[mythtv-users] UK Freeview - Over a hundred conflicting channels

Mike Perkins mikep at randomtraveller.org.uk
Wed Sep 26 10:00:00 UTC 2012

On 26/09/12 10:12, Dave Sexton wrote:
> Hi List,
> I hope someone can help.
> My region has just gone through the so-called 'Sigital Switchover', where they
> have turned off the old analogue channels, turned up the power a bit on the
> digital channels and added HD channels.
> Before this process started, my myth boxes were able to happily scan for and
> find the fifty or so available channels without any problems. Now after a san,
> it says it is able to find 34 non-conflicting channels and 139 (!) conflicting
> channels. It will not insert any of them automatically and will only suggest
> incorrect channels numbers for them. When I attempt to go through them
> manually I notice that many channels are duplicated.
> I have three separate Myth backends, so I would really like to not have to do
> this manually (using mythtv-setup across a VPN is painful). No normal TV is
> having a problem re-tuning, so it is logically a problem with Myth.
> I have even tried re-creating the 'Video Source' to try and rule out conflicts
> with old data. This did not help any.
> I have also found this bug ticket : http://code.mythtv.org/trac/ticket/10054
> I details what looks to be a similar problem but was fixed on 0.24fixes. I am
> running 0.25.2. Is it possible that there has been a regression in this area?
> The suggest option on the conflict dialog for 'BBC One' suggests channel number
> 4169. For those outside of blighty, BBC One shold be on channel 1. All other
> conflicting channels have equally incorrect suggestions.
> Attached should be the output from mythtv-setup.
> Is there anything I can do to not have to spend hours manually going through
> all of the channels every time I ned to re-tune?
> Thanks in advance,
Short answer - yep, you will, actually, have more than 100 channels sent to you 
when you go digital. The fact that most of them are complete rubbish is neither 
here nor there. I approach this by (eventually) getting a complete list (which 
includes 28 radio channels, BTW) and then setting the ignore flag on those I'm 
not interested in.

As to conflicts - yep, welcome to the club. You'll probably find that you can 
receive signals from more than one transmitter, and these will cause myth to 
attempt to allocate the /same/ channel with alternate numbering.

Note that these numbers are not necessarily a bad thing. 'chanid' is the primary 
key for the table and is (roughly) [source id * 1000] plus a number which just 
increments. For a clean DVB-T table this usually corresponds to 1000 + Freeview 
channel number. 'channum' is usually filled in with the Freeview channel number, 
but as noted above, may be something else for a duplicate. 'freqid' is what myth 
uses to actually /tune/ the channel and, I think, starts out as a copy of 'channum'.

As you watch the 'scan for channels' scroll up take a note of the transmitter 
name. If you know which transmitter is yours then you can use the transport 
editor to remove any extras and then rescan. I can see three so I do this sequence:

(i) full scan of everything.
(ii) note which transports have been found, select /one/ which belongs to my 
transmitter and delete the rest.
(iii) scan this one transport again, checking the 'use other transports' box. 
This should pull in all the other transports (multiplexes) from that transmitter.
(iv) scan each transport individually, taking note to *accept* all channels you 
are offered. The wording on this dialog is quite obscure - pick the wrong option 
and everything gets wiped. (Go to start; do not collect £200.)
(v) Now you need to *carefully* run the --configure part of xmltv, giving 
appropriate answers. Once you have a table of xmltvids go to the channel editor 
and update all those you are interested in. Set the 'ignore' flag on all those 
you don't want and delete those lines from the .xmltv file as well. If you don't 
do this last step mythfilldatabase will keep re-adding them to your channel list.
(vi) Profit! Er, start using your system, I mean...

Note that after the recent renumbering exercise one transport is solely for HD 
channels, so you can ignore that one if you don't have a suitable tuner.

There are ways of shortening this process depending where you are and how much 
time and knowledge you have. Good luck.

-- Mike Perkins

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