Quicktime Export/Conversion Frame Rates

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Level 1

8 points

Quicktime Export/Conversion Frame Rates

I've noticed a very strange bug when using "export using quicktime conversion", as opposed to using "export quicktime movie" in Final Cut Pro. I have a sequence at 29.97 that I would like to keep that way. It seems like when I export using "export using quicktime conversion", the resulting .mov file shows a random frame rate (FPS) in the quicktime info window (e.g. 24.79, 24.99), and a variable Playing FPS (e.g. 1, 30, 24). This holds true when I set "current" or "29.97" for frame rate in the export settings window. Then when I use "export quicktime movie" the frame rate (FPS) in the resulting QT .mov shows 29.97, and the Playing FPS locks in at 30. I'd use this method, but I need to change the size of the resulting movie (I don't want to change the size of my sequence because I'd have to resize every clip). I'm confused by this- any explanations? I've heard not to pay too close attention to the Quicktime info window, but this just seems bizarre to me.

Thanks, Josh

MacBook Pro Dual 2.5 GHz, Mac OS X (10.5.7)

Posted on May 26, 2009 12:23 PM

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Answer 1

pdxjosh Author

Level 1

8 points

May 26, 2009 2:53 PM in response to pdxjosh

The Editing Timebase shows 29.97 in Sequence Settings for the exported clip that I re-imported. Although I do trust this, it still seems bizarre that Quicktime would show those fluctuating and/or random frame rates only for movies that were exported using quicktime conversion, yet show rock solid and accurate frame rates for those using the "export quicktime movie".

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Answer 2

May 26, 2009 3:03 PM in response to pdxjosh

Well, I'd guess you were alright.

I've seen qt report weird frame rates occasionally, but I've never been able to trace any problems to it.
The only way I know to "reset" the metadata defining the frame rate for a quicktime clip is to export as an image sequence and then reimport using quicktime pro which allows you to define the frame rate. I doubt that helps, but that's never stopped me before.

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Answer 3

pdxjosh Author

Level 1

8 points

May 26, 2009 3:09 PM in response to pdxjosh

Thanks for trying Michael, but I'm hoping somebody out there knows exactly why this might be happening. If there's a real problem associated with it, I'd like to know how to fix it. If it's nothing, then I might set my mind at ease...

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Answer 4

Nick Holmes

Level 7

30,018 points

May 26, 2009 3:16 PM in response to pdxjosh

Here's something for you to try:

Place a ten second clip of bars and tone in the Timeline and export it using the same method as you described above. If the reported frame rate is actually changing, you should hear pitch changes in the 1kHz tone too.

If it plays back correctly, the tone will remain constant. This would indicate that the frame rate is only being wrongly reported as an inconsistent value.

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Answer 5

pdxjosh Author

Level 1

8 points

May 26, 2009 3:54 PM in response to pdxjosh

Thanks for the suggestion- interesting exercise. The movie I exported with "export using quicktime conversion" similarly showed random and varying FPS and Playing FPS (in this case 1.00 FPS) in Quicktime movie info, though the tone audio was solid (no breaks). Then I exported it with "export quicktime movie" and like before the FPS was 29.97 and the Playing FPS was 30 in Quicktime movie info.

I then realized that the compressor codec for this bar/tone sequence was DV/DVCPRO-NTSC (Final Cut default), whereas the material I'm working with is set as Animation or AppleProRes 422(HQ). Thus when I previously exported as described above, it was to an Animation codec .mov. When I exported the second time to a DV .mov using the "export using quicktime conversion" lo and behold, the frame rate showed as 29.97 in the Quicktime info. Apparently the Quicktime info window only shows the correct FPS for certain codecs (in this case DV- I haven't had time to try others); for the ones I'm exporting (e.g. Animation) it doesn't show FPS correctly, but it seems like it is, in fact, actually correct.

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Answer 6

May 26, 2009 1:53 PM in response to pdxjosh

What framerate does fcp report if you bring the exported file back in to fcp?

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Answer 7

May 26, 2009 2:58 PM in response to pdxjosh

What's the clip's frame rate? Import the clip into the browser, select and hit Command-9.

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Answer 8

pdxjosh Author

Level 1

8 points

May 26, 2009 2:59 PM in response to pdxjosh

Clip's frame rate shows as 29.97 in item properties.

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