Re: [RFC PATCH 0/2] media: v4l2: map UVC_CT_ROLL_ABSOLUTE_CONTROL

From: Michael Riesch
Date: Fri Aug 04 2023 - 14:45:58 EST


Hi Gergő,

Interesting work! I would guess that there are a lot of cameras with an
accelerometer or gyroscope that could report the rotation.

On 8/3/23 23:28, Gergő Köteles wrote:
> Hi,
>
> Logitech Streamcam can be mounted in 'portrait mode' as well.
> It reports the current roll (-90, 0, 90, 180) with
> UVC_CT_ROLL_ABSOLUTE_CONTROL.
>
> This RFC defines V4L2_CID_ROLL_ABSOLUTE, and maps
> UVC_CT_ROLL_ABSOLUTE_CONTROL to make it available to
> userspace.
> Then, the userspace can rotate the stream based on the roll.

Should we also discuss pitch and yaw while we are at it?

As far as I know there are controls to set pan and tilt of a PTZ camera,
but there are no controls that report those angles.

> Is it better to use V4L2_CID_CAMERA_SENSOR_ROTATION for this?

IMHO that would make sense.

Best regards,
Michael

> The value set matches that control.
> If yes, is it worth mapping UVC_CT_ROLL_ABSOLUTE_CONTROL to
> V4L2_CID_CAMERA_SENSOR_ROTATION for this camera only?
>
> Any feedback is greately appreciated.
>
>
> Gergő Köteles (2):
> media: v4l2: ctrls: Add ROLL_ABSOLUTE control
> media: v4l2: map UVC_CT_ROLL_ABSOLUTE_CONTROL
>
> .../userspace-api/media/v4l/ext-ctrls-camera.rst | 5 +++++
> drivers/media/usb/uvc/uvc_ctrl.c | 9 +++++++++
> drivers/media/v4l2-core/v4l2-ctrls-defs.c | 1 +
> include/uapi/linux/v4l2-controls.h | 2 ++
> 4 files changed, 17 insertions(+)
>
>
> base-commit: 06c2afb862f9da8dc5efa4b6076a0e48c3fbaaa5