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59.94 FPS slowed to 66.6% – frame “ghosting”
I am working in the old FCP with footage from a Canon 60D that was shot at 59.94 FPS. It’s for a music video that’s supposed to be in Slow Motion. The speed of the footage is supposed to be 66.6% – a weird number because the music was sped up to 150% of it’s original speed – but when I slow it to 66.6% I’m getting constant “ghost” frames.
I’m wondering a few things:
1. Did I screw up with confining my footage to 66% speed? I’m looking around at other tutorials and when testing the slow mo effect people seem to slow to 50% or 25% speeds.
2. What frame rate should my sequence be at? I thought if it was 29.97 each “original” frame would show for 2 frames, in other words moving the footage forward with the direction arrows would take twice as long, or take two presses to skip each frame. I think I figured that out though – that would only work if the video is slowed down to a clean 50%, right?
3. Can I fix this through motion blending? I get the impression that I can based on an old thread (https://forums.creativecow.net/thread/280/3201) but I’m not sure if I should reoutput the clips in AE with at 29.97 with frame blending (as suggested by Richard Harrington) or if there’s something I can do in FCP to correct this.
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6 Replies
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The files that were shot 59.94 can be changed to 29.97 in Cinema Tools which just makes it play at that frame rate so half speed. 66% is not right.
Cinema Tools changes the file permanently so if you need to keep a copy of the file at original frame rate then you should make a copy first. You can also change the file in Compressor to make a file that plays at 29.97. All neater than using speed changes in FCP particularly if you send to Color to grade as Color doesn’t like varisped footage. Better to have pre baked the speed.
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23.98 is slightly slower than 50%. My math sucks…so I don’t know if that is 66% or not…
Shane
Little Frog Post
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If you wanted to run the music at 1.5x speed and shoot fast so as to play back music at 100% with audio in sync, you needed to shot at 36fps if playback was intended for 24fps, or at 90fps if playback was intended at 60fps, or even 45fps if playback was intended at 30fps… None of those numbers fit what you shot. To shoot off speed music sync like you seemed to intend the audio playback speed shouldnt be 150%, it should have been either 250% if the intended frame rate was 24fps and the acquisition rate was 60fps. Or just 200% if the intended framerate was 30.
Bottom line is, best quality solution is to reshoot, alternatively use a motion compensated slowmo effect, such as pixel motion in ae or Optical flow in motion/fcpx or twixtor or the like, can’t guarantee good results as the effect is dependent on content. Any quick slowmo is going to either blend frames (what you are calling ghosting is frame blending meant to smooth the motion) or stutter. I’d strongly recommend reshooting, if you do the math right you’ll get a really nice looking effect.
Colorist | Online Editor | Post Super | VFX Artist | BD Author
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Thanks a lot Juan and co. You’re all right that slowing through frame rate won’t work because I did the math wrong. But I really appreciate the explanation on frame rates.
I’d really like to avoid reshooting so I will attempt the “Pixel Motion” effect in AE like Juan suggests. That’s different than the “Frame Blending” effect Richard Harrington suggested in the thread I originally linked to, correct?
https://forums.creativecow.net/thread/280/3201
Because Juan, you’re saying “Frame Blending” is actually the problem here, not the solution. “Frame Blending” is what is causing the “ghosting” – or double, slightly transparent images in each frame – and the “Pixel Motion” filter (or Optical flow in motion/fcpx) will for lack of better word unblend the frames, correct?
I understand this will likely produce a lower quality result than reshooting with the proper frame rates/music speed ratio, but I’ll try it out tomorrow and keep the thread posted.
Thanks again!
https://vimeo.com/nickhennessey
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Just in case anyone references this: the Pixel Motion effect in AE looks good in some instances but looks pretty bad a lot of the time too. Similar to the pixel bunching you see in this example: https://jonscottsupport.com/2012/02/15/super-slow-motion-in-for-adobe-after-effects-using-pixel-motion/
What looks by far the worst is just slowing the clips down in FCP. The best result seems to be slowing down in Premiere without any effects to get around the “ghosting” I previously experienced. The motion is actually really smooth by itself in Premiere.
https://vimeo.com/nickhennessey
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