Dual headed Myth - was Re: [mythtv-users] PVR350/Myth Questions

David myth at dgreaves.com
Wed Sep 15 04:14:13 EDT 2004

Jarod Wilson wrote:

> m0j0.j0j0 wrote:
>> I have a couple of lame IVTV/Myth questions. I am currently displaying
>> Myth using my onboard nVidia TV-out, but I would like to test that of my
>> PVR-350. I have a couple initial questions though, before I do this:
>> -Is it possible to simultaneously send X/Myth to both the 350 and nVidia
>> TV-outs? I would like to use the 350 for displaying everything but
>> MythGame. I'm hoping I can have the display always get sent to both
>> devices, so I can just toggle on my stereo what input gets sent to the
>> TV.
> I don't believe that's possible.

simultaneously - no, it's effectively not possible (barring silly 
vnc-like trickery). And it wouldn't get you what you want ('cos you'd 
need accelerated X commands [glx?] sent to one and not to the other)

I do something very similar though. I run 2 instances of Myth on 1 
machine on different virtual terminals and I switch between the VTs.
1 outputs to the TV, via the PVR350, the other to a vga device 
(projector) via a vga card.
I created a new user (mybhbig) and started an X session with an 
alternate config

here's the lines from my /etc/init.d/ script
        chvt 8
        nohup su - mythbig /home/mythbig/runx >>/var/log/projector.log 
2>&1 &

(chvt is a fantastic command - possibly worth putting in your .lirc file)

runx is a 2 line script:
  export QT_XFT=1
  xinit  -- :1 -layout Projector
note the use of -layout. This corresponds to a layout section in 

my .xinitrc says:
  xsetroot -solid black
  xhost +
  nvidia-settings -l --assign="SyncToVBlank=1"
  mythfrontend -v &

The first ServerLayout is used by default, the second has to be 
specified by name:
Section "ServerLayout"
        Identifier     "TV"
        Screen      0  "TV"
        InputDevice    "Keyboard0" "CoreKeyboard"
        InputDevice    "PS/2 Mouse" "CorePointer"
        Option "Xinerama" "off"

Section "ServerLayout"
        Identifier     "Projector"
        Screen      0  "ProjScreen"
        Option          "Xinerama"      "off"
        Option          "AllowMouseOpenFail"
        InputDevice    "PS/2 Mouse" "CorePointer"
        InputDevice    "Keyboard0" "CoreKeyboard"

You can then easily switch (ctrl-alt-F<x>) between TV and VGA screens.
You may have problems sharing the sound/dsp device if you switch whilst 
it's in use)


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