Is there a universal frame rate?

M

mpgxsvcd

Veteran
Let’s say you had captured some footage at 1080i with 50 Fields per second so it would display better when directly connected to a TV. Then I recorded some footage at 24p because I wanted the film look. Then I recorded some at 720p @ 50 Frames per second to use as slow motion video later. And finally I recorded some MJPEG 720p @ 30 FPS footage because I wanted to prevent compression artifacts in that particular clip.

What frame rate would you render to if you had to render a single file from all of the formats above? I know most people will just say don’t record in multiple frame rates. However, I was wondering if there is a single frame rate that would work with all of them?

I am sure 120 FPS would work because it is at least twice even the highest frame rate of the source footage. However, there is nothing that can really handle 1080p @ 120 FPS video right now. Therefore, is 1080p @ 60 FPS your best choice?

What would happen on streaming sites like youtube or Vimeo? Would they mess up the 24, 25, or 50 Frames per second video when they rendered it back to 30 FPS? Should you render to exactly 60 Frames per second or would 59.94 be a better choice?

I did a little test and rendered together all of the sample videos that are available right now from the GH2. I tried 30 FPS and 23.987 FPS as an output frame rate. The 30 FPS looked good from everything except for 1080i @ 50 fields per second footage and the 720p @ 50 frames per second footage no longer had that smooth video look. However, it didn’t seem to stutter for any of the segments either.

Then I tried 23.987 frames per second as an output file. The 23.987 footage looked perfect of course but the 1080i @ 50 Fields per second footage looked terrible and the 50 frames per second and 30 frames per second footage was not much better.

I don’t have a computer with me right now that can render 1080p @ 60 Frame per second footage in a reasonable time. Later tonight I will try that. Should a true 60 frames per second progressive file be able to render PAL footage appropriately? What about the 24p footage. Should that work without being telecined into a 1080i file?
 
If it's done properly, 24p can look very nice regardless... this is how films are done. That overcrank at 120fps or faster for slow-mo, etc. Still looks very nice at 24p.
 
mpgxsvcd said:
Let’s say you had captured some footage at 1080i with 50 Fields per second so it would display better when directly connected to a TV. Then I recorded some footage at 24p because I wanted the film look. Then I recorded some at 720p @ 50 Frames per second to use as slow motion video later. And finally I recorded some MJPEG 720p @ 30 FPS footage...
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I think the odd man out is actually the 1080i50 footage. What I'd do is interpret it as 540p50 footage and resample the frame size from 1920x540 into 1280x720. (Needs to be done with a fix to the vertical jitter.) Now all your footage is progressive and most of it is 1280x720. Since you're working in PAL territory, I'd convert the 30p footage into 50p via frame doubling. For the 24p, I'd conform it to 720p25, resample the audio to sync, and double it to 50p as well.
 
If you do it right, you can really get any frame rate to end up looking good with any other (as ipowell was suggesting). The key is to know exactly how to transcode each frame rate to the target frame rate, and to transcode in a program that can resample/deinterlace/pulldown well. I've done various frame rate conversion tests and the best transcoding method I've found is to put it in an After Effects composition, set the composition to the target frame rate, and render. What software are you using?
 
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