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60fps Slow Motion and Real Time in 24fps Timeline

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Jon Shank60fps Slow Motion and Real Time in 24fps Timeline
by on Jan 22, 2016 at 12:50:29 pm
Last Edited By Jon Shank on Jan 22, 2016 at 12:50:52 pm

I recently shot a sports related video entirely in 60fps because I knew I wanted smooth slow motion but I only had one camera and couldn't switch back and forth between 60 and 24 frames per second.

However now that I've reached the editing stage I realize I don't want ONLY slow motion clips.

I will make a 24fps sequence and then interpret the slow motion clips at 24 fps for smooth slow motion.

But I also want some real time speed clips in my edit, so my question is what is the negative side effect of dropping 60fps into a 24fps timeline without interpreting it to slow motion?

Will it look stutter-y or something when I render it out?

PS: for my next projects, what is a better workflow as far as filming goes? Just shooting at 24 for real time and 60 for slow?

Thank you!


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Tero AhlforsRe: 60fps Slow Motion and Real Time in 24fps Timeline
by on Jan 22, 2016 at 1:06:18 pm

[Jon Shank] "But I also want some real time speed clips in my edit, so my question is what is the negative side effect of dropping 60fps into a 24fps timeline without interpreting it to slow motion?"

Premiere will automatically remove frames to keep the clip running the same duration.


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Jeff PuleraRe: 60fps Slow Motion and Real Time in 24fps Timeline
by on Jan 22, 2016 at 2:59:59 pm

Hi Jon,

Here's the issue with using a 24p sequence, which means your final output will be 24p - 24p is not going to be very smooth with fast action, fast camera movements/pans, etc., will all be jerky in "realtime" playback. I'd not recommend 24p for a sports video.

Why not use a 30p sequence, which will still get you perfect 50% slow motion, and at the same time the realtime 30p video playback will be somewhat smoother than 24p. It's a compromise.

When you drop 60p video into a 30p sequence, Premiere quite simply just plays every other frame. With 24p, it's a little more complicated since the math doesn't come out evenly, so extra frames get dropped in a certain rhythm or cadence.

Thanks

Jeff Pulera
Safe Harbor Computers


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Chris WrightRe: 60fps Slow Motion and Real Time in 24fps Timeline
by on Jan 22, 2016 at 4:01:07 pm

if you are curious, stretching the film inside a 24 seq. to speed 40% (without optical flow) will give 24p slomo without major jerkyness because the frames will play back 2:1.

you can have your cake and eat it too. I'd set the sequence for 60fps or 59.94 and just slow the individual clips down.
if you sequence out a 24, you'll never get 60fps smooth motion!
https://helpx.adobe.com/premiere-pro/how-to/premiere-pro-adjust-speed-cc.ht...


also, Premiere now natively supports optical flow as well!
https://helpx.adobe.com/premiere-pro/using/duration-speed.html


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Jon ShankRe: 60fps Slow Motion and Real Time in 24fps Timeline
by on Jan 22, 2016 at 5:59:00 pm

So are you saying I could have shot entirely in 24p and slowed it down to 40% in the 24p sequence?

Or shot in 60p like I did and slow it down in a 60p sequence?

(I have CS5.5 I don't have the money for CC at the moment)


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Jeff PuleraRe: 60fps Slow Motion and Real Time in 24fps Timeline
by on Jan 22, 2016 at 8:35:04 pm

Hi Jon,

The last thing you'd ever want to do is shoot sports/action at 24p. Ouch. Shooting 24p is best reserved for "film makers" that are going for that filmic look, then you have to alter the way you move the camera to minimize jerky shots.

If you shoot 60p and drop that clip into a 24p or 30p Sequence, you can apply 40% or 50% Speed respectively and get smooth slow-motion since you have enough extra frames from the 60p clip that no frames get duplicated. You don't need to interpret, just change speed on the clip and Premiere will handle it.

60p records 60 frames each second. Drop that 60p clip into a 30p sequence and only every other frame gets played back - only using 30 of the 60 available frames, so the one-second clip still plays in one-second. So you have enough material to play for two seconds if you use all 60 frames, so doing 50% slow provides smooth playback, playing all 60 frames over a two-second period, 30 frames per second.

For 24p you want 40% slow to use all frames smoothly (60 x 40% = 24). That would play 2.5 seconds for each second of 60p footage (60/24 = 2.5).

What the other poster may have meant is that 24p is jerky in general due to low frame rate, so even your slow-mo may look somewhat choppy when viewed at only 24fps, though the source was shot at 60p.

Thanks

Jeff Pulera
Safe Harbor Computers


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Jon ShankRe: 60fps Slow Motion and Real Time in 24fps Timeline
by on Jan 22, 2016 at 9:09:09 pm

Thank you so much


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therman mermehnRe: 60fps Slow Motion and Real Time in 24fps Timeline
by on Jan 24, 2016 at 3:57:41 pm

you can also take 60fps footage , drop it to 33.3% , then frame blend it to get smooth 1/3 speed rather than just 1/2 speed.


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Per HaarRe: 60fps Slow Motion and Real Time in 24fps Timeline
by on Sep 29, 2016 at 11:11:06 am

Hi,
I did the same thing!
My output sequence is 25fps (I'm living in Denmark so I shoot Pal 25/50fps) and I shot a concert in 50fps/180° shutter so my footage is very jerky when played back in real-time. I tried "frame blending" (right click on the clip and go to time) and that helped a bit. But I got my very best results by adding motion blur (I have Boris FX) but I'm sure After effects can do the same if you have access to that. When applied it looks just like 25fps and I can cut seamlessly between 50 & 25fps and still get slow motion when needed.

/Per :-)


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