720 60p or 720 24p

[Mike Schrengohst]

What do you need to deliver?
Of course you know shooting 720 60p will only give you 4 min on a 4 gig P2 card.

Shooting 720 24pN will yield 10 min on a 4 gig P2 card.

[Barry Green]

If you shot in 720/24p mode (“over 60”) and used the frame rate converter to extract the frames, then yes the results would be identical to 720/24pN mode.

If you shot in 720/60p mode (at 60fps) and then tried to smush those frames and convert them to a simulated 24p, then no, that won’t compare well at all to 720/24pN mode.

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[Lars Wikstrom]

When you say 24p ‘over 60’ do you mean shooting in the 24p mode that when you import into FCP it say 59.something? I understand 24pn is only the 24 frame capture. Shooting standard 24p it still captures 60 FPS but flags 24 of those frames per second? So if I shot something at 60 and convert to 24p will it flag those frames? I would think that this would convert the 60 to 24.

I’m lookign at blending 2 projects that I am working on together that were shot at 24p and 60p.

That is what is confusing me.

-Lars

[Barry Green]

[doka15] “When you say 24p ‘over 60’ do you mean shooting in the 24p mode that when you import into FCP it say 59.something?

Yes, the mode that records 60fps at all times but only images 24 distinct frames (and flags those distinct/unique frames). This is the mode that works the same as the VariCam does.

Shooting standard 24p it still captures 60 FPS but flags 24 of those frames per second?

Well, no, not exactly. Let’s clarify that: it captures 24 frames per second, and flags those, but it RECORDS 60. So it’s genuine 24p progressive capture, one frame 23.976 times per second, at 1/23.976-sec intervals. But when it gets recorded, it gets recorded into a 60p data stream. So the native frames are flagged, and then duplicate frames are added to pad out the sequence.

So if I shot something at 60 and convert to 24p will it flag those frames?

There’s room for confusion here that I’d like to eliminate. If you shoot at 60fps, you’ll have 60 distinct frames per second. “converting” that to 24p will result in a frame-blended mishmash of ugly simulated 24fps.

But, if you shoot at 24fps (even if it’s recorded into a 60fps data stream) and then strip out those duplicate frames (resulting in leaving only the 24 original fps) then you’ll have what you were after. And that’s how the 720/24p mode works.

In other words, if you want the 24p look, don’t shoot 720/60p. Shoot 720/24p or, if you want only the native frames, shoot 720/24pN. If you shoot 720/24p it will image only 24fps, and embed those 24 frames within a 60fps data stream.

—————–
Get the most from your DVX camera. The DVX Book and DVX DVD are now available on ebay and at Amazon (https://www.fiftv.com/db)

[Lars Wikstrom]

Berry, I think I understand. The camera Shoots at 60 fps all the time. If I select 24p then it records at 60 but flags those frames giving me 24p (Not PN I understand that) So when I bring the footage into FCP all the extra frames are still there since it is within the 60 FPS stream, but it is only showing me the flagged frames for 24p, right?

What I can’t wrap my head around yet is why if I import a 60 fps stream and have FCP convert that to 24 it will be mushy and not the same thing as shooting in 24p. There are still 60 frames per Second. Why can’t FCP pull 24 of those 60 frames giving me the same results as shooting 24p in the first place? In other words flag those frames in post instead of on capture since all 60 frames are still there. That is what I am having a hard time understanding.

I am thankful for your help when I am trying to figure out why it is this way.

-Lars

[Frank Nolan]

[doka15] “What I can’t wrap my head around yet is why if I import a 60 fps stream and have FCP convert that to 24 it will be mushy and not the same thing as shooting in 24p. There are still 60 frames per Second. Why can’t FCP pull 24 of those 60 frames giving me the same results as shooting 24p in the first place? In other words flag those frames in post instead of on capture since all 60 frames are still there. That is what I am having a hard time understanding.”

In Post how would FCP know which 24 frames of the 60 to pull as you have 60 distinct frames? I’m sure someone will correct me if I’m wrong but when you shoot 24p it flags those 24 frames in the 60 stream and just pads out the remaining 36 with duplicates, so in post it just gets rid of those.

