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# does 1080/60i match 29.97 footage?

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 does 1080/60i match 29.97 footage? on Nov 23, 2009 at 10:48:09 pm

A client has asked me to shoot 1080i at 29.97 on my EX3. Will 1080/60i at 59.94 be basically the same thing?
Thanks,
Scott

 Re: does 1080/60i match 29.97 footage?on Nov 23, 2009 at 11:45:46 pm

I believe 29:97 refers to interlaced video, 59:94 should be progressive. If you shoot interlace (60i) you are recording 60 fields all at slightly different times. If you shoot progressive (30p) you will have one solid image that most likely will be played back interlaced, but the upper and lower fields are from one moment in time.

Good Luck
Michael Palmer

 Re: does 1080/60i match 29.97 footage?on Nov 24, 2009 at 12:16:58 am

[Scott Jolley] "A client has asked me to shoot 1080i at 29.97 on my EX3. Will 1080/60i at 59.94 be basically the same thing? "

The key is the "i" (interlace) part. i60 is 59.94 fields which is 29.97 frames.

The shorthand such as i60 and p30 is admittedly very confusing as Mike alludes to.

p30 is 29.97 frames.

so
i60 is 59.94 fields which is 29.97 frames
p30 is 29.97 frames "solid" as Mike explains

BTW
p60 is 59.94 frames "solid"

So with i60 and p30 in one sixtieth of a second (actually 1/59.94 of a second)

One frame is
i60 = an odd field followed by an even field for example. Each 1/59.94 of a second, totaling 1/29.97 of a second (frame)
p30 = one frame held through the 1/29.97 of a second (frame)

So now you have temporal resolution vs horizontal resolution. At 1920x1080
i60 is 540 odd scan lines followed by 540 even scan lines during that 1/29.97 of a second
p30 is 1080 solid held throughout the 1/29.97 of a second.

So i60 has two images during 1/29.97 but each image is half the resolution of one (p30) progressive frame.

So 1080p30 has higher horizontal resolution per image (1080) but 1080i60 has higher temporal resolution (2 images in the same time as 1 progressive image).

This is why many will shoot 720p60 for sports. You get 60 images (same temporal resolution of 1080i60) but you get 720 horizontal lines vs only 540 in the same 1/59.94 of a second of 1080i60.

 Re: does 1080/60i match 29.97 footage?on Nov 24, 2009 at 12:24:12 am

Michael,

You have it backwards. In 1080, 59.94 always refers to interlace, which is made up of 29.97 frames, but you can also select 29.97P (progressive) that gives you duplicate fields in each frame, and there is a difference in the look. The progressive frame rate compared toi the interlace is more "filmic" and less like "live" video.

Alternately in 720, there is a 59.94P (progressive) format where each field is a unique, sequential and complete picture compared to the "half" frames created in each field of an interlaced format. This 720/59.94 format gives a super "live" video look or can be used to create the best slo motion possible when converted to a 30p or 24p timeline.

Going back to the original question; yes there is a difference and if the client specifies 29.97P (progressive) they are doing so because they like that motion (like CBS News' 60 Minutes) or else because they are favoring an internet distribution where the repeated frames make it easy on the compression.

JS

 Re: does 1080/60i match 29.97 footage?on Nov 24, 2009 at 2:19:38 am

Thanks John,

I definitely know how the sensors work, it is the playback where it gets sticky.

Where I have gone wrong is the 720p=59:94 and PsF.

I would hope there aren't to many networks asking for interlaced video anymore.

I'm sorry if I confused the OP

Michael

 Re: does 1080/60i match 29.97 footage?on Nov 24, 2009 at 2:34:58 am

Not that I've done much HD Broadcast delivery but AFAIK that's 720p60 and 1080i60 and I think 1080i60 dominates. I do believe many TV shows are shot 24p and pull down is added though. In delivering to DGFastchannel for HD spot delivery they do ask for 1080i60. Unfortunately interlace isn't dead but I avoid it as much as possible.

 Re: does 1080/60i match 29.97 footage?on Nov 24, 2009 at 3:56:23 am

John,

after re-reading your response to my original post can you tell me what you meant by duplicated fields,
"but you can also select 29.97P (progressive) that gives you duplicate fields in each frame".
Odd and even fields are never duplicate as they have separate information that makes up a single frame.

I described this as "If you shoot progressive (30p) you will have one solid image that most likely will be played back interlaced, but the upper and lower fields are from one moment in time".

My 29:97 experience has come from working with Sony DV then HDV and it all was interlaced. Even the 24p from my V1U ended up on tape as interlaced with 3:2 pulldown, however it still retained the 24p look. I only know 29:97 as interlaced, until now.

I almost answered this question, "A client has asked me to shoot 1080i at 29.97 on my EX3. Will 1080/60i at 59.94 be basically the same thing? ", with YES

Michael

 Re: does 1080/60i match 29.97 footage?on Nov 24, 2009 at 4:20:16 am

Thank you all. Is is just as confusing as I suspected and the Yes answer is what I wanted.

 Re: does 1080/60i match 29.97 footage?on Nov 24, 2009 at 10:40:03 am

You know what? On the cinema screen it all seems to look the same!

I recently had a 'Making Of' shown in a cinema with the main feature. I shot my docu on my EX1 at 1920 X 1080i, the feature was shot on an EX3 (with Movie Tube) at 1080 25P. I used some excerpts from the feature cut with my stuff and it all looked the same! Maybe the difference shows more on TV screens?

Michael Slowe

 Re: does 1080/60i match 29.97 footage?on Nov 24, 2009 at 10:40:31 pm

Cinema as in 35 mm projected film?
cause that is a whole other can of worms.

Thomas Kist
Freelance D.o.P
Amsterdam,The Netherlands
PDW-700,EX-3&Letus,FCP 6