I am doing a feasibility study of an application on N900 that would set the value of aperture and leave the expousure and focuse on automatic settings, however, I need to retreive the focus distance (V4L2_CID_FOCUS_ABSOLUTE). I read through the video4Linux API and in section 1.9.6 Camera Control Reference found the following.


Exposure and aperture:

V4L2_CID_EXPOSURE_AUTO integer
Enables automatic adjustments of the exposure time and/or iris aperture. The effect of manual changes of the exposure time or iris aperture while these features are enabled is undefined, drivers should ignore such requests. Possible values are:

V4L2_EXPOSURE_AUTO Automatic exposure time, automatic iris aperture.
V4L2_EXPOSURE_MANUAL Manual exposure time, manual iris.
V4L2_EXPOSURE_SHUTTER_PRIORITY Manual exposure time, auto iris.
V4L2_EXPOSURE_APERTURE_PRIORITY Auto exposure time, manual iris.


Focus:

V4L2_CID_FOCUS_ABSOLUTE integer
This control sets the focal point of the camera to the specified position. The unit is undefined. Positive values set the focus closer to the camera, negative values towards infinity.

V4L2_CID_FOCUS_AUTO boolean
Enables automatic focus adjustments. The effect of manual focus adjustments while this feature is enabled is undefined, drivers should ignore such requests.

Using this values one could get the camera in the appropriate mode of operation and theoretically through the control class retrieve any of those values.

Will the V4L2_CID_FOCUS_ABSOLUTE value change as the camera tries to autofocus on an object? If not, is there any other value I missed that could be used for that. Where can I check if these controls are supported by the N900 hardware.

Thx for any help,

Klen