Hi Alexandre, > > I would believe that the following extended controls should actually be > > mapped onto standard V4L2 controls : > > > > "Exposure, Auto" = V4L2_CID_AUTOGAIN > > "Exposure (Absolute)" = V4L2_CID_EXPOSURE > > "White Balance Temperature, Auto" = V4L2_CID_AUTO_WHITE_BALANCE > > "White Balance Temperature" = V4L2_CID_GAMMA > > > > Or am I missing something?
For the sake of clarity, there are no "extended" controls. We currently have standard controls (defined in the V4L2 specification) and private controls (defined by drivers). There is also an extended control API, where "extended" refers to the API and not the individual controls. > There is still some ongoing discussion (euphemism alert) on how to best > map UVC controls (the USB Video Class spec defines quite a few) to V4L2 > controls. The fact is that V4L2 controls are not even kinda close to what > we need for the UVC driver. If you have a strong opinion on that or any > helpful arguments, then feel free to speak up on the v4l-list > (https://www.redhat.com/mailman/private/video4linux-list/2007-January/threa >d.html, search for "New control identifiers"). We're especially looking for > people with a background in photography/imaging. > > Back to your e-mail, though. :-) We'll certainly review these controls > once V4L2 is updated. In the meantime a few notes: > - White balance can be specified in temperature or a red/blue channel > correction. But Gamma correction is a completely different story. > - Gain and exposure time are often related, but, in camera terms, are two > different controls. > - There is relative and absolute exposure time. V4L2 does not specify what > V4L2_CID_EXPOSURE means. All standard UVC controls should be mapped to standard V4L2 controls. Mauro (the V4L maintainer) agreed to add some of the needed controls to the V4L2 spec, but still disagrees about the others. As Martin stated, we need people with technical knowledge on the subject to voice their opinion on the V4L mailing list. This is the last step before submitting the driver for inclusion in the mainline kernel. Best regards, Laurent Pinchart _______________________________________________ Linux-uvc-devel mailing list [email protected] https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
