[mythtv-users] Multiple Frontends / Backends

[Bruce Markey]

I've been staying out of this but there still seems to be some
confusion here...

John Goerzen wrote:
> I'm still unclear about the frontend/backend separation in MythTV.

------8<-------
The backend controls tuner cards and is used for recording.
It has no GUI and is needed on each machine that has one or
more TV cards but is not needed on any machine that does not
have a tuner.

There is exactly one master backend that runs the scheduler
and assigns recording tasks to other backends (if any) which
are called slave backends. Backend are normally running all
the time so they are ready to record and available to serve
any files they have recorded.

The frontend is the GUI that users use for playback. It can
run on a computer monitor or on a TV if the computer has a
graphics card that supports TV-out. A mythbackend may or may
not also run on the same machine depending on if the system
has a TV card. Any frontend can be stopped or started at any
time with no impact on the recording schedule.

There is no master or slave frontend but frontends are often
referred to as local or remote indicating whether or not they
are on the same machine that holds recorded files. Any frontend
can play files recorded by any of the backends.
------8<-------


 
> Here are two scenarios I'm looking at:
> 
> Scenario 1
> ----------
> 
> I have a main MythTV box.  It has a capture card, Ethernet connection,
> and TV out interface.  I'd usually watch TV here.
> 
> I also have a Linux box in a different room.  I'd like to be able to
> watch TV, schedule recordings, etc. there also.  This machine has no
> capture card.
> 
> In testing out this configuration, I found it's pretty easy to be able
> to watch recorded programs.  However, I can't seem to be able to watch
> live TV no matter what; it says all inputs are in use.  Also, the
> program guide data is blank (it says I should run mythfilldatabase, but
> that's already being run on the master server and works there; why
> should I run it here?)

You don't need to run setup or mythbackend on a machine that
does not have a capture card. A frontend only machine finds
how to connect to the master from the database info. If you
do not see guide data and can't get a tuner for live TV, then
the frontend is not getting the right info to connect to the
master backend. In you next message you side you've fixed this
by changing the IP from 127.0.0.1 to the real IP. Good job =).

And, you are correct, if you were actually setting up a slave
backend you would not run mythfilldatabase again. This is just
a stock message from setup.

> Scenario 2
> ----------
> 
> I have a main MythTV box like before.
> 
> Also, I have a second box with a lower-quality framegrabber.  This box
> is not always on, but when it is, it would be nice to be able to use it
> to record lower-priority programs when conflicts exist.  It could also
> be used for picture-in-picture, etc.

Right, here is where you need to run setup for a slave backend...

> However, I can't seem to be able to integrate the two schedules.  I
> don't want to have to maintain them on two separate machines.  I want to
> use make the network be seamless.

First, make sure your mysql.txt is set to connect to the same
mysql server as the master. Do no run and connect to a separate DB
on the slave machine. All frontends and backends need to talk to
the same DB. Your mysql server needs to allow network access for
remote hosts.

In setup, General, the first page, fourth item is "Master Server
IP address". Set this to the IP of your existing master then the
mythbackend run on this host will be a "slave". Only one scheduler
is run on the master that controls both cards.

Check the first messages at startup to be sure it knows that it
is a slave and that it connects to the master:
 
$ mythbackend
Running as a slave backend.
2004-07-01 09:51:51 mythbackend version: 0.15.20040528-1 www.mythtv.org
2004-07-01 09:51:51 Enabled verbose msgs : important general
2004-07-01 09:51:52 Connecting to master server: 192.168.0.35:6543
2004-07-01 09:51:52 Connected successfully
...

--  bjm