60p 60 fps 30p 30 fps 60i???

mystico

mystico

Well-known member
Please explain the differences and relationships among 30p, 30 fps, 60p, 60 fps and 60i. I may be using different terms for the same concept here, but ... as example is 30p the same as 30 fps? Some literature defines fps as fields per second, while others define it as frames per second. Quite confusing for the newbie!

Thanks for any help ...
 
it's confusing because the whole state of affairs when it comes to frames, fields, and other temporal measurments in American Broadcast are in a rapid state of transition right now. Typically, if someone writes 60i, they mean sixty fields per second, which would be the same as 30fps, which would mean 30 frames per second. fps always stands for frames, not fields. But if you see an "i" after something, that generally means they are talking about interlaced fields. "p", which stands for progressive, is the easiest to understand. 24p means 24 progressive frames per second, 60p would mean sixty progressive frames per second. 60 frames per second would be used for overcranking (for slow motion) shots.

And, to top off all of that, 24p is really 23.98 30 CAN be 29.97 or it CAN be 30, depending on wether it's a film project or not.

The best thing to do is familiarize yourself with what all of the abbreivations mean, so you can have a strong vernacular, then make sure to ALWAYS ask your post house, editor, telecine operator, whatever to clarify what they mean.

To be honest, we all use a lot of shorthand here, and at times we can mean different things. I work at a big post facility at a big film school, and, even though they have done countless projects here, things are ALWAYS wrong, exactly because of these confusions.
 
Thanks for the explanation. I'm a bit too tired to really think about this and really let it sink in, but somehow your explanation makes lots of sense to me. My confusion started while reading forums here. It deepened when I got my DVC60, and the explanation in its manual for setting FRAME vs FIELD shooting is the following: "The camera-recorder normally shoots scenes using field recording (60 fields per second)." Then later ... "when FRAME has been selected ... scenes can be shot using frame recording (30 frames per second)." From your explanation, the cam normally shoots in 60i but this is the same as 30fps. So the DVC60's FRAME and FIELD recording are the same?


I sort of understood the matter after reading the following.
http://www.dvxuser.com/articles/framerates/

And you explanation makes sense overall, but doesn't seem to go with the manual's explanation of FRAME vs FIELD recording. Then again, I'm tired. I'll revisit this tomorrow. Thanks again though ...
 
One quick (though slightly off) way to think about it is this ...

- 60i is 60 interlaced fields
- 2 interlaced fields combine to make one complete frame (each field is only half of the picture in the frame - say 1 field is the grayscale and the other is the color data)
- Therefore, 60i equals 30 fps (frames per second)

If choosing between 60i and 30p (same fps), and you are just starting out, I would go with the 30p setting. You may (depending on your NLE) experience sync problems in post using interlaced footage. If you DO shoot 60i, make sure your NLE interprets the footage correctly as interlaced footage, else your screen will show you an odd offset blur between both fields that make up a frame.

Hope this didn't just add more confusion ;)
 
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