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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Speeding up 50FPS slow motion footage to normal speed

Jamie Havill said:
Hi guys,

We shot some footage at 3K 50 or 60fps, but have decided we now want it normal (25fps) speed again.

Is there any way to do this?

Thank you,
Jamie.
Click to expand...

Yea... in your NLE, speed change the clips to 200%.
 
yeah. you commit to speed when you shoot speed with red, just like film.

you can try after effects or Twitxtor to remove the unwanted frames but it wont have the motion blur look of 24P with a 180 shutter. that would take some work.

david
 
David Battistella said:
yeah. you commit to speed when you shoot speed with red, just like film.

you can try after effects or Twitxtor to remove the unwanted frames but it wont have the motion blur look of 24P with a 180 shutter. that would take some work.

david
Click to expand...

Thanks David. I'm experimenting with Fluidmotion in Avid now, I'll try Twixtor as well. Wish we hadn't shot 50fps now... :(
 
Jamie Havill said:
Can't do that, when we do the clips look 'super' real, I think down to the fact slow motion clips are shot at 360 degree shutter.
Click to expand...

If the clips do in fact have "360 degree shutter" or an exposure of 1/50th @ 50 fps, you should have extra motion blur, which should persist in the look of the frames despite speeding them up. This would not be a super real look, but softer.

You probably have shot at 1/100 th of a second instead... which would be normal if you over cranked to 50 fps (based on a 180 deg virtual shutter), and that would give you that crisp frame look.

If you speed change your clips 200%, and then add back in motion blur (AE, FCP, Shake can all do this) by forcing the motion blur to double of what it is now, it should look very close to what normal 1/50 th exposure (25 fps) would look like.
 
Brandon Kraemer said:
If the clips do in fact have "360 degree shutter" or an exposure of 1/50th @ 50 fps, you should have extra motion blur, which should persist in the look of the frames despite speeding them up. This would not be a super real look, but softer.

You probably have shot at 1/100 th of a second instead... which would be normal if you over cranked to 50 fps (based on a 180 deg virtual shutter), and that would give you that crisp frame look.

If you speed change your clips 200%, and then add back in motion blur (AE, FCP, Shake can all do this) by forcing the motion blur to double of what it is now, it should look very close to what normal 1/50 th exposure (25 fps) would look like.
Click to expand...

Thanks Brandon, just trying this now...
 
Deal With This A Lot

Deal With This A Lot

We deal with this issue a lot shooting sports/adventure stuff, which is most of what we do. We speed up and slow down in post constantly, often shooting 50FPS as the "in between" rate, and at 1/100 shutter.

For us, using Twixtor Pro and tweaking the motion blur and other controls generally, with tweaking, can get footage sped up and not looking to saving private ryan-ish. Sometimes, we find other tools do better, but generally, Twixtor is your friend - you have to play around with the settings, render, look at it, tweak, render, play back, etc quite a bit until you get settings that work for the given clip. We usually try the basic built in FCP speed control with motion blur/frame averaging first to see if it works well enough as its a lot faster, but it only works with some types of footage.

We find that doubling the speed is about as far as you can go, same for slowing down. But as others notes, the shutter angle is critical - you can recover motion blur to a point only.

That said, we do it all the time for adventure sports and it works, but a bit of "stutter" is not as objectionable for that type of footage. With narrative work, people, and such its obviously trickier.
 
As an aside... I find that shutter angle is erroneous when working with cameras that do not have a true mechanical shutter. This includes the Red One. It might say it's at a certain shutter angle, but the meta data on the created .R3D file will tell a different story... so I recommend to disregard angle all together and just pay attention to shutter speed and frame rate because that is a true indication of motion blur.

And as Anson pointed out, you can add blur back in, but you can't really take it out once it's in.
 
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