[mythtv-users] HDHR working but channel mapping is incorrect

JS Boyd mythtv at futures.com
Mon Apr 13 02:46:37 UTC 2009

Ah yes. Isn't Comcast fun?

Given Comcast's current "digital upgrade",  I just went through 
rescanning and then matching the working channels to their listed 
channel numbers and attaching their XMLTV ids. I have a PVR500 for 
analog, an HDHomerun (QAM Tuner) and recently an HDPVR. The hardest to 
get setup and maintain is a QAM tuner on Comcast.

This is a Comcast issue and not an HDHomerun issue.

BTW, I suggest that you number your HDHomerun channels slightly 
differently, by adding a ".5" or something to the channum. Then WHEN 
Comcast moves stuff around *again* you'll be able to immediately tell 
that it is the QAM channels that have changed.

You'll know that has happened when a recording from say the HDTV NBC 
channel becomes a recording of automated current weather as happened  a 
few weeks ago here. Comcast then proceeded to move a lot of channels 
around over a period of about a week before settling on the current QAM 
line up which includes a lot of new clear QAM channels that were 
previously only analog channels.

So there is no getting around the fact that with Comcast you will have 
to go to "Watch TV", watch each channel figure out what it is and then 
use the 'E' key to update the Channel information and XMLTV id for most 
channels found in a MythTV QAM channel scan. (FYI: The "TV Listings" 
portion of the http://www.zap2it.com website is very handy during this 

Comcast updates their cableboxes so that their regional QAM channels are 
mapped to the virtual channels in their listings, but they don't provide 
those mappings to anyone else. And the actual mapping of virtual to QAM 
channels is different in different regions. So while the lineups are 
identical all over a region like the SF Bay Area, the actual mapping of 
QAM mplexid/serviceids to virtual channels is different between cities 
and sometimes even neighborhoods.

This means that my list of Comcast mplexids/serviceids to virtual 
channels does not work outside my immediate area.

So we all scan, watch and edit channel info and XMLTV entries in "Watch 

It would be nice if Comcast had a website where they provided their QAM 
to Virtual Channel lists for each region. If there is such a beast, 
someone please post it's URL!

The good news is that (thankfully) Comcast seems to only change things 
around about once a year. So you don't have to do this chore very often.


Mark Knecht wrote:
> On Sun, Apr 12, 2009 at 5:57 PM, Yeechang Lee <ylee at pobox.com> wrote:
>> Mark Knecht <markknecht at gmail.com> says:
>>> I'm thinking that possibly I've set up the wrong sort of line-up at
>>> SchedulesDirect, choosing OTA vs cable???
>> Yes you did; in your first message you listed an OTA lineup.
> Yes, I did do that wrong, so attempting to follow the HDHR
> instructions on mythtv.org I went back to choose a different lineup.
> The problem I'm having now is that there isn't a lineup specific to
> the HDHR, so I chose the digital cable which at least has all the
> channels the HDHR can tune, but also has lots that only get tuned by a
> read digital STB. Anyway, having done that Myth recognizes a few (15
> maybe) channels - but doesn't map the other 85 to anything. The other
> 85 channels work, the HDHR can tune them, but they work with strange
> channel numbers, like 100#6 instead of 9.2, etc. and don't have
> program guide data yet because they don't have XMLTV IDs.
> I got help offline learning a little about the XMLTV IDs, but I
> haven't figured out where the right channel numbers come from so I'm
> stuck.
> I have a busy week in front of me so in less someone can write a few
> sentences that really turn on the lights for me it's likely to be
> about 2 weekends before I can get back to this again. Disappointed in
> myself in that I've owned this HDHR for 4 months now and it remains
> utterly useless to me.
> I do appreciate your help. Thanks!
> Cheers,
> Mark
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Ubuntu Feisty 7.04
MythTV 0.21-fixes 20018M+VDPAU+HDPVR_patches
AMD 64 x2 4200+ 65W Energy Efficient Processor
Abit NF-N2 nView Motherboard
NVidia 9500GT (VDPAU) fanless 1GB PCIe x16 videocard 
PVR-500 (Phillips Chipset)
 IVTV 0.10.4
HDHomerun /sys/version 20071120
Moto DCH3416 Cablebox + HDPVR & Firewire
2- 500GB Seagate SATA: ST3500641AS Rev 3.AA
1- 1.5TB Seagate SATA: ST31500341AS Rev SD1B

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