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60i vs 30p for Full HD?

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Adrian Chircu
60i vs 30p for Full HD?
on May 30, 2017 at 6:10:35 pm

I know this is a lot to read, but please do so. Thank you so much!

Hi, I`ve bought a used nikon d5200 only to find out that instead of the REAL 60P it actually does 60I which is basically still 30p. [damn you snapsort for only showing 60 fps when comparing cameras!!!!]

Now I am a little disappointed to be honest but I still love the camera, I cant obviously get something else since I spent all of my budget on it and a couple of lights and a tripod. [Guess the D3300 would of been a better choice, also cheaper ☹)

Anyways, I`ve read A LOT of threads on how you shouldnt use 60i and go for 30p or 24p instead, BUT I decided earlier today to do some tests in AE and so I shot 6 different clips with me jumping in good light conditions with the following results [NOTE: the 60i videos were darker than the 30p videos at Full HD]:

first clip full hd 60i 1/400 shutter speed / everything else auto ----> Twixtor Pro at 5% yielded quite a lot of artifacts when zoomed in but actually usable when on normal zoom with not so noticeable artifacts on the video and quite some blur, the action was SMOOTH [remember this word please 😃 ]

second clip full hd 60i 1/2000 shutter speed / everything else auto ----> Twixtor Pro at 5% yielded again quite a lot of artifacts but less blur, the image was smooth, similar results to the first clip.

third clip full hd 60i 1/4000 [max] shutter speed / everything else auto ---- Twixtor Pro at 5% yielded similar results but a LOT less blur, and although there were quite a lot of artifacts as for the previous videos, it is to be expected when the Twixtor is set at 5 percent, the image was SMOOTH, nonetheless.

fourth clip full hd 30p 1/4000 shutter speed ===> Now here it is where it gets interesting, at 5 percent in Twixtor Pro the video started stuttering, it was like the video was turning to pictures, I was actually JUMPING from one place to another, sort of like a teleportation, the image was NOT smooth and there was A LOT of blur, totally unusable, even though the shutter speed was still 1/4000

fifth clip hd 60p 1/2000 shutter speed ===> this was similar to the first clips on 5 percent although I THINK it did had less artifacts, but I would say around 5 maybe 10 percent better than full hd at 60i, the blur was alright. also when zoomed in less detail, more pixels [to be expected since its only HD]

sixth clip hd 60p 1/4000 shutter speed ===> almost no blur, similar results to the first clip at 1920x1080 at 60i although again, as i mentioned before not anything special.

Also wanted to mention how on my 5 year old laptop with an i3 mobile proc, 6 gbs of ram and an integrated gpu [intel hd 3000] the video playback in ANY kind of software [quicktime, bsplayer, avc, etc] has HORRIBLE lines around the corners of things, which I think are called interlaces. When I playback the video in AE on my work PC xeon e5, titan x, 64 gb of ram, the interlacing disappeared and AE saw the video as 30 fps.

My questions are, HOW? How is 60i better than 30p when doing slow motion with no noticeable difference in artifacts if it`s basically almost the same thing as 30p?

Should I keep on using 60i in my upcoming videos since I have to crank up the ISO to get as bright as 30p if Im not planning on slowing down the footage or should I switch to 30p for normal video?

Why does the video get darker when using 60i and brighter when using 30p? ALSO, why does it seem that my Nikon is cropping the image when shooting in 60i but its maintaining the ratio when shooting in 30p?

I know this is a lot to read so thanks for everyone who took time to do so and respond, it helps a lot!


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Cassius Marques
Re: 60i vs 30p for Full HD?
on May 30, 2017 at 6:41:46 pm

Assuming you used the correct interpretation for all videos within AE and the Twixtor plugin, I can only imagine that having fields may yield more data for twixtor to compute the vectors and recreate the in-between frames more smoothly.

As to keep using 60i over 30p. Since you've done the tests I imagine you're the one to say which acchieved the better overall effect. maybe try to post a montage of your clips in vimeo to help others with the same issue decide? I'm curious about it too...

Cassius Marques
http://www.zapfilmes.com


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Dave LaRonde
Re: 60i vs 30p for Full HD?
on May 30, 2017 at 8:15:41 pm

[Adrian Chircu] "
Hi, I`ve bought a used nikon d5200 only to find out that instead of the REAL 60P it actually does 60I which is basically still 30p."


