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[Spca50x-devs] Exposure control in zc3xx driver


Recently I bought a Labtec Notebook Webcam.
Vendor ID: 0x046d
Product ID: 0x08aa
Sensor: Hdcs2020

I managed to get it working under linux 2.6.27 in Xubuntu 8.10. Some
apps (i.e. skype) needed the v4l1compat.so library, but that was no
big problem.

The webcam is working fine in well-lighted enviroment, hovewer in
darker rooms the image is very dark and full of noise. All of the
programs I tried to control webcam parameters via v4l1 (camorama,
camstream, gqcam, cheese), but also via v4l2 (v4l2ucp). Of course it
affects the picture (brighter/darker), but with no visible improvement
to the quality. Gamma adjustment helps a little bit, but far from ok.
Image becomes white (as if covered with fog), but not brighter.

It seems to me that the brightness/contrast controls work only on the
software side. There is no real exposure/gain setting in none of the
programs I tried, since there is no way to adjust the parameters in
the kernel module (gspca_main, gspca_zc3xx) itself. Tried modparm, dug
in /sys, but with no success.
Afaik most webcams can be put in some kind of "night mode" where the
framerate is reduced, but with longer exposure time image quality in
low light is better. However, I don't see a way to do it with my
Labtec Notebook Webcam.

What can I do to make my webcam work properly in low light enviroment?

Thanks from advance for any clues
Best regards

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