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Resolution changes are SLOW

Discussion in 'DIRECTV HD DVR/Receiver Discussion' started by pdawg17, Apr 25, 2009.

  1. pdawg17

    pdawg17 Hall Of Fame

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    I had been away from D* for 9 months (remodel going on) so due to a couple of new changes to my HT setup it's hard to troubleshoot what is causing my problem...

    If I change from a 720p channel to a 1080i channel it takes around 8-9 seconds for the new channel to show up...I don't remember it taking quite this long before but I'm not sure...I also have a new Pioneer 1018 receiver which my HR20 is routed through over HDMI...on my receiver however, it "passes through" HDMI signals so I wouldn't think the receiver should be slowing anything down...

    Why not just try running the HR20 directly to the TV you ask? Because all of the wiring is routed through the walls and the HR20 is not very close to the TV...so before getting too crazy I thought I would ask how long it takes in "native" mode for you to change channels so I know if my time is "normal" or not...
     
  2. harsh

    harsh Beware the Attack Basset

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    Have you contemplated trying turning off native mode temporarily to see if that changes anything (channel changing speed and/or PQ)?
     
  3. pdawg17

    pdawg17 Hall Of Fame

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    Oh yeah...didn't mention that...with native mode off it's around 3 seconds between changes...
     
  4. Steve

    Steve Well-Known Member

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    Unfortunately, that's how long it takes me too. Just broke out my stopwatch, and for an HR20-700 with native "on", resolution changes appear to take anywhere from 8-12 seconds. I'm directly connected to a Panasonic display via HDMI. The fastest changes are to/from HD to SD, the slowest to/from 720p/1080i.

    Makes me wonder how DirecTV is detecting resolution. If they're "sampling" and analyzing the new channel with each change, that might be taking more time than if they just built a table of channels/resolutions from which they could quickly do a "look-up". /steve
     
  5. harsh

    harsh Beware the Attack Basset

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    Steve's results pretty much confirm that everything is working and having the AVR inserted isn't doing any serious damage.

    Maybe this is a side effect of the way that DIRECTV is currently handling Panasonic displays. Then again, maybe you just got used to it and will again. ;)
     
  6. RobertE

    RobertE New Member

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    With native on several things have to happen, all of which adds some time to the channel change:

    1) The H/HR needs to detect what the resolution is on the new channel. Be it from an index or direct analysis of the channel after the change.
    2) If the new channel is at a different resolution from the previous channel, the H/HR needs to change resolution.
    3) Once that is done, everything downstream (AV & TV gear) then needs to do the same thing in 1 & 2.

    All of that takes time.

    If you go from a 720 to a 720 channel or 1080 to 1080, or 480/480 the speed should be pretty consistant. It's when you mix-n-match resoultions is when you will take the real speed hits.
     
  7. pdawg17

    pdawg17 Hall Of Fame

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    Thanks guys...is this a Panasonic thing or do any of you have a different brand and have this problem?

    Second, if you have a Panny with this slowness, do you keep native off? If so, do you set it at 720p or 1080i?
     
  8. RobertE

    RobertE New Member

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    IMO, little to nothing to do with Panasonic specificly.

    Personally, I have mine set to native off & 720p as the only allowed resolution. My current tv is a 720p set and I feel that the HRs that are connected to it do a slightly better job of scaling 1080 to 720 than the tv.
     
  9. Voix des Airs

    Voix des Airs Cool Member

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    It's the same with my Sony XBR6. I would rather let the TV do the format conversion as it - to my eye - does a better job, but channel changes (like everything else really) are just too slow to put up with so I just lock it to 1080i. I have an HR22 by the way.
     
  10. harsh

    harsh Beware the Attack Basset

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    Obviously this has to be done regardless of what resolution your switching from or changing to. The net impact of this item seems like it should be equal across the board.
    This would seem to involve setting a byte or two in the decoder. It shouldn't take more than a few of clock cycles.
    I suspect that the delay is largely in the display and not the receiver. Of course if the receiver is programmed re-verify HDCP at each change toward a HD resolution, that might cause some serious delays.
     
  11. TomCat

    TomCat Broadcast Engineer

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    You can minimize #3 by connecting via component rather than HDMI, which will avoid the HDMI handshake latency.
     
  12. pdawg17

    pdawg17 Hall Of Fame

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    Ok so anyone out there using component...how many seconds for a res change?
     
  13. Steve

    Steve Well-Known Member

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    Sheesh. Am I the only one with a stopwatch! :lol:

    Actually my displays are hooked-up both ways, so easy to test. It's a consistent 8-9 seconds via component, no mattter which way I go. 480p<>720p, 480p<>1080i, 720p<>1080i. So 3-4 seconds faster than HDMI, but only under certain channel changes, like 720p<>1080i. /steve
     

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