Speeding up 23.976fps footage (rule of thumb) ?

[mr.jipi_]

I’m working with a single drone shot of 3 min, shot in 24 fps. The shot is smooth and looks great in real time, but I need to speed up portions of it.

I thought this was going to be simple … but it’s not. When I speed up the footage, it doesn’t look good any more. It’s kind of jerky, like if it was skipping frames.

When I speed it up 200%, or 400% the footage, it’s OK, but anything in-between is far from perfect. Like 150% of the speed seems to be skipping frames.

Even if I could work with 200%, the speed ramping to get there look choppy in-between.

I have cache, rendered and exported the clips to make sure this was not an hardware issue. Is there some kind of math rules I should follow to make sure everything is as smooth as possible?

I have tried with Media Composer, Resolve and Premiere and I’m having the same result. Any thought?

 

[Thomas B]

You’ve answered you question. Stay with whole integer increases in speed.
The only app I have tried that is tolerant ( ie, Renders fractional frame rate changes is iMovie where You can just drag the timeline end to compress... of course the segments I change must first be cropped out to isolate the segment to be speeded up.
Others may chime in with other ideas..

 

[RadioFlyerMan]

I’m working with a single drone shot of 3 min, shot in 24 fps. The shot is smooth and looks great in real time, but I need to speed up portions of it.

I thought this was going to be simple … but it’s not. When I speed up the footage, it doesn’t look good any more. It’s kind of jerky, like if it was skipping frames.

When I speed it up 200%, or 400% the footage, it’s OK, but anything in-between is far from perfect. Like 150% of the speed seems to be skipping frames.

Even if I could work with 200%, the speed ramping to get there look choppy in-between.

I have cache, rendered and exported the clips to make sure this was not an hardware issue. Is there some kind of math rules I should follow to make sure everything is as smooth as possible?

I have tried with Media Composer, Resolve and Premiere and I’m having the same result. Any thought?

Are you using FCPX? Try frame blending. Or optical flow.

 

[Aerial-Pixel]

I’m working with a single drone shot of 3 min, shot in 24 fps. The shot is smooth and looks great in real time, but I need to speed up portions of it.

I thought this was going to be simple … but it’s not. When I speed up the footage, it doesn’t look good any more. It’s kind of jerky, like if it was skipping frames.

When I speed it up 200%, or 400% the footage, it’s OK, but anything in-between is far from perfect. Like 150% of the speed seems to be skipping frames.

Even if I could work with 200%, the speed ramping to get there look choppy in-between.

I have cache, rendered and exported the clips to make sure this was not an hardware issue. Is there some kind of math rules I should follow to make sure everything is as smooth as possible?

I have tried with Media Composer, Resolve and Premiere and I’m having the same result. Any thought?

Try to stick with even multipliers 2X's (200%) will drop out half the frames, 4x's (400%) will drop 75% of the frames. Doing uneven multipliers tends to get a little choppy as uneven frames will have to be removed from the video. Hope that makes sense. Many editing softwares will try to smooth it out the best it can though.

 

[Thomas B]

Experiment around.,, you’ll find an app or two that become your “go to”.

 

[Malcx]

A pretty simple way to understand it - if you have a very short video that is running at 4 fps.

1 | 2 | 3 | 4

Play at normal speed shows frames 1,2,3,4
Play at 200% shows frames 1,3
To play at 150% we need to show just 3 frames, so probably 1,2,4. That is obviously going to look a bit choppy as there will be a jarring step in motion between frames 2 and 4.

You need software that interpolates and would show something like frames 1, (2+3)/2 , 4 to look good at 150% speed.

So what are you using to do your editing? In premier you can look into "optical flow" I think for this

 

[mr.jipi_]

So what are you using to do your editing? In premier you can look into "optical flow" I think for this

Yes so far DaVinci Resolve with Optical Flow seems to deliver the best results. I never really had to stick to even multipliers before... But the frame drops are obvious on one smooth long drone shot.

 

[Dave Maine]

The speed function works ok on FCPX if you use either frame blending or optical flow under the quality settings. Be forewarned that optical flow thpakes a very long time to produce it’s results, as it renders the entire clip, even if you are using a small part of it.

 

[apeel]

Yes so far DaVinci Resolve with Optical Flow seems to deliver the best results.

This dialog is helpful. I have had choppy video when speeding up, and the even multiplier explanation makes a lot of sense (duh!). Regarding the optical Flow feature in Davinci Resole, I assume this is available in the free version? Also, does it basically do the frame interpolation that is discussed above?

 

[Dave Maine]

If it is like FCPX, it is better than frame blending. It builds an extrapolated path for each pixel location, and uses that to create the new frames. Sometimes it is a lot better than frame blending, and sometimes there is no observable difference.

There is a huge difference in the time it takes to calculate, however. I will do a frame blend first, and if I really really don’t like the result, will spend the time on an optical flow version.