Why is FIOS PQ so much better then DTV?

Discussion in 'DIRECTV General Discussion' started by demarco5, Jan 4, 2011.

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  1. TomCat

    TomCat Broadcast Engineer

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    Thanks, Hasan.

    I would like to make 2 other short comments:

    1) About FIOS not compressing content, that is completely false. A single uncompressed HD signal is 1.485 Gbps. Do we really think they are sending 100 uncompressed HD channels to us on FIOS? Verizon charges what, 40 bucks a month for bandwidth below 10 Mb, yet they can sell us a signal that consumes bandwidth 15 thousand times wider than that for about twice that price? Not in this universe. No consumer ever sees HD content that is not significantly compressed, including Blu-Ray and FIOS. Professionals rarely see it, except on live camera. Some HD is compressed before it even leaves the camera.

    2) As to the compression issue, even if FIOS compresses less, that does not really improve PQ. While we may notice increased artifacts ON MOTION with more compression, moving images are difficult to judge PQ on, so we naturally judge PQ by static images. If you compress you have fewer bits left to handle motion, but still images only need a certain number of bits to be rendered perfectly, and EVERY vendor compresses less than to that level, meaning that PQ is not really different between any of the vendors for the 99.9% of the time where there is not significant motion.

    If one vendor can have superior PQ to another, why is it that the PQ of OTA signals that I can record and play back on my DVR is virtually identical to the PQ of the very same signal (received by DTV and converted to MPEG-4 and then compressed even more) received via sat and recorded and played back on the very same DVR and display?

    If trained eyes can't tell the difference between the original and the processed version from DTV, then how can any other vendor's PQ be superior to the original? It can't.

    If you need to argue PQ (at least in the area of content distribution by established content vendors), get in your Wayback machine and travel to 2004, when there were infrastructure gaps, gaps long since closed making the PQ argument all but moot, because this is 2011 and things have changed leaving those arguments in the dustbin of history. Production PQ can vary, internet distribution PQ can vary, PQ of various displays can vary (as can the subjective judgment of PQ) but there is little if any visible difference between the delivered product of OTA and cable, sat, and fiber vendors that even the best trained eyes can discern.
     
  2. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    TomCat,

    A couple of "tweaks" to your post [not disagreeing]:
    FIOS simply is passing on what they get, so "in the marketing world" they can spin this as not compressing it [any more!!!], which a "dumb consumer" misunderstands [you gotta love marketing :nono2:].
    I have seen slight differences between OTA & DirecTV's MPEG-4 PQ, though your use of "virtually identical" falls within the difference.
    "Most notably" this was seen in, as you've said, fast action sports and in this case was a basketball game, with a player's dreadlocks, during a fast break down court, were quite obviously not being displayed the same.
     
  3. jpl

    jpl Hall Of Fame

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    I'll throw one more caveat out there with the notion that compression only reall affects motion. It does affect motion (greater compression artifacts like blocking), but it's not true that there's no impact to more static images if you overly compress. I can see it with folks who have Comcast over FiOS - including my wife's uncle who has virtually the identical TV that I do... and since I was the one who set it up for them, the differences in setup are extremely small). I can definitely see the affects of compression on movement. But I also see it on static images. The picture doesn't look as sharp... the colors look more muted... the picture doesn't 'pop' like it does on my TV. Those bits go to more than just displaying picture for motion.

    That being said, it is correct to say that Verizon doesn't send uncompressed PQ to your TV (which is probably why Verizon dropped that notion from their advertizing). They don't do additional compression. The worst that they do is to take mpeg-4 source material and convert to mpeg-2.

    I will agree that it really comes down to what works for each consumer. I've seen some of the mpeg-4 HD from DirecTV (another friend's house) and the PQ is damn nice. SD is another matter entirely. If there is any difference, I really don't think it's anything to lose sleep over.
     
  4. Reaper

    Reaper Godfather

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    FiOS doesn't ADD compression, they pass on what they receive (though MPEG-4 signals are transcoded to MPEG-2). DIRECTV, Dish, etc add compression to the signals they receive.
     
  5. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    DirecTV changes the MPEG-2 to MPEG-4, but changing the compression method, isn't the same as "adding compression", unless you can show anything to support your claim.
    SD is a whole other issue as the image is reduced to 480 x 480.
     
