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I want to have two separate video outputs from the carputer so I can play movies on one while GPS-navigating on the other. I am happy to say I succeeded. It wasn’t as easy as I’d hoped, but it wasn’t as hard as I feared. Here’s an install shot of the flip-down monitor playing Star Wars from the hard drive while the front touchscreen monitor shows my current location on a live GPS map.

Both of these displays are being driven by the same computer. In fact, they both are coming from the same (dual-head) video card. But I’m getting ahead of myself…

The motherboard I chose (Via EPIA M-10000) has an embedded MPEG-2 decoder chip. This is essential for watching DVD movies without using up all your CPU cycles. Unfortunately, it turned out that I couldn’t use this chip.

At first I thought I would just drop a 2nd video card in the one PCI slot on the motherboard for my GPS screen. When I powered up in this configuration I could choose to make the PCI card the primary display or the on-board VGA the primary display. I really wanted to make the PCI card the primary display since that would have the touchscreen controller. Windows correctly identified two monitors and it gave me a huge desktop. I tried to keep it split into two desktops, but then I never had any useful output on monitor number 2. So, one big desktop it is.

I fought with the touchscreen drivers enough to get it to use just one half of the “whole” desktop. It wasn’t easy, and it didn’t promise to be easy to maintain. But I got it working. Everything was looking pretty sweet (after 4+ hours of futzing around with it) when disaster struck. When I tried to play a DVD, it was choppy and my CPU was completely consumed. What happened to my MPEG-2 decoder?

I decided that the primary monitor being the VGA must have confused things. So I switched to using the on-board VGA as the primary. Still, though, MPEG-2 playback was choppy and useless. I reinstalled the VGA drivers, I checked everything I could find, but to no avail.

I decided it wasn’t worth fooling with anymore and turned my Google search from solutions to new video cards. And there it was: the ATI Radeon series of cards. The 7000-series has two separate video outputs and an MPEG-2 hardware assist. It’s not a complete decoder, but it does the hard part. I found one at my local computer shop and bought it so I wouldn’t have to wait on shipping.

Sadly, the PCI riser card I had used successfully with my old VGA card would not work with the Radeon. I should have known. Someone else had described the same problem with the same setup on the mp3car.com forums.

So I ordered another PCI Riser, the one that the was reported to work with Radeons. It cost 5 times what I paid for the other one, but it must be done…

A week or so later, my riser arrived. By now my carputer has been sitting on the bench, its guts played out everywhere, with no useful function at all. I think I experimented a bit with the power supply, but otherwise it sat drearily idle.

Now that the card was here, I could finally hook it all up again. I installed the Radeon drivers, experimented endlessly with various modes of operation, and — eventually — it all worked like a charm.

For those following in my footsteps, these are the important points I came across:

• The two-head video card has a mode where the secondary monitor is a duplicated/overlay monitor. That is, it normally shows the same image as the primary monitor. But when you play a video back and the video-overlay is used, the secondary monitor becomes a full-screen video player. Here’s an article (with screenshots in Russian?) with some helpful tips.
• The VGA output should be connected to your primary monitor. The image on the composite/TV output isn’t very readable. It’s great for movie playback, though.
• WinDVD came with my card. I found that PowerDVD and ZoomPlayer also worked well with the card’s on-board MPEG-2 decoder.
• At first I had trouble getting video to show up on the 2nd monitor like I wanted. I downloaded ZoomPlayer with somewhat low expectations, and worked beautifully. I was so impressed I decided to use it exclusively. I have since gone back to WinDVD, mostly because I want to be able to use a big-button skin for the touch screen, and because I found it works as well as ZoomPlayer now. I must have had some video card setting wrong earlier.
• I didn’t have to use the Hydravision software to select which monitor applications should run on. The overlay feature is all I need to drive movies to the rear monitor. The ATI Radeon has lots of features I don’t need. But turning them off is the easy part.

I was merely experimenting with this setup originally. I knew I would somehow make it work, and in the end it was easier than I thought. Once I got this system installed in the car, controlling movies and working the GPS at the same time on separate LCD monitors has just worked. (Well, there was that one time I accidently swapped the primary display to the wrong monitor, but I figured that out in only an hour or so. )

This entry was posted on Thursday, October 28th, 2004 at 4:22 pm and is filed under Carputer. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.