[mythtv-users] Comcast Digital transition Denver

Matt W mwood23 at gmail.com
Fri Feb 12 04:58:23 UTC 2010


On Thu, Feb 11, 2010 at 7:24 PM, Joel Donahue <joel.donahueis at gmail.com> wrote:
> I have a headless masterbackend with 3 of my 5 pvr-150's, so don't need to
> worry about that hardware being able to play anything I believe. I noticed
> the HD-5500 is pci based, and the Clear QAM stream isn't anymore hardware
> intensive than the stream from the 150's, correct? I'm hoping all I'll need
> to upgrade on the backend are the capture cards.

yes, the CPU load for recording is very low, I'm not sure of the exact
numbers but the other night I was recording (and hadn't planned it)
Lost at 720p and Nova (or "NOVA" as the guide calls it now) at 1080i,
simultaneously(!) and the system was barely working.  At that point
it's nearly all disk I/O.  The simultaneous bit comes from the
multiplexing of the channels on the cable; if the card can see two
shows you want (or more) at the same time on the same multiplex, it
can demux them, too.  I was thinking of trying to record the 40 or so
local FM radio channels that Comcast puts on the wire, all
simultaneously :-)  a snippet from scte65scan output:

 960  121.10  2 FM-KQED
 961  121.11  2 FM-KRCB
 962  121.12  2 FM-KCSM
 963  121.13  2 FM-KSJO
 964  121.14  2 FM-KNGY

if you pursue an upgrade with a digital tuner card in comcast digilog
land, scte65scan will be your new best friend :-)


> What resolution are the channels you're receiving over clear QAM? Do they
> provide Standard Def channels or is it all 720p or higher? I don't have any
> high def tv's at the moment and would rather not have to upgrade my video
> cards and/or transcode all my recordings to be able to play them.

I'm a late-comer to anything beyond NTSC 480, and just got an HDTV a
month ago.  But in my area Comcast continues to carry the analog
stations in the low band of the cable which you can still tune with a
traditional cable tuner, up to channel 34 or so (?).  Above that is
where the new material lives.  The whole thing gets 'activated' after
you connect the free STB they give you.  In fact I had several pay
stations in the clear on that box for a couple days til they figured
out I was a lowly premium basic user and shut me out :)  So if you do
get a new tv or a digital tuner box, hook it up to the cable and let
it scan, digital-only if possible.  it may take a while (my Panasonic
took like 10 or 15 minutes) but it found everything.  Locally, Comcast
seems to carry a lot of the SD channels on their traditional channel
number and then the new digital channels on an adjacent channel number
 According to the on-screen info bar on my TV (no myth, just straight
into the TV) I am getting some 720p channels and a few 1080i channels.
 I haven't compared them to actual OTA broadcasts but they look pretty
good.

Oh and I can still watch my old PVR-350 recordings, the myth internal
player handles them just fine with no extra configurations. sure they
may not look so good all blown up on the new screen but at least it's
there.

> Are you using any of the "free" digital tuner boxes with IR blasting? I know
> it's possible to use more than one blaster on a box by using different
> channel change scripts. If you have any advise on IR blasting I'm all ears.

Hmm no, I haven't delved into IR blasting since I thought it was
really cool on my VCR I bought in 1996 :)
But for the true IR blasting power user, a linux box is definitely the way to go

> Yeah if I can't extend my introductory rate for the third time, I'm moving
> to OTA and online streaming. I've played with boxee a while back.

yeah we're lucky in that we live in large metro areas, and digital tv
is all around.  be sure to check Antennaweb for what's available near
you.

> I just ordered my two "free" boxes and they should arrive in 5-8 business
> days according to comcast. If they have only RF outs that wouldn't be too
> big a deal to me. I'll just figure out how to IR blast them and plug them
> into my pvr-150's

hmm will that work?  if it just passes RF along, you'll only be able
to tune the older analog part of the band.  I don't think the cheapie
STB is re-generating QAM  :)

yes my STB box has an RF out but some reason they stuck a 4" long
piece of coax to loop it back into the box..not sure what function
that serves.  other than that, it's the yellow-white-red option.
If you decide to do some tuning without the STB, you give up the
Comcast OSD menus, and the music mix stations they have.  I can see
some use in those things.  But having all this functionality in the
Myth box makes it worth the sacrifice for me. YMMV.  Good luck with
your transition!


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