Video Quality of Digital Cable

Discussion in 'TiVo Coffee House - TiVo Discussion' started by nrnoble, Aug 9, 2011.

  1. Aug 9, 2011 #1 of 32
    nrnoble

    nrnoble Active Member

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    How do others perceive their cable's video quality is compared to 10-20 years ago?

    My perception is that HDTV signals are only slightly better than high quality SDTV from 20 years ago. For example I use to have a 10ft TVRO sat system in the mid 90s and got channels like HBO, Networks, and backfeeds. Those video signals were perfectly clean, as good as today's DVD video.

    Today I was watching Comcast HBO analog channel and it no better than a standard VHS. Lots of compression artifacts and a very soft picture. HBO HDTV channel looks pretty good, but its slightly better than the HBO standard Def signal was 15 years ago. Scan through all the major channels, most of the standard def channels look like VHS quality, and only the HD channels looked good.
     
  2. Aug 9, 2011 #2 of 32
    takeshi

    takeshi Member

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    It's different. Higher resolution is possible but then you have digital artifacts that were not around with analog. When there's little motion the images are great. A lot of motion means lots of macroblocking. I'm not sure it directly compares to the video quality issues of analog.

    When is the last time you actually watched a VHS tape?
     
  3. Aug 9, 2011 #3 of 32
    atmuscarella

    atmuscarella Well-Known Member

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    Unless you have the same TV you had 10-20 years ago you have no way of doing any type of comparison. Even then you are relying on memory.

    How good your digital HD signal is also depends on lots of factors. Including if your cable company is compressing the signal (and to what extent if they are) and how the program was converted to Digital HD if it wasn't recorded that way.

    The bottom line is a program recorded in digital HD and compressed no more than what is done by the major networks to transmit it Over the Air (OTA) is significantly better quality than any analog signal ever transmitted. On the flip side some old show that was recorded in low quality to start with and which is either still being broadcast in analog or which as had a terrible job done converting it to digital can look like crap.

    So you can be receive very high quality shows and you can also be receiving some very low quality crap.

    P.S.: The reason your TV matters is because for the most part standard def (SD) TV looks better on old tube (CRT) TVs, many of the new HD TVs just don't do SD TV very well.
     
  4. Aug 9, 2011 #4 of 32
    aaronwt

    aaronwt UHD Addict

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    it's a night and day difference. There is very little detail from an SD image. Just take any SD set from 10 or 20 years ago and look at the backgorund. There is little detail in the image. And then look at an HD set with HD content, even with a lower quality signal, like from Uverse, there is still more detail to be seen than from any SD set. And when using a provider like FiOS, the difference is a clear as night and day.

    My girlfriend has an old SOny trinitron set that is over 20 years old. Even feeding it a high quality SD signal from an HD source, it's pretty obvious there is no comparison between the SD picture and an HD on. The detail just isn't there in an SD picture on any set, whether an old tube SD set or an HD set.
     
  5. Aug 9, 2011 #5 of 32
    janry

    janry New Member

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    I agree with what the others have posted. However, I do think my cable provider is compressing more than they were, say 2 years ago, causing some degradation of video quality. I'll admit that maybe my TV has lost some performance over those two years, or maybe my vision isn't as good. I really don't understand the technology enough that I'd dare call the cable company on the carpet for it.

    One experiment I've tried that I find interesting however, is comparing the cable video quality with OTA for local broadcast.

    I connected an antenna to my TiVo and recorded the same 10 minute segment simultaneously for each local channel - one via cable and one via OTA. I then edited each recording in VideoReDo to make sure I had exactly the same starting and end point since there is a few seconds delay in cable. I then compared the resulting files sizes. On two stations, the file sizes were within 2% of each other. Two stations were about 5% different. One was about 10% different. Where I saw a huge difference was on our PBS station's sub-channel that broadcast "Ebert Presents...." (broadcast in 480i). The difference there was 58%, and very noticeable to the casual viewer.

    Oh, and in each case, the cable file was smaller than the OTA file.
     
  6. Aug 9, 2011 #6 of 32
    petew

    petew Active Member

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    One more vote against the OP.

    As other have said it really depends on the quality of the source material. Current TV recorded in HD is an order of magnitude better than SD.

    Also with DVD v BlueRay I find the BD versions of recent release to be far superior to their DVD versions however some BD versions of older movies have been disappointing.

