Is 60i Video the Same as 30p Video?

Posted on by Larry

[ This article was first published in the September, 2010, issue of
Larry’s Monthly Final Cut Studio Newsletter. Click here to subscribe. ]

 

Chris Gibbs asks:

I’ve been a stills guy for over 20 years and understand that side implicitly, the film part is new to me and I have a question about SONY’s implementation of 60fps interlacing in some of their products?

I’ve been told that SONY uses the 60i format as a wrapper and that the file is actually a 30p (progressive) inside there, just ready to be extracted as 30p in FCP??????

My concern Larry is this, I’m shooting multi-media on the Canon 5Dmkll and want to augment my 5Dmkll stills AND video with footage from a small handycam like the Sony. But I’m concerned about mixing & matching the Sony 60i footage (whatever they actually are) with my Canon 5Dmkll 24p/30p frame rates in Final Cut Pro.

I do not want to make a lot of extra steps for myself by trying to mix this SONY 60fps interlaced with Canon’s progressive format if I can help it!

Larry replies: Chris, this is not, ah, completely true.

A 60i format shoots 60 fields a second, which get combined into 30 frames a second. Each frame consists of two fields, each 1/60th of a second apart. This time difference is what causes all the grief in dealing with interlaced images on the computer, which displays all images progressively.

Since before you were born, every program we have ever watched on standard definition TV is interlaced — it was part of the format invented back in the 1930’s. There is nothing inherently wrong with interlacing – UNTIL it gets displayed on a computer, at which point, it is a disaster.

So, while a frame consists of two fields all wrapped together, it is not progressive, since the two fields are shot 1/60th of a second apart. A true progressive frame is when all lines of the image are shot at the same time. Most Sony cameras, and all their low-end systems, do not shoot progressive — except, maybe, at 24 fps.

And, while I should never say never, you are going to have a great deal of problems matching images between your Canon 5D and the Sony Handy-cam. From colorimitry, to depth of field, to quality of lens, to image clarity, to compression ratios, to … oh, I don’t know, pick anything… these cameras won’t match.

Yes, you can get them to resemble each other – but how much time do you want to spend in editing?

The differences between these two cameras are so great, that progressive vs interlacing is the least of your problems.

My suggestion is to rent or borrow the Sony camera, shoot it, and see what you think. If you didn’t have the Canon, you’d probably like it – because it looks like what you think video looks like. After you see the Canon, you won’t.


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3 Responses to Is 60i Video the Same as 30p Video?

  1. Matt C says:

    So 60i may not but the same as 30p but it is the same as regular 30 frames per second (really 29.97) interlaced video right (since it has 60 fields)? I find this confusing? I’ve worked in pro-video for over a decade and everyone always referred to 30 fps interlaced video (60 fields) as just plain old “30 fps”. I don’t mind if the industry wants to start labeling things by true actual “time samples” , like saying 60i (or 60 half frames) and 30p (or 30 FULL FRAMES) but as it is now I am hearing a lot of inconsistencies, for example sometimes I hear people refer to 60i as 60 frames per second?

  2. Donald Cherry says:

    I finally figured out how to get final cut pro x to recognize my Canon’s 30 fps “recorded as 60i” as truly 30 fps progressive. Have to use ClipWrap. Thing is, I will also be using a Sony that can only do 60i and 24 fps. Two questions: Is it a problem to mix 60i and 30 fps progressive in the same multicam clip? And two, is there a way to convert the Sony 60i to 30 fps? (I’ll try the ClipWrap procedure, but if you know another way . . . )

  3. Donald Cherry says:

    Sorry. Just checked, and the Sony can do 60p and 24p. So not 60i, but 60p. Hmm. Now I’ve confused myself. When I import the Sony into final cut pro x, I’m pretty sure it comes in as 30 fps interlaced.

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