Does this thing record H.264 video? If yes, it is NOT interlaced because H.264 is progressive ONLY.
Besides that, I have, never, EVER heard of a DSLR that could shoot interlaced video.

Oh, and incidentally, 60i is not necessarily 30P. It can be using a process called progressive segmented frame, but that isn't a given. But I don't think you have to worry about that because I don't think you're shooting interlaced video in the first place.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Adrian Chircu
Re: 60i vs 30p for Full HD?
on May 30, 2017 at 9:28:44 pm

It indeed shoots h.264 but everyone kept saying its interlaced. Here it is on their website.

http://imaging.nikon.com/lineup/dslr/d5200/spec.htm

If you look at the frame size section on that website it says:

1920 x 1080, 60i (59.94 fields/s)/50i (50 fields/s)*, ★ high/normal
1920 x 1080, 30p (progressive)/25p/24p, ★ high/normal
1280 x 720, 60p/50p, ★ high/normal
640 x 424, 30p/25p, ★ high/normal
Frame rates of 30p (actual frame rate 29.97 fps), 60i, and 60p (actual frame rate 59.94 fps) are available when NTSC is selected for video mode; 25p, 50i, and 50p are available when PAL is selected for video mode; actual frame rate when 24p is selected is 23.976 fps
*Sensor output is about 60 or 50 fps
Note: A smaller crop is used for movies with a frame size/frame rate of 1920 x 1080 60i or 50i

Can someone explain WHY a smaller crop is used for movies when using the 60i? I`m really curious as I`ve noticed myself that when usign 60i it crops the image but when using 30p it doesnt. So whats the deal?


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Dave LaRonde
Re: 60i vs 30p for Full HD?
on May 30, 2017 at 10:04:35 pm

The deal is smaller file size. It's a Nikon cheat.

And it appears you can shoot at the frame rate you want, too.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Adrian Chircu
Re: 60i vs 30p for Full HD?
on May 30, 2017 at 10:17:44 pm

Uhmm, sorry I dont think I follow. You`re saying Im shooting indeed interlace to save file size.

"And it appears you can shoot at the frame rate you want, too." I`m not sure that`s right. I cant shoot FULL HD at 60 REAL frames per second so thats a hugeeee bummer sadly.


What about the crop size for the 60i? Why is that happening?


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Dave LaRonde
Re: 60i vs 30p for Full HD?
on May 30, 2017 at 10:25:14 pm

Well, then, make a choice -- 720 60p of 1080 30p.

720 scaled up to 1080 looks okay. People do it all the time.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Adrian Chircu
Re: 60i vs 30p for Full HD?
on May 30, 2017 at 10:32:37 pm

Well, for normal videos, I guess 30p FULL HD is enough, this camera does ok in FULL HD so HD is below the OK point, at least for me, especially in low light.

As from my tests above, 60i still works a hell of a lot better than 30p when doing slow mo. The only thing I do not understand is why is there a crop on my image when shooting in 60i AND why is there quite a decrease in brightness when shooting 60i?! The Nikon website does not explain this and I cannot find information about the cropping and the low light in 60i anywhere on the net...

Can someone please explain? Thanks a lot!


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Walter Soyka
Re: 60i vs 30p for Full HD?
on May 31, 2017 at 3:25:17 am

[Adrian Chircu] "My questions are, HOW? How is 60i better than 30p when doing slow motion with no noticeable difference in artifacts if it`s basically almost the same thing as 30p? Why does the video get darker when using 60i and brighter when using 30p?"

60i is not basically the same thing as 30p.

60i means that you have 60 fields per second (where a field is every other line in a frame). 30p means you have 30 frames per second. 60i trades away spatial resolution for temporal resolution. In other words, you are taking twice as many pictures per second, but they are essentially half-res.

Your camera is probably using a faster shutter speed with 60i than it is with 30p; remember, it's taking twice as many pictures per second. That means less light hits the sensor in every exposure, so the image is darker.

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive [twitter]   |   RenderBreak [blog]   |   Profile [LinkedIn]


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