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Understanding 1080-60i (1920×1080, 29.970 fps)
Hi – probably a dumb question here, but every time I think I start to get a handle on frame rates, aspect ratios, “i” vs “p” etc., something comes up that throws me off.
I’ve read a lot about rendering “1080-60i (1920×1080, 29.970 fps)” – but my question is this … is it “i” or “p” … is it 60 fps or 29.97 fps? How can it be both in the same settings?
Like I said – p’bly a dumb question … but ….
TIA!
KenM
Sound Works R&P -
14 Replies
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[Ken Matson] “I’ve read a lot about rendering “1080-60i (1920×1080, 29.970 fps)” – but my question is this … is it “i” or “p” … is it 60 fps or 29.97 fps? How can it be both in the same settings?”
Hi Ken, That’s not a dumb question at all. The only thing that’s dumb would be not asking the question and then making a mistake because of it. 😉
The confusion stems from the fact that our terminology is imprecise. 60i is short hand for 59.94i. People are too lazy to say 59.94i so they say 60i. This really means 59.94 interlaced fields per second where each frame is made up of two fields (odd and even). Since it takes two interlaced fields to make a frame, then 59.94i / 2 = 29.97 frames per second. This is how 60i = 29.97 fps. (one is expressed in “fields” while the other is expressed in “frames”)
The “p” stands for “progressive”. With p there is no interlacing and therefore are no fields, just frames. Unfortunately, we tend to allow our terminology to be imprecise again and 30p is short hand for 29.97 progressive frames per second. Likewise when people refer to 60p they really mean 59.94 progressive frames per second.
If all that wasn’t bad enough… some camera manufacturers sell cheap cameras (and sometimes more expensive still image cameras that also shoot video) that really do shoot 30.00fps! This is a blatant disregard for industry standards but what do they care? Unsuspecting consumers still buy the cameras and then have all sorts of ghosting problems when they try and render and play their 30.00fps footage on their 29.97fps TV.
So… it’s a confusing topic due to the imprecision that we use in our terminology. Feel free to ask more questions if this doesn’t clarify the subject for you.
~jr
http://www.johnrofrano.com
http://www.vasst.com -
> some camera manufacturers sell cheap cameras (and sometimes more expensive still image cameras that also shoot video) that really do shoot 30.00fps!
If I have 720-30p video taken with a point-n-shoot which actually is 30, how do I best convert it to 29.97?
Thanks.
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Use John Rofrano’s Fix30pMedia.cs script (this script changes the playback rate of 30p media to 29.97 and disable resampling), located at https://www.johnrofrano.com/vegasscripts.htm
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Thanks much!
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You’re welcome.
If it solves your problem, give a big thank you to John for the script. -
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John, you’ve forgotten more about Vegas than most of us will ever know so it’s you we thank wholeheartedly 🙂
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Thanks john – definitely clears it up quite a bit ….
THANKS!
KenM
Sound Works R&P -
Let’s say I have a bunch of clips
a. 720-30p (some are really 30, others 29.97)
b. 1080-24pI can use John’s handy script to fix the “bad” 30-ps.
Target will be 720-30p.
What is the best way to convert the 24p (items in b.) to 30p?
Thanks again.
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[Yuan Soong] “I can use John’s handy script to fix the “bad” 30-ps.”
Yes. It will only affect clips that are 30.00fps.
[Yuan Soong] “What is the best way to convert the 24p (items in b.) to 30p?”
I would simply have Vegas do it at render time. Vegas is very good with managing multiple frame rates in the same project. If you really want to convert the footage before you edit it, you can just render it out to 30p and then edit that footage.
~jr
http://www.johnrofrano.com
http://www.vasst.com
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