Progressive v Interlaced
 

Hi all.

From doing some research this topic is widely discussed. However, as I'm a newbie I'm not up-to-speed on all the jargon etc and so was hoping for some advice on the problem I am having.

I recently used my Z5E to record a conference. After watching it back I noticed what I can only describe as a blur effect when someone walks across from left to right. After reading on the web, it seems this happens when shooting progressive. I've since checked the settings on my camera:
Rec Format - HDV1080i
HDV Progressive - Rec Type (Progressive) Scan Type (25)

Back home I changed the setting for HDV Progressive to Interlaced and the Scan Type to 50 - I then tried to replicate the problem I was having with the Progressive setting - the motion blur didn't seem to happen.

Everyone seems to say that shooting progressive is the way forward. Is this motion problem a common occurrence with progressive, and if so would interlaced be a better way to go? Or is there a way to get round the problem while still shooting progressive. What should I be changing my settings to?

Thank you.

Yes, and yes. You'd shoot progressive precisely because you want this look. It's the nature of the beast. Even with a faster shutter speed (which will reduce blur) 30 pictures per second will never be as smooth as 60, regardless of resolution.Everyone's a dope. Lots of argument about this over in the film look forum.

What is being missed here is talk about the frame rates, it's wrong to simply talk about "progressive" as if it uniquely describes a situation. You need to talk about it in conjunction with frame rate. In the US that can be 24, 30 or 60 (progressive) frames a second. The motion effect you are referring to applies to the lower of those figures, shoot 60p and the motion will be identical to what you experience shooting interlace. "Progressive" does NOT necessarily mean "jerky motion".

OK, now the difficult bit. HD video formats have three basic features - frame resolution (normally 720 or 1080), frame rate (24, 30 or 60 in the US), and interlace or progressive. Ideally, you'd want the best of each of those three - 1080 resolution, 60fps, and progressive. Unfortunately, current technology simply doesn't allow that in cameras at present, and practically at least of them has to be compromised.

If "film look" is actively wanted, it's easy - keep 1080 res, keep progressive, and you want 24fps, so shoot 1080p/24.

If (like you) you want smooth motion, you have to make a choice - EITHER compromise resolution and shoot 720p/60, OR compromise the scanning, use interlace, and shoot 1080i/30. (The last number should nowadays always indicate frame rate, so i/30 means 30 FRAMES, 60 FIELDS per second.)

So yes, progressive is the way forward, and hopefully before long 1080p/60 will be generally practical. Until then, compromises will be necessary.

He noted he's using a Z5E, so it has to be 25p.

But you're right, generally it's meaningless when people keep chanting "1080p....1080p...." without specifying a frame rate. That wasn't the case here, though.

This has been discussed to death in the Film Look forum.

Fair enough, but whilst you may realise that, others may not, and the latter part of the first thread was talking about progressive and interlaced in more generalistic terms. Unfortunately there is widespread confusion that equates progressive with jerky motion, period.

...and quite rightly so, as there's no 60p at all in the Sony HDV world (i.e. this forum and its parent). None, in fact, until you get up to the EX1. And as I'd guess about 99% of what shooters mean by progressive is either 30p or 24p, it's not a bad assumption. It's what progressive fans mostly want because they think it looks like film.

James, I can't point you to the article I'm thinking of that discusses shooting style when shooting 24fps, etc. but one thing I remember being mentioned is you need to follow the action. In other words, when someone walks across the frame, you WILL experience the blur, etc. as as been rightly said it is the nature of the beast...as I recall the article said that even the "hollywood" cameras have this issue, but they shoot with the help of high-paid cinematographers who plan each shot so the issue doesn't manifest itself in their movies.

This is one reason, among others, why I do not shoot in 30fps, etc. As an event videographer, I don't have the control over the scenes I shoot needed to overcome the blurring issues.

Another issue the fans of 24p forget is that normal TV's cannot playback 24p. The refresh in NA is 60hz ( interlaced for most CRTs and progressive for most flat panels) The player must be able to send true 24p to the TV and the TV has to be able to display. Refresh thus has to be a multiple of 24 ie 48, 72, 96, 120. Otherwise the 24p playback is modified with some form to double or drop frames to line up with the refresh rate. Some Plasma displays will refresh at 72hz and the latest 120 and 240 hz LCD have the capability to correctly playback 24p normally from a Bluray player over HDMI and then only if they are set up for that. Normally they will interpolate extra frames to smooth out the motion. To me the only valid reason for 24p shooting is to go to film for projection in a theatre. For video 60i or 60p makes a lot more sense both for temporal motion and compatibility with displays. I too look forward to a full HD progressive 1080P60. I am sure the technology is now available but of course this is not part of the Bluray spec!!!!!!
The film look is a lot more than the frame rate. The framing and focus controls as well as the colour saturation were used to mask the deficiencies of the low frame rate for economic reasons. These techniques can still be used without the frame rate being 24fps.

Ron Evans

Feature films are usually shot in 24fps. What is done in post or in the DVD version preparation that allows them to be played on DVD players and still retain the qualities of the of film?

They do the same 2:3 pulldown that you'd do in your NLE if you were having to deal with 24p. They just have better equipment than we do.

Here's an explanation Jeff, Telecine - Wikipedia, the free encyclopedia. The frames of film are blended over the 60 fields of video ( NTSC) As you can see it is not uniform so the film will not look the same on a TV this way compared to watching from a film projector. Film projectors will have 3 or 5 blades as shutters so the frame rate will be 24fps but the flicker rate will be 72 or 120.
This is not possible in a purely progressive video format which must be integer multiples. Its either 24 or a multiple thereof. NTSC TV's are 60 hz or more so not 24 and there will have to be a multiple of 24 to work( 72, 96,120,144,168,192,216,240 etc).
DVD's are interlaced and will have a 2:3 pulldown for film sources. Some TV's can identify this and correct back to 24fps if they have a high enough refresh rate ( 72, 120 or 240 sets). Bluray can have a true 24fps recording but again will need a high refresh rate TV to take advantage.
So apart from the motion ( which I dislike) most people cannot playback 24p anyway. They either have to translate it to a source that is interlaced(2:3 pulldown) and/or playback on a display that is not capable of displaying 24p.
What people normally see is 24p modified by pulldown.

Ron Evans

Thanks for the explanation Ron and Adam.

I shoot alot of surfing and use a sony A1U and FX 1000 @ 30p. No motion blurring problems.

Here's a recent clip using the FX1000@30p.

YouTube - SURFING SATURDAY 10 10 09

And how do you edit in 30p?

Good evening,


you edit in exactly the same way as anything else. When you set project settings make certain you have it as 30 P.

I shoot a lot of 30 P generally it will give you smooth motion, however in really fast movements like the surfer running up the beach look at his left arm and you will see what people are talking about.

you can also shoot in 60i, in Vegas set it as progressive and that will give you 60 full frames a second. this is good for setting the play rate at a slower rate which slows the motion down without duplicating frames. Next best affordable thing to a full 1080x60P video camera.