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Newbie Q on HD vs SD

Discussion in 'Archived Threads 2001-2004' started by David_Schiller, Feb 1, 2002.

  1. David_Schiller

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    Does "HD" mean both 720p and 1080i?

    Where does 480i and 480p fit in? Are SD broadcasts 480i on satellite and less than 480i on cable and OTA antennas? Is one difference between 480i and 480p that 480p is in widescreen (e.g., the Superbowl and the show ER)?

    If I get better clarity on my local SD channels through my OTA antenna compared to my dish, does that mean that the OTA VHF broadcast has higher resolution than the satellite? I'm thinking "no".
     
  2. Eric S M

    Eric S M Agent

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    David,

    720p and 1080i are the HD resolutions. Most televisions today only display the 1080i high-def. 720p requires higher bandwidth components and is therefore more expensive to produce, transmit, and display. Some will argue that 720p is a better picture because it is progressive where 1080i is 1080 lines interlaced. But, with 1080 lines, can most people really tell the difference? I don't know, since I haven't seen a 720p picture on a set capable of that output. Note also that most HD programming (i.e. CBS and HDNET) are broadcast in 1080i. ABC broadcasts in 720p.

    480p (like FOXs superbowl this year) is referred to as EDTV (or enhanced definition).

    The difference between 480p and 480i is that 480p displays the entire picture in one pass of screen refresh (scan) and 480i displays 240 lines in one pass interlaced with the remaining 240 lines in the next pass. That is one reason you see tearing or combing during scenes with horizontal motion with an interlaced signal; the scan rate of the TV cannot keep up with the ability of your eyes to discern the first set of 240 lines from the next set. So, the 480p signal has a higher perceived resolution because you see it all at once instead of in two pieces.

    No, the OTA SD channels do not have higher resolution than the satellite. For me, the sat signal is definitely of higher quality than any OTA or cable that I can get. A friend had 'digital' cable, and he found the satellite signal is marginally better than that.

    Eric
     
  3. David_Schiller

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    Thanks, Eric, for the excellent explanation.

    -David
     

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