[mythtv-users] Two tuners showed up

Simon Hobson linux at thehobsons.co.uk
Sat Aug 6 07:24:47 UTC 2011

Stephen Atkins wrote:

>  > indeed, multirec means recording multiple shows on the same 
>'broadcast channel' (laymans terms)
>>  For example, my cable company manages to squeeze 9 to 11 SDTV 
>>channels on one catv channel (a multiplex).   When I chose to watch 
>>any of those 11 channels, the data for all 11 arrives at my card 
>>and it only passes the one I am interested in to the rest of the 
>>system.  With Multirec on, the tuner simply passes more of the data.
>>  I have recorded as many as 5 shows concurrently from that one 
>>multiplex (never wanted more than that).
>>  You see the same thing in broadcast.  Most channels share a 
>>multiplex with others, the bandwidth of a standard NTSC channel is 
>>wide enough for 2 HD, and 4 or more SD channels multiplexed.

Over here (UK), we get all our terrestrial SD channels on just 5 
muxes (HD is on a 6th) - though some areas haven't done their 
switchover yet. Multirec works very nicely indeed.

>Okay now that makes sense.  Now the only problem is the stations I get
>here don't multicast.  At least not yet.  We are just switching to
>digital OTA as of Aug 31.  They have had test signals going for a few
>months now and that's what I'm recording.  Out cable companies feel the
>need to force people into renting or buying boxes to get the digital
>cable signals and won't let us use cable cards or anything like that.
>So I'm stuck with OTA and until they figure out how to multicast I'm
>hooped.  Thanks for the info everyone.  I'll keep it configured as it is
>but I'm not holding my breath for our TV networks.

They will be doing multiple programs in a stream - no-one is going to 
pay for a full transmission frequency and only put one channel in it. 
Expect to see anything from 4 to 10 SD channels on one multiplex 
depending on whether their criteria is quality or quantity !
You will find that you'll need to rescan frequently. It seems that 
because it's now easy to add/remove/move/change channels, the 
broadcasters feel the need to do it - frequently. It's a right pain 
with some TVs and STBs where they either don't allow channel 
renumbering, or the process is long and tedious.

If you search the wiki, you'll find several of us wrote SQL scripts 
to handle this side of things when we do a rescan on MythTV.

Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.

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