Let's say I have a 30fps video created by a camera panning at a constant speed while filming some static scenery.
If I watch the video, the motion in the video is perfectly smooth. If I double the speed, the motion continues to be perfectly smooth. If I half the speed, the video looks choppy but again the motion continues to look smooth.
The problem comes when I try to change the speed by irregular numbers. Let's say I want to change the speed of the video to 120%. I then export the video at 30 FPS. The motion in the video then becomes visually choppy, jerky.
I quickly figured out what is happening: by increasing the speed, my 30 FPS video becomes 30*1.2=36FPS. But I am exporting at the standard 30FPS so every 6th frame is dropped. This means that every 5 frames the camera moves at double speed. If I look at the motion frame by frame the camera movement is: slow, slow, slow, slow, FAST, slow, slow, slow, slow, FAST, slow, slow, slow, slow, FAST, etc.
So finally my question is what option do I have to get smooth motion or hide this problem when changing the the speed of the video by small intervals?
Shooting at a higher shutter speed is not an option in my opinion, as it just blurs the motion until the problem is not visible.
I use Adobe Premiere and Adobe After Effects. Will the Time Warp plugin in After Effects be able to create smooth motion by using motion vectors? What if there is active movement in the scene? will it still look good?
I have yet to see people truly understand this problem. How is this effect called? Does anyone have any link or article explaining what I described?