On Wed, Jul 22, 2020 at 10:23:19PM +0200, Marcus Glocker wrote: Hello Marcus,
> I've tested this here as well in the meantime by leaving mmap_init() on > its original location (doesn't get involved for '-c reset') with three > different cams: > > * Logitech C930e: I see the same problem like you do with your C920 > finally. > * Logitech QuickCam Pro 9000: reset works fine. > * SunplusIT Inc Integrated Camera: reset works fine. Hmph, that's slightly annoying of Logitech :/ > This seems to be a problem only with some cams when turning the > auto white balance temperature back on while the stream is off, the > setting doesn't get recognized by the cam afterwards. > > I'm basically OK with your last diff, except the mmap_init() location > change: I don't like to turn the cam stream on only for setting this > parameter because some cams can't handle the obvious. > > I tried out some things with the C930e to get the auto white balance > temperature back on without having the stream on, but no luck so far. > > I would aim to get your diff in without the mmap_init() change. Maybe > we'll find a solution/workaround for this partial problem later? If we can find a change that allows this, I'd be happy! When I briefly tested things on Windows, the Logitech app there activated the stream before changing settings, so it's quite possible that they never tested changing some settings with the stream off. v4l2-ctl might have some clues in it, but their model is subtly different than ours and forces the user to understand a lot more about their camera (e.g. they force the user to turn off auto white balance before they allow them to set manual white balance, a differentiation which IMHO only makes sense if you've read the UVC spec). That makes me think that if/when uvideo is extended to deal with terminal control requests (e.g. zoom, exposure, focus) we'll find that other settings with "auto" options have similar problems. Honestly, if the price of controlling exposure and focus is having to turn the camera stream on, I think I will consider that an acceptable trade-off, given how useful those settings are :) >> +.It Fl c Ar reset | control=value >> +Set control value (e.g. brightness) and exit. The special name >> +.Ql reset >> +resets all values to their default. The available controls can be >> found +with >> +.Fl q >> +and the default values with >> +.Fl c Ar reset >> +.Fl v . > '-c reset -v' will not only display the default values, but also do > reset the cam to them. Shouldn't the sentence be more something like > the following since this sounds like '-c reset -v' can only display the > default values? > > "The available controls can be found with -q and the default values > are displayed during a reset with -c reset -v." Works for me! Laurie
