[mythtv-users] multi-seat linux & mythtv

Guillaume Membré guillaume.ml at gmail.com
Sat Apr 2 16:22:03 UTC 2011

On Sat, Apr 2, 2011 at 10:30, Richard Morton <richard.e.morton at gmail.com> wrote:
> Hi,
> I have recently moved my combined master backend/frontend from a
> cupboard near the lounge downstairs to a cupboard above the lounge
> upstairs, which has the added bonus of also moving the machine to
> within 5 metres of both primary viewing locations. I am therefore
> looking to use multi-seat linux.
> The box is a Q6600 based system, 4gb ram with nvidia 8500gt/512MB
> (dvi-d, vga, svideo outputs) and using ubuntu 10.04LTS 32bit,myth
> 0.23.1 and the proprietary nvidia drivers (196 series I think).

I have a similar setup : Q6600, 4gb ram, nvidia 7600 GT, ati rage XXX
(PCI bus), debian stable 64bit, mythtv 0.24 and nvidia proprietary

> So this is my plan/desire...
> Using a single graphics card (either the currently installed one or if
> required; upgrade it to a new one)...

I never managed to get multiseat working with the nvidia only where as
dual display works fine with this card.
So I looked for a cheap pci card and managed to get the multiseat working.

>  - VGA output of graphics card and USB speakers run to bedroom
>  - DVI-D output runs to lounge and digital audio output from MB runs
> to AV receiver which then powers the left,centre&right speakers (no
> surround sound)
> both are independently to be controlled via a combination of PS3
> bluetooth remotes (currenlty using the uinput module -
> http://www.mythtv.org/wiki/Sony_PS3_BD_Remote#uinput_kernel_module_method)
> and network control ( i saw that each frontend will need to have its
> network control port changed)
> So, my questions:
> 1. is anyone doing this or something very similar and is there a guide
> to do this that someone has used to implement this and recommends?

I had to setup a few things :
- First I told the bios to boot on the pci card
- I had to write a Xorg conf file the 2 layout : one for each setup
(graphic card with bus id, driver, screen, mouse, keyboard)
- launch asap during boot process Xorg with the -probeonly arguments
to initialize the second graphic card. It starts X and exit
- start gdm with auto login for display :0 with the argument -sharevts
-novtswitch for Xorg
- launch automaticaly startx for display :1 with the argument -sharevts

I took me about 2 days to get this working, a bit painfull but now it
works like a charm : one seat for my wife on the ati card, one for me
with compiz &co on the nvidia. Graphic acceleration works only on the
nvidia card.
Mythtv works great on both screen at the same time if needed, but no
vdpau (the 7600 is too old)

For the sound, I also have 2 sound card : one on board sound card for
"normal" speaker, and an usb one for headphone. When I play game, I
just export a variable for alsa (don't remember the name, I'm not @
home) before running it and I get the sound of the game in the

If you want more details, I can send you in private all my config files.

> 2. is the graphics card 8500gt up to the job - I have been using it in
> dual head mode for sometime with no issues.
> 3. how do I segregate the bluetooth signals (for the remotes) to the
> different "seats", will I need to find an alternative to uinput?
> 4. I am using VDPAU currently; I assume I should disable this for one
> of the frontends, What would happen if I leave it on and both systems
> attempt to access vdpau at the same time; will the second frontend
> silently fail to get the resource and drop back to cpu decoding or a
> user noticable error?
> 5. the same questions as 4, but with a gt430 card instead! ?
> 6. anticipated upgrade of linux issues?
> 7. anticipated upgrade of mythtv issues?
> I have seen and read threads about this; but these specific questions
> have never been answered. I also saw and read the thread on dual-head
> / multi-frontends... but thought this was different enough to deserve
> its own thread.
> thanks for your time.

best regards

> Richard

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