[mythtv-users] question involving multiple frontends

Michael T. Dean mtdean at thirdcontact.com
Mon Feb 9 23:25:43 UTC 2009

On 02/09/2009 06:06 PM, Simon Hobson wrote:
> Michael T. Dean wrote:
>> Simple formula:  1 capture card per simultaneous LiveTV user + 1 
>> capture card per desired scheduled recording or 1 capture card per 
>> channel (multiplex, if using multirec), whichever is smaller.
> I have a supplementary question to this, at the risk of thread hijack ...
> Is it possible to lock a card to a multiplex ? And is it possible to 
> have the system work with that ?

Yeah, you could do it by having separate Video Sources defined in 
mythtv-setup for each capture card.  The Video Sources could all use the 
same grabber.  (With Schedules Direct, the configuration would be 
transparent as it would still generally download listings for all Video 
Sources simultaneously--ignoring the lineup maximum on SD.  With XMLTV, 
though, it likely means running the grabber multiple times (so you'd 
likely want to use the XMLTV-provided caching capabilities).

> Over in the UK, we have a max of 6 multiplexes on terrestrial digital. 
> So with multirec, it would seem logical that with 6 tuners it should 
> be possible to access any combination of channels - even well in 
> excess of 6.
> But unless the system can cope with it, we'd still be in a position 
> where two LiveTV users could take up two tuners - set to the same 
> multiplex.

Right.  So in this case, if you have people using LiveTV and don't want 
to buy more capture cards for them, you'd have to have 6 Video 
Sources--one for each multiplex.  Then, each capture card would be 
associated with a single Video Source.  It would be important to choose 
the Video Sources to associate with particular cards very carefully if 
you have multiple backends (to ensure that you don't have all the 
channels with interesting shows on the master backend and have a slave 
backend whose channels are never recorded/whose storage would never be 

> And getting even more off topic, does the same hold true for 
> Satellite, or does that use lots of different frequencies rather than 
> a small number of multiplexed streams ? 

No idea.  Unencrypted satellite in the US doesn't offer much, so I've 
never looked into that.


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