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PC-Based Digital Cable Decoder Hack?

Posted by Cliff on from the since-you-can't-TELL-the-cable-box-to-tune-itself dept.

musicbadger asks: "Hey, I just got one of the ATI All-in-Wonder Radeon cards and it is pretty good. It has a 125 cable-ready tuner on the back. I have an IRMAN which allows me to change channels with a regular remote. The AIW allows me to record shows, as well as pause/rewind live TV. But it only tunes in the basic non-premium channels. Shouldn't there be a way to use the same decoder algorithms used in the hacked cable boxes to decode premium channels using the computer's CPU? Of course, I would still pay for the premium channels, this is just a way to allow me to "time-shift" them using my VCR of choice." I think it's high time that decoder boxes had an external input to allow it to be "slaved" to another device. This way, such hacks would be unneeded. What say you? If such devices do already exist, where can they be found?

26 comments

  1. pay? by duplo · · Score: 0

    Of course, I would still pay for the premium channels...

    I was also meaning to pay M$ for those copies of windows I trialed over the years too

    1. Re:Pay? by billcopc · · Score: 1

      Not so. In the case of digital cable, the decoder box is much like traditional pay-tv, in that it is programmed from the CO. You receive all channels, but it decodes only the ones it has been specifically instructed to. The signals are still encrypted when they enter your home. In computer terms, the cable company relies on trusted client (the decoder).

      If you wanted to tape a pay-tv show, you had to daisy chain your cable box to the VCR, and then to the TV, setting both devices to channel 3 or 4 and only using the cable box' integrated tuner. By writing a software-based decoder, you get to watch any channel, whether you've signed up for it or not, without needing to cascade your decoder into the PC's tv-tuner. It results in slightly better image quality and allows you to retain use of your pc's channel tuning abilities, so you can do time-shifting across channels.

      Effectively, for the TiVo to work with premium channels, it would need to decode the signals itself, otherwise it would be restricted to recording only the channel that is active on the cable box.

      --
      -Billco, Fnarg.com
    2. Re:Pay? by lkaos · · Score: 1

      Analog cable is addressable. This means that the cable company sends a special signal to your box that helps your box unscramble the signal. Home-made (illegal) descramblers scan the signal to brute force the descrambling signal. It is not really true that the CO relies on a trusted client but rather on really pure encryption.

      Digital cable is much the same, but more sophisticated. A much more advanced encryption algorthm is used and a public/private key system is used to control authentication.

      Your digital cable box cannot decode channels it's not allow to see. You will also have a much harder time trying to brute force decrypt the channels.

      I think your also confused about how tuners work. TiVos, cable boxes, and PC cards all have a single tuner (most of the time). The tuner can extract ONE channel from a cable stream. A software decoder could not decode one channel and let you watch another one.

      Software decoders work reasonable well for analog cable systems but are just like normal descramblers. They do not work (and probably will _never_ work real-time) for digital cable.

      --
      int func(int a);
      func((b += 3, b));
    3. Re:Pay? by lkaos · · Score: 1

      TiVo has a tuner, similiar to your cable box, but has no descrambling abilities (although it would be relatively easy to add if one had all the source available).

      --
      int func(int a);
      func((b += 3, b));
  2. fsck tv by Gordo · · Score: 2, Informative
    Fsck tv (freshmeat entry) is what you are looking for.

    Project seems to be on the back burner, it was written during the 2.2.13 days, and includes a mod of the xawtv package, and only seems to work for North Amercian cable. FORTYoz you still out there? Anything you want to add?

    1. Re:fsck tv by Gordo · · Score: 1
      *smacks head*

      Err, sorry that is for analog cable only decoding...

      not digital, it's too early in the morning to be posting...

  3. Not really possible... by lkaos · · Score: 2, Informative

    well, fsck works for bttv type cards, not All in wonders so that's out of the question.

    It's pretty simple to decode regular analog scrambled channels. One just has to search for the 20 shade bar and adjust the picture based on that.

    Digital cables a whole nother mess. Digital cable is actually MPEG encoded. It uses a totally different frequency too so the normal tuners can't access these channels. I imagine that the cable company finally wised up and employes some form of encryption for the pay per view channels.

    If each box has a private key, then the cable company can just encrypt the stream with access for only the cable boxes that have order it.

    The truth is I am pretty sure they didn't do it this way but I'm sure it's something to that effect.

    --
    int func(int a);
    func((b += 3, b));
    1. Re:Not really possible... by Anonymous Coward · · Score: 0

      then if I had a radeon how would I look at analog tv then??? hey analog is better that nothing!!

