[mythtv-users] Trying to understand the multiplex values

[Harry Devine]

Kevin Kuphal wrote:
> On Dec 17, 2007 8:56 PM, Harry Devine <lifter89 at comcast.net 
> <mailto:lifter89 at comcast.net>> wrote:
>
>     Hello everyone,
>
>     I've been having trouble getting my Myth box to tune all of the
>     channels
>     that is being provided by Comcast.  I just upgraded to the SVN
>     build as
>     of 11/19/07, and tonight I thought I'd go through the effort of
>     re-scanning my channels to see if my luck has improved.  I have my
>     system set to NTSC for TV Format, us-cable as my frequency table (in
>     mythtv-setup), and when I scan my channels on QAM-256 using the Cable
>     frequency table, I get alot of channels that are named
>     UNKNOWN108#5, etc.
>
>     Now, taking that channel as an example, I'm trying to figure out what
>     the relationship is between the information for that channel in the
>     channel table and the dtv_multiplex table.  For this channel, I
>     see the
>     following (I'm only showing the relevant columns):
>     chanid   channum   freqid   sourceid       callsign
>     mplexid   serviceid
>     2112      108#5      108      1            UNKNOWN108#5   67      
>          11
>
>     For the dtv_multiplex table, I see the following information:
>     mplexid   sourceid   frequency       modulation   sistandard
>     67            1            699000000    qam_256      atsc
>
>     How does all of this information tie together?   
>
>  
> The mplexid from the channel table ties the channel to the frequency.  
> The service ID represents the PID (I think I have that right).  How 
> you identify the channels really doesn't have much to do with any of 
> those.  You really need to tune each channel in the frontend, bring up 
> the channel editor, and enter the XMLTVID for the channel which will 
> tie it to the guide data.  I believe from that editor then you can 
> also change the callsign to match your channel for easier 
> identification.  Remember, channel numbers really mean very little 
> since the tuning information on QAM is the frequency and serviceid.
>  
> I think it is all outlined here:
>  
> http://www.mythtv.org/wiki/index.php/Frontend_Channel_Editor
>  
> Kevin
I did that initially when I setup my system, but when I rescanned 
tonight, I told it to delete all channels, so I'll have to do it again.  
Luckily, I created a spreadsheet that contained all of the xmltvid's in 
it for the channels that I do get, so it shouldn't be too difficult.  
The last time I did this, I found that I only can tune 50 of 
approximately 320 channels (50 that I could determine what the channel 
was).  The remaining channels are left as UNKNOWN???#? (i.e. UNKNOWN108#5).

As a side note, I also have Firewire running to my STB.  When I go to 
the Firewire setup in mythtv-setup, I don't do a scan.  I click "Fetch 
channels from listing source", but I don't see any difference in 
channels.  I only have 1 channel lineup with SchedulesDirect that I'm 
using for both my tuner card (pcHDTV 5500) and Firewire inputs.  Any 
ideas on this?

Thanks for the help,
Harry