[Solved] how to "rescan" on MythTV

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jim247
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[Solved] how to "rescan" on MythTV

Post by jim247 » Wed Oct 16, 2019 2:34 am

The US is in the process of moving broadcast stations to different frequencies. This is due to the FCC reallocating the broadcast spectrum to auction off some of it. Stations in my area are in the process of moving. About half (14) of the stations will move. The first one occurred today. WTTW (virtual) Channel 11 has moved from 47 to 25. The station sent out a notice that everyone needs to rescan their TV. Now that they have moved, I have confirmed that I can no longer record the channel on MythTV.

What do I need to do to “rescan” on MythTV?

I am particularly concerned about losing my recording schedule and/or losing my recording history. Will the procedure to “rescan” ruin either of those?

I am running Ubuntu 18.04, MythTV 2:29.1+fixes.201909121531, HDHomeRun tuner, and an over-the-air antenna.

wesnewell
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Re: how to "rescan" on MythTV

Post by wesnewell » Wed Oct 16, 2019 4:29 am

With normal tuners, run mythtv-setup, Channel editor, delete affected or all channels and scan again. There may be more things you have to do with hdhr or other standalone devices.
BE/FE-Asrock AB350 Pro AMD Ryzen 3 2200G, 6 atsc tuners. Frontends-GF8200's,,AMD Athlon II's. Mythtv user since 2005.

wmorrison
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Re: how to "rescan" on MythTV

Post by wmorrison » Thu Oct 17, 2019 8:14 pm

I haven't had to deal with this because the channels in my area had moved (in August) before I got my system running to the point of scheduling recordings. Not sure if there is another phase coming.

I did run some rescans while setting the system up, didn't have to delete anything first, and didn't end up with any duplicate/dead channels in the database. Can't remember whether any channels were still moving during all this or whether it was after.

I was using antennaweb.org and tvfool.com to try and keep up with repacked channels, but found they are sometimes weeks behind, if not more. MythTV would find channels on frequencies other than those shown on those sites. Or even the official FCC site.

Definitely not an expert but I believe there are IDs for channels which should not change even if the frequency changes, so I assume a rescan should be able to resolve these changes.

Maybe make a database backup just before you rescan, so you can restore if anything really messes up?

What I did is, even though I'll probably never watch TV directly through the TV's tuner, I used a splitter to feed both the TV antenna input and MythTV. That way, I can test channel scans on the TV before doing one in MythTV. Or just move the coax from the MythTV box to the TV antenna input if you're in a hurry.

jim247
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Re: how to "rescan" on MythTV

Post by jim247 » Thu Oct 24, 2019 2:46 am

Just a followup. I ran mythtv-setup, Channel editor, delete all channels, and scan as suggested by wesnewell and it went fine. The moved channels are recordable again. The recording schedule and recording history were not impacted. Some channels had NO DATA in the lists, but it turned out that I had those channels disabled in SchedulesDirect. Once I enabled the channels in SchedulesDirect and did a fill, all channels had data in the listings. Thanks everyone.

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