    One final point your perception also depends on the size of screen and distance from the screen. SD looks great on my 32" CRT but unwatchable on the 96" front protection screen.
     
  7. Aug 9, 2011 #7 of 32
    Mike Pfeifer

    Mike Pfeifer What?

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    I recently switched from Directv to Comcast and a TiVo Premier. I have noticed a significant downgrade in the video quality with the switch. I figure it has to do with more compression from Comcast than what Directv was broadcasting. Some channels are more noticeable than others, however. I can see it most in high action footage where I can see tiling artifacts, such as grass blowing in the wind or water waves and splashes, etc. I doubt there is anything I can do about it though, short of switching to another provider.
     
  8. Aug 9, 2011 #8 of 32
    atmuscarella

    atmuscarella Well-Known Member

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    That is the nuts of it different providers use different amounts and different types (MPEG2 & MPEG4) of compression. Also different stations start out with more or less compression before the providers do their thing.

    Your TV, where you sit, and your eyes determine how much difference you can actually see.

    Blu-Ray disks are the Gold standard. After that everything else is something of lesser quality. The major networks OTA prime time HD broadcast are normally very good and premium cable channels like HBO are also normally very good. Streaming can be anything from very good to flat out poor quality.

    Not much one can do about it other than to draw your own line in the quality sand and refuse to purchase/watch anything that doesn't meet your quality standards.
     
  9. Aug 9, 2011 #9 of 32
    miadlor

    miadlor Member

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    A while back I sold my SD 60" Mitsubishi projection to upgrade to my now 50" HD.
    While the HD is great..... SD looked extremely poor (analog no receiver). When I 1st hooked it up, I was wishing I had not upgraded (there were not many HD channels offered at the time). Now I never even go to SD channels.
    Between the Digital SD being compressed and the TV made for HD (SD being stretched as an option) it is a poor picture.

    *I have a sony 27" Trinitron from 1990 hooked up to a S2.......blows away the picture on my 50" SD channels.
     
  10. lrhorer

    lrhorer Active Member

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    The comparison is a ridiculous one. Analog SD doesn't even come close.

    "Clean" is a different issue. Until 1990, I worked as an engineer for a CATV system. Amplifier cascasdes were only supposed to be no more than 21 trunk amps and 2 line extenders deep. Some were up to 26 amplifiers and 3 line extenders deep. I even discovered one that was 4 line extenders deep. USually, within ten amplifiers or so of the headend, PQ was exceptional unless there were problems that needed to be addressed. At the end of the cascades, pictures were at best acceptable most of the time. Some cascades had all manner of stability issues. The tug-of-war between noise and distortion was often a losing battle for the signal.

    Today, most CATV systems deploy no more than 3 amplifiers between the fiber node and the subscriber tap. Both noise and distorion are much lower, but with digital signals, neither are anything like the sort of problem they were with analog.

    Analog signlas do not ever suffer from compression artifacts. They are uncompressed.

    I'm not sure what "soft" means. Poor analog resolution can be produced by bad IF filters in analog translators or modulators.

    Not even. You've just gotten spoiled.

    Try recording one of the channels on a VHS tape and making a side-by-side comparison. The difference is night and day.
     
  11. lrhorer

    lrhorer Active Member

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    San...
    Not true. First of all, as I suggested above, one can haul out an old VCR, tape a digital video, and then compare the two side-by-side. I have a copy of Discover's Planet Earth series that broadcast an SD commercial just before the HD video started. The SD comnmercial looks HORRIBLE. It's blurry and indistinct (not to mention 4:3), and the text, although large, is quite fuzy. When the HD video comes up, it is downright startling.

    These days I can only just tolerate the best DVD material. Analog SD over a miles-long CATV cascade? Forget it, especially in my theater.
     
  12. mattack

    mattack Well-Known Member

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    Huh what? HBO *ANALOG*? I highly doubt that. Plus, it wouldn't have "compression artifacts", unless it was really just the digital channel being rebroadcast as analog (which is actually what is happening for those of us that still have some analog channels).

    (Long ago, I used to get HBO without any cable box.. it was analog, and was filtered outside my house if I unsubscribed.)
     
  13. nrnoble

    nrnoble Active Member

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    IrHorer, You're responses are as if I personally offended you. And overall I'm very surprised at the level of anger and hostility. Try to view my questions and comments more casually as if we were having a friendly discussion, not as if I came into the room and insulted your wife, and you feel its necessary to get into my face because I was very rude to her. I rarely post in the forum, so I don't even think we've communicated before; I don't understand your level over hostility over this issue.

