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DirecTV National HD Listing/Maps Discussion Thread (Technical - Not Anticipation)

Discussion in 'DIRECTV Programming' started by Sixto, May 29, 2012.

  1. Jul 7, 2012 #301 of 653
    veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    This is why they have horse races.

    I tend to lean more towards #2.
    I think they've looked at the numbers/logs and cut the overhead/headroom a bit tighter.
     
  2. Jul 7, 2012 #302 of 653
    veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    I'm by no means an expert on encoders.
    My understanding is they're basically like JPEG, where they sample a part of the image into bits. The sample size when too large looks like crap.
    MPEG-2 does this for each frame.
    MPEG-4 does this for only what changes in the frames.
    I don't see how "more efficient" would yield anything more than less errors.
    You have only the sample size and the threshold of what determines it to be different from the frame before, that you can change to reduce bit rate. Both would degrade PQ.
     
  3. Jul 7, 2012 #303 of 653
    Davenlr

    Davenlr Geek til I die

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    I may be totally wrong, but I think the current system throws away redundant bits i.e. it is not lossless like some of the audio codecs. I would guess that by being more efficient they might tweak the math to be able to throw away even more bits without a noticeable degradation to the PQ? Or maybe the faster current processors available just make for more calculations/second so they can beef up the analytical pass. I know at home, using a slow 2 pass process vs a 1 pass real time process results in much smaller files. Maybe their upped their processing to allow two pass processing in real time or something to that effect.
     
  4. Jul 7, 2012 #304 of 653
    veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    Throwing away redundant bits is fundamental to the MPEG-2 to MPEG-4 conversion. If the older encoders were producing errors [not throwing all redundant out] then, as I posted, more efficiently might be true.
    The VOD uses multiple passes, which can be done when it isn't real time. This may be what you're talking about as it reduces redundant bits more, or at least in each pass "refines" what it redundant.
     
  5. Jul 7, 2012 #305 of 653
    Davenlr

    Davenlr Geek til I die

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    Yea, basically that is what I am talking about, but with real time encoders using faster processors, the efficiency of that should be increased. As you say, more redundant bits are being thrown out. As the processor speed increases, the closer to real "two-pass" we get.
     
  6. Jul 7, 2012 #306 of 653
    veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    The video editing folks that start with truly uncompressed use banks of servers to encode, so "two-pass" is peanuts.
     
  7. Jul 7, 2012 #307 of 653
    cypherx

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    PA - Berks...
    That's what I always thought... Something along the lines of better processors that can do multi-pass analysis.

    Say the video goes into a 5 second buffer.. The CPUs could run 2 or 4 passes per frame (running at 120 or 240 Hz vs 60). Plus in a buffer they can look between frames better to get more accurate positional information of what changed.

    So what if the output is delayed 5 - 10 seconds. Most people wouldn't know unless they have the same channel tuned in from different providers. That might make you wonder if the ABC Rockin' New Years countdown is spot on.... But everyone watching that feed thinks it is!
     
  8. Jul 7, 2012 #308 of 653
    Sixto

    Sixto Well-Known Member

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    There's a link in this thread to a presentation describing the newest encoding technology. I'm out now but can repost later, or just look back.
     
  9. Jul 7, 2012 #309 of 653
    Davenlr

    Davenlr Geek til I die

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    It is delayed several times anyway. Satellite uplink-downlink-reprocessing-uplink-downlink. I really doubt anyone would care, or notice. Unless they were watching the new years countdown with an atomic clock on top of their TV :)
     
  10. Jul 7, 2012 #310 of 653
    veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    "Maybe" DirecTV's newer batch of encoders might have better processors, but the bulk of their millions of dollars of encoders are only getting firmware updates.
     
  11. Jul 7, 2012 #311 of 653
    cypherx

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    PA - Berks...
    Well firmware updates can bring better performance through optimization and unlock new features so maybe that is helping too.
     
  12. Jul 7, 2012 #312 of 653
    veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    There has been a long standing problem with the #$^$^% Harmonic encoders. "Maybe" DirecTV was finally able to leverage their buying power to get Harmonic to fix their crap.
    "I don't know", but suggested this several years ago and the encoders have improved, since we no longer have the audio dropouts that lasted a couple of years. http://www.dbstalk.com/showthread.php?t=182017
    Maybe this was done in firmware, or maybe they were finally RMA'd and Harmonic addressed the problems.

    :shrug:
     
  13. Jul 7, 2012 #313 of 653
    georule

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    It's here: http://www.globecommsystems.com/pdf/Techforum2010-Ericcson-Wagner.pdf

    The front part of the thing is about mpeg2. The E8190 is the high-end mpeg4 encoder we've been theorizing is at play in the recent changes. Somebody also had a link to a PR where D* is buying encoders from these guys.

    The mpeg4 part of the doc starts at pg27. They claim a 20-25% efficiency improvement over the previous generation E8090 model on pg28.
     
  14. Jul 7, 2012 #314 of 653
    trainman

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    Sherman...
    I actually do have an "atomic" clock above my TV. (Not atomic itself, but it's set from the atomic clock radio signal.)

    So I know DirecTV is a few seconds behind, but that's acceptable.
     
  15. Jul 7, 2012 #315 of 653
    georule

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    They also jiggered channels around --i.e. they didn't just do this to an existing mix + 1. They created a new mix on the TPs where they've done it. So I'd say a combination of #2 and #3 is more likely.

    Of course, it could be a combination of all 3 in different proportions.
     
  16. Jul 7, 2012 #316 of 653
    georule

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    Wouldn't that actually be less errors *for the same bitrate*? The distinction is important, right? Because then you could lower the bitrate to get back to the same error level you had before at the higher, less efficient bitrate.

    Take a peek at that document starting at pg27.
     
  17. Jul 7, 2012 #317 of 653
    veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    I think we all might agree that they know what they're doing. :lol:
     
  18. Jul 7, 2012 #318 of 653
    veryoldschool

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    That all looks well and good, "but" DirecTV is using Harmonic encoders.
    These are the same folks that:

    Local broadcaster uses their MPEG-2 encoder, which feeds the DirecTV MPEG-4 encoder, with the end result having problems.
    The broadcaster checks everything on his end and even sends the encoder back to Harmonic, who say there's nothing wrong. Now the DirecTV Harmonic encoder [more that likely was sent back too] isn't the problem either, but they claim is the feed it's getting.
    So Harmonic has two customers using their encoders and can tell both it's the other encoder that is the problem. :nono:
     
  19. Jul 7, 2012 #319 of 653
    georule

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    Well, you may be better informed than I, or perhaps they're using both in different applications.

    Ericsson certainly thinks D* has been using Ericsson mpeg4 encoders since late 2004 or so.

    http://www.ericsson.com/televisionary/content/ericsson-and-directv-market-leading-hdtv-partnership



    I believe the E8190 was actually developed by another company that Ericsson subsequently bought, and that Sixto can point at a press release saying DirecTV was working with them.
     
  20. Jul 7, 2012 #320 of 653
    Sixto

    Sixto Well-Known Member

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    They both have latest-and-greatest technology that is similar, technology that was not available back several years ago when the satellites were put into service.

    The reference to the document was more of reference to the technology. It's not confirmed which they're using, but it wasn't really important to the discussion, the point is that technology has advanced to allow 6 HD in the same bandwidth as previously only allowed 5 HD for similar picture quality.
     

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