Building my own DVR with Linux and Comcast

When you hear talk of clear verses encrypted digital cable channels they are talking about QAM most TVs nowadays can decode clear (unencrypted) QAM and many tv tuner cards can decode clear QAM. Cable companies are required to send some channels in the clear to their subscribers but typically they don't tell them which channel or sub channel they are on. the only likely way to get all of your digital channels is to connect the video and audio out of your set top box directly into your capture card and then use the dvr software to control the set-top box via an IR blaster. My understanding is that cable card probably won work well if at all in Linux. If you want to do this from a hobby standpoint to learn about all of this that's great but if you want something that will just work without hours of tweaking just get a DVR from Comcast.

The software project you are looking for is called http://www.mythtv.org/, and specifically (since you mention ubuntu) you probably want the http://www.mythbuntu.org/ distribution. A list of compatible tuner cards can be found http://pvrhw.goldfish.org/tiki-page.php?pageName=pvrhw_tuners. I personally used a Hauppauge WinTV PVR 350 for a few years in my mythbox, but that was pre-digital cable.

So: a) Encrypted channels are not necessarily HD, they are also channels that they bother to encrypt for whatever reason. On Time Warner in Brooklyn, for instance, I can get the networks, cable access, some shopping, Food Network and TNT "in the clear" everything else is encrypted. I'd definitely look into this before going down that route. That being said, you should still be able to get the analog channels (maybe). b) You can get around this with a cablecard. The cablecard is basically the decrypting-only part of the set top box. Unfortunately, because of Big Legal Things, you can only get a cablecard in a Vista-Only peripheral in a PC with a special BIOS from the manufacturer. http://www.engadgethd.com/2009/05/12/how-to-install-a-cablecard-tuner-in-your-diy-media-center?icid=sphere_blogsmith_inpage_engadgethd Just so you're aware of the state of things, MythBuntu's april fools joke this year was to announce CableCard support. . . http://www.mythbuntu.org/cablecard? c) It sounds like you already have a cable box. I don't know anything about it, but I believe you can use what's called an "IR blaster" to have your computer control the cable box as if it were a remote. This way the computer would not be doing any of the actual tuning, it would just be recording the raw analog out from the set top box. You would only be able to record one stream at a time this way, as it would be whatever the cable box was playing. Honestly, unless you have a good reason for it, or are bored, I've never really found a great reason for rolling your own DVR. But, I usually don't archive things myself (easier to download from usenet than to capture), so what do I know. Good luck!

The other option, I believe, is to record the programs off the cable box via firewire. I don't remember if it works for encrypted QAM. I have done it with a Motorola box and a Windows PVR with some modifications, and it worked pretty well. Another problem I constantly run into is that my cable company constantly changes the channels that the stations are on. So my PVR (BeyondTV) starts recording, but there is nothing on that channel. I then have to go through the setup process again. I love the PC-as-PVR, but that's a huge pain.

your simplest path to victory: 1. install MythTV w/ Ubuntu or other compatible Linux Distro 2. acquire a http://www.mythtv.org/wiki/Hauppauge_HD-PVR and get around the requirement for a cablecard in your PC 3. use https://help.ubuntu.com/community/MythTV_External_Channel_Changer to change channels on your set top box To gjc's point above regarding recording via firewire, when I was an RCN customer, I was able to hookup a firewire cable to capture the digital transport file for all of my channels as RCN didn't 5c encrypt their firewire ports at all. So, I was all about having digitally perfect HD copies of Return of The Jedi and The Prestige recorded off of Cinemax or Showtime. It is still, to my mind, the best way to go if you have a provider who is charitable enough to leave this hole open in their distribution channels. Both Verizon FIOS and Comcast encrypt their firewire ports, so now I'm dealing with the pale shadow that is the Hauppauge HD-PVR and its associated flakiness. In my experience, the HD-PVR has had about a 90% success rate with recording stuff and not losing anything or crapping out in the middle of a broadcast. The 10% of stuff is tolerable because I can just re-record the broadcast, but I imagine that if I was a sports fan or had some other demand for recording live events, I'd be pretty annoyed by it over time.

bl1nk has it, but I don't think firewire will work to change channels. Not a problem since the Hauppauge has an IR blaster that will.

You should definitely head over to the SageTV forums (http://forums.sagetv.com). I have used SageTV (on Windows) for years and it's a great product. Not free or open source, but well worth the money at $80. To record more than one program, you'll need more than one tuner. If you want both tuners to have the same lineup, and you have cable boxes, you'll need to rent more than one cable box. For changing the channels via IR to the cable box, I recommend the USB-UIRT. Sage has some great benefits: - low power extenders boxes (so that you don't have to put a computer at each viewing location, although you could if you want to) - integrated video, music, and photo libraries - a strong, helpful forum - solid support (although email only) - many user-developed plugins They have a 2 week trial. Give it a try!

I am currently using the firewire cable to change channels on my Verizon FIOS set-top box with an HTPC that has been running for four years, so step 3 isn't some piece of advice that I pulled out of vicarious trawling of forums. I'd also give a huge thumbs up to Sage.TV, they're a great option if you want something that just works and aren't particularly interested in tinkering (though there is still a lot to tinker with on Sage)

Sorry, but folks saying you can't use a cable card with a PC are simply wrong. We have that set up, and it works. Yes, they seem to change the channel set-up, and that IS a pain. But we just got around to implementing HD, and it's good. The HD is decoded in the new graphics card. With our cable setup, you can sometimes record 2 different things at once. It has to do with the tuning. Apparently, there are multiple channels for a given tuning. If both things you want are from related tunings, then you're good. (I don't handle the technical stuff on the PVR, it bores me. The other half enjoys it). We're running Mythbuntu on a dedicated box, configured specifically for compatibility with things Linux, and being quiet. This is our second MythTV box, and our second configuration when we moved from South Africa to Switzerland. In South Africa, the system worked like a charm, but we didn't have the computer doing the tuning. Here, it seems to be a constant fight, but maybe now it will settle down (until the next time they remap the tunings). Oh, to be fair, our arrangement is extra complicated because we are only interested in English language material, and so our main channels are from the UK, so we have to get schedule information from multiple sources (Swiss channels frequently have an English audio choice). Frankly, the local cable company seems seriously amateurish to us.