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interlacing and progressive scan

Old 12-29-05, 08:23 AM
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interlacing and progressive scan

Have i got this right?

As i understand it, traditional TV's generally display interlaced video. DVD-Videos of TV episodes are interlaced, and so playing the video on TV is straighforward.

But, playing on a PC is a different matter. PCs play video by progressive scan. SO playing such DVD-Videos require deinterlacing to play it properly.

As for DVD-Videos of films, these are usually in progressive scan. Playing these DVDs on PC are simple. Playing on a traditional TV require the opposite of deinterlacing? I.e. interlacing of progressive scan?
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Old 12-29-05, 11:01 AM
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afaik all DVD is interlaced. PC and progressive DVD player with progressive display play the DVD by de-interlacing the video signal.
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Old 12-29-05, 11:50 AM
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eedoon is correct. All DVD video is interlaced. In order to play on a PC or an HDTV, the video must be deinterlaced either by the DVD player or the display. Film content is easier to deinterlace than video content. Here's an article that explains how progressive scan works:

http://www.hometheaterhifi.com/volum...e-10-2000.html
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Old 12-29-05, 12:52 PM
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Thanks for clearing this up for me.

In that case, if the movie industry wants to increase the quality of DVD playback further, they ought to produce new progressive scan DVDs to go with the new progressive scan DVD players and TVs. That is the only way to squeeze the most out of progressive scan DVD players and TVs.

This is because some quality is inevitably lost in the deinterlacing process.
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Old 12-29-05, 02:26 PM
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Actually...some DVD's are encoded progressively and some are interlaced. I have an article about that as well. My malata will tell me whether the DVD I'm playing is interlaced or progressive.
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Old 12-29-05, 04:17 PM
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Originally Posted by fawkesuk
In that case, if the movie industry wants to increase the quality of DVD playback further, they ought to produce new progressive scan DVDs to go with the new progressive scan DVD players and TVs. That is the only way to squeeze the most out of progressive scan DVD players and TVs.
HD-DVD and Blu-Ray movies will be stored on disc in 1080p format. Standard definition DVD is 480i and always will be.

Originally Posted by digitalfreaknyc
Actually...some DVD's are encoded progressively and some are interlaced. I have an article about that as well. My malata will tell me whether the DVD I'm playing is interlaced or progressive.
All DVD video is interlaced, but the disc contains flags that can tell a DVD player how to assembled the original film frames. Unfortunately, 95% or more of DVDs have bad flagging. The better deinterlacing chips disregard the flags and analyze the cadence of the video instead. This is called motion-adaptive deinterlacing and is the reason why some progressive scan DVD players are better than others.
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Old 12-29-05, 06:41 PM
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Huh. That's strange because I can ALWAYS tell when I'm watching something interlaced on my malata becuase it always looks like shit Yet, if i put a disc in that's labeled "progressive" on my malata, it looks spectacular. I don't think it ever flags it improperly.
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Old 12-29-05, 09:22 PM
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Labeled progressive? Like what? I've never seen this.

The flags are encoded on the disc, that doesn't come from the player.
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Old 12-30-05, 11:27 AM
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Originally Posted by digitalfreaknyc
Huh. That's strange because I can ALWAYS tell when I'm watching something interlaced on my malata becuase it always looks like shit Yet, if i put a disc in that's labeled "progressive" on my malata, it looks spectacular. I don't think it ever flags it improperly.
The Malata has a poor flag-reading deinterlacer. I think the menu screens you're looking at that say "Progressive" and "Interlaced" are really referring to whether the disc is flagged as "Film" or "Video". If the disc is properly flagged for the right content, the player can assemble the frames adequately, but if it's mis-flagged it will look like crap.

As Spiky mentioned, the flags are on the disc itself, not something the player does. Also, the flags are not necessarily constant from beginning to end on a disc. It's not just one flag for the whole disc; it's a running sequence of them. A movie/show can require a variety of different cadences. For example, a TV show may be shot on film but have video overlays or special effects that screw up the cadence of certain shots.

My old Malata 996 has a number of different deinterlacing modes to use depending on whether the material is film or video. You have to manually select them, which is a pain and also highly inaccurate if the material switches cadences mid-content. A good motion-adaptive deinterlacing chip will read the cadence of the video and switch to the appropriate algorythm automatically.
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Old 12-30-05, 01:05 PM
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Regardless...

All i know is that the ones that come up as "interlaced" look like crap and it never happens with R1 discs unless they're full frame. All full frame discs come up as interlaced and most non-anamorphic ones as well.

I never meant to say it comes from the player. It's what the player is reading on the disc. If you press the "info" button, it will say either interlaced or progressive.

I have an article on all this at home. I just have to find the link. I'll post it here.
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Old 12-30-05, 01:41 PM
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Originally Posted by digitalfreaknyc
I have an article on all this at home. I just have to find the link. I'll post it here.
Read the link that I posted earlier in the thread.
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Old 12-30-05, 02:18 PM
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Originally Posted by Josh Z
Read the link that I posted earlier in the thread.
I did.

It's a different article.
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Old 12-30-05, 04:36 PM
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Originally Posted by digitalfreaknyc
I did.

