Skype

Skype works without quirks by now (up to 720p for some); the following information is purely historic:

Skype had a somewhat broken v4l2-implementation, which unfortunately made it sometimes a bit quirky, to use it with a v4l2loopback device.

Luckily, it seems that things have improved since I last checked, and when I tried it today (using "skype-4.0.0.8" for Debian/32bit) it worked out-of the box using a video-signal I produced with gstreamer:

(Skype version in 2020: 8.60.0.76)

gst-launch-1.0 videotestsrc ! videoconvert ! "video/x-raw,format=YUY2" ! v4l2sink device=/dev/video1

dev/video1 is my v4l2loopback device, and I'm only using a test-video here.

People found that forcing the colorspace to "YUV2" is important if you want Skype to be able to read the video. for an explanation check the Colorspace Issues page.

Sending a desktop capture through Skype

You can use ffmpeg to use your desktop (or part of it) as producer. If you want to use Skype as consumer, you need to make ffmpeg use a pixel format supported by Skype. The following works for me:

ffmpeg -f x11grab -s 640x480 -i :0.0+10,20 -vf format=pix_fmts=yuv420p -f v4l2 /dev/video1

(In this example, 640x480 is the size of the capture area and +10,20 is the offset.)

In 2020 the produced image will be seen by Skype but looks scrambled