====== virtual video driver ======
source : linux magazine France n°192 (april 2016)

===== Install v4l2loop =====
[[https://github.com/umlaeute/v4l2loopback|Source code]]
<sxh bash>
apt-get install v4l2loopback-dkms v4l2loopback-utils
</sxh>

===== Load the driver =====
<sxh bash>
sudo modprobe v4l2loopback devices=1 video_nr=1 card_label=toto
</sxh>

==== Permanently load the driver ====
/etc/modules-load.d/v4l2loopback.conf
<sxh>
v4l2loopback
</sxh>
/etc/modprobe.d/v4l2loopback.conf
<sxh>
v4l2loopback devices=1 video_nr=1 card_label=toto
</sxh>

===== Get driver infos =====
<sxh bash>
v4l2-ctl --list-devices
v4l2-dbg --info --device=/dev/video1
v4l2-ctl --list-formats --device=/dev/video1
</sxh>

===== Change settings =====
<sxh bash>
v4l2-ctl set-fps 25 /dev/video1
</sxh>

===== Send video =====
Exemple using a webcam
<sxh bash>
ffmpeg -f mjpeg -i http://webcam.st-malo.com/axis-cgi/mjpg/video.cgi?resolution=352x288 -pix_fmt yuv420p -f v4l2 /dev/video1
</sxh>

===== Read the video =====
Use vlc or ffplay
<sxh bash>
ffplay -f v4l2 -i /dev/video1
</sxh>
==== Capture ====
<sxh bash>
ffmpeg -f v4l2 -i /dev/video1 -f mjpeg ./video-capture
</sxh>

===== Use with chrome =====
Load the driver
<sxh bash>
modproble v4l2loopback device=1 video_nr=1 exclusive_cap=1
</sxh>

Inject with gstreamer
<sxh bash>
gst-launch-0.10 -v videotestsrc ! "video/x-raw-yuv, width=640,height=360, framerate=30/1, format=(fourcc)I420" ! v4l2sink device=/dev/video1
</sxh>
Test with http://opentokrtc.com or http://apprtc.appspot.com
===== Use with skype =====
<sxh bash>
gst-launch videotestsrc ! ffmpegcolorspace ! "video/x-raw-yuv, format=(fourcc)YUV2" ! v4l2sink device=/dev/video1
</sxh>

{{tag>video cli}}