Reassure Me Please!

Hi all:

Need an editor to help me wrap my head around this. I am shooting a PBS special with the AG-HPX170. I will not be editing this project. Am I correct in thinking that if I shoot in 1080 30p, this footage will cut okay with a lot of archival footage that has been telecine transferred to 1080 60i. They will using FCP 6.04, I believe. I know that normally it is a no-no to mix native progressive and interlaced footage on the same time line but isn't it also true that all DVCPRO HD 1080 rates are recorded in a 60i stream anyway? Am I correct in thinking that 1080, in DVCPRO HD terms is always 1080i, the camera just lays it down in that 1080i stream in different rates but the end result is always 1080 60i essentially? I normally shoot 720 24pN so I have not dealt with DVCPRO HD very much in the 1080 realm since up until recently I did not have enough P2 cards to deal with 1080 very often.

I shot the last PBS show for this client in 1080 60i. They were happy with the footage but for this show, it is a different subject and we will be using a lot of dolly and jib so I recommended that we shoot either 60i or if they like progressive better, 30p. In my experience 24p and 24pA have a bit too much strobing when I am flying the camera around on a jib a lot. They want progressive so am I okay in sending them off into their edit bay with 1080 30p to happily match up with their 1080 60i archival footage?

Thanks!

Dan Brockett

Remember, first, that "30p" means 30psf. And all that that implies.

Remember, second, that 30psf generally looks terrible on television. Your mileage may vary on this, but at the very least you must test-test-test-god-test before committing to a non-standard frame rate for broadcast.

Remember, third, that PBS has their own set of broadcast technical standards. These are defined in the Red Book. I don't remember off the top of my head whether 1080/30psf is a permitted delivery format.

As for your issues with 24, it sounds like you're simply moving the camera too fast. As you know already, I'm sure, there are two ranges of acceptable speed for moving the camera. If you move the camera relatively slowly ? as in a normal camera move, be it on a dolly or a crane or whatever ? everything's fine. Likewise, if you move the camera relatively quickly, as in a whip pan, everything's fine. But if you move the camera in that middle range, there's too much angular motion between frames, but not enough motion blur to hide it. You can get tables of angular speed per focal length in the ACS manual. You can also probably find something equivalent online. I bet there's even an app for that now. But the best thing to do is just to try it yourself. Put your camera on sticks and shoot a series of pans, from really-very-slow to break-the-tripod-fast. When you watch your footage back on a broadcast monitor you'll be able to see very clearly where the ranges of acceptable motion are.

Now, as to your underlying question itself ? technically you can cut 24p-with-pulldown and 30psf together. That is, they have the same timebase, so you can mix the material without having to interpolate. But artistically ? I'm gonna go ahead and say "no" here, with the implicit understanding that it's a matter of opinion. The motion quality of 30psf and 24p aren't similar. Cutting between them is very jarring, and isn't the sort of thing you can get away with in all situations. Whether it's acceptable or not depends on the circumstance, but in my opinion, it never works.

Hi Jeff:

Thanks for replying. I don't think I communicated my main concerns very well from my post, judging from your reply.

1. Are you positive that 30p means psf in the DVCPRO HD codec? This is from the AG-HPX170 specs from the manual:
Recording Format DVCPRO HD:
1080/60i (30p over 60i, 24p over 60i, 24pA over 60i)

2. Have already shot tests. 60i and 30p look best for the type and speed of jib arm moves the director wants to perform. 24p has too much stutter at the rates the director wants me to move the camera. These are intros mainly that begin on a theater marquee and arm down to reveal a talent walking into frame, so there is precise timing involved here for the camera to hit the marks and meet with the talent. So we are definitely shooting either 30p or 60i. I am very familiar with the ASC Manual pan and tilt rates, I began using those formulas back with the DVX100A, back in the day and before that with my S16 camera.

So my ultimate question is, if we shoot 1080 30p, will that footage work okay when intercutting between it and the archival 1080 60i footage that the producer has?

Will they be able to use easily and successfully use 1080 30p footage on a 1080 60i time line? Since the 1080 30p signal is recorded in a 1080 60i stream, technically, it should be one and the same to FCP. That was what I was looking for an editor to verify since I have never tried it myself. Perhaps I will shoot some footage today and just try it but I was posting to avoid having to do that since I don't have any 1080 60i archival footage here. I guess I can shoot some 1080 60i footage, then shoot some 1080 30p footage and then put them on the same time line and view the output with my Kona 3 and monitor. I was just trying to save time by posting here. I will post back with the results.

Thanks,

Dan

Tricky to explain, but when you do anything to match frame rates, aside from conforming the footage, the motion quality will always look different, so naturally you won't want to have a camera A on 24p with a pulldown and cam B on 30p together in a dialogue scene, as it'll look like a**. It really depends on the look you want.

You won't have a problem playing out 30p in a 60i stream, but you should check the specs with the station.



www.strypesinpost.com

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Are you positive that 30p means psf in the DVCPRO HD codec?

There is no such thing as "30p." When people say "30p" they really mean "30psf." I wrote up a big long thing on this a couple weeks ago; search the forum for it if you're interested in the technical details.

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I am very familiar with the ASC Manual pan and tilt rates

Didn't mean to imply that you weren't. It's just that if you need to move the camera too fast in order to catch the actor coming into shot, you need to move the actor's mark back. The director should understand this, but you never know.

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So my ultimate question is, if we shoot 1080 30p, will that footage work okay when intercutting between it and the archival 1080 60i footage that the producer has?

And my answer is emphatically no. But again ? I really can't emphasize this enough ? this is not a technical issue. It's an artistic issue. Gotta judge it by eyeball.

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Since the 1080 30p signal is recorded in a 1080 60i stream, technically, it should be one and the same to FCP.

Okay, this is really nitpicky, but I'm gonna say it anyway just for the record: there's no such thing as a 30p signal. The only difference between 30psf and 60i is the sensor read timing. (And, sometimes, some filtering that happens in-camera after demosaicing but before encoding.) As you correctly conclude, Final Cut won't care if you're feeding it 30psf or 60i, because there is literally no difference whatsoever downstream of the camera backplane. That's why 30psf and 60i can be intercut, but it's also why 30psf looks terrible on television.

Thanks for the discussion guys, I appreciate it. I agree, I have never personally favored 30p but the client specifically mentioned it. I copied some of your better soundbites to the client and I heartily recommended that we just be done with it and shoot 60i. We did our last PBS special in 60i, the archival material is all 60i, I think it will be better. We know it will work well and I will avoid any sort of strobing or stuttering on any jib arm moves.

Seems to be the only logical choice, given the situation.

Cheers,

Dan