Live Video on Dashboard

[buchanan]

2077 did this last weekend at WI.

We sent an 80x60 (later scaled up) image split into 5 interlaced fields at 8 bits per pixel with no compression in the usual sense. Is there an API for compression? We used the 8 bits as a 4-bit red channel and a 4-bit green channel, giving "sorta-color" sufficient to distinguish targets.

We got usable video at 10 fps with occasional dropped fields (jerkiness, smears). Latency seemed to be around half a second with our final setup, though some earlier tests did better at the price of less acceptable blurring. Not sure what the limiting factor in this was.

The key things we found were 1) controlling the rate at which we sent frames into the Dashboard class (the cRIO->DS loop is asynchronous at .02 seconds) and 2) using the lower level NI imaq APIs to access pixel data in the Image object quickly.

I suspect considerably better performance is possible with some tweaking, and especially if real compression were used, but that's were we got in the time available, and it was certainly usable.