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Gorpro Hero 4 Black, 120fps, CC 2014

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Todd SchmidtGorpro Hero 4 Black, 120fps, CC 2014
by on Dec 19, 2014 at 9:11:04 pm

Hi all,

I know this might sound, and is probably a stupid question, but here goes. How do I work with PPCC 2014 and the 120fps, 1920x1080 footage shot on the Hero 4 Black in PP. I would like to utilize the 120fps footage to achieve the slow mo effect and do some ramping. Do I start off with a23.976 sequence the interpret the footage to 23.976? It seems a bit confusing to me...and I feel a bit stupid asking this question but it's hard to find any real explanation to this.

Thanks!

Todd


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Jeff PuleraRe: Gorpro Hero 4 Black, 120fps, CC 2014
by on Dec 19, 2014 at 10:12:42 pm

Hi Todd,

You should not need to interpret footage. Example, put 60p clip into 30p sequence and Premiere plays clip at normal speed. However, apply 50% speed and all original frames are used for smooth slow-motion with no interpolated frames.

Or use a 23.976 sequence and 40% slow to use all 59.94 frames.

For 120fps in a 23.976, try 20% to use ALL frames, which I guess is 1/5th speed. 40% ought to use every-other frame to also provide perfect slow-motion. Etc.

Thanks

Jeff Pulera
Safe Harbor Computers


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Todd SchmidtRe: Gorpro Hero 4 Black, 120fps, CC 2014
by on Dec 20, 2014 at 3:27:25 am

Thank you Jeff,

I've been playing with it, but it just seems so choppy. The true frame rate is 119.88 not exactly 120fps.

With my EX3, I will record at 60fps and the slow motion plays in slow right back. There's no need to reduce the speed. Example; If I play back in my camera I can see the slow motion effect. Same with the .mp4 that's created. So I bring that clip into PP and it automatically plays slow mo. Just wondering why the gopro files have to be reduced n speed? Does that make sence or am I really missing something?

Thanks!

Todd


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Al JensenRe: Gorpro Hero 4 Black, 120fps, CC 2014
by on Dec 20, 2014 at 4:11:04 am

(29.97 x 4) = 119.88

119.88 means that if you put it at 25% it would be exactly 29.97. That might be why it looks choppy on 23.976.



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Todd SchmidtRe: Gorpro Hero 4 Black, 120fps, CC 2014
by on Dec 20, 2014 at 2:15:02 pm

Thanks Al....I need a math lesson, lol! Gopro should really have a guide for converting.

Todd


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Jeff PuleraRe: Gorpro Hero 4 Black, 120fps, CC 2014
by on Dec 22, 2014 at 3:47:14 pm

Hi Todd,

From what I've read in the past, some cameras that offer "overcrank" will actually record one second of video as two seconds on the card so that the slow-motion does play back "automatically". In other words, maybe you record 60 frames per second, but it gets written to the card as two seconds of 30fps video.

With GoPro, one second is one second, but there are 120 frames in that second of video. Premiere is intelligent enough that if you put that 120fps video into a 30p or 60p sequence, the playback speed still seems normal... it just skips the "extra" frames. A 120p clip in a 30p sequence will just play every fourth frame, which should look no different than a clip actually recorded at 30p.

However, if you do a Speed Change, Premiere also has the intelligence to utilize the extra frames from the 120fps clip rather than interpolating frames (blending/repeating frames).

For instance, you have a 30p clip in a 30p sequence and apply 50% slow-mo, each frame gets played TWICE, so it looks a little choppy. But if you put a 60p clip in that same 30p sequence and apply 50%, Premiere takes two seconds to play one second of source clip, playing each frame once, so it should look silky smooth. You have 60 frames, and playing them at 30fps takes two seconds.

Your 119.88fps divided by 5 = 23.976, so to use ALL of the 120 frame per second for slow mo, you would use 20% slow motion (one-fifth speed) and one second of raw video will take 5 seconds to play back, using every frame. Of course, 24p always looks a little choppier because of the lower frame rate, so it may not provide results as smooth as 30p for instance. In a 30p sequence, you would use 25% speed to use all 120 frames, or 50% would use every other frame (60 of the 120 frames).

For the 23.976 sequence, stick with multiples of 20, like 40 or 60 for instance for best results. If my math is correct, 40% will use every other frame and should also provide smooth results. 60% would use every third frame, 80% every fourth frame.

Hope this all makes sense (and that I got it right!)

Thanks

Jeff Pulera
Safe Harbor Computers


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Todd SchmidtRe: Gorpro Hero 4 Black, 120fps, CC 2014
by on Dec 24, 2014 at 9:48:30 am

Thank you so much Jeff! That explained it so well, and simified it so I could actually understand it! I've become a custom to 23.976 comps because always shooting in that. Me still experimenting with the Gopro. Thanks so much!

Todd Schmidt
http://www.schmidt-VFX.com


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Tim KolbRe: Gorpro Hero 4 Black, 120fps, CC 2014
by on Dec 30, 2014 at 4:38:38 pm

...I'm going to go directly against the grain here and tell you that you were most correct to go to 'interpret footage' first.

1. Doing the math for the percentage speed control is rarely perfect and it's not nearly as smooth as just changing the framerate in the overcranked footage in 99% of cases I've encountered.

2. Every time you use the clip in the sequence you need to apply speed control on the timeline vs. adjusting the framerate interpretation once...in the bin.

I've done an awful lot of this type of thing and I've never had a situation where the speed control was as smooth as fundamental frame rate interpretation. It's one of Premiere Pro's lesser mentioned but truly time-saving features.

TimK,
Director, Consultant
Kolb Productions,

Adobe Certified Instructor


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Christian SeelRe: Gorpro Hero 4 Black, 120fps, CC 2014
by on Jan 13, 2015 at 2:32:58 am

I'm having this issue with the Hero4 Black, 1920x1080 footage shot at 120fps in PPCC2014. PP and AE show the clips in the project window as 59.94 and 119.88 frame rates respectively, so I know they were shot correctly.

When I put the 59.94 or 119.88 clips into the 23.98 timeline, they playback at normal speed - as if they were shot at 23.98. When I do a speed/duration control (20% for 119.88) it just multiplies the existing frames:

119.88 @ 100% = ABCD
119.88 @ 20% = AAAABBBBCCCCDDDD

I tried interpreting the footage in both PP and AE and it does the exact same thing.

Can someone help me with this?

_______________________________

Christian Seel
Photographer/DP
Los Angeles, CA
http://www.christianseelmedia.com


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Christian SeelRe: Gorpro Hero 4 Black, 120fps, CC 2014
by on Jan 13, 2015 at 3:35:46 pm

An update: I did solve this problem:

If you have the "low light" feature of the gopro on, it will not properly record the higher frame rate, despite the settings. Weird.


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Samad KhanRe: Gorpro Hero 4 Black, 120fps, CC 2014
by on Apr 30, 2015 at 2:55:45 pm

Thank you so much. That solved it for me as well.


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kit cummingsRe: Gorpro Hero 4 Black, 120fps, CC 2014
by on Jul 6, 2015 at 9:29:33 pm

thanks so much Christian, was going mad reading tutorials on older hero's that dont seem tom have this problem.... the low light setting is set ON as default when you buy the camera....it seems it manages frame rate to aid exposure regardless of your settings

will stop pulling hair out now!!

thx


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