It's a different article.
Yes, and the one I posted is how it actually works. I don't know what the other article you read may have claimed.
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Old 12-30-05, 05:09 PM
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Alright, a bit off-topic but this always bothered me.

720p is 720 lines of resolution (720 lines "stacked" horizontally), all playing progressive.

1080i is 1080 lines of resolution, but interlaced. So every other line plays and the human eye is tricked into seeing the entire image.

I can see why 1080p is better than 1080i. But why is 720p necessarily always better? Aren't you seeing things in a lower resolution?

So here's my illustration of each type:


480p


540p


720p


1080i


1080p

Am I off-base in thinking the higher resolution 1080i would look better?



Or is 1080i simply a misnomer, and is it really 540 lines of resolution from the source image?

(Assume we're talking about something like a game console, that can natively create "true" 720p or 1080i.
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Old 12-30-05, 05:11 PM
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Originally Posted by Josh Z
Yes, and the one I posted is how it actually works. I don't know what the other article you read may have claimed.

Ok. i'll let you and your ego know as soon as i get home.
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Old 12-30-05, 08:19 PM
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Bus, you better post that elsewhere. Too much going on here.

Freak, Josh is correct. Just because your strange DVDp tells you something weird doesn't mean the industry has magically changed. Standard TVs are interlaced, so were ALL of the first DVD players. The discs cannot be progressive, it isn't part of the DVD Forum specs, and they wouldn't have been compatible with hardware in 1997. I know that some Malatas have run some bizarre actions before getting the video out of the player, like running everything through the de-interlacer, even when using interlaced output. This is partly why they have so many unique features. And the company certainly is incapable of translating into English. (I also had the 996 once)

Last edited by Spiky; 12-30-05 at 08:25 PM.
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Old 12-30-05, 08:23 PM
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BTW, since it is mainly non-R1 discs or non-anamorphic discs, it seems pretty easy to find the answer. "Interlaced" must mean video sourced, or other...perhaps it gets confused by PAL discs or poorly flagged discs. I would hazard a guess that this means the player shifts into a Video cadence reading mode, which probably sucks, as Josh mentioned about Malatas in general. "Progressive" probably means a film-based source with flags it can understand, so it is flag-reading instead of trying futilely to do a cadence calculation.
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Old 01-01-06, 02:35 PM
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Originally Posted by The Bus
I can see why 1080p is better than 1080i. But why is 720p necessarily always better? Aren't you seeing things in a lower resolution?

Am I off-base in thinking the higher resolution 1080i would look better?
People's opinions can get very heated over this, but the truth is that neither 720p or 1080i is necessarily "better" than the other. 1080i is higher resolution but interlaced. 720p is lower resolution but progressive. They both have their strengths and weaknesses, and in practice come out about even.

The key determining factor is what type of display they will be watched on. 720p looks better than 1080i on a 720p display. 1080i looks better than 720p on a 1080i display.

Or is 1080i simply a misnomer, and is it really 540 lines of resolution from the source image?
No, 1080i is not the same thing as 540p. 1080i has more resolution and real picture detail than 540p, but is presented interlaced.

1080i = 1920x1080 pixels (2,073,600 pixels total) interlaced.
540p = 720x540 pixels (388,800 pixels total) progressive.

That's more than 5 times as many pixels, presented in 2 interlaced fields, each of which is more than twice as much resolution as 540p is in total.
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Old 01-03-06, 02:53 PM
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Originally Posted by Josh Z
HD-DVD and Blu-Ray movies will be stored on disc in 1080p format. Standard definition DVD is 480i and always will be.
I hadn't really thought about this before, but I'm assuming HD-DVD and Blu-Ray players will be able to output 1080i as well? Otherwise, I'd think there would be a lot of people with HDTVs who have no use for the new formats. I know my HDTV won't do 1080p.
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Old 01-04-06, 03:25 PM
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Originally Posted by maxfisher
I hadn't really thought about this before, but I'm assuming HD-DVD and Blu-Ray players will be able to output 1080i as well? Otherwise, I'd think there would be a lot of people with HDTVs who have no use for the new formats. I know my HDTV won't do 1080p.
I believe the plan is that the discs will be encoded at 1080p but players will output at your choice of either 720p or 1080i. Final specs are still pretty sketchy, so it isn't known yet whether first-gen players will even offer 1080p output (much like progressive scan wasn't available on DVD players for a couple of years).
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Old 01-05-06, 10:27 AM
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So, with my 1080i HDTV, how would a HD/Blue Ray DVD outputting in 1080p look on my screen?

Would there be a discernable difference in PQ, or would it have as bad PQ as trying to watch a 16x9 DVD in 480i?
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Old 01-05-06, 11:19 AM
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It would not display properly. Jumping frames or just plain no sync at all, with a blue screen or whatever your TV displays with no signal.
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Old 01-05-06, 03:44 PM
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Originally Posted by sparks
So, with my 1080i HDTV, how would a HD/Blue Ray DVD outputting in 1080p look on my screen?
The player will downcovert the 1080p format stored on the disc to 1080i for input to your TV. It should look just as good or better than any 1080i programming you may be watching from TV now.
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