[mythtv-users] How To Deal With New and Modified Channels and Scanning?

Douglas Peale Douglas_Peale at comcast.net
Sat Sep 17 21:10:56 UTC 2011

On 09/17/2011 01:45 PM, Brian Fischer wrote:
> I am currently on Comcast in Michigan.  Comcast enjoys changing channel
> frequencies at least every 6 months which has been a painful process.
> My current method is to head back to mythtv-setup and re-run the channel
> scanner.  For channels that are not found, I "delete", for channels that
> have "changed" I update, and for "new" channels I add.
> There are a few problems with this method:
> 1. The problem is that the majority of new channels only get a "partial
> lock" and do not display anything.  Is there a way to automatically remove
> these?  I am comfortable with python scripts, but am not sure on how to tune
> a new channel on my Air2PC card or HDHomeRun.
> 2. channum, callsign, and description fields seem to be reset although the
> XMLTVID is maintained.  Does anyone have suggestions on how to maintain
> these?  Why is the XMLTVID maintained although everything else has changed?
> Any advice on how to ease the "rescan" process would be greatly
> appreciated...
> -Brian
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> mythtv-users mailing list
> mythtv-users at mythtv.org
> http://www.mythtv.org/mailman/listinfo/mythtv-users
Comcast usually only messes with a couple of channels at a time.

I use the HDHomeRun Config GUI to see which channels have changed (keep a spread sheet of channels so you can see what changed
since you last looked), then I use the "MythTV Backend Setup" channel scanner to scan only the channels that have changed. This
way I don't have to edit every single channel every time, just those on transport streams that have changed.

Also the channel editor in mythweb is much easier to deal with than the one in the "MythTV Backend Setup".

Identifying channels is another issue. Comcast has gotten better about including channel IDs, but most are still unidentified.
scte65scan is a useful tool for identifying most of the the SD channels.

This still leaves the problem that no existing channel editor for mythTV will tell you both the frequency ID and the subchannel
ID. For this I use these instructions to dump the channel database from MythTV:

    from a post by inovermyhead on AVS forum

        Re: Identifying channels
        Sorry it took so long but the wife had too many overdue "honey do" projects this past weekend and had no intention of
        allowing me to spend it hunched over the keyboard playing with my toy. Frustrating since I new I was close.

        Anyway, the difficulty I had was trying to figure out how to correctly get into mysql with permissions and what not, and
        also how to select the right database. I'm a complete linux and mythtv noob and had never done any of that before. I'm
        on mythbuntu 9.04 release version. In my case, to get into the database I typed the following at a terminal command line:

            mysql -u mythtv -p mythconverg

        I then entered the password when prompted(mythconverg is the name of the db, and -p tells it to prompt for a password, I

        That got me the mysql prompt which is what I'd been trying to do since Friday. Didn't expect it to take me this long to
        figure it out but I find that this stuff is humbling me daily. From there it was easy, lots of examples of how to use
        the "select" command to display individual channel table entries or the whole table based on some specified criteria. In
        my case I just asked it to dump all rows with sourceid 2 which is what all of the channels found in the scan from the
        backend were assigned to(as also displayed in mythweb). Not sure what fields are most interesting to you but in my case
        it was the serviceid field which corresponds to the virtual channel. I used the following select command to yield a
        nicely formatted table that has everything I'm interested in:

            mysql> select channum, xmltvid, callsign, name, freqid, serviceid, mplexid from channel where sourceid='2';

        I chose to use basically the same column order as the "channel info" table in mythweb so that I can now easily cross
        reference between the two as I make the changes in mythweb.

        Hope this is helpful to you also.

        (edited to fit my machine, and for changes to version 0.22 of MythTV)

You will have to modify the source ID for various sources you have set up.
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