Hi Daniele,

On Friday 10 October 2008, Daniele Paganelli wrote:
> Dear UVC developers,
>       I'm trying to program UVC devices using the video4linux2 API.
> I have problems understanding the output UVC driver give for a
> VIDIOC_QUERYCTRL ioctl.
>
> Response struct (v4l2_queryctrl):
> id: V4L2_CID_EXPOSURE
> type: V4L2_CTRL_TYPE_MENU
> name: 'Exposure, Auto'
> minimum: 0
> maximum: 0
> step: 9
> default_value: 8
> flags: 0
>
> The video4linux2 api specification states that, for a Menu type, the
> meaning of the queryctrl response given by the driver should be:
>
> min: 0
> step: 1
> max: N-1
>
> where N is the number of menu choices.
>
> So how should I interpret the UVC response min=0/max=0/step=9???

As a bug somewhere between the device and the console :-) It can be a driver 
issue or a userspace issue.

First of all, please make sure you're using a recent driver version. SVN head 
or the driver included in the Linux kernel should do.

If it still fails please post a code sample I can test.

> I got this response for Logitech QuickCam Pro for Notebooks
> and Logitech QuickCam Deluxe for Notebooks
>
> Best regards
> and thanks for the great driver ;)

You're welcome.

Best regards,

Laurent Pinchart
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