Interlace problems

[Slimothy]

Hello,
I always see what I think are called "interlace lines" on alot of peoples footage and was wondering what it is from and how to avoid it. I always notice it when something is in motion would love to know what this is. Tim.

[Shooter]

Its interlace lines...but you knew that already. Shooting progressive scan will avoid it.

Interlace lines are the slight time differences between alternate scans on consecutive fields. Most obvious when the frame is moving because each field has shifted slightly.

[Slimothy]

How do you shoot Progressive scan w/ the DVX...I thought Progressive scan was done by shooting 60i. Sorry if I am WAAAAYYY off base.

[scharky]

yeah, your a little bit off. 60i is the "interlace" mode. YOu want to switch to either 30p, or 24p-24padvance for shooting progressive. THis can be found at the end of the scene file settings menu.

[Aejaz]

or more easily .... by selecting F5 or F6 on the scene file dial on the back of the camera, you are straight away in the progressive mode..

[Slimothy]

Ok...but I've seen work on here done in 24p that does have interlace lines showing. I've actually even seen other sites where people say " this was shot in 24p etc" and the interlace lines are rampant.

[Barry_Green]

Depends on whether the footage was edited at 24P, and whether it was mastered to a raw 24P file or as 3:2 pulldown.

24P footage, straight from the tape, will have interlace lines on 40% of the frames. You have to edit it in a 24P timeline and produce raw 24P output in order to get rid of all interlace line artifacts. But in order to display it on a television, you'll have to add pulldown, which will introduce interlace lines.

[Slimothy]

So there is no way to avoid these lines if you want to watch it on a television?

[Barry_Green]

You won't see lines on a television.

The lines only show up when you're watching interlaced footage on a progressive monitor (although you can get comb artifacting if watching progressive footage on an interlaced monitor).

[Slimothy]

ok...thanks alot barry.

[Guest]

You WILL see interlace lines on a television however, if you change the speed of the video, and there is alot of movement in the frame. Correct? How to you fix that, aside from de-interlacing the clip?

[Barry_Green]

You won't see "interlace line artifacts" on a television, regardless. A TV is interlaced. It displays the fields as interlace.

The only time you really see interlace artifacts on a TV is if you pause a frame that has a lot of movement in it, and then you'll see a very flickery picture, but that's only if you pause it.

The other artifact you can see is if you shoot thin-line mode, and some of your detail is so small that it can be rendered entirely in one scan line... that type of thin-line detail will flicker on an interlaced television.

But mainly when people talk about seeing interlace lines, they're viewing interlaced footage on a progressive-scan monitor. On a progressive monitor, which doesn't display fields, you'll definitely see interlace artifacts. But if you're viewing on an interlaced display, by design you don't see those same artifacts.

[XCheck]

I am interested in purchasing a monitor. How do I know which is progressive vs. interlaced, and if I shoot in 24P, should I only get progressive?

[scharky]

I am interested in purchasing a monitor. How do I know which is progressive vs. interlaced, and if I shoot in 24P, should I only get progressive?

Well, the price will be a prime giveway. *Progressive scan Televisions are much more expensive, and are usually defined as hi-def and larger screen televisions, however, there are smaller LCD and Plasma displays that are progressive, but still very expensive. *Shooting 24p will work with both progressive scan monitors and interlaced. *When you watch a hollywood DVD on your regular television, you are watching a progressive scan DVD on an interlaced TV. *Shooting 24p will give you the same effect, ie. it looks different then regular 60i video. *When you watch that same footage on a progressive scan monitor/tv, you will be seing the full frames of the progressive scan footage, if 1. you have encoded a 24p dvd, and 2. you have a progressive scan capable DVD player. *I don't know if this answers your question as to what television to get, it really depends on how much money you want to spend, but progressive scan televisions do look great with progressive scan footage.

BTW, all computer monitors are Progressive scan, if that was your question.