Can plasma / DLP TVs display interlaced material?

[jeanl]

I have a question for you expert guys (this might not be the best forum for it though):
- Can a modern TV (i.e. plasma or DLP) display an interlaced video stream "native" (i.e. without de-interlacing it)? I know they all have de-interlacing chips, but can they disable the de-interlacing if needed?

I'm wondering out of curiosity, and also because I'm still wondering if I should de-interlaced my original DV material, knowing that eventually it might have to be seen on a progressive-only display (there might be coding gain involved in doing that).

- If they are able to display interlaced material without de-interlacing it, how do they do it????
- If they don't, does that mean that some of the "advantages" of interlaced material (for rapid movement for example) are lost when the video is displayed on one of these displays?

Jeanl

[edDV]

I have a question for you expert guys (this might not be the best forum for it though):
- Can a modern TV (i.e. plasma or DLP) display an interlaced video stream "native" (i.e. without de-interlacing it)? I know they all have de-interlacing chips, but can they disable the de-interlacing if needed?

I'm wondering out of curiosity, and also because I'm still wondering if I should de-interlaced my original DV material, knowing that eventually it might have to be seen on a progressive-only display (there might be coding gain involved in doing that).

- If they are able to display interlaced material without de-interlacing it, how do they do it????
- If they don't, does that mean that some of the "advantages" of interlaced material (for rapid movement for example) are lost when the video is displayed on one of these displays?

Jeanl

Complex issues but here is the quick answer.

Plasma and LCD TV are natively progressive. They have internal hardware deinterlacers to handle interlaced inputs. These internal deinterlacers are getting better each generation.

CRT EDTV/HDTV sets are able to display interlaced (usually 480i/1080i) or progressive.

Interlaced sources are of two types.
- Natively progressive material (like film) that has had its field sequence altered to match TV display rates. This type of material is the easiest for hardware chips to detect and "deinterlace" on the fly. It's not really deinterlacing, it's reassembling field order.

- Native Video (NTSC, PAL, digital component) that was never progressive. Deinterlacing this material is a complex task that will take hours to days in expensive software (many compromized hacks are available) or done in realtime with sufficiently sophisticated chipsets. Broadcasters and theaters have this realtime equipment ($$$ and rack style equipment) and it works well. Adapting this (and better) technology to DVD player and HDTV chipsets will gradually be done.

So,what to do for DVD authoring?

1. You can choose to manually apply IVTC (inverse telecine, reverse pulldown) for film material. If you don't do it right, you may do perminent damage to the material.

2. Deinterlace native video? I argue no if your goal is TV display. The hardware deinterlacers will do a better job. Current sets may be a compromise but the same interlaced DVD will play better on each new DVD player or TV. If you software deinterlace now, you are locking today's poor S/W deinterlace technology into the frames.

Just my 2 cents.

[jeanl]

Thanks edDV!
What you're saying makes sense... I take it projectors also are progressive by nature and can't display interlaced video "natively".
Thanks for the advice. I know your opinion on this. So far, I've been following your advice, encoding my DV films as interlaced material...
Jeanl

[edDV]

I have a question for you expert guys (this might not be the best forum for it though):
...

- If they don't, does that mean that some of the "advantages" of interlaced material (for rapid movement for example) are lost when the video is displayed on one of these displays?

Jeanl

Yes and maybe not.

Yes.
Interlaced TVs will do a better job with motion (from interlaced sources). 1080i is even better because vertical scan artifacts are reduced as well for small-medium sets.

Progressive display of interlaced sources will always be a compromize.

Maybe not
This all gets solved in the future as broadcasting moves to progressive. When this happens, the burden for deinterlacing falls upstream on the broadcaster. He will always (most always) have better pro level deinterlacers for interlaced sources than any home equipment.

You are still left to deal with your local interlaced sources.

For the above reasons, I think the best current solution for HDTV is a CRT based system. It can deal with both kinds of sources optimally. True you must delay huge displays but those will continue to get better and cheaper as you wait.

PS: I skipped projectors becuse the the various technologies are more complex and the tradeoffs differ. It comes down to how much one is willing to pay in cash and artifacts in exchange for screen size.

[junkmalle]

In theory, any progressive display that can switch fast enough (50 or 60 times a second) can display interlaced sources natively. They could just display each field with the alternate field forced to black. Of course they would then have all the flicker of interlaced SDTV.

I don't know if any progressive displays do this. One reason may be that power consumption goes up -- some of the technologies consume more power the more often pixels are switched.

[jeanl]

junkmalle, I agree, but that wouldn't be exactly equivalent to a CRT because you wouldn't have the remanence that you have in a CRT so the flickering would actually be way worse than on a CRT! Maybe you could fake it if your refresh rate was much larger than 60Hz but I doubt that anybody does that!
jeanl

[edDV]

In theory, any progressive display that can switch fast enough (50 or 60 times a second) can display interlaced sources natively. They could just display each field with the alternate field forced to black. Of course they would then have all the flicker of interlaced SDTV.

I don't know if any progressive displays do this. One reason may be that power consumption goes up -- some of the technologies consume more power the more often pixels are switched.

Different TV display technologies offer different deinterlace strategies. The previous generation sets (low to mid range HD ready) seem to be using traditional deinterlace algorithms and get the traditional artifact errors: flickering edges, pixel breakup in motion areas and variable motion resolution. The artifacts seem to be highly noise and compression sensitive. After the local cable system was upgraded the same progressive HDTV sets seemed to handle standard digital channels far better as compression was reduced and noise improved.

added:
It's been interesting watching HD Channels that switch between interlace and progressive sources (like ESPN HD). The deinterlacer they are using is performing very well on these high motion interlaced sources. It's only a matter of time before we get this level of performance in our TV set deinterlacers.