[mythtv-users] Comcast Digital HD and HDTV-5500

[Brian Beaty]

Ok I did figure out the NTSC part, turned out in playing with  
scanning the QAM channels I had altered my xmltv/Zap2It settings  
somehow - going back to labs.zap2it.com and resetting my lineup fixed  
the NTSC scanner and the analog channels now show up with /dev/video  
with the DVB driver.

Still totally stuck on the digital channels though.

-bb


On Nov 18, 2006, at 12:20 AM, Brian Beaty wrote:

> I'm a Comcast Digital/HD subscriber in the Fresno, CA area. I got  
> myth 0.20 up and running via Firewire to the DCT6200 that Comcast  
> gives out as their HD STB. It tuned 85% of my channels (pretty much  
> all but in-demand, PPV, and HD versions of subscription channels).  
> Probably ~150 digital channels, and nearly 100 analog channels total.
>
> After 3 firewire chipsets, I gave up on it, I couldn't get a  
> reliable setup via firewire. The best I could get was about a 50%  
> success rate with recording, the rest of the time the Firewire port  
> would just fail to get any data or fail to change the channel. From  
> all the research I could find, this was "common" with firewire  
> setups (of course, most of the people that write to the mailing  
> list, or post on net are doing so trying to answer problems they  
> have), and I suspect it's more a failing of the DCT6200 than linux  
> firewire support. The firewire issues are not the subject of this  
> letter, however...
>
> So I decided to sink a bit of money into it, and got a pcHDTV 5500  
> card. I studied the wiki carefully (http://www.mythtv.org/wiki/ 
> index.php/Adding_Digital_Cable_Channels_%28For_ATSC/ 
> QAM_Tuner_Cards_--_USA/Canada%29) The driver installed fine, Myth  
> picks it up fine. Scanning channels, I get 210 distinct QAM256  
> channels (which is pretty darn close to what my subscription has).
>
> Some other research on pcHDTV's forums revealed that Comcast strips  
> out all channel/program info, so all 210 channels show up as  
> "Unknown". No big deal. I sat down for 3 hours, going through them  
> in Live TV mode, and editing the channel information.
>
> Out of the 210 channels, only 31 had any signal, and of those 31,  
> only 22 of them actually matched up to anything on my subscription  
> list (9 mystery or bonus channels, depending on how you look at  
> it). The other 177 channels were black background with a small blue  
> square in the lower right hand corner.
>
> I understand that QAM-capable tuner cards can't decode encrypted  
> (5c) digital channels. I also was under the impression that  
> Firewire couldn't pass these channels through either. So ~150  
> channels via firewire, and only 31 via the 5500, it doesn't quite  
> add up. I also can't get NTSC signals via Myth at all (they work  
> fine via tvtime on /dev/video). Supposedly the DVB driver supports  
> this, but scanning /dev/video with myth, and it doesn't even  
> attempt to scan, it just skips right to an empty scan list.
>
> Also interesting to note, is that mythtv's scanner finds 210 QAM  
> channels, linuxtv's dvb apps scan detects 243 QAM channels, and the  
> dtvscan util from pcHDTV finds 252. None of them list any signal  
> strength or channel info, but from what I can tell, this is a bug  
> with DVB support in the 2.6.18 kernel, and Comcast stripping all  
> program information.
>
> I  could get all channels if I use the CATV or S-Video output on  
> the DCT6200 (assuming I can stumble upon getting NTSC working in  
> myth), set the 5500 up to just record NTSC Ch3, and use 6200ch (or  
> an IR blaster, but that would be even more money...) to change the  
> channels; I get all my subscribed channels (even encrypted ones),  
> but I lose HD, still have to go via the STB, and I could have just  
> gotten a $30 capture card rather than a full-blown QAM-compatible  
> HD tuner card - so I'd rather not do this.
>
> For the purposes of troubleshooting, I've connected the tuner card  
> straight to my cable outlet, with no other devices or splitters on  
> my cable line. I'm running Fedora Core 5, Kernel 2.6.18.2239, with  
> the latest 5500 drivers compiled and installed from pcHDTV's site.  
> Myth 0.20-144 from the atrpms distro.
>
> Any advice on getting this 5500 working, or should I ebay it and  
> head back via either the firewire/STB output route?
>
>
> -bb
>