Hi,
I have checked out the latest v4l code from the mercurial repository on
linuxtv.org, and successfully compiled and loaded the uvcvideo module, which
I tested with a logitech quickcam sphere af (046d:0994). I have comments and
questions regarding the V4L2 controls to pilot the pan and tilt motors:
After mapping the dynamic controls (with uvcdynctrl), the following controls
become available:
- Pan Reset: min: 0, max: 1, step: 1, type: integer
- Tilt Reset: min 0, max: 1, step: 0, type: integer (note the step value of
0 which should really be 1 here)
- Pan (Relative): min: 4480, max: 4480, step: 1, type: integer
- Tilt (Relative): min: 1920, max: 1920, step: 1, type: integer
- Pan/tilt Reset: min: 0, max: 3, step: 1, type: integer
Creating a user interface based on these controls is quite hard because of
their types and step values:
Trying to set a value of 0 on any of the Reset controls fails, even though 0
is reported as an acceptable value.
Setting a value of 1 on either Pan (Relative) or Tilt (Relative) succeeds
but results in no movement.
Keeping the GUI up-to-date is not possible because calling
ioctl(VIDIOC_G_CTRL) on any of these controls fails (which makes sense when
you know what the controls are). But from a programming point of view, if
you try to create an interface that will work with any controls, the way
these are reported (integers) makes it almost impossible to keep track of.
I have a couple of suggestions to improve this, and would appreciate
comments on them:
- Reporting the Pan/Tilt Reset control as a menu and Pan Reset and Tilt
Reset as buttons instead of integers, will solve the previously mentioned
issues.
- Change the Pan (Relative) and Tilt (relative) step value to one that
actually results in a slight movement of the camera.
Is there a way to make these changes when mapping the controls, or do they
have to be coded in the driver itself ?
Thanks
Gilles
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