Fake a webcam using a video loopback device?

The gst-launch manpages tells us that we need to decode the video first, and the easiest way to do so is like this:

gst-launch-0.10 filesrc location=[location] ! decodebin ! v4l2sink device=/dev/video0

gst-launch does not need to be run as root, and [location] can be relative too!

Just use v4l2loopback with mplayer.

1. Download it,
2. compile it (make and su -c 'make install'),
3. load the module with su -c 'modprobe v4l2loopback',

4. then change one line in the file examples/yuv4mpeg_to_v4l2.c of the v4l2loopback source folder from

   v.fmt.pix.pixelformat = V4L2_PIX_FMT_YUV420;
   

   to

   v.fmt.pix.pixelformat = V4L2_PIX_FMT_YVU420;
   

5. and do make in this folder.

6. Then run it from the examples directory like this:

   mkfifo /tmp/pipe  # only needed once, as long as you do not delete the file /tmp/pipe
   ./yuv4mpeg_to_v4l2 < /tmp/pipe &
   mplayer movie.mp4 -vf scale=480:360 -vo yuv4mpeg:file=/tmp/pipe
   

   where you replace movie.mp4 with the name of your video file. And replace /dev/video0 with your loopback device.

MPlayer is able to play any webstreams, all kind of video files and so on. I just tested it with a file from http://www.tagesschau.de which is a german news site.

TS=$(wget 'http://www.tagesschau.de'$(wget http://www.tagesschau.de -q -O - | grep 'Letzte Sendung' | sed -e 's%.*href="%%' -e 's%".*%%') -q -O - | grep '\.webm\.webm' | sed -e 's%.*href="%%' -e 's%\.webm\.webm".*%.webm.webm%')
./yuv4mpeg_to_v4l2 < /tmp/pipe &
mplayer $TS -vf scale=480:360 -vo yuv4mpeg:file=/tmp/pipe