[mythtv] Multiple input/card behavior - Coding question.

[Steve Davies]

Hi all,

I am currently in a position where I have MythTV working pretty much perfectly 
if I stick to using one input from one card. I do have a DVB card, which is 
mostly working, but I'll cover that in a separate email ;-)

(FYI, I am using ivtv latest as of today, MythTV CVS also as of today.)

Looking at the code (I am no expert) it seems to me that the backend on 
startup builds a list of all cards, local or remote, from the database. For 
each of these it creates a TVRec:: object, and this will create either a 
Channel:: object, or a DVBChannel:: object (One per card) - So far so good...

 From the code, It looks like it assumes that from this point on, "channum" is 
unique across all cards. In my case, several channel numbers appear three 
times, with differnt tuning parameters and details. This assumption comes from 
  Channel::SetChannelByString(QString &chan) - It queries the channel table by 
channel number, but has no idea whatsoever at this point which "sourceid" it 
is viewing, so often gets the wrong, or no frequency from the table.

My first thought was to add a private "sourceid" member to the Channel class, 
and add it to the constructor. Channel is only ever created by TVRec, so this 
seemed sensible. Then I moved on up to looking at TVRec - Could I get hold of 
sourceid easily?

Unfortunately, I could not see how this could be done. The TVRec::GetDevices 
call gets getails of the current cardid, but the input (and hence the 
sourceid) is chosen using the DefaultInput for the card, rather than using the 
currently selected card-input.

I cannot in fact see where the code refers to the current input at any time.

To make matters worse, I have actually got 3 different sources, ALL of which 
serve channel numbers "1" thru "5", using 10 different frequencies, and an 
IRblaster. Originally, I created a single source, and connected it to all 3 
inputs, which only caused even more pain :-)

I may of course be talking out of my rear-end, but if someone could comment, I 
would be most appreciative, and more than happy to try and go further with 
improving the code in this area. It is possible to 'c' between inputs on a 
card, so I assume I am missing SOMETHING :-(

Kind regards,
Steve
-- 
Steve Davies                   steve at one47.co.uk

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