On 2002.04.19 18:57:23 +0200 Munaut Sylvain wrote: > Hi > > I'm new to the USB world, and to this ml so ... > > I've a webcam based on the NW812 chip which is not supported under > linux. And i'd like to write a driver for it. But the firm that sell > this chip don't want to release technical spec about this chip ... So > I'd like to "guess" it's protocol ...
Don't forget to put a warning with the driver that users shouldn't buy cameras with this chipset because the vendor is an idiot :) > My first question is : Are all usb webcam using about the same protocol > ( i mean is there a lot of similarities between protocols or are they > all completel different ? ) Most cameras use a yuv derivative although there are also cameras using the bayer format. If the camera is a low cost one the compression might not be very though, but most compression formats aren't easy to find out. But most webcams also have a noncompressed mode (often used for still images or snapshots) that might be easier to start with. > And the second one : I suppose some people have already done this ( > guessing protocols ). Do you have some tip on how to do ? It isn't easy... but try snooping on while showing some familiar patterns: all white image (directed at lightbulb), all-black image (bit harder due to noise), half black half white (might show linelength), alternating pattern, different collors (might give you a clue about the colorspace used (yuv vs rgb) and so on. > I use a USB spy program under win32 to listen to the USB port while i'm > using the web cam. Do you knwo better spy program than "usb snoop" ? Jeroen _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
