[TriLUG] mythtv, QAM 256, & Time Warner Cable...

[Aaron S. Joyner]

Trey Ethridge wrote:

>Is anyone currently running mythtv and using Time Warner cable?  I'd
>like to know what channels I can receive by just hooking up the cable
>to a pcHDTV 5500 tuner card (I'm considering buying one).  I believe
>that I can receive some channels since they use QAM.  Could I receive
>digital channels in addition to the analog and HD channels?
>
>Right now, I have the digital cable package and the HD PVR from
>Scientific Atlantic.  I would like to replace it with a mythtv box, but
>I don't want to loose functionality.  If I would have to watch just HD
>channels and analog channels, then I think I'll stick with what I have
>now.  
>
>Thanks,
>-- Trey
>  
>
So this isn't really what you asked about, but I'll throw it out 
anyway.  Since moving out to CA, and recently acquiring a 50" plasma TV, 
I've started tinkering with MythTV.  I picked up a pcHDTV 3000 a while 
back, and it works reasonably well to receive QAM256 cable from Comcast, 
locally.  I only have basic cable (2 through 30-something, and some 
other high-order channels thrown in, 82, 86, golf, home shopping, 
whatever), yet I'm able to get almost all of those cables over the 
QAM256 modulation, as well as some that I can't tune via normal NTSC 
cable broadcast.  This includes more than 10 HD channels, even some I 
was very surprised to find on my basic cable (ESPNHD, ESPN2HD, etc).

So, this is where the words of caution start.  Up until mythtv 0.20 
(released just recently), it was *very* *bad* at dealing with errors in 
the mpeg stream.  By very bad I mean the front end would simply freeze, 
crashing out-right, and occasionally the backend would crash as well.  
Errors in the stream seems to be a frequent problem with Comcast, and I 
think it's something stupid the local guys are doing, as the errors 
often occur on the break between national and local commercials (thus, 
commercial skipping is sketchy, and fast forwarding through the 
commercials often results in a crash -- very annoying).  Having said 
that, it's better with 0.20, in that it often can make it past the 
errors in the stream, but it's still occasionally a problem.  At this 
point, I might make it through watching a single program, successfully 
skipping commercials, 20% of the time.  70-75% of the time I'll hit a 
snag, and crash at least once during a program, but can navigate past 
that point with careful use of the time skipping (ie. ffwing to 10 mins 
before, and skipping 10 min at a time, past the error).  The remaining 
5-10% of the time, I'll hit an error that the frontend simply can't get 
past, or the backend will mysteriously crash during the recording, with 
no output at all.  So, QAM256 users with pcHDTV cards... please do give 
it a try, but be ready to stick through a potentially non-perfect 
experience.

A note on comparing what's available in one area, vs another.  At my 
house, technically in San Jose, and part of the San Jose Comcast 
department, I get the experience described above.  Joel lives ~8 miles 
away, has the same service from the same company (Comcast, although in 
Sunnyvale not San Jose), and gets essentially no channels over QAM256.  
He gets the "must carry" channels, ie. the networks in HD and analog, 
but he actually gets more channels with a simple indoor hdtv antenna.  
Be careful of assuming you'll get the same results as your relatively 
near-by neighbor.

I'd be very curious to hear about other's experience with pcHDTV cards 
and QAM256,
Aaron S. Joyner