I am doing and experiement where I need 2 camera but the capability of handling an external Sunc signam.Most of the units I have seen are either too large or too expensive. A single board unit would be perfect.
Many thanks BDk6 for the detailed explanation. I do agree - it sucks that the standard off the shelf video goggles drive both LCS's off the one video feed.
My first set of goggles did use 2 driver boards to give stereo vision but that was only a 320x240 display and I want something with more detail. Unfortunately more resolution means MUCH more cost soI was hoping to do the stereoscopic work with electronics.
Hopefully in the future with the price of powerful controller computers will go down and one can use webcams and do the merging in software and then just use a set of shutter googles infront of the video goggles.
Again many thanks for the detailed explaination. It was very helpful
I am making a stereoscopic video system for a animatronic costume. Normally I would butcher 2 video glasses and merge them so that each of the LCS's is run by it's own controller board. Unfortunately this is expensive since all I need out of one of the unit is the controller and the optics/lcd's go to waste.
With the above each camera feed's to it's own LCD giving stereoscopic vision.
If I can work out a way to merge the video signals and use something to blank the LCD (backlight?) then I can show one frame to the unblanked LCD - switch the blank states, and then show the next frame to the other LCD.. essentially giving me stero vision but still only using one video goggle.
The big issue is syncing the two camera signals. There is this article http://webpages.csus.edu/~heinega/Two_Camera_Field_Sequential_3D_Circuit_Design.htm
which uses an LM1881 however it still rely's on having the two camera's synced together.
This shows possibilites http://letsmakerobots.com/node/29869 where I could use the same clock to both camera's.
Camera's are cheap... $400 a pair video goggles are not :)
I won't argue the point that all goggles drive both displays from one board since I have no knowledge of them. However, that sounds like a really stupid way to do it. I would think there would be "some" that have separate video inputs. In any case, it seems the easiest way to go would be a second driver board in the goggles, whether you can buy one as a repair part or even have to make it yourself. Syncing the cameras is no easy task. The link you gave to LMR shows that. That is exactly what I was suggesting, and you can see it is a lot of work.
If you DO manage to sync the cameras and switch displays, I think you will be disappointed in the results. If you turn off the backlights, you will get ghosting, seeing a faint image from the other eye with the desired image. That is a really fast way to get good headaches. I've had this happen to me from different types of systems. If you turn off the display you will lose resolution either in number of lines or number of frames per second. Are you using NTSC or PAL? They are similar but slightly different. I am most familiar with NTSC so I will assume that. It has 60 scans per second, but each scan shows half the image. There are 525 lines, scanned 262 1/2 each 1/60th of a second. If you switch displays each scan, you will only get those 262 1/2 lines, not all of which have video. With the full image, the effective scan rate is 30 times per second, marginal for good video. Deleting every other frame leaves 30 per second, at half resolution. If you show both scans, then switch displays, you get full resolution but only at 15 frames per second. Your video will be quite jittery. Plus, either way, the brightness will be cut in half. You may be able to adjust that with a brightness control, but that isn't the best option. PAL is 50/25 scans per second but more lines (560?) so the frame rate problem is a bit worse and the resolution a bit better. I don't think either will be acceptable frame rate wise, and only marginal line number wise. By feeding both displays the full video image you remove these problems.
You might be better off building your own goggles. You can get very small LCDs pretty cheap. Some may be NTSC or PAL input. If not, it would be possible, but not easy or elegant, to use a small processor board to decode the video signals and display them on both screens. The FIRST thing I would do is look for goggles that have two video inputs. Hope this helps.
why you want the backlight synced to the video. I would think you would want the backlight on all the time. But assuming that really is what you want, why not just sync left goggle with left camera and right goggle with right camera? I'm pretty sure I'm missing something here.
Unfortunately all video goggles work with 2 LCD's connected to the one video board which takes one video feed.
To do what you are suggesting I would have to take 2 sets of goggles and remove the controller board from one and patch it into the second video goggle unit so that one board drives the left and the other board drives the right
Ok. I want to use two camera's in a stereoscopic system so I can get depth perception using video goggles. With two camera's running with a master clock it is made simple as I can syncronise the left and right frame to the backlight of the individual goggles lcd display.
Failing this I will try and to a left/right system using an LM1881 and likewise use the backlight to illuminate left or right.
Third possibility is to use an wired version of a 3d glasses and sit that between the video goggles and the wearer.
You want two (or more) cameras whose sync signals are synchronized, like professional tv cameras. If that is correct, I am unaware of any that would be low cost. I assume you want to mix or switch between video signals. If you can't find any off the shelf, and your skills are up to it, you might be able to find some whose chips allow hacking to clock one from another, or all from a master clock. It would certainly take a lot of research and work.
What exactly are you trying to do? There might be an easier/cheaper way.
This http://letsmakerobots.com/node/32507 is what came to my mind though.