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Interlaced vs Progressive (fps)


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#1 shane grace

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Posted 19 November 2008 - 12:30 AM

If there are any resources where i can find out the difference between Interlaced and Progressive, especially with regards to fps and video formats (PAL + NTSC)

thanks in advance
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#2 The Tramp

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Posted 27 November 2008 - 10:20 PM

From what I learned in TV Production class:

Interlace scans the amount of lines in this order (NTSC, 525 lines/480 underscan) 1, 3, 5, ect, odd numbers first, and then even numbers 2, 4, 6, 8,.

Progressive scans the lines in a consecutive order, 1 2 3 4 5 6.
hope this helps


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#3 Adrian Sierkowski

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Posted 27 November 2008 - 10:24 PM

Christopher, you must change your name to your real first and last name as per the forum rules. This can be accomplished by going to "my controls" on the upper right side of your screen, then on the middle of the bar on the left-hand side "change display name."

Also interlacing can lead to interlace artifacts from fast moving objects, whereas Progressive won't. Personally, I think interlace is going the way of the do-do, but I may be wrong in that too. I'd also say it's easier to go from progressive to interlace than the other way around, so if shopping for a camera, I'd look for a "p" system.
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#4 Josh Bass

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Posted 28 November 2008 - 02:07 AM

I'll try. . .

So basically, see, you have these things callled "fields'", when you're looking at footage. Each field is either all the even lines in a frame of video, or all the odd lines. So you have two fields per frame.

When you talk about interlaced video , you are actually seeing two images at once (hence the term interlaced), one field (one set of lines) from one image, and one field from the next image. Pause a VHS tape (if you have access), and sometimes you see it jittering. . .that's cause you're seeing the two images at the same time.

With progressive footage, all the lines are from the same image. This means a couple of things:

Higher resolution, since you have twice as many lines representing a given image, and a more stuttery motion signature. Interlaced video looks much smoother because you're seeing two images simultaneously, leading to smoother motion.

Speaking from an NTSC standpoint, you might associated interlaced footage with the look of news, some reality shows, etc. Progressive footage looks more "cinematic" to most folks, and can be found in narrative television shows (sometimes) and movies, although it's starting to make its way into reality TV and related things.

The standard for NTSC is 30 frames per second, interlaced (this is also called 60i, meaning 60 fields interlaced per second (30 frames x 2 fields/frame = 60 fields). Now, check THIS: even though when you watch a movie or narrative TV, anything that looks progressive on TV, it's STILL interlaced, it's just that the source footage has been transferred in such a way as to fake a progressive look. When we're talking about film or video shot at 24 frames per second, the method is called the 2:3 pulldown, and I'll let someone else explain how it works. Suffice to say, when you watch NTSC signals, you are ALWAYS seeing 30fps interlaced, no matter how it LOOKS.

To sum up. . .progressive footage looks stuttery, generally more "cinematic" or "film-like", interlaced is smoother, more like reality, news footage, etc.

As for PAL. . .I really don't have experience or much knowledge with it. I believe it is 25fps instead of 30, and has 625 lines of vertical resolution instead of 525. It's also generally agreed to be a nicer looking signal than NTSC. But oh well!
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