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1080p vs. 1080i for acquisition and post

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Galen Yeo
1080p vs. 1080i for acquisition and post
on Aug 20, 2008 at 12:18:51 pm

Hi guys

I have a client who wants to shoot 1080p / 24p for a project.

I am wondering if we can stick with 1080i instead.

While I do know that we're heading for a 1080p future, I wanted to check if there was a significant difference for post if they are outputting to broadcast or web.

I believe they still have to convert to 1080i for final output.

Thanks for any advice.

G Yeo





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Craig Seeman
Re: 1080p vs. 1080i for acquisition and post
on Aug 20, 2008 at 1:01:25 pm

The temporal differences between 108024p and 60i are discernible to most. I tend to shoot at 30p to get better temporal resolution that 24p and, when shooting sports, will use 720p60 or 1080i60 in some circumstances.

You have to know what your clients want, why they want it, what you are delivering for. If the clients likes the look of 24p they will not like 60i.



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Galen Yeo
Re: 1080p vs. 1080i for acquisition and post
on Aug 20, 2008 at 1:07:41 pm

Hi Craig

Thanks. What I meant is: we are still shooting in 24p no matter what. The issue is how shooting 24p in 1080i vs. 1080p affects things.

thanks

g yeo



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Nick Lammers
Re: 1080p vs. 1080i for acquisition and post
on Aug 20, 2008 at 1:32:38 pm

I don't think it's possible to shoot 24p and 1080i. The P and the I don't play well together.

Nick Lammers
Media Mill, Inc.
St. Louis, MO

Media 100i XS 8.2.3a on an old G4
Producer 11.5.1 on MacBook Pro 2.33 GHz core 2 Duo


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Galen Yeo
Re: 1080p vs. 1080i for acquisition and post
on Aug 20, 2008 at 3:23:30 pm

Nick

The Sony Cinealta and Panasonic HDX 900 cameras do 1080i and 24p. I'm not sure what you mean.

They do this: 1080/23.98p (over 59.94i)





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john sharaf
Re: 1080p vs. 1080i for acquisition and post
on Aug 20, 2008 at 3:27:53 pm

Nick,

Not exactly; the F900's (Cine Alta) slow down the tapr when recording at 24 (or 25fps) and only write the 24 frames per second, unlike the Panasonic cameras which write the tape as if it's the result of telecine to include the pulldown frames.

JS





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Nick Lammers
Re: 1080p vs. 1080i for acquisition and post
on Aug 20, 2008 at 3:39:01 pm

Sorry - when I saw 24"p" I assumed that meant progressive which would not be "i" or interlaced. I understand slowing down to 24 frames - just didn't think 24p and 1080i were compatible. I need to stick to just reading this forum.


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Michael Palmer
Re: 1080p vs. 1080i for acquisition and post
on Aug 20, 2008 at 3:37:43 pm

What camera will be used to shoot with? If this is for broadcast it will most likely end up 60i, but you can shoot progressive in any format you choose.

Good Luck
Michael Palmer


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Galen Yeo
Re: 1080p vs. 1080i for acquisition and post
on Aug 20, 2008 at 3:52:15 pm

Hi Michael,

Some material is being shot I assume on a Sony HDCam 900 in 1080p/24p.

However, we may need to pick up material on a different camera - a Panasonic HDX900 which only shoots 1080i/24p. The issues are whether there will be (a) differences in the final product or (b) hiccups in post if cross conversions or transcoding are needed.

If the visuals are essentially the same - then I'm not too worried. I understand that there might be motion artefacting in this situation.

Thanks



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john sharaf
Re: 1080p vs. 1080i for acquisition and post
on Aug 20, 2008 at 3:59:48 pm

Galen,

There is no such thing as 1080i/24p. When the HDX900 is set to recors at 1080/24 it writes progessive frames with "flags" just like a recording from telecine, where each progressive frame is repeated in a 2:3 pulldown cadence. NLE software can remove the extrda frames and integrate the resulting 24 frames per second into a 24fps timeline/project.

JS







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Galen Yeo
Re: 1080p vs. 1080i for acquisition and post
on Aug 20, 2008 at 4:14:08 pm

Hi John

I am aware of that. I understand the Sony vs. Pana difference. What I want to ascertain is the difference between 1080p and 1080i capture and post. 1080p is technically a higher data rate in post and has more information than its 1080i counterpart. I've been told that shooting in two modes will look different. I haven't at this stage been able to test it. Is this a potentially ugly situation? Thanks



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Tim Allison
Re: 1080p vs. 1080i for acquisition and post
on Aug 21, 2008 at 3:35:49 pm

I'm still not sure what the heck you are asking, but this is the part I do know.

If you shoot 1080i, you will be shooting at 59.94 fields per second. I have never seen a camera or an editing system that can handle interlaced footage at 24 frames per second, or 48 fields per second. In a previous post, you said that you will be shooting at 24 frames per second. That means you have to shoot 24 progressive. I am not aware of any interlaced option at that frame rate.

We're all supposed to be communication specialists. Are we all just failing to communicate? Have I still totally misunderstood your question?



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Galen Yeo
Re: 1080p vs. 1080i for acquisition and post
on Aug 21, 2008 at 4:31:52 pm

I'm not sure why people are getting confused.

There are two aspects that I am looking at: 1080p and 1080i.

Assuming that I am shooting the same frame rate for the above - regardless of whether progressive or interlaced - my question was: what were the differences. I believe I have it roughly answered as:

1080p = sharper resolution / higher data rate / superior format

In editing both 1080i and 1080p material on the timeline, I will probably have to convert one or the other to match up.

I believe Michael has answered the question on 24p for the Panasonic camera. See here for specs:
https://eww.pavc.panasonic.co.jp/pro-av/sales_o/02products/products/aj-hdx9...



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Tim Allison
Re: 1080p vs. 1080i for acquisition and post
on Aug 21, 2008 at 6:30:55 pm

So if I understand you correctly, you are asking for a comparison between 1080i/60 and 1080p/30? That's a valid question. I just got confused when you were talking about recording 24 fps interlaced video.



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John Sprung
Re: 1080p vs. 1080i for acquisition and post
on Feb 6, 2009 at 10:52:24 pm

> 1080p = sharper resolution / higher data rate / superior format

Correct except for data rate. 30p and 60i have exactly the same data rate. With 24p, you have a lower raw data rate, so you don't need to compress as hard.

It's absolutely true that nothing can really be both progressive and interlaced at the same time, just like those commercials where you can't go both downtown and to the airport at the same time. There is an unfortunate choice of terminology, used mainly in the consumer and prosumer realm, something like "progressive over interlace" or "p/i". What this refers to is what Sony calls "segmented frame" recording. What they do is shoot progressive frames, but read the data out to tape as if it were interlaced, in two "segments" instead of fields. This is just a recording convenience for the manufacturers, allowing them to make progressive cameras and recorders using their existing interlaced designs. Stuff gets flipped back and forth between segmented and true progressive all over the place in post, it's a completely harmless and invisible to the user thing that goes on inside the boxes. It only confuses us when we find out about it. ;-)




-- J.S.




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