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Old October 14th, 2010, 11:50 AM   #1
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Editing mixed frame rates Question

Hi all,

I am starting a project with footage that I took for my child and they are from various camera/camcorders. The format are as follow:

-720x480 at 29.97fps (taken from a mini-dv)
-320x240 at 30fps (clips from a digital camera)

Majority of my footage are from mini-dv and I never had this problem since I would just edit straight 29.97 timeline. However, I recently got a canon 60d and I am just loving to shoot at 1080p at 24fps.

I read a really good article about converting frame rates:
Converting Frame Rates in Compressor

Now, I am not sure what I should do. Should I bother shooting 1080p at 24fps knowing I have to convert to 29.97 for editing or should I just shoot 1080p at 30fps?

Any pointers appreciated!
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Old October 14th, 2010, 05:14 PM   #2
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The first question needing an answer is what editing software are you using? I know that Premier Pro can mix frame rates. You just need to apply a pulldown or reverse pulldown depending upon which frame rate you end up using. It seems like you're using Compressor for part of your process so I'll assume that you'll use some flavor of FC. Can't comment on that since I've never used it.

If most of your footage is 29.97/30 and it's going to DVD, stick with 29.97. Keep in mind the only difference between 29.97 and 30 fps is the drop frame time code. They both run at 30fps.

24fps can be very pretty and if you like it, stay with it. It might not always be your best choice for each shooting situation but it will give you a place to start getting used to some of the things you'll deal with shooting at that frame rate.

One final thing. To me, it's easier to make 29.97 look like 24 than the reverse, but that may be totally subjective. I've learned that it's easier to take away stuff from video (like frames, or more accurately fields in this example) than it is to replace what's missing.

Hope that helps.
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Old October 15th, 2010, 03:49 PM   #3
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Final Cut Pro also works with various framerates and even SD/HD/720/1080 in the same timeline in real time. I personally feel that 30FPS cut down to 24FPS can look jerky in FCP. I shoot exclusively in 24FPS and sometime have to add older footage shot by someone else, or use smaller lipstick cam footage in 30FPS. The stuff just seems to chatter a little bit to me. But I would rather the inflight/in car/etc footage be a little choppy and the other 90% of my shoot at 24FPS look so much nicer.
Jim Ross, Cinematographer
CinematixHD www.Cinematixhd.com
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Old October 17th, 2010, 10:32 PM   #4
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The real downside of 24p is it is not in the DVD spec., only 29.97i so any frame rate conversion will look choppy. Although talking heads look great, pans and horizontal movement is also a problem for 24p.

Unless you're going to BD or the web, 30p is the best choice currently for progressive DVD.
Rusty Rogers | Films
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Old October 20th, 2010, 05:18 PM   #5
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To convert 24p to 29.97i you can apply a 3:2 pull-down - this basically splits the 24p frames into fields and duplicates/sequences them in such a way that that you end up with 60 fields per second. It's not choppy at all, and is the same method when distributing feature films (shot at 24p) on DVD or when broadcasting them on TV. It's imperceptible for most viewers

You could either do this with all your raw footage and edit on a 60i timeline, or you could edit on a 24p timeline then do the conversion to the rendered file.

The biggest issue with mixing frames rates is dropped & blended frames. These are often very noticible, and even though many software now allows multiple frame rates on the timeline, the results can be varied. Often re-conforming your footage (this is not the same as transcoding or converting) is a quick and easy way to deal with frame rate problems. What you'd need to to is conform your 30p footage to 29.97p before you drop it on the timeline - basically you are telling the software to only play back 29.97 frames every second instead of 30 - resulting in a very slight time shift, but pefectly clean footage with no dropped or blended frames. The bigger the difference between the frame rates, the more speed change there will be - so you could change 25p to 24p with much better results than 25p to 30p.
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