RCA video to USB conversion?

Kirk Fraser

How can I use a Propeller to convert a common yellow RCA video output from a common security camera into a USB connection and driver so I can work with machine vision software on my computer for my robot?

Reasons for this are:
1) an ordinary security camera can be had about as cheaply as a webcam but often has a bigger lens and sometimes better color.
2) the same system would enable hooking up to other video sources including a TV Tuner, VCR/DVD player.
3) unfortunately IP cameras which have better resolution also have an unadvertized 8 second delay which is unacceptable for real time robot work.
4) a Roxio unit purchased with software years ago has zero support, even via their forum, unless a very kind and rare employee takes an unofficial interest.
5) existing machine vision software varies greatly in functionality, price, and ease of understanding - openCV for example supplies some useful functions but not enough for typical robot work so I want to be able to add functions.
6) at my age, with a just passing driver eye test, I'm convinced a security camera has sufficient resolution for my needs at a far more affordable price than special high resolution industrial cameras.

Related questions
1) what category and possible name would this project be called if it is in the OBEX library?
2) is this biting off more than I can chew? Would I be better off to try what comes up for "rca to usb video converter" on Amazon or Ebay?

Thanks.

Mike Green

Probably not doable. There are video input objects, but they're relatively low resolution. Two issues: 1) There's special hardware in each cog for producing video output, but nothing similar for handling video input. 2) There's limited memory for buffering video input. 32K bytes have to be shared with Spin programs and any program data among other things. ViewPort has provisions for streaming video from a Propeller to a PC and displaying / filtering it. Have a look at the ViewPort documentation.

Rayman

It would be much cheaper to get a video capture device from Amazon.

You would need some special extra hardware to do it with Propeller.

Still, I would think a USB webcam could give better results, if you got a more expensive one.
NTSC cameras have limited resolution, but webcams can have higher resolution...

I think Phil sells PropCam or something in the Parallax store, you might see if that is good enough.
Also, he sells the Backpack, which I think is capable of video capture.

But, what would be better is if the Prop could capture at full resolution, encode with jpeg and then transmit over USB.
Or, better yet, include local display on LCD screen with option to save to SD as well.
I have a plan to do this with Propeller, but it's probably several months away...

ericball

Hi Kirk,

I suspect the mentioned Propeller options will not satisfy your requirements as the Propeller doesn't have the specific digitizing hardware nor general USB capabilities.

That being said. I'd recommend first attacking the question from the receiving end - what is going to handle the video once it has been digitized and what are it's requirements / recommended options. If your processing is being done by Windows software which is using the standard Win32 video streams, then a webcam or video capture dongle will likely work without much effort. But if you're running Linux or OSX or custom hardware then you may need something more specific.

Also, standard definition TV resolution is around 640x480 depending upon how good the chroma filtering is. Webcams may be better as they can digitize straight from the sensor array, skipping several steps. Picture quality will also be dependent upon the size of the sensor, the size of the lens, and the amount of available light. (Which is why cellphone cameras look so bad indoors - small lenses & even smaller sensors with far too many pixels.)