[mythtv-users] hdhomerun scan versus ATSC channel 76

Adam Felson a.f.8 at pobox.com
Sun Sep 23 16:01:31 UTC 2007

On Sep 21, 2007, 5:31 AM briandlong at gmail wrote:
> I'm running MythTV from atrpms-bleeding (SVN from beginning of
> September) and when I scan Cable QAM256 or QAM64, it scans channel 77
> just fine (and finds MyRDC). I've just gotten my HDHR this week and
> I'm running the latest firmware as well.
> Not much help; just another data point.

Yet more information:

The frequency for channel 76 is actually 537000khz.  Myth isn't skipping it, 
it just isn't seeing the two hidef stations on 76.  It isn't that they're 
seen as encrypted -- I've had mythtv scan everything including encrypted and 
it still misses it.

I tried doing the channel scan on myth-20-2 as well as svn versions 12618 
(2007-01-22) and 13949 (7/16/2007).  It was around july when I had done the 
setup the first time around so unless the hdhomerun firmware or the cable 
company is to fault, mythtv should have found the stations.  I'm betting the 
cable company is the problem.  However, HDHR can tune the stations as I've 
seen them on windows vlc.

I discovered a branch in svn called mythtv-channel-scan that looks promising. 
It's scanning is far more robust, but it unfortunately is an unfinished work 
and merely leaves a bunch of incompatible data in some parallel tables.  

I hopeing that I can figure out how mythtv uses the channel and dtv_multiplex 
tables to store hidef channels.  I ran mythtv-setup with '-v database' and it 
looks like it is the serviceid column of the channel table that determines 
which hidef channel gets tuned.  I haven't quite figured out what the 
dtv_multiplex table does.  I've seen examples where several hdtv stations on 
the same frequency will all have the same mplexid.

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