Re: [Ekiga-list] Ekiga should save settings (gamma, saturation) of my USB webcam

[Stefan Monnier <monnier iro umontreal ca>]

>> > luvcview then prints this out:
>> > "Video driver: x11
>> > A window manager is available
>> > video /dev/video0
>> > Unable to set format: 5.
>> >  Init v4L2 failed !! exit fatal"
>> > Only solution I know to get back my video is to reboot the entire system
>> > (annoying, so MS Win 3.1.). Anybody who knows how to get that v4l2 driver
>> > working again without rebooting?
>> 
>> I'm cc'ing Luc Saillard, an expert in terms of video and V4L2 ;-)

> I found a solution on mailing-list  
> https://lists.berlios.de/pipermail/linux-uvc-devel/ :
> "the only way is to reset camera, either by calling usb_reset_device() or by 
> unplugging the cord."
> The USB Logitech webcams appear to have a hardware bug (something about usb 
> timings) and as far as I understand it, there isn't a workaround for it.
> Unplugging the cord of my webcam I can do but I'd like to know with what 
> command i can do a "usb_reset_device()".

> I guess some  experts on linux-uvc are Laurent Pinchart and Evgeny.

There's a patch to linux-uvc that does the usb_reset_device when it seems
necessary.  Check the linux-uvc list for it.  The latest version of the
patch I could find was pretty old and the code has been completely shuffled
since then (split into several files), so it took me some manual work to
apply the patch.  I posted the resulting new patch to the linux-uvc
mailing-list recently (maybe a couple weeks ago).  It seems to work for me.


        Stefan