Exporting frame rate?

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AaronR1985 Author

Level 1

8 points

Exporting frame rate?

Hi.

I am struggling with iMovie 10 on Yosemite.

Say i import a bunch of GoPro clips at 1080 x 120fps and trim them so i don't have long raw clips and want to export them for a later date. Why does iMovie cut it down to 23.5fps and double the size of the video clip? Is there no way to export at the original frame rate? All i want to do it trim off all the un-usable footage and keep the rest without losing the fast frame rate. Otherwise it is pointless and will i have to purchase a proper program?

Any links to articles that might help would be appreciated.

Regards

Aaron

MacBook Pro (Retina, Mid 2012), OS X Yosemite (10.10.2)

Posted on Apr 25, 2015 12:33 PM

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Answer 1

GeeD

Level 6

9,173 points

Apr 25, 2015 1:12 PM in response to AaronR1985

"Say i import a bunch of GoPro clips at 1080 x 120fps and trim them" - if you want save storage by removing unwanted footage you have to do this before importing into iMovie 10. Unlike earlier versions you cannot trim imported clips.

"Why does iMovie cut it down to 23.5fps" - 23.5 is a strange number as far as I know iMovie 10 can only export at 24, 25, or 30 fps. It does read in every frame on import though (at least it does with 50 fps media) so you can use high fps input to make high quality slow motion.

"double the size of the video clip?" - The original media is usually highly compressed (e.g. AVCHD). In order to edit it has to be transcoded into Apple Intermediate Codec which can be edited with much less CPU work but is much larger in file size.

You can trim your media using Quicktime Player before import and the result will still be at the original framerate. If you want to edit then export at 120 fps you will have to use Final Cut Pro X or similar ( maybe iMovie 9 could export at 120 fps - I don't remember).

Geoff.

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Answer 2

AaronR1985 Author

Level 1

8 points

Apr 25, 2015 1:22 PM in response to GeeD

Thanks Geoff.

I can import the 120 fps into iMovie but when you try and slow it down 5x which would still be around the 20fps mark it seems very choppy. So guessing it doesn't actually import at 120fps. Is there a way to tell what the frame rate is once inside iMovie?

As for using Quicktime to trim. Even if i open a 30 sec clip at 80 fps original file size of 250mb trim 1 sec off each end and save it the file size then becomes approx 50mb but at least it keeps the 80 fps but why the huge drop in file size? If going by what was said about if the file is compressed from camera surely it would be a lot bigger?

Shame you have to purchase a hugely expensive program to do something simple. Since i make no money off the clips. Makes it hard to justify the price tag.

Thank you for your help tho.

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Answer 3

GeeD

Level 6

9,173 points

Apr 25, 2015 1:40 PM in response to AaronR1985

"Is there a way to tell what the frame rate is once inside iMovie?" - well yes but its a bit fiddly because of the lack of a precise playhead position display. When you are skimming a clip in the timeline each press of the right arrow key advances by one frame. So if you have a clip of a known duration you can count the number of fames in it. I only tested this with 50 fps input and satisfied myself that all frames were present and that if I slowed to 50% it used every frame in the resulting 25 fps output. According to: http://www.macworld.com/article/2050020/how-to-use-iphone-5s-slo-mo-videos-on-th e-mac.html

120 fps media from an iPhone can be imported into iMovie and the thumbnails get a little '120' label in them.

So Quicktime Player seems to be compressing the file - are you sure the output resolution is the same as the original?

FCP X is very good value for money but not, of course if you don't make full use of it.

Geoff.

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