29.97p vs 23.98p for live house of worship

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dsorbera

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29.97p vs 23.98p for live house of worship

PostFri Jan 11, 2019 10:44 pm

We are running an ATEM 2 M/E Production Studio 4k with 4 cameras into high end Panasonic projectors with variable refresh rates from 24-120hz.

We've been running a 59.94i project in the ATEM with the cameras and projectors set to match.
I've been contemplating making the jump to 23.98p or 29.97p to get the different look for the cameras.

What unforeseen obstacles will I be facing and what benefits will either format provide?

There is a single Mac Pro plugged into the ATEM via HDMI running pro presenter. We are live streaming the service over Livestream.com which seems to only support 29.97p from glancing at their tech specs page online.

Advice?
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Denny Smith

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Re: 29.97p vs 23.98p for live house of worship

PostSat Jan 12, 2019 6:03 am

Well 59.94i is the same frame rate as 29.97p, so no difference in the overall look
Cheers
Denny Smith
SHA Productions
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Robert Betzner

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Re: 29.97p vs 23.98p for live house of worship

PostSat Jan 12, 2019 9:40 am

Denny Smith wrote:Well 59.94i is the same frame rate as 29.97p, so no difference in the overall look
Cheers



Interlaced vs. progressive? That's a huge change in the overall look!
You will get a more "film-like" look in 29.97p - regarding the motion. Fast motion in the frame will look a little choppy so this look may not be what you want to achieve if you are doing imag. IMHO I would stay interlaced or switch to 60p if your cameras support this. The 4k Production Studio will only support 60p in HD mode nevertheless. If you want this "film-like" look for the recording you can easily convert the interlaced recording to a progressive one in post in your NLE.

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Robert
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Denny Smith

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Re: 29.97p vs 23.98p for live house of worship

PostSat Jan 12, 2019 6:31 pm

Yes, you get a resolution difference of the look between interlaced and progressive, but it is not very noticeable to the final viewer in a TV. As for subject motion blur, 1080i59.94 is 29.97fps, no no difference in image motion. Interlaced 59.94 is 29.97 divided into two fields, upper half and lower half, with the first half displayed, then the second half displayed. The 59.97i referees to 59.97 fields per second, which each frame being two fields. So the actual video frame rate (fps) for both is 29.97 = same motion blur effect.

This tech goes back to analog CRT TV days, where the image was scanned onto the tube, one line at a time, and interlaced gave the best scan results. Today’s flat screens are a native “Progressive” display system, which takes an interlaced signal, and reconverts it back to a 29.97 pros Progressive signal before displaying it.

If you want a more film like look, then use 24fps Progressive, which will have the similar mention blur associated with film projection. ;)
Cheers
Denny Smith
SHA Productions
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Robert Betzner

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Re: 29.97p vs 23.98p for live house of worship

PostMon Jan 14, 2019 10:19 am

Denny Smith wrote:Yes, you get a resolution difference of the look between interlaced and progressive, but it is not very noticeable to the final viewer in a TV. As for subject motion blur, 1080i59.94 is 29.97fps, no no difference in image motion. Interlaced 59.94 is 29.97 divided into two fields, upper half and lower half, with the first half displayed, then the second half displayed. The 59.97i referees to 59.97 fields per second, which each frame being two fields. So the actual video frame rate (fps) for both is 29.97 = same motion blur effect.


Sorry Denny but you are wrong.

Do a search on that subject interlaced vs. progressive framerates. You will find that your assumption that both fields refer to the same time base is totally wrong. Indeed these are two frames divided in two fields but they have a different time position. In other words: A single frame consist of 2 captures of 2 different moments in time. Field1=Time1, Field2=Time2. That is the reason why you cannot simply convert an interlaced signal into a progressive one, because you would get jagged edges between the fields coming from the different time position of the fields. And in addidtion to that - that is why interlaced formats look a lot smoother regarding the motion than progresive formats with 29.97 fps (because they are actually 59.94p with discarded odd or even lines of each frame combined togehther into one frame). What you are refering to is 29.97psf which would be 29.97p over an interlaced (59.94i) format (both fields have the same time position).

BTW - the motion blur is not really a big difference between 29.97p and 24p. But the motion blur between 29.97p and 59.94p is noticable. But you can compensate for that with your shutter.

There is no resolution differnce between interlaced and progressive signals. You would only lose resolution if you convert from interlaced to progressive. There are even some old conversion methods that just discard the odd or even field so you would devide you horizontal resolution by 2. But nowadays the conversion methods (f.e. Teranex) are much more sophisticated so you won't lose that much resolution with the conversion.

If you are interested in that subject you can find more and good information here:
http://www.100fps.com/


Cheers

Robert
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Denny Smith

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Re: 29.97p vs 23.98p for live house of worship

PostMon Jan 14, 2019 6:54 pm

OK thanks Robert, perhaps I was over simplifying this here, and got PsF mixed up with interlace conversions, thanks again for the clearing this up. Yes, I was not saying there was a big difference between 29.97p and 24p, just that the latter has a more filmic/cinematic look, but this is subtle. Yes, there is a big difference between 29.97p and 59.94p, as motion blur goes, with the latter being sharper, with less blur and more video like in its look. I was trying to say, there was not a noticeable motion blur difference due to fps difference between 29.97p and 59.94i, which is technically the same frame rate. That said, yes, I agree overall, interlace is overall, smoother looking as a result of the interlaced signal, and that is a difference you will see.

So the bottom line, and my original reply, I do not see the OP getting more or smoother looking motion blur using 1080p over interlaced, as was his original question, wanting to use 1080p29.97 or 1080p24, instead of the interlace signal he is currently doing. To me, the only reason to switch, would be if upgrading to cameras that do not have a 1080i output.

Bottom line, the OP should just shoot some tests, and see what he likes. ;)
Cheers
Denny Smith
SHA Productions

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