[mythtv-users] Reducing Mythtv computer "proliferation"

Ma Begaj derliebegott at gmail.com
Sun Nov 4 20:12:49 UTC 2007

> With the advance of computer technology (Quad cores,
> 64 bit memory addressing, Virtualization), could this
> not all be on 1 $1000 computer with a bunch video
> cards, a serial mux for LIRC, a couple sound cards,
> and cables protruding to each monitor or
> TV/LIRC/Speaker system.

It should be possible.

> Ideally I would like: 1 Mythtv master computer, 3+
> Mythtv frontend instances configured to work as 3
> completely separate environments (I.E. 3 different
> sound channels, 3 LIRC channels, 3 different video
> outs, some 150 feet away) and one Virtual Windows
> system out with sound and KVM?
> Is anybody doing anything like this?  If so, how, what
> are the tricks and traps, cable length issues.

I would leave out Windows, because VMs are pretty heavy for CPU and hard disk.

Comparison: I have a Athlon AM2 X2 3800+ which is a multiseat system
without MythTv. Two users are working without any problems in Gnome
and a Windows in VM is running all the time in one of these two
sessions. I have 2GB of RAM and two 7600GS passive nVidia cards.

To be able to run this, you need three X servers running (one for each
Mythfrontend). I have two X servers running, one for each Gnome
session. If you want nVidia, you will need three graphic cards also.
Some ATI cards can have separate 2 X servers running on two different
outputs on one graphic card.

You should use XVMC for every frontend, because that could be pretty
heavy for the CPU if you have 3 frontends watching.

Lirc is also not a big problem, you can start ten sessions if you
want. You just have to specify different input and output devices.
Cable length should not be a problem, I used to have a 10 meters long

Although I said that lirc cable length should not be a problem, video
cable might be a problem. 10-12 meters is probably OK, but signal is
probably getting weaker and weaker with every meter. You will probably
have to get more expensive video cables.

And ... I can imagine that HDTV could be a reason for the CPU/HDD bottleneck.

One more "and" ... you will probably run out of PCI/PCIe/USB slots
pretty fast (3x graphics, a few TV cards, 2x sound (1x is on
motherboard), 3x lirc, maybe USB mouse(?) etc...), so you should write
down everything you need and than find a motherboard which have enough
place for everything. Motherboards have usually a lot of 6-8 USB ports
which is pretty good because you could use LIRC USB receivers or USB
sound cards. Use the PCI/PCIe slots for graphics and TV cards.

Modern motheboards have usually up to 3 PCI slots and up to 3 PCIe
slots (max. two of these are fast enough for graphics like PCIe x16)
and that is maybe enough. I you are watching SD, buy PVR500 which will
give you 2 tuners for every card. Two PVR500 should be enough, and you
could use one PCI slot for graphic card in combination with two PCIe
slots. Third PCIe slots (usually PCIe x1) could be used for a nice
RAID card :).

And a big tower case with a lot of big quiet fans if you are also
going to use this as desktop machine.


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