Add Support for Kinect as Webcam on Linux

[dedsec995]

Add Support to use Kinect as webcam on linux
Just found an old Kinectv2 lying around and wanted to use it as webcam as it has decent camera. Searched a lot (I mean a lot) and found nothing.
So I modified Protonect to use Kinect as webcam
The C++ code captures RGB video frames from a Kinect device using libfreenect2 and writes them to a virtual webcam device (/dev/video10) with the help of opencv created by v4l2loopback.

[dedsec995]

This commit try to solve the issue #1144 #1151 #1175. It contains an app inside examples called kinect_webcam that allows users to use kinect rgb as a webcam on Linux
It introduces 2 new dependencies OpenCV and v4l2loopback
@JoshBlake

[accplan]

thank you so much, it works perfectly except chromium-based apps like Discord refuse to recognize the camera. Turns out chromium accepts only specifics pixel formats, so I replaced V4L2_PIX_FMT_BGR24 with V4L2_PIX_FMT_RGB24 and now it works even with Discord!
Took the constant from this comment: v4l2loopback/v4l2loopback#274 (comment)

[joelis10]

I tried cloning your repo and following the ReadMe, but I still can't get a stream from my Kinect v2 working. I always get logs from either Viewer program ending in Segmentation fault (core dumped) and running Kinect_Webcam doesn't seem to work either, as it can't find the command.
I'm running Linux Mint Debian Edition with an AMD APU: 03:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Cezanne [Radeon Vega Series / Radeon Vega Mobile Series] (rev c1)

[weirdal3333]

It has been almost a year, and this has not been merged in... What gives?

[p0Rp-rs]

I tried cloning your repo and following the ReadMe, but I still can't get a stream from my Kinect v2 working. I always get logs from either Viewer program ending in Segmentation fault (core dumped) and running Kinect_Webcam doesn't seem to work either, as it can't find the command. I'm running Linux Mint Debian Edition with an AMD APU: 03:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Cezanne [Radeon Vega Series / Radeon Vega Mobile Series] (rev c1)

@joelis10 I get this segmentation fault error as well from running the Protonect test app, I'm using an RX 6800XT. Have you found anything to get around this? I tried getting a pcie usb controller with a different chipset and still haven't figured out the issue. I'm not sure if you can run the app as well with the -norgb flag, but that will allow it to run successfully and open the viewer with the other two views but the RGB feed is black.