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Framerate conversions without encode

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Lewis Costin
Framerate conversions without encode
on Aug 22, 2013 at 7:38:23 am

Hi,

I'm just wondering if it's possible to change the framerate of a file (in my case a quicktime h.264) without reencoding the footage? I understand that the framerate is just a header, and I want to change it in such a way that will slow down the video (29.976 to 25).

On a mac I used to use Cinema Tools to "conform" a clip to a different framerate - and this is how I was able to change a 60fps video to 24fps, creating nice slow motion video instead of throwing away frames. On Windows, I haven't found a way of doing this that isn't a part of my editing suite.

Thanks.


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Jim Sustacek
Re: Framerate conversions without encode
on Aug 27, 2013 at 1:57:08 pm

This seems to be good advice, although I was unable to get it to work just now, but other people have reported success:

http://blog.grio.com/2012/01/fast-and-slow-motion-video-with-ffmpeg.html


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Paddy Uglow
Re: Framerate conversions without encode
on Aug 27, 2013 at 4:16:12 pm

If you're editing in Premiere, you can right-click the clip and choose "interpret" (or "modify" on newer versions) to choose what framerate you want to convert to (ie slowing down the clip). It will also slow and pitch down any audio, but it will keep all the frames.
I expect other "pro" editing apps will do the same, but I don't know the method.

In QuickTime Pro, you can export to an image stream at the native fps, then import the images at the slower rate of your choice. That'll do the same thing, but you'll lose the audio.

Good luck.
Paddy, creativemedia.org.uk


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Reuben Martin
Re: Framerate conversions without encode
on Sep 9, 2013 at 11:22:08 pm

It's more than just a header. Individual frames have timestamps. You can change it with the setpts video filter. You can also do it in MP4Box using the rescale option (not well documented).


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