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There is a 60 FPS video clip, with 1 Second total duration (So it has 60 frames, each 1/60s duration)

I make it 2× faster. So it's has a 0.5s total duration. How about frames?

How many frames are in my 0.5s video? 60 frames each 1/120s, or 30 each 1/60s?

In a tutorial the author says: "I recorded those images at 60 frames a second and time remapped the video to about 2-3x getting about 120-180 frames to work with."

I just wonder if speeding up (in this case time remapping) the video clip for 2x will result in removal of half of the frames, how the tutorial is saying it give you 120 frames to work with?

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In the simplest case, half the frames -- every second frame, or all the even (or odd) numbered original frames -- are just gone, discarded. The frame rate of the resulting video does not change, it's still 60 fps.

It's possible to create a video where each new frame is a blend of two original frames but this is unusual and often not effective. Or in a field-based system where each original frame is composed of two distinct half vertical resolution images, you can discard half the fields instead of half the frames. But still, the result will be 60 fps.

If you were working in a 60 fps environment and imported a 30 fps clip, you could effectively double the frame rate of the original clip, but that isn't what you asked about.

  • Please checkout the edit I made to my question – Farzad Jun 27 '15 at 17:26
  • @Farzad - If you get 180 frames from 60 frames, you're not speeding up, you're slowing down. "Time remapping" works both ways. A utility like Twixtor ( revisionfx.com/products/twixtor ) can create new "in between" frames using motion estimation when you slow down your video. – Jim Mack Jun 27 '15 at 18:31
  • Take a look please: filmmakeriq.com/lessons/… "The slowness of the move has been sped up using After Effects’ Time remapping tool. The purpose of this is to give us as many frames to work with" – Farzad Jun 27 '15 at 18:46
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    You're misreading. What the author is saying is that the deliberate slowness of his original motion gives him more frames to work with. – Jim Mack Jun 27 '15 at 20:58
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When a 60 fps clip is sped up or slowed down, the frames are skipped or duplicated accordingly. For example if we speed up a 3 second video which has (3x60frames) 180 frames, the frames are dropped according to the speed up ratio. To be more clear, if you speed up your clip from 100% to 150%, the frames will be reduced by skipping automatically, giving a feeling that the clip is running faster now.

When we slow down a clip from 100% to lower than 100%, lets say 50%, the frames are duplicated at a specific interval to give a feeling that the clip is slower. To be more clear, if a 180frame 3sec video is slowed down to 50%, now it will have 360frames for 6sec.

No editing software has the magic power to create a new frame out of thin air. It can either drop frames or duplicate them.

  • either drop frames or duplicate them or interpolate. – Gyan Mar 12 at 14:03
  • No. There are techniques which create additional images. PRemiere Pro offers 2 besides Dropping/Duplicating Frames – Timothy Lukas H. Mar 12 at 15:33

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