Tuesday, December 10, 2013

Raspberry Pi Journal #40

Portable Webcam Software - motion

Last part, we have all the software and hardware installed and ready to go. In this section, we are going to set up the software that does the motion detection: motion.

First, we're going to SSH into the device:

SSH hostname

Enter your password. Next, we're going to set up a few configurations options. We want to set up some directories. We need to be careful here because we're going to run the software as daemon, which means its own user name and priviliges. The user name is called "motion". The password? I don't know. I can tell you that "sudo login" followed by "motion" and no password does not work.

So, the first thing we want is to set up a directory for the webcam. I'm going to set it up under /home/common/webcam

  • sudo mkdir /home/common/
  • sudo mkdir /home/common/webcam
  • sudo cd /home/common
  • sudo chown motion webcam
  • sudo chgrp motion webcam
  • sudo chmod 777 webcam

That will create a special webcam directory, that is accessible by all. Hopefully, nobody will login into it and cause trouble. I would prefer chmod 775, but let's make things easy for now.

Next, we need to configure the motion program and set up some parameters. Specifically, I want:

Save a picture per second everytime motion is detected, continue for about 10 seconds after.
Create a time-lapse movie for the day
Create a time-lapse movie for all motion capture
Set a webserver, so we can view it on the web browser
Create a log directory and file

So, the first thing we need to do is to locate motion.conf file. I found it in /etc/motion/ directory. Otherwise, check /usr/local/etc/ directory. If all else, you can do it the hard way:

  • cd /
  • ls -lR * | grep motion | grep motion

Yes, I did "grep motion" twice. I did it to filter out the error messages because I run the command as a normal user, instead of root.

So, let's get to /etc/motion directory

  • cd /etc/motion
  • ls -l

You'll see the files motion.conf, and thread1.conf-thread4.conf. This is because motion software can handle up to 4 simultaneous webcams. I'm using only one, so I don't have to worry about threadN.conf files. The first thing I want to do is make a backup or motion.conf before doing anything else.

  • cp motion.conf motion_conf_orig
  • sudo nano motion.conf

Next, I'll just scan the file and change the appropriate fields, according to my wish list above.

  1. daemon on
  2. width 640
  3. height 480
  4. framerate 2
  5. minimum_frame_time 1
  6. brightness 200
  7. threshold 6000
  8. noise_level 128
  9. pre_capture 1
  10. post_capture 10
  11. gap 120

All right, so that was for the camera settings. Now we go to the Image File Output settings:

  1. ffmpeg_cap_new on
  2. ffmpeg_timelapse 5
  3. ffmpeg_timelapse_mode hourly
  4. ffmpeg_video_codec mpeg4
  5. text_double on

Now that we have all the files set up. Let's set up all the file names and directories:

  1. target_dir /home/common/webcam
  2. jpeg_filename %H%M%S
  3. movie_filename %H%M%S
  4. timelapse_filename lapseview

Finally, we're into the server territory. We want to configure the ports for our webcam. There are two factors here: control and webcam. Control is the user interface for our webcam. webcam is the address that we want to use as mjpeg streamer to see what our camera see

  1. webcam_port 8081 <-change this to any open port you like
  2. webcam_quality 50
  3. webcam_motion on
  4. webcam_localhost off
  5. webcam_limit 600

  6. control_html_output off

And that should do it! There are other settings that I can use, especially the ones regarding picture/movie generation. This is useful if we want to copy the movie files somewhere.

So, now, let's reboot, and see if everything works as expected!

  • sudo reboot

and load a web browser, connected to the camera host address and port, and check to see if there's a web stream out there!

Pinging cloudypi seems to work, but I don't see the webcam being on? This where trouble starts. How come I can't start the process? Because there's something that I need to do, that is missing from the step. Reading the magazine, it says to set "start_motion_daemon yes" to motion.conf. And yet, reading the manual "man motion", it does not mention it at all!

So, which should I believe? The printed one? Or the one live on my device? Obviously, the one on my device. Is there no hope for me? There is something about user guide. Let's check it out:


Well, that didn't help at all. I know there's something that I need to change in order to start motion from boot, but what?

I tried to run motion from command line. Failed due to lack of permission. Create the motion.pid file, and change all permission.

sudo mkdir /var/run/motion
sudo touch /var/run/motion/motion.pid
sudo chmod 666 /var/run/motion/motion.pid

Now, let's see if it works. Well, the daemon works. The SSH hangs. Not good at all! In the end, I had to unplug the cable, and replug. Second time around, I got clever and use the setup mode:

  • motion -s -c /etc/motion/motion.conf

It works fine. I see avi, jpg, and mpg files. Set up is a success, now to automate it. There's quite a bit of assumption that you know how to start a program during boot, but as you can see, it's not obvious. With wrong headed instruction such as "start service" things, then I'm just as confused as ever.

However, there is the salvation that is the net. Digging around for hours did yield something. There is a motion file in /etc/init.d. Aha! Let's check it out.

It sure looks like one of those service files. So, maybe the instruction does mean something. Just not 100% accurate. Looking at the file, I see this:

  1. check_daemon_enabled () {
  2.     if [ "$start_motion_daemon" = "yes" ] ; then
  3.         return 0
  4.     else
  5.         log_warning_msg "Not starting $NAME daemon, disabled via /etc/default/$NAME"
  6.         return 1
  7.     fi

And the simplest thing is to go open up /etc/default/motion file and see what it says.

  1. # set to 'yes' to enable the motion daemon
  2. start_motion_daemon=no

Uh, I think we hit the jackpot, here! Are you kidding me? This is all that's needed? How come there's not one single line telling me to do this in the manual? Do you know how much time I wasted looking for this one line? Sigh.

Well, change it to "yes", and see what happens! Changed the file. Reboot. SSH into it. Run "top". Yes, it's up there. Check webcam directory. Does not seem to write to the directory. Stop the program and check it out.

  • sudo service motion stop

Further checking yields images still not being written. There's only one conclusion that I can gather: motion.conf is not being read correctly. Strange thing is, if I just start it normally, it works fine! So, back to /etc/init.d/motion and see if I can force motion.conf to be read.

  1. DAEMON=/usr/bin/motion -c /etc/motion/motion.conf

I just don't see how nobody is running into these kind of problems! Or if they did, they don't say. Did the setting somehow changed? I don't know. It certainly is frustrating. I know it is possible, but there's absolutely no instructions, and so, I have to try things out myself.

Did not work. After reading the manual for start-stop daemon, I came up with this:

  1. if start-stop-daemon --start --oknodo --exec $DAEMON -b --chuid motion -- -c /etc/motion/motion.conf ; then

That seems to work. Alas, no new images is loaded. So, maybe the configuration file is read correctly, after all, but then what is wrong with the process? Doing it interactively works fine, after all. Why would putting it into the service fails?

Interestingly, not only starting it manually with service fails to write images, but it somehow kicked the "output_motion on", and yet, checking it via the web control interface shows that it's off. Obviously, there's something seriously wrong here, but I don't know what. Gremlins, that's what it is.

Checked /var/log/user.log

It turns out that the program is having trouble writing to timelapse.mpg. I changed the attribute with

  • chmod 777 timelapse.mpg

And restarted the service. It works fine, now. Jeez. Do you know how long it took me to find that? There's just not enough instructions on the web!

So, reboot, and see if the process still hopefully works.

Everything looks good to me! Well done!

And it only took one whole day!

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