[gst-devel] generic control and forward ioctl for elements like v4l2src

Edgard Lima edgard.lima at indt.org.br
Tue Mar 25 17:32:14 CET 2008


I would like to propose:

1- a generic control interface, like GstColorBalance but more generic and
2- a interface to allow app call specific ioctls.

The use cases are:

1- create a generic GUI app that exposes all the controls available in
v4l2src or other GST element. So we have to enumerate controls and
related properties (name, desc, range, type, etc..)

my camera driver export lot of controls
some of then are predefined (like V4L2_CID_SHARPNESS) and others are
camera specific. For the predefined ones that are also related to color
balance is already ok, we can just use GstColorBalance, but, for
non-color-balance and driver's specific we can't touch then in our

2- For applications written to a specific camera model would be nice to
  call some ioctls directly. For example, there is a Logitech camera
that allows to rotate the camera by sending specific ioctls to the driver.
btw: I not talking about rotate the image, I'm talking about rotate the
camera using a motor in the base, or what else, like turn on the flash
or ask for a pizza ;-)

a- for use case 1 I would propose something quite similar to
ColorBalance but a bit more generic, possible including flags (like
V4L2_CTRL_FLAG_SLIDER, hint to app that a slider would nice) and
category to help app to group them.

b- for ioctl must be as simple as possible (int request, ....)

What do you thing about? Ideas please.


More information about the gstreamer-devel mailing list