[mythtv-users] Sources and inputs

Nick Morrott knowledgejunkie at gmail.com
Wed Jul 9 01:01:57 UTC 2008

2008/7/8 Chris Dennis <cgdennis at btinternet.com>:
> Thanks for your comprehensive reply Nick.  It took me a while to get my
> head around it all, and raised more questions I'm afraid.
> Nick Morrott wrote:
>> On 08/07/2008, Chris Dennis <cgdennis at btinternet.com> wrote:
>>> Hello MythTV People
>>>  My MythTV backend has two DVB-S tuner cards, and a twin DVB-T card,
>>>  giving me four inputs in total.
>>>  Having read all the documentation I can find, and tried various
>>>  combinations of settings, I can't work out how many Video Sources I
>>>  should set up.
>>>  DVB-S and DVB-T carry different channels (with some overlap), but the
>>>  only workable xmltv source of listings is tv_grab_uk_rt.
>>>  I've set up a separate channel listing file for DVB-S and DVB-T, i.e.
>>>  the files with lines like   channel cbeebies.bbc.co.uk
>>>  channel channel5.co.uk
>>>  It seems sensible to just have one Video Source defined in mythtv-setup
>>>  for DVB-S, and one for DVB-T, because they refer to a single source of
>>>  information.  But on the other hand, 'Video Source' also seems to mean
>>>  the same thing as 'Input Card' when it comes to switching sources in the
>>>  front-end menu.  If I only define one Video Source, I can't use 'Switch
>>>  Source' from the Live-TV menu.
>>>  What is the best way to set this up?
>> I would define 2 video sources using the tv_grab_uk_rt grabber, and
>> run mythfilldatabase manually for each videosource.
> Do you mean one videosource (as defined in the videosource table) for
> DVB-T and one for DVB-S, or two for each?

One videosource for DVB-T, and one videosource for DVB-S.

>> A video source
>> should contain the channels available on a /card input/ (or card
>> inputs if you associate the same video source to multiple card
>> inputs). Note that multiple videosources can use the same source of
>> listings data (for example you have an analogue tuner, a DVB-T card,
>> and Sky Digital) but the channels configured on each videosource will
>> be different for each platform.
>> As long as the 'same' channels (in UK parlance) have the same XMLTV
>> IDs associated with them, they will be treated as identical to the
>> scheduler, allowing scheduling of programmes on the channels common to
>> each videosource on either DVB-S or DVB-T.
> That's useful to know.
>> Current DVB-S (since the EIT patches were committed to -fixes) and
>> DVB-T EIT listings data is now pretty good, so it is an option, but
>> there can be differences between the listings for the same channel
>> (ITV Central for example) between the two platforms which confuse the
>> scheduler enough to wreak havoc with duplicate detection. Using a
>> common listings source for each videosource (such as XMLTV) gets
>> around this issue, but adds the requirement of an internet connection
>> to the mix.
> The internet connection is not a problem.  Are you suggesting that I
> should use a single XMLTV listings file (with 'channel
> cbeebies.bbc.co.uk' etc.) for both DVB-S and DVB-T?  Re-reading the
> previous three paragraphs confirms that you are suggesting that.  Are
> there any disadvantages to that approach?

It is an option (although removes the ability to run MFDB
automatically via mythbackend), and is what I have done for the past
few years. See my reply to Ma's messages for more details on the
tv_grab_uk_rt grabber.

>> If you run the current development version of XMLTV (a new 0.5.52
>> release is imminent, however) you will be able to try out my recent
>> work on adding lineup support (basic at the moment) to the grabber.
>> You can choose Freeview and FreeSat platforms when running
>> configuration, and this will automatically filter the list of
>> available channels to those available for the chosen platform from the
>> uk_rt grabber. Choosing 'all' to the first channel will instantly
>> create your config file containing all channels on the platform*. It
>> still doesn't enable automagical channel numbering in MythTV, but that
>> is on the horizon with the XMLTV lineups project.
> Is there more information on that project somewhere?  I've cobbled
> together some scripts of my own for assigning channel numbers and
> associating xmltvids with channels.  I'm only running xmltv 0.5.49
> though in the standard MythBuntu setup at the moment.

The XMLTV proposal page is at
http://xmltv.org/wiki/lineupproposal.html. The xmltv-dev list archives
also contain some relevant messages, I'm planning on looking at it
seriously in the upcoming weeks.

>> * It is possible to use a single XMLTV file containing all channels
>> you can receive on all sources, and run mythfilldatabase (with the
>> --update switch) once for each source pointing to this file. It is
>> also possible to use both XMLTV and EIT data on the same source to
>> cover cases where the XMLTV grabber does not provide listings data for
>> certain channels.
>> Nick
> On a related theme, what does mythfilldatabase do apart from retrieve
> program listings?  I understand that it changes channels and icons if it
> is run without the --update option.  Is this documented anywhere?

mythfilldatabase --help gives a good overview of the available options.

Nick Morrott

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