    Under more friendly circumstances, I would go into more detail and explain further of what I meant in my OP, but that would evoke further responses that are argumentative and tear downs. If there are individuals who are interested in having a discussion (without a condescending tone\insult and not looking to debate\argue), I am interested. I know there are people in this forum who have communication skills to have interesting\informative discussions as well as maintain a friendly tone as if we are good neighbors\friends talking in the backyard.

    Thanks :)
     
  14. nrnoble

    nrnoble Active Member

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    I also had a 60 inch Mitsubishi projection TV. When it was connected to my TVRO system, the picture was amazing. It was as good or better than what I was getting from my laserDisc player.... As funny as it might sound, when I first got the TVRO system working. I would love to just watch colorbars from the Sat feeds simply because how amazingly clear the picture was even when compared to laserDiscs.
     
  15. lrhorer

    lrhorer Active Member

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    San...
    Not at all, although your mis-spelling my name is annoying.

    There was no anger or hostility, nor would I be upset if you insulted my wife. IMO, that would be a pretty silly thing to be upset about. I have no idea what you mean by "get into my face". You made a patently absurd statement unsupported by fact or experimentation. I countered. That is all. In these fora, inferring an emotional state from the words posted on the page is a perilous thing to do in any case, but in this case there is no emotional context at all.

    Analog video has a maximum resolution of 480 lines, interlaced. The maximum effective pixel resolution is about 310K, give or take. The S/N is highly variable depending on the transmission medium, but typically may have been no better than 50dB. When the transmission system was impaired, it was often much worse than that. The picture was subject to artifacts from second and third order distortion, ghosting, and interference.

    By comparison, digital signals have resolutions of precisely 1200 x 720 (864K) or 1920 x 1080 (20,736K), depending on the broadcast. The picture may or may not be interlaced. The S/N is precisely the same as whatever it was leaving the broadcaster's equipment, typically 65dB. The picture is not at all subject to artifacts due to noise, distortion, ghosts or interference unless those items (due to defects in the transmission system) exceed maximum tolerance levels, in which case the picture will begin to break up badly. Up until then, it will be "perfect".

    There can be significant artifacts produced by excessive rate shaping at the CATV headend, and artifacts produced by digital conversion are inevitable, although generally un-noticeable to most people most of the time.

    There is little point to this. If your provider is delivering poor service to you, then they need to fix their issues. Shy of that, there is simply no reasonable favorable comparison between analog and digital video, with the exception that analog video fails gracefully with degrading transmission parameters, becoming slowly poorer and poorer in quality, but still watchable, as the system degrades. Digital video, OTOH, will tend to remain absolutely perfect until suddenly it fails altogether.

    This is nonsense. Nothing about my post was in the least argumentative nor did I cast even a single personal aspersion in your direction. This is a technical discussion. There is nothing personal or subjective about it.

    :rolleyes:
     
  16. Gregor

    Gregor save the princess save the world TCF Club

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    From 20 years ago? Much, much better.

    The switch to FIOS (all digital) from Comcast (mix) was nothing short of spectacular. Since FIOS doesn't compress, the pictures are outstanding.
     
  17. lrhorer

    lrhorer Active Member

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    I still have a LASERdisk player, as well as a CED Disk player. The video from the LVD is generally superior to analog video from the CATV system, but significantly inferior to DVD. The DVD's 480i output is OK, but quite inferior to broadcast 1080i or 720p.
     
  18. nrnoble

    nrnoble Active Member

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    I think that this is a factor when I watch SD channels combined with the fact everything analog gets compressed by the TiVo. Nearly all SD channels above 13 are digital (only can be received with cablecard or cable box) so the SD channels are compressed. I've have Starz and and I can stream the Netflix versions and get a better picture than the SD versions of the same movie on cable.
     
  19. dkraft

    dkraft Member

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    My experience is the opposite. I just moved from DirecTv to Tivo Premier this week. The first thing I noticed was how the picture quality was different. Matter of fact, that was the first thing my wife said "Man that picture looks better."

    I have Comcast cable in Naples Florida
     
  20. kenvinlee89

    kenvinlee89 New Member

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    Im new in here, Hope to enjoy this forum
     

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