Motion

Motion is a daemon that captures images and videos from a Video4Linux compatible webcam.

This page will go over the steps to set up motion on a Raspberry Pi running ArchLinux.

Setup

# pacman --noconfirm -S motion

The package doesn't seem to come with systemd service files. You may need to create it manually:

# cat <<EOF > /usr/lib/systemd/system/motion.service
[Unit]
Description=Motion web cam server

[Service]
ExecStart=/usr/bin/motion
Restart=always

[Install]
WantedBy=multi-user.target

EOF

# chmod 644 /usr/lib/systemd/system/motion.service
# systemctl daemon-reload
# systemctl enable motion
# systemctl start motion

Configuration

Edit the configuration file at /etc/motion/motion.conf.

The important fields are:

• videodevice
• width
• height
• target_dir

Motion can be configured to monitor multiple cams per instance (one per each thread). However, this is very flaky for me on a Raspberry Pi and causes corrupt/mangled images or causes webcams to disconnect.

If you plan on monitoring multiple cameras, I suggest running multiple instances of motion each recording one webcam discussed below.

Single Instance, Multiple Cameras

Specify each camera in its own individual thread file in motion.conf.

Multiple Instances, Multiple Cameras

Create an individual motion.conf file for each instance. My configs for the Raspberry Pis are:

# cat /etc/motion/motion1.conf
daemon off
process_id_file /var/run/motion/motion1.pid
setup_mode off
roundrobin_frames 1
roundrobin_skip 1
switchfilter off
threshold 0
threshold_tune off
noise_level 32
noise_tune on
despeckle EedDl
smart_mask_speed 0
lightswitch 0
minimum_motion_frames 1
pre_capture 0
post_capture 0
gap 60
max_mpeg_time 1800
output_all off
output_normal on
output_motion off
quality 75
ppm off
ffmpeg_cap_new on
ffmpeg_cap_motion off
ffmpeg_timelapse 0
ffmpeg_timelapse_mode hourly
ffmpeg_bps 500000
ffmpeg_variable_bitrate 0
ffmpeg_video_codec mpeg4
ffmpeg_deinterlace off
snapshot_interval 10
locate off
text_right %Y-%m-%d\n%T-%q
text_changes off
text_event %Y%m%d%H%M%S
text_double off
quiet on
thread /etc/motion/thread1.conf

# cat /etc/motion/thread1.conf
videodevice /dev/v4l/by-path/platform-3f980000.usb-usb-0:1.5:1.0-video-index0
v4l2_palette 8
norm 0
frequency 0
rotate 0
width 1280
height 720
framerate 2
minimum_frame_time 0
netcam_tolerant_check off
auto_brightness off
brightness 0
contrast 0
saturation 0
hue 0
snapshot_interval 3
locate off
text_right %Y-%m-%d\n%T-%q
text_changes off
text_event %Y%m%d%H%M%S
text_double off
target_dir /mnt/nfs/pi07-cam01
snapshot_filename snapshots/%Y%m/%d/%v-%H%M%S-snapshot
jpeg_filename motion/%Y%m/%d/%v-%Y%m%d%H%M%S-%q
movie_filename motion/%Y%m/%d/%v-%Y%m%d%H%M%S
timelapse_filename %Y%m%d-timelapse
webcam_port 8081
webcam_quality 80
webcam_motion off
webcam_maxrate 1
webcam_localhost off
webcam_limit 0
track_type 0
track_auto off
track_motorx 0
track_motory 0
track_maxx 0
track_maxy 0
track_iomojo_id 0
track_step_angle_x 10
track_step_angle_y 10
track_move_wait 10
track_speed 255
track_stepsize 40

# cat /etc/systemd/system/multi-user.target.wants/motion1.service
[Unit]
Description=Motion web cam server

[Service]
ExecStart=/usr/bin/motion -c /etc/motion/motion1.conf
Restart=always

[Install]
WantedBy=multi-user.target

Create these 3 files for each individual instance you desire, then reload systemd and enable/start the service.

Troubleshooting / Issues

On the Raspberry Pi, the webcam sometimes disconnects (a power issue?). The video4linux path changes because of this (from /dev/video0 to /dev/video3 for instance).

My work-around is to use the hardware path which doesn't change. You can see the paths correspond to the proper video device by listing:

# ls -al /dev/v4l/by-path/
total 0
drwxr-xr-x 2 root root 80 Mar  4 13:00 .
drwxr-xr-x 4 root root 80 Mar  4 13:00 ..
lrwxrwxrwx 1 root root 12 Mar  4 13:00 platform-3f980000.usb-usb-0:1.2:1.0-video-index0 -> ../../video0
lrwxrwxrwx 1 root root 12 Mar  4 13:00 platform-3f980000.usb-usb-0:1.3:1.0-video-index0 -> ../../video1