On Thu, 8 Sep 2011, Sakari Ailus wrote: > On Thu, Sep 08, 2011 at 02:35:54PM +0200, Guennadi Liakhovetski wrote: > > On Tue, 6 Sep 2011, Sakari Ailus wrote: > > > > > On Tue, Sep 06, 2011 at 01:41:11PM +0200, Laurent Pinchart wrote: > > > > Hi Sakari, > > > > > > > > On Tuesday 06 September 2011 13:36:53 Sakari Ailus wrote: [snip] > > > > > Typically such sensors are not controlled by general purpose applications > > > > > but e.g. require a camera control algorithm framework in user space. This > > > > > needs to be implemented in libv4l for general purpose applications to work > > > > > properly on this kind of hardware. > > > > > > > > > > These sensors expose controls such as > > > > > > > > > > - Per-component gain controls. Red, blue, green (blue) and green (red) > > > > > gains. > > > > > > > > > > - Link frequency. The frequency of the data link from the sensor to the > > > > > bridge. > > > > > > > > > > - Horizontal and vertical blanking. > > > > > > > > Other controls often found in bayer sensors are black level compensation and > > > > test pattern. > > > > May I suggest a couple more: > > > > (1) snapshot mode (I really badly want this one, please;-)) > > Sounds good. > > > (2) flash controls (yes, I know we already have V4L2_CTRL_CLASS_FLASH, I > > just have the impression, that these controls are mostly meant for > > either pure software implementations, or for external controllers, I > > think it should also be possible to have them exported by a normal > > sensor driver, but wasn't really sure. So, wanted to point out to this > > possibility once again.) > > There was a lengthy discussion during the review process. Do you see that > something would be missing from the current interface? I didn't try to systemise them. Just having a look at a couple of datasheets I see a few more parameters, like flash strobe delay, etc. But I don't think we should just add as many of them as we can just for the sake of them. I think, as soon as someone comes with a new requirement, we'll think of a way to implement it. > I vaguely remember that you had a sensor that expected to be controlled by > the flash controller considering the flash timing, rather than the other way > around. Maybe:-) But again - let's wait until someone needs that functionality. > > (3) AEC / AGC regions > > This might get tricky. I wonder how we could eventually standardise these > ones. > > > (4) stereo (3D anyone?;)) - no, don't think we need it now... > > I wonder what is needed to support this on V4L2. It might also depend on how > the hardware will look like. The sensor, that I looked at (mt9v022) has one bit to turn stereo mode on or off, and one more bit to set master or slave. > > > > > None of these controls are suitable for use of general purpose applications > > > > > (let alone the end user!) but for the camera control algorithms. > > > > > > > > > > We have a control class called V4L2_CTRL_CLASS_CAMERA for camera controls. > > > > > However, the controls in this class are relatively high level controls > > > > > which are suitable for end user. The algorithms in the libv4l or a webcam > > > > > could implement many of these controls whereas I see that only > > > > > V4L2_CID_EXPOSURE_ABSOLUTE might be implemented by raw bayer sensors. > > > > > > > > > > My question is: would it make sense to create a new class of controls for > > > > > the low level sensor controls in a similar fashion we have a control class > > > > > for the flash controls? > > > > > > > > I think it would, but I'm not sure how we should name that class. > > > > V4L2_CTRL_CLASS_SENSOR is tempting, but many of the controls that will be > > > > found there (digital gains, black leverl compensation, test pattern, ...) can > > > > also be found in ISPs or other hardware blocks. > > > > > > I don't think ISPs typically implement test patterns. Do you know of any? > > > > Yes, i.MX31. > > Good to know that. > > But you already know I'm with Laurent in believing that the controls should > be classified based on what they do, not where they are implemented. :-) Sure, I agree too, that was just FYI. Thanks Guennadi --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer http://www.open-technology.de/ -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
