[mythtv-users] Different mux frequencies for 2 DVB-T cards possible? (due to buggy hardware/firmware/driver)

Nick Morrott knowledgejunkie at gmail.com
Wed Sep 26 23:26:24 UTC 2007

On 26/09/2007, Kevin Page <mythtv-users-list at krp.org.uk> wrote:

> 1) From what I can see the mux frequency is referenced from channel, and
> therefore from videosource - there's not a direct association with
> cardinput/capturecard? It doesn't make sense to e.g. have double the
> entries in dtv_multiplex (with working frequencies for both cards)
> because each channel entry will only use one mplexid?

Quickest fix is to use two videosources, each with a channel
configuration that works for the card it is attached to. Card inputs
are attached to video sources (see mythconverg.cardinput)

> 2) So to use both cards I need to have two videosource, either xmltv or
> EIT - but identical in all but name - and tie one to each one to a card,
> then fudge the frequencies for the mplexid used by the Freecom? Myth
> will then fix channel equivalence higher up the stack using channel
> number/callsign matching?

This is what I would do. EIT (the over-the-air date) will be the same
for both cards, and if you use the tv_grab_uk_rt grabber from XMLTV
you can configure it to get the same channel listings. The scheduler
will then be able to match across videosources with no problems, and
you should be able to let the backend get on with recording.

> 3) Apart from fetching xmltv twice, are there any other problems or
> downsides I'm likely to experience?

You only need to fetch the data once, if you run mythfilldatabase. I'm
working on adding caching support to the grabber so this will also
work if MythTV runs the grabber automatically. I currently run the
grabber once, get listings for channels on all sources into a single
XML file. I then run mythfilldatabase against each videosource, and
use the --update flag so that data is only applied against channels
that exist on each source, and no new channels are created during the

Only slight downside I can think of is a slightly longer listings
retrieval/import time, as each source has to be updated. If your cards
were sharing a single videosource, this process would only need to be
carried out once.

Nick Morrott

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