[Jeremy Garchow]

That’s pretty much it, Frank. The 720p60 scheme was setup for the Varicam so that you could pull out those 24 distinct flagged frames out of the 60p stream since it was not possible to record 24p Native to tape. The SMPTE spec requires 720p60, there’s really no 720p24 according to SMPTE. The HVX works in the same way with the firestore as the 720p24 data stream is wrapped in a 60p cadence out of the firewire port. You then have to remove the extra frames upon import of FCP. It’s kind of like shooting 24p advanced on a DVX100. The 24p frames are recorded to a 60i stream down to tape. You can then remove the advanced pulldown frame upon ingest into FCP leaving you with 24 distinct progressive frames. The same applies to the HVX. Click the option to remove the redundant frames and you will be left with 24p media and will work in a 24p sequence. If you don’t do this you will work in a 60p timeline, but still retain the 24p look.

If you are working in 720p24 out of a capture card or firewire out of FCP, you are actually watching a 720p60 stream. FCP adds in the redundant frames automatically. The advantage to working in 720p60 is that some people like to work with exactly what they are going lay back down to tape, especially for broadcast. You can still retain the 24p look, but there’ll be no surprises with pulldown and the timecode will match exactly back to the DVCPRO HD tape.

Hope that helps.

Jeremy

[Lars Wikstrom]

[JeremyG] “If you don’t do this you will work in a 60p timeline, but still retain the 24p look.”

This is what I was talking about. I am editing in a 60p timeline even though I shot the footage at 24p because of the 24 frames that comes from the 60 frames the camera shoots. Just so I am not confusing myself even more, the camera flags the frames for 24p and 24pn or just 24pn? Is the camera always recording at 60p even though it captures 24pn and saves those flaged frames to the P2 card?

Since almost all of my work is going back to tape I shoot 24p not pn and I still retain the 24p look in the 60fps timeline. When I play the timeline or frame by frame is the timeline skiping frames to show me only 24 frames per second from the 60 fps clip? an example would be frame 1,3,5,8,10,12,14,17-> even though the true frames captured on the clip are; 1,2,3,4,5,6,7,8 and so on.

Thanks again.

-Lars

[Jan Crittenden livingston]

Hi Lars,

The HVX records 24P capture in two different ways at 720P. The first selection is 720/24P. Here it records just like the Varicam, there are 60 frames total, with 24 frames that are flagged as the key frames. These frames can be pulled out of the 60 with the frame rate converter that is a plug-in to 5.1.1 or outside of FCP with the Frame Rate converter that is on the HVX200 product page under Resources. Or they can be left in the 60 frame sequence. Just be careful of where you edit as when it is converted to interlace for broadcast you do not want to have edits in the wrong place. For a more complete discussion please see the techincal White Papers on our website, https://www.panasonic.com/business/provideo/app_hd_tech_papers.asp

The second way is to shoot in 24PN. This records just the flagged frames and not the padding. You can add pull-down on your output to tape. This mode has several benefits, the first being that it gives you more time on the P2 card by about 2 1/2 times, instead of 1 minute per GB, you get 2 1/2 minutes per GB. The second benefit is that you can just edit to your abandon, place your edit anywhere. When done, FCP will insert the pull-don necessary at the output for tape. This is the way I would work if I were using the camera.

I hope this helps,

Jan

Jan Crittenden Livingston
Product Manager, DVCPRO, DVCPRO50, AG-DVX100
Panasonic Broadcast & TV Systems

[Gary Adcock]

[Frank Nolan] “In Post how would FCP know which 24 frames of the 60 to pull as you have 60 distinct frames?”

Just to be clear here -this 720p24 over 60 workflow predates the HVX200 and has been in use since the varicam arrived on the market 5 years ago.

FCP knows what to do for 2 reasons.

1) the cadence of redundant frames in Panasonic’s 720p HD is the industry standard 3:2 pulldown, where as the first frame ( which is actually the zero frame) is duplicated twice while the next frame is duped 3 times, with this cadence repeating over and over again. Becuase it is always the same it is simply math to remove the redundant frames that are always in the same order.
It works because all of the frame are progressive and there are NOT interlaced fields to make any “combined from interlaced fields” the normally mushy looking frames in SD.

2) There is something called an RP188 Time code track where the “flags” or markers to what frame rate the camera is recording FCP can also see these which confirms the time base. When working with Varicam footage from a deck over HDSDI FCP can read these “User Bits” indirectly from within the Kona Control Panel ( I do not believe that decklink does not allows for this)
This is where all of the variable frame rate data is held – the flags here allow for My Kona board or the software FRC in Final Cut to see what frame rate the camera was working in and remove the redundant or repetitive frames.

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows
Chicago, IL