell Hart] "...I still ended up with the same outcome: a video file of identical length (audio is the same) but the video is crunched up (read: goes by 4 times the speed)."

You know what? I gave you bad information. I was working under the incorrect notion that you wanted to speed up your video, which is what conforming 5fps to 24 fps will do. The downside to spreading 5 frames across 24 frames -- which is your goal -- is that motion in the video will be choppy. There isn't any way around it. You can try frame rate conversion software, which can create intermediate frames of motion, but at a 4:1 ratio, the results won't look great.

When you record screen captures, just record them at the desired frame rate.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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