How to enable the camera module on a Raspberry Pi

rpi-enable-camera-module.md

Enable camera module

Edit your /boot/config.txt file and make sure the following lines look like this:

start_x=1             # essential
gpu_mem=128           # at least, or maybe more if you wish
disable_camera_led=1  # optional, if you don't want the led to glow

Load bcm2835-v4l2 module

sudo modprobe bcm2835-v4l2

or add bcm2835-v4l2 to /etc/modules.

Create loopback device

The video device /dev/video0 can only be accessed by one process at a time. Use a loopback device to allow mutli process access at /dev/video1. https://raspberrypi.stackexchange.com/a/19897

Install v4l2loopback

# Install kernel headers
# Note: Kernel headers may not be up-to-date. 
# To downgrade the firmware to a specific firmware use sudo rpi-update <commit hash from https://github.com/Hexxeh/rpi-firmware>
sudo apt-get install raspberrypi-kernel-headers

# Download source and install
git clone https://github.com/umlaeute/v4l2loopback
cd v4l2loopback
make
sudo make install

Load v4l2loopback module via

sudo modprobe v4l2loopback video_nr=1 # creates /dev/video1
# sudo modprobe v4l2loopback devices=1 

If you want to load the module on startup add v4l2loopback to /etc/modules and the options to /etc/modprobe.d/v4l2loopback.conf. https://askubuntu.com/a/822136

# /etc/modprobe.d/v4l2loopback.conf
options v4l2loopback video_nr=1

Then copy the video from /dev/video0 to /dev/video1.

ffmpeg -f video4linux2 -i /dev/video0 -vcodec copy -f v4l2 /dev/video1