Speeding up the footage from 24 fps to 30 fps and slowing from 24 fps to 18 fps

[julianm44443758]

I'm editing a feature film which was filmed mainly at 24 fps.   I have an action scene filmed at 24 fps which i would like to speed up to 30 fps to imitate a normal speed. I was told that if I will have this final movie in 24 fps (as I guess most distributors want...) , then all the clips converted to 30 fps will be converted back to 24 fps when i export the final product. So is there any realistic way to have the action scene in 30 fps although most of the rest of the movie would be in 24 fps ? if so, how ?

Second question : I have a drone footage shot at 24 fps where the drone moves forward too fast. Can I slow it down to for example 18 fps in post production ? Thank you.

[excited_Genie16B8 · Accepted solution]

I have an action scene filmed at 24 fps which i would like to speed up to 30 fps to imitate a normal speed.

Speeding up the footage won't imitate "normal speed".  It will provide the Keystone Cops effect, where the action moves faster than normal.

To see normal speed, don't change the frame rate.

To slow down the footage, you can change the frame rate.  Right click the lips and choose Modify>Interpret Footage...

[julianm44443758]

Hi Jim,

1. I  mean converting one 24 fps scene to 30 fps....if it works, doesn't 30 fps imitate closer to real life motion than 24 fps ? and then slowing down one drone footage down from 24 fps that was moving forward too fast.

Can the above me accomplished?

2. If not, I assume i would need to film the action scene again in 30 fps variable frame rate and drop it in the 24 fps timeline ?

[excited_Genie16B8]

24 fps will provide the best, most professional "look" to the project.  I recommend leaving it there.

The drone shots you can slow down as previously explained.  Use Optical Flow.

Optical flow time remapping | Premiere Pro CC | Adobe Creative Cloud - YouTube

[julianm44443758]

Jim thanks for your right to the point short efficient answers.

1. I have earlier sped up some footage up from 24 fps by using the speed/duration dialogue default frame sampling option and speeding it up about to 107% ( i assume this is increasing the framerate 7% ?) which looks ok, but do you mean that it will revert back to 100% once i export the entire film in 24 fps ? or it does still remain at 107 % but you don't like the look ?

2. And  i assume that speed/duration optical flow option does slow down the footage and it remains slowed out even finally after exporting in 24 fps the entire film ? and it does not slow down the clip by reducing frame rates but some other means ?

[excited_Genie16B8]

1. I mean the motion in those clips will be sped up, even after export.  That's not "normal speed".  Normal speed or motion only occurs when you shoot and display at the same frame rate.  Any change to frame rate will be abnormal motion, either sped up or slowed down.

Now if you want an altered motion look for an effect, that's fine.  I just don't want you believing that it's "normal".

2. Speed/Duration will change the speed of playback, even after export.  Optical Flow is one method for creating the effect, often better that the other two options (but not always).

[julianm44443758]

Very good.  I called last week Premiere Pro support ( i assume in India) twice and two different people claimed that if I change the speed/duration or frame rate of a 24 fps footage to 30 fps for example , and then finish/export the film in 24 fps as i assume most do , they claimed that all footage will revert back to 24 fps, which didn't make sense to me, because then what would be the purpose of changing frame rates if they revert back.

[excited_Genie16B8]

I think you're becoming confused here, so just to keep it very simple...

Don't change the frame rate.  Edit and export at 24 fps.

[julianm44443758]

I can't keep everything at 24 FPS because for example the drone shots were shot at 30fps which cannot be reshot . And another drone shot was shot at 24fps but the Drone was moving too fast I need to slow it down.  The third item which is optional for me speeding up a few other action scenes from 24 fps to 30 fps I could let go if it's not possible to do I guess

[eikonoklastes]

Like Jim said, edit and export at 24 FPS for the smoothest motion. For the most part, you shouldn't have to worry about the different frame rates. Drop the 30 FPS drone footage into your 24 FPS main sequence and just edit like normal, and then export at 24 FPS. Premiere will handle the conversion itself.

If, in the export, you find that the drone shots are unacceptably choppy, then you could look at doing a 30 FPS to 24 FPS conversion beforehand, but it really shouldn't be that bad.

About the drone shot at 24 FPS that's moving too fast, you can slow it down by using the Speed/Duration or Rate Stretch tool in Premiere.  Also, like Jim mentioned, for this speed change, you can use the Optical Flow method for the Time Interpolation.  This generally produces excellent results, but occasionally produces unacceptable visual artifacts, depending on the footage and amount of speed change. In this case, you can try one of the other two options: Frame Sampling or Frame Blending.

Be sure to render the clip when using Optical Flow as it is a processor-heavy effect and will generally not play in real time.

[julianm44443758]

1. ok so to sum this up, only if needed, to slow down or speed up the footage for the final product i can use speed/duration for those.

2. And if 30 fps to 24 fps conversion is needed beforehand, can i use again the speed/duration or some other means ?

[eikonoklastes]

1. Yes.

2. Your question is a bit vague. If you are asking if you can do a Speed/Duration on footage that has been converted from 30 to 24 FPS, then yes.

If you are asking if you need to use Speed/Duration to do a frame rate conversion, then the answer is a bit more complicated:

In the Project Panel, duplicate your source 30 FPS clip and then right-click > Modify > Interpret Footage as 24 FPS. This will alter the clip's duration (slowing it down). Place it on your 24 FPS timeline.

If you are ok with the longer duration (slower playback speed), then you do not need to take any further action. Edit away. Just be aware that you will get repeated frames as Premiere tries to fill out the extra time.

If you want to restore its original playback speed (and get rid of the repeated frames), then place the source clip with the original frame rate (that's why we duplicated earlier) on your timeline as a reference, and use the Rate Stretch tool to shrink your modified clip to the duration of the reference clip.

Alternatively, you don't need a duplicate as a reference if you note down the original timing of the clip, and then type in that value into the Speed/Duration dialog. Premiere doesn't let you copy the duration from the Interpret Footage dialog, so the reference clip method is more straightforward.

Try using Optical Flow if you feel the speed change is choppy.

Ideally you would want to use After Effects for the frame rate conversion as it gives you far more control over the Optical Flow effect, which allows you to selectively adjust problematic areas that might be producing artifacts.

[julianm44443758]

Good. I tried googling repeated frames to see but are repeated frames usually noticed by the mass audience while watching ?