Tag Archives: webcam

Webcam image refresh with jQuery

Code snippet to refresh images on a web page without refreshing the whole page.

Add the header with a reference to jquery.

   <script type="text/javascript" src="js/jquery.js">

Set the refresh interval on document ready, calling our function reloadImages()

<script type="text/javascript">
$(document).ready(function() {
   setInterval('reloadImages()', 60000); // 60 seconds

Add our function reloadImages to reference our image ID of c131a in this case. Then change the src image to the same name plus some random attribute to prevent caching.

function reloadImages()
  $('#c131a').attr('src', 'c131a.jpg?' + Math.random());

In the body of the script, add a normal image reference making sure the id matches the one in the above reloadImages function.

  <img src="c131a.jpg" id="c131a" border="1" />

AspireOne Petcam

Have a spare AspireOne sitting around not being actively used? With built-in wireless and webcam it can easily substitute for a dedicated wireless webcam. As the prices of these netbooks continue to drop they may even be better deals while providing the additional features of a display and full operating system.

I’ll be looking at using an AspireOne netbook with Ubuntu 9.04 netbook remix installed, other linux distributions should also work. For Windows netbooks I like the program Yawcam, that provides lots of functionality along with a GUI.

A quick search for ‘webcam’ in the Synaptic Package Manager will show a variety of available programs that support webcam capture with ftp uploads. I tried these but had little success.

  • camstream – program hung when run
  • camgrab – the AspireOne camera wasn’t found
  • camorama – could not connect with the webcam
  • camE – came the closest of the ‘webcam’ apps. captured images to disk, connected to the ftp server, but failed to complete uploads. I was not able to resolve the upload failure.
  • vgrabbj – fails to connect to the webcam
  • webcamd – sort-of worked. captured images, uploads worked. however it seemed to have upload troubles and be low on options and/or documentation.

The best program for webcam monitoring on linux is Motion. Install it using the Synaptic package manager. This will place sample configuration files in /etc/motion/motion.conf

Since I plan to occasionally use the netbook for casual surfing and want to keep an eye on the camera operations to easily stop it for privacy, I’ll run it as a user rather than in daemon mode. Copy the sample configuration to your user directory /home/<user>/.motion/motion.conf

I changed just a few settings to support uploading a snapshot every 60 seconds. I also disabled the motion images and videos for now. I’ll include these in a future setup, but for now the captures would quickly fill the small drive of the netbook if left running.

Edit the motion.conf file in your user ~/.motion directory and modify the following settings:

# turn of daemon mode, I'll run in a shell
daemon off
# optionally use a larger image size
width 640
height 480
# turn off motion capture images
output_normal off
# turn off motion video
ffmpeg_cap_new off
# take a picture every 60 seconds
snapshot_interval 60
# reuse the jpg image file name lastsnap
snapshot_filename lastsnap
# run an FTP upload script after taking a picture
on_picture_save /home/<user>/ftppicture %f

Motion does not include any FTP functionality, but it does provide a set of events that can be used to run external scripts. on_picture_save allows you to specify a script that will be run after each image is taken and stored to the local drive. Here we will run the script ftppicture, the contents of which are listed below:



quote USER $USER
cd cams
put $filename
delete aspireone.jpg
rename $filename aspireone.jpg
exit 0

Fill in the constants at the top with your ftp server login information. This script will connect to the server, upload the file lastsnap.jpg , delete the image aspireone.jpg from the ftp site, then finally rename the new lastsnap.jpg to aspireone.jpg on the server.

From a terminal run the program with ‘motion’. Motion includes a web server, so you can view the live camera image for adjusting its postion by opening a web browser to http://localhost:8081

It will now take and upload images every 60 seconds. Stop the program with CTRL-C in the terminal and run motion to restart.