Variable Frame Rate Issues?

T

toddeastman

Active member
I set the RECORDING SETUP in the camera to record 720P/24P. Then I move up to SCENE FILE and change the frame rate to 48 FRAME.
With this set up, I am expecting to see a slow motion clip when I play it back in the camera. Instead, the browser identifies the clip as a 720P/60 clip and plays it back looking very much normal speed. Whats up?

Also the only setting I have been able to playback slow-mo footage is recording it 720/24 native. In the browser, those clips are properly id'ed as 720p/24 clips. I read Barry's "Understanding the New Framerates on the HVX200" article. Now I am wondering how he got slow-mo in anything other than native mode. Is there an NLE/post step I am missing? I have the frame rate converter in FCP but that doesnt seem to do anything.

Thanks!
 
You can only do slow-mo in the native mode in 720p, in camera. I'm sure you could record some 1080 24p or 60i stuff and slow that down in post.
 
i dont think that is true - in the native mode its easy to see how the slow mo happens cause you only get the needed frames - you can however perform slow mo over a 60i stream the same way the varicam does - it tags the needed frames - in fact this is the ONLY way to do it while streaming over firewire instead of to a card.

Todd - i suspect your NLE is not recognizing the tagged frames - what NLE are you using?
 
Page 35 of the manual says it can be done 720p/60p, 720p/30p or 720p/24p. It also mentions using an effective frame extraction function in Varicam equipped NLEs. Looks like its a post job then.

It also says "After ediiting, materials are output from the NLE in 1080i/24p or 720p/60p (24p over 60p) format."

Huh? Does that just mean that I bring my 60p media into a 24p timeline then do the frame extraction. Then finally export the finshed edit in 24p?

I'm using FCP 5.0.4. Using the Import->Panasonic P2 funtion to bring 'em in. When I tried theDVCPROHD Frame Rate Converter the resulting file looked like it was shot with a very high shutter speed.
 
I set the RECORDING SETUP in the camera to record 720P/24P. Then I move up to SCENE FILE and change the frame rate to 48 FRAME.
With this set up, I am expecting to see a slow motion clip when I play it back in the camera. Instead, the browser identifies the clip as a 720P/60 clip and plays it back looking very much normal speed. Whats up?
Click to expand...
You're confusing "over 60" with "native". If you shoot 720/24P mode, that's considered "over 60" and gets recorded as a 60p clip. So what you're seeing in your editing program is exactly right, that's how that works.

Instead you should be using 720/24pN mode ("native" mode). That will let you do what you want; it shows you the slow-mo function right in the camera right when you play it back.

Page 35 of the manual says it can be done 720p/60p, 720p/30p or 720p/24p. It also mentions using an effective frame extraction function in Varicam equipped NLEs. Looks like its a post job then.

It also says "After ediiting, materials are output from the NLE in 1080i/24p or 720p/60p (24p over 60p) format."

Huh? Does that just mean that I bring my 60p media into a 24p timeline then do the frame extraction. Then finally export the finshed edit in 24p?
Click to expand...
You can, yes. That's how it would be done if you'd shot in 720/24P mode (instead of 720/24pN). If you shot in "N" mode, no extraction is necessary.
 
Barry_Green said:
You're confusing "over 60" with "native". If you shoot 720/24P mode, that's considered "over 60" and gets recorded as a 60p clip. So what you're seeing in your editing program is exactly right, that's how that works.

You can, yes. That's how it would be done if you'd shot in 720/24P mode (instead of 720/24pN). If you shot in "N" mode, no extraction is necessary.
Click to expand...

So the term "Shooting 60p for 24" means what? Shooting 24fps (720p/24p) when the camera is actually laying down 60fps to the record media?

Also if the 720/24p setting records a 720/60p file is there a pull down kinda like shooting 24p on the DVX going on? The standard for 720 HD is 60p isnt it?

And just so I get this straight, if I shoot 720p/24p and set the frame rate for 48fps, I would take this file into at 720p/60p timeline and use the Frame Rate Convertor to bring it down to the recorded 24fps then yielding the 48fps motion I set up? Whew!:huh:

I usually don't have trouble with this stuff but it's got my head spinning with all the timebases and frame rates. Thanks for the help!
 
there is no pulldown needed since you are shooting progressive frames - the "good" frames are marked and those are the only ones use - the others are not displayed
 
toddeastman said:
So the term "Shooting 60p for 24" means what? Shooting 24fps (720p/24p) when the camera is actually laying down 60fps to the record media?
Click to expand...
Well, yes, sort of. There's two things you can do -- you can shoot 24p "over 60", which is what you describe -- 24 frames are imaged, but 60 are recorded. That's the way the VariCam works, that's the way DVCPRO-HD tape works.

The second thing you can do that might apply to the term "shooting 60p for 24" would be shooting in a 24P timebase, but actually shooting 60fps. That would be what you'd get if you shot 24pN mode, at a 60fps frame rate. Playing back that footage would result in a 2.5:1 slow-motion effect.

Also if the 720/24p setting records a 720/60p file is there a pull down kinda like shooting 24p on the DVX going on? The standard for 720 HD is 60p isnt it?
Click to expand...
Yes that's what happens. There's no field-based pulldown, it's progressive frames. In 30P "over 60", each frame gets recorded twice. In 24P "over 60", each even frame gets recorded twice, and each odd frame gets recorded three times. This lets you get the 24P look carried within a 60p broadcast.

And just so I get this straight, if I shoot 720p/24p and set the frame rate for 48fps, I would take this file into at 720p/60p timeline and use the Frame Rate Convertor to bring it down to the recorded 24fps then yielding the 48fps motion I set up? Whew!:huh:
Click to expand...
I guess. I don't know as I haven't tried it -- I'm still a complete Mac newbie. What I would do is use a 24p timeline instead of a 60p timeline. If you shot 720/24pN at 48fps, you'd drop that clip directly on a 720/24p timeline and it would work exactly as you want. It's my understanding that using the Apple FRC utility will result in a quicktime mov that is fundamentally identical to a 720/24pN file, so you probably wouldn't use a 60p timeline at all. I guess.
 
But in FCP you don't really need it if you shoot in 24pN mode. In 24pN mode it does the frame-rate-conversion process automatically, internally in the camera as it writes the clip to the card.
 
You guys are great! After reading all the help you have posted, the manual, and the docs with the Frame Rate Converter I am getting predictable results with the camera.

Next issue is what timeline to use in FCP. Does any particular time base work better in certain delivery cases (DVD, HD-DVD, Blu-Ray, SD Broadcast, HD Broadcast)? Is there a website with the criteria for these?

Thanks again everybody.
 
Just wondering if I shoot in 24pn mode with a VFR of 48. When I import into FCP do I have to do any slowing down of the clip or is the clip already effected prior to capturing?

Also it seems like alot of trouble to work in 24p and use VFR. What would be the benefit of not using native to achieve VFR work in regular p mode?
 
It's already ready to go. It will import as a 24p clip that plays back with half-speed slow motion.

As far as the 24p/FRC workflow, the benefit is the ability to stream via firewire to another recording device (such as a computer capturing your footage, or to a FireStore). But, when streaming to the Mac at least, the Mac is smart enough to strip out duplicate frames during capture (so it's like it automatically does the FRC step for you). Don't know whether the FireStore will strip out the frames or not during recording; if it doesn't, you'd still need to run the FRC.
 
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