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Jittery/Choppy Playback after Interpretation

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Nathan RiceJittery/Choppy Playback after Interpretation
by on Mar 15, 2013 at 9:39:24 am

Hello All!
I am having a small issue tonight. I have some footage that was shot in 60fps. specifically for use as slow motion. I was told to get the best result is to interpret footage inside AE and tell it to conform to 23.976fps. and then render out lossless. However after doing this I find that after I play back the footage in quicktime, Premiere Pro, or Final Cut that the footage is jittery and stutters a bit. Am I doing this right? The footage came from a Sony FS100, originally .MTS file. Any input will do! Thanks in advance...

Cheers,
Nathan


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Paul RoperRe: Jittery/Choppy Playback after Interpretation
by on Mar 15, 2013 at 10:17:16 am

It's possible that the jittery playback is a result of the speed of the drive(s) it's stored on. Lossless compression produces huge files compared to compressed formats, and you need very fast drive(s) to shove that amount of data through. If you're sure that drive speed is not the issue, open the movie and step through it frame by frame. If you find any duplicate frames (eg. in QuickTime or FCP you're pressing the right arrow on the keyboard, and you find you've pressed it and nothing changed) then yes, something odd has happened in After Effects. If on the other hand, each press is accompanied by the expected frame change, then it's the speed of your drives that's the issue.

You could, instead of using lossless, output from AE using one of the ProRes codecs. They generally play back OK, produce a smaller file and are so slightly compressed as to be unnoticeable.

Unless you're going to be outputting to tape, you could just 'live with' this stuttery playback in the knowledge that once you output your final compressed version, it should be fine. You could do a test, by compressing your stuttery movie into something like H264 and playing that back. If that plays fine, then you can be sure that your uncompressed version is fine. Then delete that H264 test version - you definitely don't want to be editing/compositing with that.

- Paul


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John CuevasRe: Jittery/Choppy Playback after Interpretation
by on Mar 15, 2013 at 11:44:01 am

FAQ: Why is my output file huge, and why doesn't it play back smoothly in a...

If you are using a lossless codec, it actually takes a pretty beefy machine to play video smoothly. Another codec you might consider using are the Avid DNxHD, great looking and pretty good playback.

Johnny Cuevas, Editor
Thinkck.com

"I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work."
---THOMAS EDISON on inventing the light bulb.


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Nathan RiceRe: Jittery/Choppy Playback after Interpretation
by on Mar 15, 2013 at 11:51:42 am

Thanks for the speedy replies. I am fairly certain its not the drive. I have played 100+GB lossless files before without a problem, and these are just little 10 sec. clips. No matter what I will be doing some tests later on today as you have suggested to make sure. I will post as soon as I find something out. Thanks.
-Nathan


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Dave LaRondeRe: Jittery/Choppy Playback after Interpretation
by on Mar 15, 2013 at 2:34:34 pm

You did the right thing by interpreting the 59.94 footage as 23.976. Did you also put the footage into 23.976 comp before you rendered?

If it was a 59.94 comp, it is the source of the problem.

Dave LaRonde
Former Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Darby EdelenRe: Jittery/Choppy Playback after Interpretation
by on Mar 15, 2013 at 3:52:41 pm

[Nathan Rice] "I have played 100+GB lossless files before without a problem, and these are just little 10 sec. clips."

The size of the file isn't a good indicator of playback performance. The data rate is more important. A 10 second 6GB file is more likely to stutter than a 3 minute 100GB file. In addition the data rate of the Animation codec can be variable within a single file as it uses run line encoding to compress data.

That mumbo jumbo aside you should trust the RAM preview in AE over the playback of the file in another application. If that's stuttering you might want to check for frame rate mismatches between the comp and the footage.

Darby Edelen


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