    2. Re:Not really possible... by lkaos · · Score: 1

      Well, if you have a radeon, you can easily look at analog tv with the Xv extension. A relatively new video capture API has also recently been added (if they did it the way I think they did, it is through a v4l loopback device since the Xv interface really is incomplete and has no means for video capture). This interface could then be used to decode frames and display them to screen in pretty close to real time. The bitch is that the ATI cards do everything in CYV(sp) instead of RGB so it's a little different to search but the basic algorithm is this:

      begin searching the first line for a 20 shade difference (color changes but it will always be about 20 shades lighter where that little bar is). Once you find that on the first line, it is reasonable to assume that on the next line, that same bar should be about that same position (there is a slight variance, but not much usually).

      Use this as a basis to copy the data in to the video overlay area. The real question I guess is it possible to put the AIW cards in something other than overlay mode. You'll never succeed if you try to just go through normal displays to display the data. You'll need an overlay area. Since the AIW drivers are mostly in usermode implement through X, this means some X hacking (not very fun...).

      The video capture stuff is relatively new and I haven't followed the project in quite some time but email me if you actually get anywhere on it...

      --
      int func(int a);
      func((b += 3, b));
    3. Re:Not really possible... by GiMP · · Score: 1

      Yes, public/private key cryptography is being used already. I know for a fact that my digital cable uses it.. I managed to find white papers on the box which my cable company (adelphia) uses.

      The box I have hasn't been fully exploited however, it has usb support which seems to have no use with the software installed. It does have some kind of proprietary removable media bay, but I haven't investigated this throughly yet.

  4. Pay? by man_ls · · Score: 2

    Now, would you *really* pay for the channels, or was that just the way to get the question posted? Ohh that reminds me, I need to pay for my copies of Windows...Ohh well I paid for Windows 3.1, I'll just keep using these that I have.

    The flamebait out of the way, its an interesting idea. How does the TiVo work? Does it do the actual decoding, or does it just slave to your decoder box? I'd imagine if you had a hacked decoder, you could just connect the video-out coax cable to the video-in coax port on your ATI card, and go like that - but that implies you actually have a hacked decoder.

    Try SourceForge. There's a lot of good stuff there.

    JKoebel

  5. Re:TiVo by CMiYC · · Score: 2

    TiVo just sits between the Cable Box and your TV (or whatever your setup). It doesn't do any decoding of cable channels what so ever.

  6. would have to be "adressable" by BroadbandBradley · · Score: 2

    Much like an ISP would hand you an IP, your digital box is addressable. When you change channels on a digital system, your box tells the headend "give me this channel" so it's not like you can just decode the stream coming down the pipe, digital is a 2 way deal. Many if not most cable systems are working twords all digital and will drop the analog part of the frequency as soon as they can (I think FCC is making them phase analog out slowly for some reason but I may be wrong on that).
    One solution is to use some Infared controller on your pc to make the digital box do it's thing from the PC.

    to see how this all works, go to www.cablemodem.com the cablelabs website. cable labs does DOCSIS certification on equipment, DOCSIS is the Protocol of cable networks and it supports Video, Data(internet) and Telephony (your phone service. if you could design a PCI card that could talk docsis, you could fake like your pc was the digital box, but I'd rather hack an IR to control the digital box.

    --
    "The Most Fun Possible on 4 wheels" is at SunBuggy in Las Vegas
    1. Re:would have to be "adressable" by lkaos · · Score: 1

      The standard for Digital Video (and digital cable) in the US is ATSC (Advanced Television Systems Committee). Because American business people are such pains in the ass, of course we are the only country in the world not using DVB. Many companies are not using ATSC or are using DVB because it is cheaper anyway so there is sort of mass chaos right now in America.

      The FCC has no interest in phasing out analogy but does have interest in standardizing ATSC.

      Your box doesn't request a channel, but rather a frequency range which carries multiple channels. It's actually, a bit more sophisticated than that though...

      --
      int func(int a);
      func((b += 3, b));
    2. Re:would have to be "adressable" by erpbridge · · Score: 1

      "I think FCC is making them phase analog out slowly for some reason but I may be wrong on that"

      I think they're referring to the mandatory HDTV shift in 2005, but I'm not sure... can someone explain the difference between HDTV, digital cable, and analog cable, I think I know but I'm probably wrong.

  7. Extra Cable Box by topham · · Score: 2

    For those of us who are already paying for the service, are there any reasonable options? Is it possible to have a second cable box for digital cable?

