[mythtv-users] Repack - Rescan question

[Klaas de Waal]

On Wed, 11 Mar 2020 at 09:19, Stephen Worthington <stephen_agent at jsw.gen.nz>
wrote:

> On Tue, 10 Mar 2020 19:27:24 -0700, you wrote:
>
> >I just ran into the same problem.  I too wonder if there is some automatic
> >way to do a rescan; in the past I've noticed when I scan channels lots of
> >other stuff of I've done needs to be redone (e.g., picking the subset of
> >interest).  FWIW, omitting the rather confused process of figuring out
> what
> >was going on, these were the steps:
> >1. hdhomerun_config  MyTunerID scan 0
> >Results include
> >SCANNING: 575000000 (us-bcast:31)
> >LOCK: 8vsb (ss=100 snq=93 seq=100)
> >TSID: 0x0141
> >PROGRAM 3: 2.1 KTVU-HD
> >PROGRAM 4: 2.2 KTVU-SD
> >PROGRAM 5: 2.3 Movies!
> >PROGRAM 6: 2.4 Buzzr
> >
> >The key items are from the line SCANNING: 575000000 (us-bcast:31)
> >
> >2. In the database find the relevant entries in channels; change freqid to
> >31 there for atsc_major_chan = 2
> >Those records also have an mplexid which can be used to locate a record (I
> >had just one) in dtv_multiplex.
> >
> >3. update dtv_multiplex set frequency=575000000 where mplexid=13;
> >
> >2 alone was insufficient.
> >
> >I know directly messing with the database is frowned on, but it seemed to
> >work for me.
> >
> >Ross
>
> The channel.freqid values are not used for digital TV such as DVB-T
> and ATSC.  What matters is that the channel.mplexid points to a
> dtv_multiplex entry with the correct dtv_multiplex.frequency value.
> Having the freqid value set correctly is only for humans looking at
> the database, so it should either be set correctly, or if it is not
> going to be kept set to the correct values, set to 0.
> _______________________________________________
>
> Figuring out what the problem is and modifying the database to solve your
problem is great fun when it goes OK so enjoy! The flipside is of course
that it can fail but that is life.

As Stephen says, the freqid values are not used anymore but they are still
filled in when you do a scan across frequencies. If you would delete all
channels and then do a "Scan of all transports" then the values are not
filled in.

If you have figured out the old and the new frequency then you can also use
the Transport Editor of mythtv-setup to change the frequency, see
https://www.mythtv.org/wiki/Channel_Scanning#Transport_Editor

Changing the frequency only works if all the bits inside the transport
stream such as the service ID stay the same which appears to be the case
here.
Starting with mythtv v31, if you do a scan on the new frequency like Allen
has done then the channel would have been updated, identified by the major
and minor channel numbers. For older versions you first have to delete the
old channels as Allen has done, or, even better, first delete the old
transport with the Transport Editor which then also deletes all the
channels of that transport.

It would have been much easier if you just can do a "Full Scan" and let
mythtv-setup sort everything out. The problem, as described by Alan, is
that the same transport stream can be received from different transmitters
on different frequencies with as result that the scanner finds duplicate
channels. To be continued...

Klaas.
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