  6. P Smith

    P Smith Mr. FixAnything

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    Why not ? One lossy compression plus another lossy compression will definitely degrade picture more then one stage.
     
  7. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    This could be true if these were cascaded, which I simply don't know.
    "Would this" be true if the MPEG-2 was decompressed and then compressed with MPEG-4?
    "It would seem", that an OTA which isn't more than 19 Mb/s, could be become 9-12 Mb/s "simply" by changing to MPEG-4.

    For any of use to know, we'd need to be able to monitor the source, and use it to compare.
     
  8. P Smith

    P Smith Mr. FixAnything

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    I see it as inducing 'noise' in two stages, one after other, rather then one. So it will bring double MPEG transforming 'noise' if not multiply it. :(
     
  9. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    "but" the first stage is a given, unless DirecTV was given access to the uncompressed feed first.
    FIOS would have this same noise.
    The transcoding could add more noise, but if it does it would seem to be very slight to barely noticeable.
    I'm fairly sure most of us would love to have a 40 Mb/s feed for each channel, but I'm also sure few of us would want to pay for this bandwidth too.
     
  10. P Smith

    P Smith Mr. FixAnything

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    I see no problem to get the 40-50 Mbps bandwidth. :) Bru-Ray Player, hehe.
     
  11. Gooney

    Gooney New Member

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    Quote:
    Originally Posted by P Smith View Post
    Why not ? One lossy compression plus another lossy compression will definitely degrade picture more then one stage.
    This could be true if these were cascaded, which I simply don't know.
    "Would this" be true if the MPEG-2 was decompressed and then compressed with MPEG-4?
    "It would seem", that an OTA which isn't more than 19 Mb/s, could be become 9-12 Mb/s "simply" by changing to MPEG-4."


    Hi guys.... there is a lot of confusion in the whole "compression" area because of the terminology used. Nobody liked the accurate verbiage, either in audio (eg MP3) or video. Most people think of compression as like 'pushing all the air out of something" so it is smaller, and later it can be decompressed by letting air back in. All that has NOTHING to do with media compression. It is actually "digital bit reduction". The various methods, MP3, MPEG2 OR MPEG4 decide which audio or visual elements you cannot hear or see. A filter removes that part of the audio or video. It is gone. Forever. Like if you made your family compressed by throwing the wife and teen out the plane window. Can't uncompress that situation. Nonetheless you are happy because of compression. So the audio or video that is "compressed" is gone forever; there is no parity track that lets you add it back. Now, if you transcode, or compress again, the second - and different - formula decides there are audio or video elements on this previously bit reducted sound or picture, which is no longer in its original, virgin film quality and fullness, and picks out elements it thinks your brain won't miss that were left in the first encoding. So to make a long story longer, yes, multiple encodings remove more information. That said, I don't think the first couple are noticeable if bandwidth is sufficient. OTOH, even one encoding will sound or look terrible if BW is nil; think cell phone sound.
     
  12. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    Gooney

    You mean the TV shows are faking it when they pull up a license plate from 2-4 pixels from an ATM camera? :confused: Oh my. !rolling
     
  13. HoTat2

    HoTat2 Hall Of Fame

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    Los...
    And Gooney in your "compressed family" analogy are you saying that there are family situations where the loss of one's wife and teen could be considered as "imperceptible?" :lol:
     
  14. Reaper

    Reaper Godfather

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    This isn't compression though. As previous posters stated, compression is when software removes information that is purported to be unnoticable to the naked eye. Squeezing the air out is a fine anaology. What D* does with its SD channels is down-rezing - or stripping out pixels that WILL be visibly missed.
     
  15. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    Maybe semantics, but if you reduce the pixel count and then average it back in, you have lost image information and compressed it into a smaller bandwidth.
     
  16. Gooney

    Gooney New Member

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    Ummm, actually I thought I was quite clear that the family situation was indeed perceptible..... and would most likely make one happier due to the reduced...... er, compressed.... er..... size, ummm... WE ARE GOING TO BE 70 TOMORROW HERE IN FLORIDA!!!!!
     
  17. Gooney

    Gooney New Member

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    Are you trying to be a pain in my aching NCIS LA?????
     
  18. Brennok

    Brennok Legend

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    [YOUTUBE]PaMdXjTn9rc[/YOUTUBE]
     

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