[mythtv-users] Digital switchover channel confusion

John Pilkington J.Pilk at tesco.net
Fri Apr 1 09:00:27 UTC 2011

On 31/03/11 10:53, Mike Perkins wrote:
> On 30/03/11 21:19, John Pilkington wrote:
>> For the Waltham transmitter the multiplexes are now on 490, 538, 570,
>> 642, 666 and 698 MHz.  The 538 has moved from 514.  The 'new' multiplex
>> that I saw ( and deleted) was from the Nottingham relay.  I think I
>> should have deleted all channels before scanning the new set of muxes;
>> I'll try that later.
> Yup. I guess the digital scanning system isn't particularly optimised for UK
> users. I find that to get the best results I have to do the following:
> - Delete all channels.
> - Do a full scan to pick up all available muxes.
> - Figure out which muxes I'm actually interested in by reference to web
> documents [1].
> - Using the Transport Editor, delete('D') the extraneous ones [2].
> - Do a scan of each specific transport one by one, carefully replying 'Ignore'
> to all questions about off-air channels. Note. This /will/ give you different
> results than you would get doing an all-transport scan. No idea why.
> - Run tv_grab_uk_rt --configure<sourcename>  to get list of xmltvids
> - Use the channel editor to insert the correct xmltvids [3] in the channel
> entries for those channels I am interested in [4], otherwise the next run of
> mythfilldatabase will fail to match anything and insert a whole load of
> duplicate - and useless - channel entries [5].
> [1] The transmitter name is available in the received data, because you can see
> it scrolling up the 'terminal' screen during the scan. This field ought to be
> added to the mux records in the database and displayed in the transport editor
> to help find the ones of interest.
> [2] The output of the transport editor mux list ought to be sorted on frequency.
> [3] In the US I guess xmltvids are numeric values. In the UK they are URIs and
> can get quite long, I've seen them up to 40 characters or so. Editing these in a
> field that displays about 6 characters is a pain.
> [4] Yeah, I know there's a script I can use to skip this step, but it doesn't
> help when the names of the channels keep changing.
> [5] mfdb appears to match on the 5-character call sign. This is a North-American
> construct, UK channel identifiers are just strings and don't work this way at all.
> Yeah, I know, I should keep up with what's going on and submit patches. Maybe if
> I wasn't so ill and didn't have enough other pressing things to do I would be
> more active here. All I can do right now is perform a QA function. Just running
> the procedure outlined above takes enough effort.
I said I would try a rescan after deleting all channels, so I should 
report back.  The initial deletion is a good idea.  After a rescan 
without it some of the chanids in the filenames bear no obvious 
relationship to the Freeview channel numbers - for example,  BBC Radio 4 
has Freeview number 704 but had a chanid of 19688, so a typical filename 
was 19688_20110330205800.mpg.  After delete-and-rescan that would have 
been 1704_20110330205800.mpg - still cumbersome but more easily identified.

With that brief explanation out of the way I'd say that Mike's procedure 
looks very sound, although I use EIT for programme info and haven't done 
any of the XMLTV related stuff.  And I did find the www.ukfree.tv site 
helpful, even if it isn't definitive.


John P

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