9

Does video from the backup camera or side mirror camera travel to the (NAV) display via the CAN bus or some other mechanism?

I'm really curious if you can get access in some way to that video - or replace it. (E.g., grab it from the bus and put it on your own display with your own overlays. Or replace it with a stream from a different camera.)

Update: I should have made this clear originally: I'm speaking of video from manufacturer standard equipment (the backup camera and side mirror camera are standard features of the car).

  • 4
    I don't know for sure, but would bet it's a dedicated source. It would take up too much bandwidth to be transmitted over the CANBus. I know every aftermarket one transmits through a dedicated line and is picked up via the display. I would bet even OEM ones do the same. – Pᴀᴜʟsᴛᴇʀ2 Feb 16 '16 at 23:47
  • 1
    What @paulster2 said. Aftermarket cameras usually run their wires under the interior molding on the bottom of the door frame, and (depending on the type of vehicle) under the rear seats into the trunk. I'd imagine OEM cameras follow a similar path, possibly the same path as the rear speaker/amp wires if you have them. – MooseLucifer Feb 16 '16 at 23:52
  • Agreed with Paulster, highly doubt it would be CANBUS. Probably a dedicated analog/digital video line coming straight to the multimedia unit. – I have no idea what I'm doing Feb 17 '16 at 9:25
  • 2
    No, we CAN't. CAN has a max raw data rate if 1Mbit/s, which reduces to <600kBit/s net rate due to massive overhead. I just wrote an answer about this on EE.SE This is sufficient for a 480x280 video, but who wants this? Also, CAN is used for networks with many devices on one cable. This heavily decreases the bandwidth more. I guess the cams use standard interfaces like video or LVDS, may be HDMI-like. Some 3rd-party systems use wireless technology, too. – sweber Feb 17 '16 at 10:16
  • @sweber - thanks for the bandwidth information and link to your other post, that's very helpful. I knew CAN had a limited data rate but didn't know how limited. – davidbak Feb 17 '16 at 16:46
4

I've shopped for a rear-vew camera for my car in the past, and one thing you see time and time-again are standard RCA-style video jacks like the picture below from an AliExpress seller:

enter image description here

You can easily find other examples by searching for OEM camera kits for cars that had a camera as an option. The cameras all have at least a power plug and an RCA video jack. Many of these cars will already have the wiring in the trunk - they just don't have the actual camera.

Because it uses this ubiquitous 2-wire analog video protocol, you can easily intercept, split, or replace the video stream with common, inexpensive video devices.

Also, another bit of info you might find interesting - in many of the aftermarket "basic" cameras the parking lines that are displayed are generated in-camera rather than being overlayed by the video display. Some nicer, OEM units have animated lines that are computer generated in the display.

  • Thanks - I updated my question to clarify that I was speaking of manufacturer standard equipment. What I'm really curious about is that some of these cameras have "parking lines" that they generate themselves. How do they get steering information - or do they? (My car's backup camera shows lines that "warp" as the steering wheel is turned.) – davidbak Feb 17 '16 at 16:47
  • 1
    That's what I was saying - the animated or warping lines are computer generated by the display unit, and it probably gets CAN data from whatever module handles the steering wheel position. The basic, static lines can be simply hard-coded in the camera module itself to save cost and complexity. – JPhi1618 Feb 17 '16 at 16:59
  • Pretty sure the basic cheap cameras online use static lines, unlike more advanced integrated OEM units. – I have no idea what I'm doing Feb 17 '16 at 17:07

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.