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SD on High Def (1 Viewer)

snash22

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Nov 23, 2006
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Steve Nash
I have seen a lot of discussion regarding the quality of SD content on HD displays and I have a question of how it is implemented. I don't own a HD display but I'm planning on purchasing in the next few months.

Is the problem that it is difficult to convert the SD resolution (480 lines) up to a HD resolution with a number of lines (720, 1080) that is not a multiple of the SD resolution?

If this is the case, wouldn't the 1080 displays be able to cleanly show the SD content by just scaling to only 960 lines of resolution? This would leave small black bars at the top and bottom as well as the sides.

Is my initial assumtion correct? Is this scaling an option in 1080 displays?

I am really concerned about this - although I have a HT for movies, 80% of the viewing will be SD content for a few more years.
 

Jeff Gatie

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No, the problem is two fold -

1) SD (meaning NTSC) quality stinks, especially when coming in compressed by cable/sat. It was originally created for 12 inch black and white screens back in the 50's and it is a wonder that it even looks as good as it does.
2) Not only does it stink, but the majority of people making the jump to HD are also increasing the size of their screens. So where you used to have a SD picture that is optimized for your small NTSC TV set, suddenly you have it blown up to big screen size and displayed on a set that is supposed to display HD. Add to that any stretching of the 4:3 picture to fill the 16:9 space and the faults of NTSC are magnified about 10 times over.
 

snash22

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Steve Nash
OK, so there is no conversion issue here. When people on this forum are asking how a particular set displays SD content, they are asking about the quality of the NTSC tuner, same as they would have asked pre-HD.
 

Allan Jayne

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There are still a few HDTV sets that don't make the most of what little quality SD has to offer. The weak link is the "de-interlacer" which converts ordinary interlaced video into 480, 540, or 720 scan lines to fill the HD screen. (SD converted to 1080i only needs to use 540 scan lines at a time).

Unfortunately I don't know which sets are the poorest.

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

Jeff Gatie

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Well as Allen said, some do the conversion better than others, but none do it well. My real point is to say that NTSC performance should not be a primary concern for buying a set because (A) you may miss out on on better HD set chasing the holy grail of NTSC upconversion perfection and (B) just like the holy grail, you may be searching for it a long, long time.
 

snash22

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Steve Nash
Jeff - Point taken, I'm not going HD to watch CNN.

But look at it this way, I have a 36" 4:3 display right now. If I get a 46" widescreen, the SD 4:3 image will be about the same size as it is now, but will the quality suffer due to upconversion?

If so, why so? If the upconversion to was from 480 lines to 960 lines, there should be no loss of quality, and no upconversion artifacts. The de-interlacing should improve the quality!
 

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