Film-Tech Forum ARCHIVE: Blockiness in progressive scan; what causes this?

This is topic Blockiness in progressive scan; what causes this? in forum The Afterlife at Film-Tech Forum ARCHIVE.

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Posted by Tom Mundell (Member # 4555) on 09-16-2008, 07:05 PM:

I've come across a few dvd's that display exceptionally poorly on my DLP tv with Panasonic Blu-Ray player or Pioneer dvd player. For whatever reason, the picture is very blocky. This doesn't happen on a standard def tv in interlaced mode, so I'm assuming there's something odd going on when the picture is being de-interlaced. The worst offender is my Lexx dvd's which are blocky throughout the whole show. I have other tv shows that display more or less fine, so I'm wondering what is it about these particular dvd's that cause the problem that other dvd's don't have?

I tried to take a few pictures to illustrate:

Actually I think the problem looks a lot worse than in those small pictures; Here's a closeup that may better show the problem:

I don't know if there's any way to eliminate this, I haven't figured it out yet; I tried all the de-interlacing options available and nothing helps.

Posted by Joe Redifer (Member # 3) on 09-16-2008, 08:06 PM:

You are playing video sources that were interlaced to begin with and it must deinterlace each field to display properly in 480p. So basically each field is doubled and that gives it the blocky effect. Interlaced video contains only half the information as progressive video at the same "resolution". True 480p video won't look blocky at all, only interlaced.

Interlacing is evil, it serves no purpose and should be against the law and punishable by extreme pain.

Posted by Tom Mundell (Member # 4555) on 09-16-2008, 08:29 PM:

Why does this extreme level of blockiness seem to be much more noticable in this particular show though? I have other tv shows on dvd which I would expect to also be interlaced that look significantly better; offhand Seinfeld and The West Wing come to mind, the dvd's for both of those don't have nearly this level of blockiness and look like pretty much like most of my dvd's upscaled. (or were these shows filmed giving them a progressive source to go back to when creating the dvd vs. Lexx being 'filmed' on video? Can't say I know much about how modern tv shows are created...)

Posted by Joe Redifer (Member # 3) on 09-16-2008, 08:45 PM:

Seinfeld and West Wing were shot on film. The DVDs are naturally progressive. The show in your pictures was likely shot on video.

Posted by Tom Mundell (Member # 4555) on 09-16-2008, 08:50 PM:

Ah, ok, thanks; that makes sense then.

Posted by Charles Greenlee (Member # 3856) on 09-16-2008, 10:03 PM:

Interlacing is/was necessary to deal with the limited bandwidth of the broadcast signal. Otherwise you'd have to put up with a picture progressively scanned, but with half the apparent resolution, or one progressively scanned at half the frame rate. I think it was a brilliant solution at the time, just now antiquated and obsolete.

Posted by Joe Redifer (Member # 3) on 09-16-2008, 10:42 PM:

The people who invented TV were idiots. They should have tried harder.

And that's all there is to it!

Posted by Jesse Skeen (Member # 586) on 09-17-2008, 04:33 AM:

I'm contemplating getting a rear-projection DLP but I'm wondering how old stuff is going to look on it. If it looks worse than it does on a regular picture tube I'm going to be mad. I'll be getting a Blu-Ray player but will still want to be able to watch all my Beta, VHS, CEDs and laserdiscs in all their analog glory.

When I go TV-shopping I'm going to be carrying along a DVD with old stuff transferred from Betamax tapes with things like this:
http://video.google.com/videoplay?docid=8260939633013344840

Posted by Damien Taylor (Member # 4255) on 09-17-2008, 04:55 AM:

In my personal experience, laserdisc/CED and VHS/Beta look like poo on anything but a CRT

Posted by Anslem Rayburn (Member # 1267) on 09-17-2008, 05:51 AM:

Standard definition programming looks awful on HD sets. I have a 51" Hitachi CRT rear projector which I bough about 2 years ago and love. But SD stuff looks fuzzy and muddy on it. When I have to watch something in standard definition, I use the trusty old Sony 27" CRT. That thing has a pretty good picture for SD stuff.

[ 10-14-2008, 07:05 PM: Message edited by: Anslem Rayburn ]