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usb webcam with ehci periodic scheduler

Posted: Sat May 09, 2015 11:51 am
by ehenkes
I started with sourcecode for usb webcams (uncompressed format, YUV2) currently driven by the ehci periodic scheduler and the usb video class:
http://sourceforge.net/p/prettyos/code/ ... sb_video.c
http://sourceforge.net/p/prettyos/code/ ... hciQHqTD.c (cf. ehci_addToPeriodicScheduler)

It runs fine now, but I could not find tutorials, comparable code, discussions and hints at this forum, therefore I am interested to discuss the features of webcams and how to handle the different parameters, formats, etc.

I currently get best results with the Logitech C270, but want to use all kinds of webcams.

Re: usb webcam with ehci periodic scheduler

Posted: Mon May 11, 2015 5:34 pm
by SpyderTL
Very cool. You need to add some information to the wiki. The USB page is pretty good, but it would be nice to have some details on the different usb device class interfaces.

Re: usb webcam with ehci periodic scheduler

Posted: Tue May 12, 2015 2:53 pm
by DavidCooper
The latest edition of Benjamin Lunt's book on USB (http://www.fysnet.net/the_universal_serial_bus.htm - written specifically for OS developers like us) has a section (part 5) on using USB video devices which may be helpful.