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622 Picture Quality

Discussion in 'ViP612/622/722/722K DVR Support Forum' started by zdman, May 26, 2006.

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  1. zdman

    zdman Cool Member

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    May 26, 2006
    I currently have a comcast motorola 6412 PVR. I am considering going to Dishnetwork to get more HD channels. Has anyone compared the HD picture quality of the new 622PVR with with a motorola 6412 PVR. I have read that Dish re-compresses their HD channels and it is my understanding that the cable companies do not. Just wondering if the HD picture quality will drop if I go to Dishnetwork.
     
  2. Rob Glasser

    Rob Glasser Hall Of Fame Staff Member Super Moderator DBSTalk Club

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    Feb 22, 2005
    National HD channels should look the same as cable, i.e. ESPN-HD, and Disovery HD. Local HD Channels, if available from DISH, is where you may see a difference. It all depends on whether or not the cable company in your area compresses the channels or not. I know in my area they do not appear to do so, they look better via cable than they do from DISH and MPEG4 compression. If you can get OTA reception of your local HD channels, they can be integrated into the DISH ViP622, which would give you the best possible picture.
     
  3. SaltiDawg

    SaltiDawg New Member

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    Aug 30, 2004
    Just one data point. We are in the suburbs of Washington, DC. My wife and I can not discern a difference in picture quality between digital locals OTA and Sat provided HD locals. Given the choice, we record from the Sat rather than OTA because we sometimes have tree issues during the summer that cause loss of OTA signal. (We didn't do the comparison with this being an issue. lol)

    As I understand it, MPEG-4 is an encoding/decoding methodolgy and does not cause any compression to occur in and of itself. The reason it is being brought to play is that it allows greater compression without visible additional picture degradation OR it allows a better quality image for the same amount of bandwidth as was required for MPEG-2. If I've got it wrong, let me know. Just trying to clarify things.

    I do not know how to determine the degree of compression that E* opts to use - for local HD or anything else.

    For the OP, how does your local Cable HD channels look compared to them received OTA?
     
  4. dave1234

    dave1234 Icon

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    Oct 9, 2005
    Actually in the case of MPEG-4 and MPEG-2 the encoding is where the compression occurs.
     
  5. harsh

    harsh Beware the Attack Basset

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    Jun 14, 2003
    Salem, OR
    MPEG4 is uniquely a compression method. Whether dish uses it or not is another issue, but when they do, the MPEG4 receivers will be able to decode it.
     
  6. SaltiDawg

    SaltiDawg New Member

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    Aug 30, 2004
    I now see that. Thanks.
     
  7. Rob Glasser

    Rob Glasser Hall Of Fame Staff Member Super Moderator DBSTalk Club

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    Feb 22, 2005
    Sorry for the delay, just got back in town. In the Seattle area I'd say they look the same. I'm guessing nothing is being compressed, they are sending the entire feed. I can't say for sure. I don't have them in my house, I've just watched them at friend's and family's houses, so I can't compare them side by side.

    Going back briefly to MPEG4 encoding and compression. The differences vary from channel to channel. In some cases it's very minor and if I wasn't on a 42" plasma sitting 7ft from the TV I probably wouldn't notice it. i.e. if I had a 37" plasma like you I may not pick up on differences myself. However, other channels, in this case NBC, which multicasts, it is a fairly big difference. My guess is the source isn't as pristine so the encoding and compression amplifies the flaws, just like any any other encoding process that involves compression. You see the same thing on SD MPEG2 encoding and compression.
     
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