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stamped
02-15-2007, 06:31 PM
I am thinking about building a system that reads composite video and writes it to an SD card. I have searched through the forums and cannot find anything on reading composite video and storing it. The application is to read a reasonable resolution·camera·stream such as a color lipstick camera (TV resolution - much higher than webcams).·I have found some useful information on·writing to the SD card. I am more looking for some specific informaton on using the Propeller with composite video.·I am just in the beginning stages of my investigation into how to put this together and would appreciate some pointers if anyone knows of some reference information?

Thanks in advance.

Javalin
02-15-2007, 07:05 PM
I think Bean was looking into it - think I saw a post. I guess the key bits would be a very fast ADC, a signal-decoder chip (LM1881) and a fast memory card.

James

Bean
02-15-2007, 09:27 PM
Yes you will need a "sync seperator" ic and a flash ADC.
Some extra memory wouldn't hurt either.
If you store 256x192 pixels @ 4 bits each (16 gray levels) that would be 24K.
The SD card is not nearly fast enough to store the image directly.
Storing color images would be alot more complicated because you need to phase lock to the color burst frequency.

Bean.

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mahjongg
02-15-2007, 11:01 PM
For professional video capture solutions see here:

www.conexant.com/products/entry.jsp?id=203 (http://www.conexant.com/products/entry.jsp?id=203)

Mahjongg

Graham Stabler
02-15-2007, 11:01 PM
This is an interesting topic as Omnivision do a range of camera sensors that output NTSC directly, I think you supply the clock so perhaps that would mean a sync generator was not needed? They are also dirt cheap BTW.

These chips include the 1/18" array that can be fitted in a capsule and swallowed, I don't have a price on that one yet however.

Graham