Hacking Your Car: How to Get Clean Audio and Video Signals into Your Car
Pages: 1, 2, 3

Video Inputs

There are numerous reasons why you'd want to use the video screen in your car for something other than navigation. One of the more popular upgrades is to install a rear-view camera lens, so that when you back up, a fish-eye view of the obstacles to your reverse motion show up on the console screen. Another popular, if controversial, use is to play back movies and DVDs, which is generally prohibited while the car is in motion, at least in the United States.

Europe is not so restrictive, so one of the solutions people use for their high-end BMWs and Mercedes vehicles is to buy an import version of the entertainment system and transplant that into their car, which has easily accessible video input options.

But you don't have to start wearing tight shirts and socializing medicine to get video into your head unit. Just as with audio, a number of companies have developed adapters to fill this consumer need for video. Generally, these aftermarket adapters provide several video inputs, allowing you to manually switch between them, and even to automatically trigger an input for a rear-view camera when the vehicle switches into reverse.

Now, if you're looking to connect a car PC to the factory navigation screen in your vehicle, there are a few considerations. Nav screens actually have a higher resolution than your average LCD TV screen--they have to have enough resolution to show street names and roads crisply. However, most adapters assume you're just putting video on the screen, so they only input lower resolution S-Video or composite video.

Video input adapters usually inject your video in the path between the navigation system and the LCD display, allowing you to switch between the two without affecting what the navigation screen is currently showing. This nav-LCD connection can be RGB (fixed frequency, analog), TTL (an older digital connection using a lot of wires), or the more modern LVDS/LDI interface. (The latter two of these are the same interfaces used in laptop LCD screens between the video card and the screen.)

figure 6 Figure 6. G-Net RGB nav screen video adapter

With a few of the newest LVDS cars and adapters, a high-res VGA signal can be input. But for the bulk of the cars out there, S-Video is the sharpest you can get--which is fine for anything but reading fine text.

Just as in audio, every car has its own proprietary Morex adapter, that is, some collection of multicolored and unlabeled wires, that connects the nav system to the LCD screen. While early adapters required the installer to locate and carefully snip and splice the right wires, the newer adapters have harmless plug-and-play interfaces so you can safely install them, even on a leased vehicle.

(If your car did not come with the factory screen, there are still a number of ways to get a video screen installed into your car. For more information, see Chapter 3 of my book, Car PC Hacks.)

So, the easiest ways to get video into your factory-installed automotive screens are:

  • If you have a fold-down screen/DVD combination, splice your audio and video in between the DVD player and the screen, or find if there are already AUX in jacks on the DVD player

  • If you have a factory navigation screen, find an aftermarket adapter that allows you to splice in composite, S-Video, or even VGA video

  • If you have a foreign vehicle and its European cousin has video input to the NAV screen, buy the Euro-entertainment package and transplant it into your own vehicle

Manufacturers

There are only a handful of primary manufacturers in the "12V" accessory market (as they call it.) There are also a large number of one-off products designed and manufactured to solve a specific vehicle and model need, such as "AUX in adapters for late '90s Jettas" or the like.

In addition, in these niche markets, sometimes one manufacturer makes the adapter and a number of other companies buy it and put their sticker on it, but don't actually make it. Some companies will also clone other companies' adapters, selling knock-offs, so the standard make-sure-you-can-return-it-if-anything-goes-wrong consumer advice applies.

Resources

Here's a list of audio adapter companies:

And here's a list of video adapter companies:

Damien Stolarz is an inventor who's made different kinds of computers talk to each other for a decade. He co-founded Blue Falcon Networks to architect and develop networking software. In 2002, Damien created Robotarmy, a high-technology consulting firm.

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