[mythtv-users] cards vs sources vs inputs confusion, problems and possible bugs

Petr Stehlik pstehlik at sophics.cz
Sun Nov 29 01:18:23 UTC 2009

Hi all,

I've got two cards - a DVB-S and a DVB-S2. Each is connected to its own
LNB so they're independent of each other tuning-wise etc. The Card#1
(DVB-S) can receive X channels while the Card#2 (DVB-S2) can receive X+Y
channels (Y channels being DVB-S2 only). This is actually simplified a
bit since Card#2 is in fact connected to DiSEqC switch and can receive X
+Y+Z channels (Z channels are those from three other LNBs) but for the
rest of the story this simplification shouldn't matter, hopefully.

Since I didn't know how to map the video sources to inputs smartly I
created two independent sources - Source1 and Source2, mapped to Card#1
and Card#2 inputs respectively. I think it would be much better if I
could say that there is source for X channels and source for Y channels
and then set that Card#1 can use SourceX and Card#2 can use both SourceX
and SourceY but I didn't know how to arrange that so I ended up with
Source1 and Source2 where Source2 largely duplicates Source1 channels.

This has the annoying disadvantage that if I need to tune to a new
channel (or fix tuning to a channel that changed its identifications on
the satellite) I have to scan and tune twice, first for Source1 and then
for Source2. Everything regarding channels in "SourceX" is duplicated in
the database. Is this correct approach at all?

Also, as I use multi-recording with 5 simultaneous recordings there are
actually 10 virtual tuners. Tuners 1-5 for Card#1 and tuners 6-10 for

As the channels on both cards are largely identical I set them the same
channums and callsigns across both sources so when you're using Live TV
you can use the channum you know and whichever tuner is free it'll show
you the channel you're after.

However, there are two weird issues that might even be bugs. Please help
me figure out if this is just wrong configuration or if I need to report
it to Trac. Both are LiveTV related.

First, whenever I am browsing through the channels that are duplicate
(available on both cards) then no matter what channel I choose the next
time I use the ArrowUp/ArrowDown for browsing the LiveTV channels it'll
start on the first channel.

Example: there are channels with channums "1" to "9" available on both
cards (and duplicate on both sources etc). I browse with the ArrowUp to
the channel "5", press Enter, and watch channel "5". Now if I press
ArrowUp it will not offer the channel "6" but channel "2" instead
because it sort of reset its position(?), or perhaps because it is using
the index from the other free card? Please note that I have the "Browse
on all inputs" switch enabled. Also please note that this problem
doesn't occur if I watch any of those SourceY channels, i.e. available
on the Card#2 only. Then the "index of current channel" is correct and
ArrowUp/Down will offer the next/previous channel correctly.

Anyway, this is still sort of "cosmetic" issue. The second one is a
serious one. Since I have the "try to avoid conflicts live TV with
recording" switch enabled then recording starts from tuner1 (i.e.
Card#1) while LiveTV starts from the last tuner (tuner10, and Card#2).
Now if Card#1 is recording I can watch anything I want using liveTV on
Card#2, but if Card#2 is recording something then LiveTV is restricted
to only those channels in the multiplex the Card#2 is currently
recording even though the Card#1 is empty and the Browser of LiveTV
allows me to select any of the Card#1 channels.

A recording starts on a channel in multiplex "A" and Myth picks Card#1
(tuner #1) for it. Another recording starts on a channel in multiplex
"B" so Myth picks Card#2 (tuner #6). Now LiveTV is restricted to just
multiplexes "A" and "B", that's OK.
But after the first recording on Card#1 ends the LiveTV is free to watch
any channel on the Card#1 so it offers all channels from all
multiplexes. However, if I select any channel from any multiplex
different from the currently recorded multiplex "B" Myth sort of ignores
my input and falls back to first channel of the currently recorded
multiplex "B". 

In short it looks like Myth is unable to use the Card#1 for LiveTV but I
can't believe it so I suspect that perhaps the duplicate channums
confused the system for picking up a free tunner or that there is a bug

Please advise. Thanks in advance.


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