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Strange picture issues

Discussion in 'DIRECTV Programming' started by achildfromthe80s, Oct 17, 2007.

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  1. achildfromthe80s

    achildfromthe80s AllStar

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    Mar 15, 2007
    I'm not sure if this is the right place to put this and i'm sure it may have been addressed but in case it hasn't...

    I'm having some strange picture issues. On some of the stations I get this weird pixelated line at the top or at the bottom. I'm pretty sure they aren't dead pixels and I only get it in native mode and only on HD stations that arn't broadcasting in 1080. The ones i've gotten it on are some of the locals, FX, Animal Planet and the Smithsonian stations. I don't get it when I turn off native on my HR20 and it also goes away when I change my TV from Just Scan to 16:9.

    My setup is as follows
    Samsung 40' Full 1080p LCD
    HR-20 DVR
    Hooked up via HDMI

    I also tried changing the HDMI cable and still get the same result.

    Thanks guys!
    Brad
     
  2. litzdog911

    litzdog911 Well-Known Member

    12,221
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    Jun 23, 2004
    Mill Creek, WA
    Your probably seeing a portion of the "vertical blanking interval" that includes digital text, closed caption information, etc. It can look what you're describing and is usually hidden by the normal "overscan" present in most TVs.
     
  3. achildfromthe80s

    achildfromthe80s AllStar

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    Mar 15, 2007
    Thanks for the suggestion!! Very interesting! My next question is, how do I go about fixing it as i'm not sure if it will damage the TV over time.
     
  4. Dusty

    Dusty Icon

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    Sep 21, 2006
    It's not the "vertical blanking interval". This is a digital TV.

    Just scan mode is supposed to support 1:1 pixel mapping, which should give you the best clarity when you have 1080i and 1080p output. When the source and the display don't have exact matching pixel count, the TV will have to scale the pixels to their capability.

    For example, I have a 1330x768 TV. It always scale the 720p or 1080i signals to its own pixel count. If say I use 720p and my TV supports Just Scan, I will only be getting from the source (say HR20) 1280x720 pixels of data. Since my screen has more pixels, there will be some pixels on the edge that have no data. I suppose a less than ideal design can leave some arbitraty contents in those memory locations.

    In your set up, if you pass through 720p data in native mode to your TV and ask it not to scale the pixel, since your TV has more pixels, what would it do with the memory locations that has no incoming pixels? My guess is you are seeing that.

    It doesn't make a lot of sense to me to feed 720p native signal to 1080p TV in Just Scan mode. Something has to scale your pixels. Either the TV or HR20. Experiment and take your pick.
     
  5. litzdog911

    litzdog911 Well-Known Member

    12,221
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    Jun 23, 2004
    Mill Creek, WA
    True. But some stations/broadcasts that are upconverted from 4:3 SD will show that portion of the VBI used by the analog transmission. While not relevant for the HD feed, it's still there and sometimes visible, and always annoying.
     
  6. Stuart Sweet

    Stuart Sweet The Shadow Knows!

    37,060
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    Jun 18, 2006
    Litzdog is right. Information in the VBI can be cross-encoded into a digital signal, and is usually considered harmless, if possibly annoying.
     
  7. achildfromthe80s

    achildfromthe80s AllStar

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    Mar 15, 2007
    Is there anything that can be done about this other than changing to 16:9 on stations it happens on? It's not that many but still annoying!

    Thanks guys for the help!!!!! :)
     
  8. litzdog911

    litzdog911 Well-Known Member

    12,221
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    Jun 23, 2004
    Mill Creek, WA
    Not really. Complain to the station.
     
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