Raspberry Pi ffmpeg video4linux2, v4l2 mmap no such device - ffmpeg

Question

On my Raspberry pi I've installed ffmpeg. At the begin I type
uv4l --driver raspicam --auto-video_nr --width 640 --height 480 --encoding jpeg
to run driver. Then I check if devoce0 is registered:
ls -la /dev/video*
and it returns video0 so it is registered. Then I type command to run server:
ffmpeg -v verbose -r 5 -s 640x480 -f video4linux2 -i /dev/video0 http://localhost/webcam.ffm
and the camera lights up for a while and then turns off and I get error like bellow:
[video4linux2, v4l2] mmap: No such device /dev/video0: No such device
What I should do to resolve it? It looks like internal error one of these libraries.
This command works:
uv4l --driver raspicam --auto-video_nr --encoding h264 --width 640 --height 480 --enable-server on

Answer 1

Try adding the following line at the bottom of the file /etc/modules and rebooting your Raspberry Pi.
bcm2835-v4l2
Mine now looks like this in toto:
# /etc/modules: kernel modules to load at boot time.
#
# This file contains the names of kernel modules that should be loaded
# at boot time, one per line. Lines beginning with "#" are ignored.
bcm2835-v4l2
This ensures that the Broadcom Video For Linux 2 (v4l2) driver is loaded at all subsequent reboots.