GH1 - Frame Rate Conversion Tests - 720 60p & 30p to 24p vs. HPX 170 1080 24p

[Dalton Boettcher]

As others have said, thanks Jack! The hard work and time you've put into guides like this will make things easy on me, whenever I get my hands on a camera. Cheers

[Nighthawk]

Like the others I can't thank you enough. Looking forward to the workflow tutorials. Your work here exemplifies why this forum's the best.

[Ben_B]

60p - conform in Cinema Tools then retime in FCP or Compressor

You mean conform to 24p (making slow motion) and then changing the speed (command-J?) in Final Cut? Or reexporting it with compressor or what? How do you do that? Are there any advantages to this over just dropping the stuff in a 24p timeline in FCP? I know it does sort of a stutter-step thing but I don't think there's any way around that.

[Jack Daniel Stanley]

You mean conform to 24p (making slow motion) and then changing the speed (command-J?) in Final Cut? Or reexporting it with compressor or what? How do you do that? Are there any advantages to this over just dropping the stuff in a 24p timeline in FCP? I know it does sort of a stutter-step thing but I don't think there's any way around that.

Yeah the way around it is through method 1. Compressor alone, or 2. Cinema tools and then compressor or 3. Cinema tools and FCP. You get glass smooth 60p to 24p any of those three separate ways. Only dropping right into the timeline with 60p give you stutter.

Dropping 30p into a timeline is the worst, but method 1. or 2. help some. 3. and 4 (dropping in a timeline). are really bad.

For 60p, 1,2, and 3 are all really good. 4 may be fine for somethings of if you are not crazy picky.

For 60p to 24p with no stutter I'll be using one of the Cinema Tools combo methods (method 2, or 3):
In Cinema tools you "conform" to 23.98. That makes it slow mo.
Then you can
A. Set the duration of the newly slowed down clip back to the duration of the original in compressor (method 2)
OR
B. Set the duration of the newly slowed down clip back to the duration of the original in FCP. (method 3)
A or B gives you 24p.
B (FCP) uses frame blending. A (compressor) I think uses some more advanced interpolation where it's trying to render new frames. To my eye, the quicker method B yielded a result that looked a little more like 1/48th shutter motion blur, but it is frame blending, i.e., more of a fudge and not as good as whatever compressor does - in theory. Like I said, for the type of motion I was doing from 60 - 24p it looks more like 1/48th motion blur, but both the methods A and B looked smooth.

But this way you don't drop any frames, you kind of over (or would it be under?) crank the footage

THE TRICK: The trick is that you want to retime your duration to the duration of the original clip AS IF the original clip had been reverse telecined. Not the time of the original clip at it's original Frame Rate. For example. An almost 2 second clip will be 1.59 in 60 fps and 1.23 in 24 frames per second. When I get the tutorial up I can show you how to determine the target duration.

[sdhurley]

Thanks for the thorough work on this, much appreciated.

on the results... is anyone else seeing some bad color rendition in the clouds/sky on the GH1 footage near the begining of the clips?

[Ian-T]

on the results... is anyone else seeing some bad color rendition in the clouds/sky on the GH1 footage near the begining of the clips?

I thought it was the other way around. The sky looks blue in the GH-1 footage where as the HPX seemed white and blown out a little.

Then again...in the GH-1 clips when you look at the pickup truck...or anything that is supposed to be white...they have some sort of blueish tint to it.

Thanks for this test JDS.

[Ian-T]

I also find it amazing that the 720p in the GH-1 looks more detailed than the HPX. The 24p is super sharp...but unfortunatley very unpredictable. It wouldn't stop me from using it though.

[Jack Daniel Stanley]

Thanks for the thorough work on this, much appreciated.

on the results... is anyone else seeing some bad color rendition in the clouds/sky on the GH1 footage near the begining of the clips?

I thought it was the other way around. The sky looks blue in the GH-1 footage where as the HPX seemed white and blown out a little.

Then again...in the GH-1 clips when you look at the pickup truck...or anything that is supposed to be white...they have some sort of blueish tint to it.

Thanks for this test JDS.

I wouldn't judge any color from this. The HPX was a tad over exposed, the GH1 was not properly white balanced and I push / pulled a lot to try to get them into a similar look. And they seem more washed out than in FCP. Color grading this was what took the most time.

In terms of latitude the GH1 definitely seems more forgiving though and has more resolution even in 720.

[Jack Daniel Stanley]

I also find it amazing that the 720p in the GH-1 looks more detailed than the HPX. The 24p is super sharp...but unfortunatley very unpredictable. It wouldn't stop me from using it though.

Yeah. Make note of the smeary-ness of the asphalt in the AVCHD modes, and the super sharpness of the asphalt and everything else in MJPEG.

This is probably happening due to two things
1) You're starting with a 4K sensor, and no it doesn't do a crop of the sensor - it uses all of it then down rezes. Whether it does some kind of column skipping or something we don't know, but it's not a crop. So in terms of resolution, it's like starting with a Red and then downresing to 1K - make that 1920X180 vs. the 1280X1080 or 1280X720 vs 1280 X1080
2) the 170 is prefiltered to 1280X1080 (the subjet of much discussionb and debate around here) so starting 4K and going to 1280X720 seems better than starting 2K and going 12080X1080.

[Ken7]

Jack, thanks for all your hard work. I'm a bit new at this 1080p 24 stuff, so I'm a bit confused. You mention "This problem is significantly reduced in 60p AVCHD making it suitable for most applications where 1080 24p might fail, and non existent in 720 30p MJPEG an intra frame codec".

I guess where I'm confused is your reference to 60p. I know that the GH1 doesn't have a 1080 60p option, so are you talking about dropping a 1080 24p clip into an editing project set up as 1080 60p? If that's the case, are you saying that this procedure doesn't require reverse pulldown (which I still can't find in my Edius Pro program)?