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Way basic question on 24p
I’ve wondered about this forever – so now I’m going to ask. When do you actually get to see 24p? I’ve been learning about 30i and 24p and so on and so on, but there’s much I don’t understand… For instance – broadcast NTSC is 30i (or maybe you call it 60i – I don’t know), anyway, 30 interlaced frames per second (or 60 fields). Is this a broadcast thing or an NTSC monitor thing? Is it possible to view 24 frames per second on an NTSC monitor – or is this something reserved only for the theatre and digital television? I’m way curious. Everybody’s squawking about the wonders of shooting their indies in 24, and I’m wondering – when I view something on DVD at home, am I even seeing the 24? Or has it been upcoverted to 30 at that point? What’s the point of taking great pains to shoot in something that “feels more like storytelling”, when it’s lost on everybody that doesn’t view it on the big screen. Sigh. I’m way confused…
If you just want to point me to some reading that would be fine.
Nick
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4 Replies
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You’re mostly right…at home you’re usually watching 24p converted to 30 frames per second (usually 60 fields, interlaced).
But you’re missing one very imortant fact: 24p converted to 60i looks NOTHING like something shot in 60i. This is the main reason why “Raiders of the Lost Ark” on network TV looks different than the local news that follows it. It’s also why most prime-time TV was shot on film (and still 24p if done digitally now).
Now that’s the “film-to-video” thing but it’s important to understand because the METHOD for converting 24 fps film to NTSC video is EXACTLY what the Panasonic DVX-100 does in its 24p mode. It takes 24 progressive images per second (just like film) and it does the conversion in-camera to 60i. So you get that LOOK that I mentioned before even though it’s really NTSC video.
Now, in 24pAdvance mode, the camera does something different. It turns the 24p images it takes into NTSC video, but in a different way. It doesn’t look good watching it back from the camera but it lets you put it into a computer and convert it back to 24p video.
So if you’re going to play it on an NTSC monitor, you’d use the normal mode, but if you were going to copy it to film you’d use the Advanced mode.
If this is just starting to make sense to you (if I’m explaining this halfway well at all) you should read this entire page to really understand:
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Advanced 24P is intended to be easily removed for subsequent editing in a 23.976 FPS timeline BEFORE it goes to film. If you try transferring Advanced 24P video straight to film, you’re heading for disaster.
====Given the self-ascribed beginner status of the questioner I was going for the simple explanation for what the modes meant…no so much a walkthrough of how to actually use them. Hopefully he’ll read the page I linked to and be able to put your comments into context.
Let us know if you have any more questions after reading that, Nick!
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Alright, thanks guys – this is starting to make a little bit of sense! I’ll read the link and see what else I can find and let my brain cogitate…
Nick
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Ok, the cogitation has produced a question… If an NTSC monitor only ever produces 30i images – how does one accurately preview footage on an external monitor when editing in 24p? Is it pulleddown (or “pulled-up”) on the fly? Or… Wait, wait, I think I may have this one… Since it’s 24p, you don’t monitor externally, since your computer monitor is progressive scan already, right? Or wrong?
Nick
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