Thursday, August 28, 2008

XBox360 - multiple displays?

What a mission! My kids saved for nine months and between them bought a 360 - I'd always maintained that because we have a powerful PC a console is not needed but they disagreed! Anyhow - we have it connected to the living-room standard-def TV over RGB but there are occasions when Sarah and I want to watch the TV and nobody is using the PC next door in the dining room. The Dell LCD panels I have on the main family machine have several inputs - using the mighty Synergy is what I use for taking control of Sarah's Mac on the PC and by switching the right-hand monitor to the 2nd DVI input you can have a proper two-machine setup without all the laggy behavior of VNC/ARD. I also have the output of the MediaPortal PVR on another input of that right-hand monitor and so if I want to watch TV recordings full-screen (or window'ed - the Dells do that) I can.
So, with all these inputs I figured I could just take an HDMI output from the xBox and feed it into the LH monitor and because the controllers are wireless we'd be good - however - if the xBox sees two monitors (i.e. terminations on the analogue SD output - RGB) and the HD HDMI output it won't boot! No problem I thought - I'll just feed the YUV output (which is also available on the analogue connector) to the Dell - but no, all the TV outputs (Composite PAL, SVideo, RGB & YUV) are at the mercy of the frame rate of the game (typically 60hz for 90% of the titles) which the Dell won't display! They assume that 625-line signals are going to be 50hz and display an error message for all analogue inputs from the xBox for most games.
Hmmm - at this point I was starting to think it would be impossible to have two displays fed off the console if one was a Dell LCD monitor - however, help was at hand in my box of bits with an on Lindy video->SVGA convertor. This takes composite or SVideo and converts it to SVGA in a veriety of rasters - but it maintains the frame rate. It turns out that the Dells are entirely happy with 60hz SVGA (no suprise there!) and so I attached the Lindy (oh, it's a 32555 and still available) BUT the SVideo output of the xBox uses the same driver amps for the green and blue outputs as the Y and C (on the 4-pin SVideo connector) - so, if you hang an SVideo output at the same time as the RGB the screen goes a funny shade of Cyan on the RGB and very dim on the SVideo! Given that both connectors are there on the breakout cable this seems like a poor bit of design!

So - next step was to lift the 75ohm terminating resisitors in the Lindy box - colours all good now but some reflections present on both inputs while the Lindy box is powered. The eventual config was to use a remote mains switch on the Lindy controlled of my NetIOm remote system. An icon on the XP desktop switches on the Lindy, switches the left-hand Dell to SVGA input and routes the xBox audio to the windows mixer! All this automation is done with a MacroScheduler macro.

The SVideo -> SVGA adaptor produces a very usable feed and although is only standard def on what is an HD-capable display the kids are very happy to have a 2nd location to play xBox!

1 comment:

k said...

wow Phil.

i wish my dad could nice me up with an MTV-cribbed video stroke home-cinema type joint.

your post is very detailed. i think it will take me a whole afternoon to go through it and find out what's going on with the signal paths... my first reaction was... "wot"?