[mythtv-users] Ignoring certain channels from certain inputs

[Simon Hobson]

Mark Greenwood wrote:

>In the UK, DVB signals include channel numbers, so by 'sensible' I 
>mean 'following the channel order as defined in the signal'.

There we differ, I think the Freeview channels numbers have many 
attributes - but logical or desirable ordering are not amongst them. 
For example, I like the BBC channels to be together - so I have BBc1, 
BBC2, BBC3, BBC4 as 1-4 and so on.

>Mythtv appears to ignore this.

No it doesn't. See later ...

>A rescan on my myth box takes 15 minutes, then I have at least 2 
>copies of each channel so I have to work out which one is the best 
>for each channel then set a channel number and delete the others.

You are doing it wrong. Select the transports that match your "good" 
transmitter and do a "Scan existing transports" instead of a full 
scan. You'll find you get a fairly quick scan and the channels will 
be numbered according to the Freeview setup. The renumbering is 
because of the duplicates ...

>But then because I've set my own channel numbers but myth invents 
>new ones when I rescan (e.g. 4283 for BBC1..huh?) I get loads of 
>duplicates as well. It's a nightmare. It also doesn't take account 
>of the signal strengths of the channels it finds, whereas my TV will 
>choose the best signal for each channel and discard any duplicates, 
>hence I only get one BBC1 and it's on Channel 1, instead of 3 of 
>them randomly distributed across the channels like I get with mythtv.

You are very, very, very lucky with that TV. What make/model is it ? 
Every TV I've tuned for others where they have multiple signals does 
something like Myth does - tunes in everything it finds and usually 
puts the better ones in obscure places. There is even a standard for 
this !

If you read the forums etc (not Myth ones, general TV, AV, and 
Freeview ones) you'll find it's a real and common problem. Very 
often, there is a local infill with a poor signal which is at lower 
frequencies than the main signal they get (or in some cases, there's 
a different region altogether). So they put a poor BBC1 at channel 1, 
then the good BBC1 at 800, a poor BBC2 at 2, and a good one at 801 or 
802. It's in the Freeview spec that if duplicates are found, they 
should be put at 800 onwards I believe. One trick is to unplug the 
aerial lead for part of the scan so the TV or box can't pickup the 
transmissions you don't want to receive.

>  (The first scan, I had BBC1 on channels 1, 46, and 4283. Where did 
>it get those numbers from? The only one that gives a decent picture 
>is the one on 4283 so it sho
>  uld have chosen that one and thrown the other 2 away).
>
>Like I say, I live in a low signal area with three transmitters 
>nearby. I'd like myth to do what my TV does, because it's 
>repeatable, sensible, and easy and proves it's possible to automate 
>all the hours of effort I put in today. I'm happy to code it too. Or 
>at least try to.

The above tweaks will deal with that. Pick your good transports and 
only scan those.
The problem with what you propose is that Myth is a truly 
international project, and the DVB code is used in many countries. 
Just because we have a situation where is two channels from two 
transmitters are (say) BBC1 means they are "the same thing" doesn't 
mean that applies elsewhere. In fact, from following this list it 
sounds very much like some US viewers get different stuff (even if 
it's only a 1 hour time zone shift) depending on which local OTA 
transmitter they get their "channel something" from.
-- 
Simon Hobson

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