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HD Formats


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7 replies to this topic

#1 of 8 OFFLINE   andy_brehm

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Posted November 17 2003 - 03:51 PM

i have a bit of an idea of what the HD formats are but i was wondering where i could read up to understand exactly what 1080i 720p etc are and what their sources are.

thanks

#2 of 8 OFFLINE   Rob Ritch

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Posted November 18 2003 - 02:22 AM

Basically the number indicates the the number or horizontal lines or resoltuion ie 480 720 960 an 1080. Then there is the i or p, these indication interlaced or progressive. With interlaced, the display "paints every other line going down the screen and then fill in the remaining lines coming back up. With progressive, the display paints evey line as it goes down. Hope this helps.
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#3 of 8 OFFLINE   ChrisWiggles

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Posted November 18 2003 - 10:48 AM

Basically the number indicates the the number or horizontal lines or resoltuion ie 480 720 960 an 1080. Then there is the i or p, these indication interlaced or progressive. With interlaced, the display "paints every other line going down the screen and then fill in the remaining lines coming back up. With progressive, the display paints evey line as it goes down. Hope this helps.


I'd like to clarify/correct.

The number that denotes the scanlines is per frame of video. The P and I denote, as mentioned, progressive or interlaced, which indicates whether the number of scanlines is ALSO per *field.* A progressive display scans the entire resolution of a frame of video in each field. An interlaced display runs two fields, even and odd lines, to create one frame of video. Also, another nitpick, is that a CRT does not scan coming up. It scans one way, returns to the top, and scans again, for each field in an interlaced picture. It does this twice, once for both even and odd sets of scanlines, in two fields, to create the one frame of video. Progressive does this all at once, going the same direction, every line after the previous one.

Here is also a good link:

http://members.aol.c...ejr/vidhdtv.htm

#4 of 8 OFFLINE   ChrisWiggles

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Posted November 18 2003 - 11:08 AM

I'll also link you here:

http://www.digitalte...mer/index.shtml

Theres lots of info there, and in that list, pay particular attention to "consumer basics" parts 1-3.

Also beware that those are a tad out of date, but the technical info should still be solid.

#5 of 8 OFFLINE   ChrisWiggles

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Posted November 18 2003 - 11:09 AM

And this:

http://digitaltelevi....book/toc.shtml

And as for sources, the current hi-def sources for the home are limited to hi-def OTA, via cable, or with D-VHS.

#6 of 8 OFFLINE   WayneG

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Posted November 25 2003 - 11:28 PM

Last night a rep. from my cable company (Rogers) was on TV. A caller asked him about HDTV. He explained that regular TV was 300 lines of resolution, DVDs 525 lines, and HDTV 480 to 1080 lines. I found those numbers unusual because I understood that TV and DVDs were 480 and HD 720p or 1080i. I wonder how he came up with those numbers.

#7 of 8 OFFLINE   Lew Crippen

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Posted November 26 2003 - 02:42 AM

Quote:
I wonder how he came up with those numbers.
Your understanding is correct. I’m not sure how he came up with the numbers, but it is probably information overload.

For example VHS resolves about (I can no longer remember exactly) 300 lines. The NTSC specifications are for around 540 lines (don’t remember exactly), but only 480 for display—the others are used for sync information and text or other non-picture data. For many, many years, most TVs could not resolve even the 480 lines available for display.

DVD is 480—that is the spec and I don’t know where he would have come up with a different number.

The ATSC (digital) specifications do allow for 480p (this is what Fox broadcasts on their digital channels)—it is not HD, however. So even though it is in the digital broadcast specifications, it fails the HD definition test—which begins at 720p.
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#8 of 8 OFFLINE   ChrisWiggles

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Posted November 26 2003 - 03:59 AM

because 480 actually is more than that, hence the 525. He was incorrect with the hi-def that's 720p and up, usually 720p/1080i. I gotta run but im sure someone can explain the 480 to 525 number better.