[mythtv] Ramblings on the 128 Channels and Satellite

Andrew C. Ohnstad mythtv-dev@snowman.net
Thu, 24 Oct 2002 07:48:27 -0700 (PDT)

Two things going on at once here...

1) Not changing above channel 128 - I had this problem
too, but I'll be darned if I can remember what fixed
it.  It definatley wasn't hard coded.  There's a
setting in settings.txt for 'reciever type' or
something.  Try tweaking that.  If not I'll look at my
system at home tonight, and if I can't figure it out
I'm sure Issac will reply when he gets back from

2) Using digital cable/DSS boxen - As it is now Myth
doesn't change channels on external decoder boxes. 
You're right Tarek, that the answer lies in the
Composite:123 thing.  Basically that tells Myth and
MythEPG to tune the composite input, but pretened it's
really channel 123.  This fuctionality was added when
it became clear that a single channel database
wouldn't work.  When attempting to record something on
channel 203 Myth would change the channel off
Composite to 203 (which was invalid to the tv tuner
card) instead of leaving things be if you set your
decoder beforehand.

As for actually changing channels, according to Issac
the possibility is there.  I guess in the code there
are hooks for lirc to TRANSMIT a code when you press
channel up/down, but nobody's bothered to code them
yet, mainly because Issac doesn't use a set top box. 
"I am not a coder" (tm) or else I would have done it
myself months ago when I first asked about this.

You'll also need to build an IR Flasher circuit to
hook up to a COM port.  Myth will call lirc which will
flash the TRANSMITTER hooked up to a com port.  Tons
of info about this is available at the lirc site.

Keep in mind that the IR Flasher that you just hooked
up to your com port is NOT and IR reciever.  So if you
want to use a remote control to do Myth, and have Myth
control your decoder box you'll need a flasher on one
COM port and a reciever on another COM port.


--- tarek Lubani <tarek@tarek.2y.net> wrote:
> Well, I did a little bit more reading, and the key
> here seems to be the 
> Composite1:123 setup.. So, some new questions:
> 1) How do I *call* Composite1:123? Could this be
> done by doing a CHANNEL 
> UP? or what? I have the time and interest, and would
> *really* like to 
> develop this..
> tarek : )
> On Thu, 24 Oct 2002, tarek Lubani wrote:
> > Well, I have spent the better part of the night
> trying to figure this 
> > puppy out.. to no avail..
> > 
> > The problem: 
> > 
> > a) I have a satellite hooked into my composite1
> > b) Said satellite (DirecTV) goes from 100 - 999.
> > c) Myth won't let me go beyond ~125 channels..
> i.e., I can't type in more 
> > than "125". If I do, it just spits back the
> original channel I was on.
> > 
> > I've been going through the code, but being a
> novice programmer and not 
> > knowing this program well at all, I was completely
> unsuccessful... Here's 
> > what I have found, though:
> > 
> > 1) This was reported as a database issue some time
> ago.. I don't exactly 
> > know why.. but it was : )
> > 
> > 2) Isaac Richards stated in an email back in
> august 2002 that there was a 
> > hard-coded 128 channel limit. This boggles my mind
> for several reasons. 
> > Which isn't to say much, since I truly don't know
> much in this area.. but 
> > why can't hitting "500" just bring up the OSD?
> isn't this what currently 
> > happens? or is my tv tuner actually switching
> channels??
> > 
> > I really had trouble finding the 128 "line", since
> god knows 128 is common 
> > enough in code : ) However, in the end, I found a
> line of this variety in 
> > guidegrid.h in /usr/libs/libmyth .. Surely enough,
> this was set to 128.. 
> > So, I changed it to 999 and recompiled.. nothing.
> Still the same 
> > behaviour. still the same problems.. In fact, I
> cannot at all figure out 
> > what this setting does when a person is trying to
> change channels in 
> > composite mode..
> > 
> > Anyway, suffice it to say that after breaking a
> whole bunch of things in a 
> > whole bunch of files around, I just had to
> mothball the effort and 
> > regroup.. So, I'm seeking more advice here..
> > 
> > Questions I currently have:
> > 
> > 1) If I hit 500, what does myth do?
> > 
> > 2) What is an approximate vicinity of the code
> where I should be looking?
> > 
> > 3) Why is this a problem? Why can't I just hit
> "500", have it execute a 
> > 500 external command, and then we just be done
> with it.. Why does it do 
> > this internal dissonance checking? And more
> importantly (as relating to 
> > question 2), where does said checking occur??
> > 
> > Thank you all for your help..
> > 
> > tarek : )
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