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Logitech QuickCam Express Plus

Update: Merged into gspca2 (thanks to Ihor Catson for pushing this patch to the maintainer :))

Two weeks ago I bought a cheap webcam device Logitech QuickCam Express. Upon purchase we were not sure that this will work under Linux, the reports were positive, but you will never know for sure what hardware is inside today.

Having heard of Micael Xhaard and his awesome work to make webcams function under linux I decided to give it a try.

The camera is working fine, the sensor is spca561 (Sunplus) revision 012A which radically decreases the possibility of brightness/contrast control. It is done in software layer under Windows driver and there are few things that are configurable in hardware. The max resolution is QCIF 352×288 (640×480 under windows is done via software scaling).

The configurable items are exposure, gain, red/blue balance (which i guess is called white balance). spca561.h has nice implementation of brightness/contrast being controlled via exposure and gain, probably it will need to be done in decoder, but then we don’t have v4l interface to control these values.

So the only thing that was bothering me was white balance, i.e. I too brown (due to high red value as compared to green/blue). This was configurable by sending appropriate numbers to module parameters GRed/GBlue/GGreen but I missed the ability to fine-tune this while already broadcasting the video.

So i took gvim and hacked up white balance setting support via whiteness setting.

Have fun :)