Stuart Moss

Confused in relation to HD & SD Plasma TV

Ok, here is a problem which I came across today with regards to SD and HD plasma TV's.

About a month ago I bought a HD Plasma TV with DVI inputs and component inputs for displaying 1080i which at the time I thought thats what HD was all about. Fast forward to today my dad just bought a SD plasma and his has DVI inputs and the ability to display in 1080i as the screen was being demoed in the store displaying a HD broadcast. So the question is this how does my unit differ from his and what defines whether the set is HD or SD.

JeremyErwin

In the US, there are three grades.
HD: 720p/1080i
ED: 480p
SD: 480i

HDTV is, of course, a 16:9 format. It is, however, possible to use a squarer (4:3) screen to watch HDTV in letterbox mode. A footnote in the Consumer Electronics Association definition allows such 4:3 HDTV sets, provided that the letterboxed region is composed of a minimum of 540 progressive scan lines (75% of 720p) or 810i (75% of 1080i).

In Australia, 576p sets are considered HD.

Allan Jayne

Your father's plasma being SD (or ED if you insist), it has 480 rows of pixels and also accepts HDTV input. The HDTV video signals are digested (downconverted; downrezzed) to occupy the screen without having the entire bottom of the picture being sliced off.

Your plasma probably has 720 rows of pixels. Incoming 720p HDTV shows are displayed as-is. 1080i HDTV shows are digested to fill the screen (using line duplication and/or re-using lines from the previous 540 scan line field). It is possible that the digestion results in just 540 lines of resolution vertically, which would be a downconversion reducing the picture quality to SD.

Although 576p might be labeled as high definition for better or worse, it is simply PAL made progressive.

Video hints:
http://members.aol.com/ajaynejr/video.htm

JeremyErwin

Ah, now I understand. In Australia, HDTV is required, but the broadcasters balked, the government relented, and now, converted 576i material counts towards the requirement.

Theoretically, 576p is superior to 576i, but only if those additional scanlines contain additional picture information. In the case of "576p on the cheap", they don't.

So:

1. Australia allows 576p to be listed as HD.
2. The manufacturers advertise cheap sets as HD
3. Hundred of thousands of Australians buy the cheaper sets.
4 The broadcasters determine that the majority of their audiences won't be able to watch a 720p or 1080i picture anyway, and standardize on 576p
5. A 1080i set becomes a luxury, as there's little or no "True HD" programming available to watch.