    (Slave mode or something.)

    1. Re:Extra Cable Box by DragonPup · · Score: 1

      Yes, second digital boxes can be added, though after 2, there may be problems, depending on the cable company, but you can also add analogs in addition to the digitals depending again on the cable company

      -Henry

      --
      "Useless organic meatbag" -HK-47
  8. Re:TiVo by ncc74656 · · Score: 1
    There are two kinds of Linux users, those who INSTALL it and those who USE it.
    Actually, there are three kinds...the third group consists of those who compile it.
    --
    20 January 2017: the End of an Error.
  9. I wish you luck, but.... by unitron · · Score: 2
    You're talking about a situation that moves control out of the hands of the cable company and into the subscriber's.

    Holdeth not thy breath.

    There aren't enough tech-savvy subcribers to create the demand to make mass-production of the necessary hardware feasible. Telling the local cable company that you want to kludge together their hardware and some do-it-yourself stuff of yours will not be met with enthusiasm.

    If you want to descramble more than one premium channel at a time, you have to rent a separate box from them. If you want remote control over the process, you have to rent a remote control from them. If you don't subscribe to premium channels and have an older TV or VCR that only tunes up to cable channel 36, you'll find that the extra unscrambled channels that you're paying for (CNN, Nickelodeon, etc.) will get shifted up above 36 and the premium channels shifted down so that you have to rent a converter box and remote control from them to get what you're already paying for.

    Beginning to see a trend yet?

    --

    I see even classic Slashdot is now pretty much unusable on dial up anymore.

    1. Re:I wish you luck, but.... by lkaos · · Score: 1

      The business model of most cable companies is dictated by the technologies of their time. The old, analog cable system was too poor to have proper safe guards to prevent theft, hence the stupid limits on cable boxes and such. Once the cable companies work out standards issues, you will probably see cable turn to more of a subscription service where you subscribe to a channel and can then access it on any of your registered devices. They will not have to worry about unauthorized use as before. The scary thing is that they will also probably track how much time you spend watching (or atleast receiving) a certain signal. This could be very interesting as far as privacy and such is concerned.

      --
      int func(int a);
      func((b += 3, b));
    2. Re:I wish you luck, but.... by ivan256 · · Score: 2

      I just wish that they didn't use those stupid limits to essentially charge me for an additional subscription for each TV I wanted to hook up. They could easily charge a very small amount for each box instead of charging $15 a month per box. It sucks paying $55 a month for basic cable on two TVs.

      Oh and also, if they're going to require you to use their external tuner, they could at least provide a decent way of getting the signal to the TV. It sucks that it has to be sent through another tuner again.

    3. Re:I wish you luck, but.... by lkaos · · Score: 1

      Once they phase out analog cable, you'll probably see alot of that changing.

      Alot of the newer equipment has alot of digital throughputs that avoid the whole tuner mess. Right now I go RF from my digital cable to the VCR, but then totally digital connections from there on.

      I have one of the older digital cable boxes but I hear the newer ones have digital outputs too.

      They also have the standard control inputs too so they should theoritically work with a TiVo like device.

      What I still want is a huge splitter that divides all the channels into individual feeds that I can then stream to whatever TV I want.

      --
      int func(int a);
      func((b += 3, b));
    4. Re:I wish you luck, but.... by ivan256 · · Score: 2

      What are you using for a digital interconnect between your components? Which VCR has digital out?

  10. software based non-digital cable decoder? by Anonymous Coward · · Score: 0

    where can i find one? the ones i've found just crash on win98se.

  11. Digital Cable by inKubus · · Score: 1

    You know, a digital cable box is just an Ethernet router.. Probably shouldn't say anything more.

    --
    Cool! Amazing Toys.
  12. Why bother. by thud2000 · · Score: 1

    TV sucks anyway, cable moreso. After years of dealing with continually-escalating cable bills, I finally had ours yanked. Rabbit ears, baby! I get better news on the Net than cable offers anyway; I still get the local news that's hard to find on the Net; and I still watch a little (very little) network stuff. Yeah, I miss some of the cable-only programming, but I'd rather have the extra $45/month, which is what Time Warner's standard package costs in my area.

    The funny thing is, I had intended to go DSS eventually, but the longer I go without all the extra channels the less I miss them. Now I have more time for constructive activity and self-improvement, such as reading Slashdot and playing Diablo. Is it really worth the effort to hack up a PC to emulate a cable box to get scrambled channels that for the most part suck anyway? But yeah, it does have a high cool factor; that in itself is justification enough I suppose.