Quick Question on progressive scanning

[Clive]

Will I be wasting money buying a RPTV with progressive scan and 3:2 pulldown capabilities, seeing that my Panny RP91 does this already. Do I need to bypass the machines' Progressive scan mode and use the Tv's own or the other way around? or.............. do I use both for the cleanest picture I can get? What do I need to know about all this to aid in a purchase decision?




CLIVE




HEY!! Why buy movie tickets when you can own a Theater?

[George Bellefontaine]

Hi, Uncle Clive,
I stand to be corrected on this, but I believe the right course is to use whichever has the better progressive scanning, the tv or the player. In most cases, from what I've read, the dvd players usually have the better progressive scanning chips. As far as the HDTVs go, I do believe most have progressive scanning capablities. Even if they all don't, I would go with progressive anyway, just to be sure.




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[JonMarsh]

Hi Guys,

It's probably helpful to remember that "progressive scan" is just a display that sweeps every line sequentially, as does a computer monitor. What I think you're really concerned about here is where do you employ video de-interlacing?

If you have many sources which are interlaced video (sat, Laser disk, VHS, std DVD) it can be worthwhile to have a TV which does have a good de-interlacer (conversion from interlaced to progressive scan) built in. Ideally, it should support "smart" recongnition of film and video source, and switch between 3:2 pull down compensation and conventional 30 frame video smoothly on the fly. This costs more, and isn't as common. Some sets, like the better Pioneer models, have gone to using special chips, like those in the iScan line doubler, for this purpose.

However, this method may not offer the ultimate in DVD quality, because using the TV's de-interlacer means the video signal has to go through an A/D step, conversion, then a D/A step. More opportunites for problems, and most of these chips are only 8bit at best.

With a top flight DVD player with progressive scan (which again, involves a digital de-interlacer), the processing is doen after the MPEG decoder, but before the D/A conversion, in the digital domain. Then, the DVD player does some oversampling and smoothing, before outputing to it's own DACs, which in most cases, these days, are 10 bit 40 MHz DAC's- in a few recent models, 12 bit. The use of higher bit depths makes it less likely you'll see gradient banding in the playback.

If you only watch DVD, concentrate on the DVD player. If you watch a lot of other sources, it will probably be worhwhile to pick a set with a better than average de-interlacer. The set being "progressive capable" means that it will handle a signal like 480P, but doesn't describe what it will do with a 480i signal.

Regards,

Jon




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[George Bellefontaine]

As usual, a good solid reply and some sound advice from Jon, who really knows his stuff.




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