HDTV picture quality... Why is there so much compression???

Discussion in 'Displays' started by JoeRiley, Nov 6, 2003.

  1. JoeRiley

    JoeRiley Stunt Coordinator

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    I'm not 100% sure this is the right forum, if it's not, I apologize.

    But I get a LOT of what seems to be compression, on all digital channels (at least most of them), including the HD ones. It's tough to explain, but basically for a moment or two, I'll see a pixelated area of the screen... then it will go back to normal for a few seconds, then come back for a beat. Kinda on a rythm like a heart-beat... one second it's what you'd expect of HD, then the next a large area will get pixelated. I assume the whole picture is affected, but you can just notice more in certain areas.


    My question is... is there something wrong and I should get a service call, or is this standard practice by all (or most) cable companies/stations?

    I have Cox HD service, in RI... if anyone near me has had the same problems.
     
  2. Michael TLV

    Michael TLV THX Video Instructor/Calibrator

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    Location:
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    Greetings

    Spend billions of dollars to increase the available bandwidth for all the programming. [​IMG]

    Regards
     
  3. JoeRiley

    JoeRiley Stunt Coordinator

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    So I guess you're saying that it's just normal compression, and not something that can be fixed? (that's what I wanted to know).
     
  4. anthony_b

    anthony_b Screenwriter

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    What might help a bit is to limit the amount of excess cable going from the outside to your tv set. The shorter the length the better. This was the case in my bedroom.
     
  5. Jason Charlton

    Jason Charlton Ambassador

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    Have you calibrated your set using Avia or Digital Video Essentials? Sometimes digital artifacts and compression issues can be minimized with a properly set up display.
     
  6. Jeff Gatie

    Jeff Gatie Lead Actor

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    MichaelTLV is most likely correct. Outside of a bad connection at the set or the pole, the problem is your cable infrastructure does not have the bandwidth and/or reliability to handle the HD signals going through it. The digital breakup is due to loss of signal or a weak signal, most likely due to the lack of bandwidth. It has nothing to do with your set.
     
  7. StephenL

    StephenL Second Unit

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    I receive local digital broadcasts over the air via UHF antenna. Ever since the Washington/Baltimore area PBS stations began digital multicasting (broadcasting one SDTV and one HDTV program simultaneously) the picture quality of the HDTV programs has suffered with noticable compression. I don't think it can accurately be called High Definition.
     
  8. Michael Reuben

    Michael Reuben Studio Mogul

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    If occasional pixelization is all you're suffering, you're doing better than many. I have Time Warner Cable in Manhattan, and I have largely given up watching HD broadcasts. The bandwidth problems are so severe that the picture often disappears completely (sometimes with the sound) for seconds at a time. This happens several times an hour. My wife finally decreed that she'd rather watch a standard definition image but get all of the broadcast.

    M.
     
  9. JoeRiley

    JoeRiley Stunt Coordinator

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    Thanks for the replies, guys.

    It's too bad that they ruin an HD signal by not having enough bandwidth. I know the business side of things (stations make cable co's buy all thier channels, not just one), but maybe it's time to cut back on some of the useless channels to make room for HD. Hell, I get SEVERAL NBA.com/NBATV stations EACH, the same damn station, yet it's on a bunch of different channel numbers.

    I was so excited to finally get HD... yet the constant pixalization pretty much ruins the feel. It's hard not to be distracted by it durring a sports event like football, when every few moments, there's a large pixel shift that's really noticable in the yard lines and in the crowd.

    Like Michael's wife... I'd almost rather just watch a solid Standard Def broadcast then an HD one that constantly shifts.

    Is satellite HD any better?
     
  10. anthony_b

    anthony_b Screenwriter

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    Ive been with cablevision for a month (switched from directv) and I don't notice much pixelization on my 48 inch JVC.
     
  11. Allan Jayne

    Allan Jayne Cinematographer

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    Are you sure the problem is not in your tuner? (set top box, cable box, built in ATSC channel selector if your TV has one) The tuner has to decompress the incoming channel and deliver the 1080i field pair 30 times a second. If the processor inside is not powerful enough, it can't keep up with the data flow on scenes with lots of details and lots of motion and then you get pixellation, tearing, or the other problems you described.

    Video hints:
    http://members.aol.com/ajaynejr/video.htm
     
  12. JoeRiley

    JoeRiley Stunt Coordinator

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    Allan,

    The cable box came from the cable company (Cox), it's a Motorola. It's silver, with a smartcard slot on the front. It upconverts all HD material to 1080i. I'm not sure of the model number, since it's not anywhere on the face of the box.

    On standard def channels, I get a LOT of brightness flicker. Shows will just kind of flicker a shade darker once in a while... but it doesn't really happen on the HD channels (or with DVD, or any other device). Does this seem to be consistent with the other problems?
     
  13. Mike Capulli

    Mike Capulli Stunt Coordinator

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    Im having the same problem with an RCA DTC-100 with DirecTV. Picture looks great, however it seems like when watching a movie, high action scenes are rediculously pixelated. Even though I have good signal strength, the dish is pretty far from the TV.. Perhaps the long cable is the problem? But then howcome some channels are worse than others?
     
  14. Rick Faldo

    Rick Faldo Stunt Coordinator

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    I think you have a Motorola DCT 5100 cable box and according to the cable provider tech in my area, they have been having some problems with pixilization with those boxes. Of course, he didn't have a solution.
    Rick
     

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