Friday, March 25, 2016

X-Cam Part 1: X-Carve Spindle Camera for Positioning

After several weeks of running my X-Carve, I have wanted to connect a webcam to my Raspi in order to:
  1. More accurately set the home position of a work piece (i.e. Zeroing CNC with Camera)
  2. Monitor a carve (a different post)
  3. Create a time lapse video of a carve (review when things go wrong)
Previously, I had used a Raspi to create a motion detecting security camera and video streaming device (that was recently replaced by a Canary); therefore, I knew it was possible to transmit video from a Raspi over the web to be viewed in a web browser. The question now was just how to do it...

 After some research on Chilipeppr, Raspi and the TinyG, I came across many of the articles listed in the reference section, which eventually led me down the rabbit hole of the mjpg-streamer. This article claimed that one could stream 30FPS video from a Raspi2 to a web browser with extremely low CPU usage (<15%); sounds like a winner!

Items used in this build: (purchasing through these affiliate links helps me to hack on)

How I Installed mpjg-streamer for Raspi2

I followed this tutorial put together by Rober Cudmore (thank you!!!) for the most part; had to hack it a little bit to make it work for me.

Step 0: Get a Raspi2, Install Raspian and update and upgrade it.

I used a Raspberry Pi 2 for this build as it is what I use as my JSON sever for my CNC machine. THe 4 cores of the Raspi2 make it great for this build, so I do not have to worry about the camera(s) streaming affecting the commands sent from Chilipeppr (CNC control program).

Download and install an OS for the Raspi. I chose Raspian - Here is an installation guide.
sudo apt-get update
sudo apt-get upgrade

Expand the file system and enable the camera with:
sudo raspi-config

Step 1: Install mjpg-streamer

install libjpeg8

Check that USB camera is detected by the Raspi:
lsusb
Now check the format of the camera with:
v4l2-ctl --all
Output from Pi.... (about half way down you will see 'Pixel Format' - this is important to note for later)
   :
   :
 Pixel Format  : 'MJPG'
   :
   :

Now let's download the mjpg-streamer... 
 wget http//sourceforge.net/code-snapshots/svn/m/mj/mjpg-streamer/code/mjpg-streamer-code-182.zip

 and upzip it...
unzip mjpg-streamer-code-182.zip

 and then build it...
# build with 'make'
    cd mjpg-streamer-182
    cd mjpg-streamer
    make mjpg_streamer input_file.so input_uvc.so output_http.so

 Now, let's copy some configuration files to a new location...
# install by copying
    sudo cp mjpg_streamer /usr/local/bin
    sudo cp output_http.so input_file.so input_uvc.so /usr/local/lib/
    sudo cp -R www /usr/local/www

 And change the LD_LIBRARY_PATH to where we copied the previous configuration files...
#export LD_LIBRARY_PATH=/usr/local/lib/

 If all went well, we should be able to run it with:
/usr/local/bin/mjpg_streamer -i "/usr/local/lib/input_uvc.so" -o "/usr/local/lib/output_http.so -w /usr/local/www"

 Well no errors were thrown, but there is no video displayed in the browser (see below for links to view)...

 Raspi Output: 
MJPG Streamer Version: svn rev:
Using V4L2 device.: /dev/video0
Desired Resolution: 640 x 480
Frames Per Second.: 5
Format............: MJPEG
Adding control for Pan (relative)
UVCIOC_CTRL_ADD - Error: Inappropriate ioctl for device
Adding control for Tilt (relative)
UVCIOC_CTRL_ADD - Error: Inappropriate ioctl for device
 : 
 : 
www-folder-path...: /usr/local/www/
HTTP TCP port.....: 8080
username:password.: disabled
commands..........: enabled

Let's go to the google machine... 
    Search Term: 'UVCIOC_CTRL_MAP - Error: Inappropriate ioctl for device'
After some reading and deciphering, I found this forum that gave some insight to the issue. With some trial and error, I got it running with the following command:
/usr/local/bin/mjpg_streamer -i "/usr/local/lib/input_uvc.so -d /dev/video0 -n -y f 15 -r 640x480" -o "/usr/local/lib/output_http.so -w /usr/local/www"

 Here is a snap shop of the stream (viewed at http://<raspi-ip>:8080 or http://<raspi-ip>:8080/?action=stream



Step 3.1: Reduce CPU Load (optional)

Using htop, I noticed it was running at 100% CPU for one core. I knew this could be reduced from reading this article, so I gave it a shot.

 Install vlc
sudo apt-get install vlc
Create a script to run vlc with the desired settings...
sudo nano videostream.sh
Make it executable:
sudo chmod +x videostream.sh
Then run it:
./videostream.sh

 I got some errors (shown below), but it still works...
@JsonCNCpi ~ $ ./videostream.sh
VIDIOC_ENUM_FMT: failed: Invalid argument
unknown control 'compression_quality'
Frame rate set to 30.000 fps
VLC media player 2.0.3 Twoflower (revision 2.0.2-93-g77aa89e)
[0x197dee0] inhibit interface error: Failed to connect to the D-Bus session daemon: Unable to autolaunch a dbus-daemon without a $DISPLAY for X11
[0x197dee0] main interface error: no suitable interface module
[0x1981230] main interface error: no suitable interface module
[0x18118f0] main libvlc error: interface "globalhotkeys,none" initialization failed
[0x1831850] dummy interface: using the dummy interface module...

Here is a snap shop of the low CPU use stream (viewed at http://<raspi-ip>:8554/webcam.mjpg)



Step 4: To view your mjpg stream:

Type this into your web browser to access the interface
  http://<raspi-ip>:8080

 Type this into your web browser to view the stream directly
  http://<raspi-ip>:8080?action=stream

 To view the stream using the low CPU stream:
  http://<raspi-ip>:8554/webcam.mjpg

Step 4.1: To view your mjpg stream within Chilipeppr:

To view you webcam stream in Chilipeppr, head over to http://chilipeppr.com/xpix


In the Cam(v1) widget, click on the gear (settings), and enter in your MJPEG URL. Click close and you should be able to see your webcam view. 

Note: By hovering over the screen shot, the image will zoom in 4x.
Note 2: You can set the X and Y offset along with the real distance width fields to use your camera as an accurate positioning device. 


Step 5: Auto-Start Camera - Coming soon 

Resources

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