Saturday, 22 August 2009

Practical Experience using the Edimax IP Camera

We were away on holiday last week so I got to try using the Edimax IP camera 'for real' as a monitor to keep an eye on our disabled son - known as 'BenTV-ng' (next generation) to distinguish it from 'BenTV' which was the old analogue system I used to use.

I gave up on using ad-hoc networking and instead took my wireless access point with me. This had the added advantage of improving the range of transmission because I could arrange for the access point to be between the camera and the computer. The computer I used was a Toshiba netbook running Ubuntu Linux.

The first thing I noticed was that when I powered everything up, nothing happened. At first I thought it was because the access point needed to see a wired connection as well as a wireless one, because when I connected the computer to it using a wire things started to work. I soon realised that the range was awful - it stopped working as soon as you were outside of his room. This turned out to be my fault because I had also switched on the analogue camera, which transmitted on the same frequency as the wireless network, so the noise level was huge. Things got better when I switched off the analogue camera.

At first everything appeared to work - vlc rtsp://admin:1234@bentv/ipcam.sdp played the video stream with sound.
I soon noticed that if the network got interrupted vlc froze, giving an apparently good picture, but no movement, which was no use to me. Instead I changed to mplayer - at least if that got into trouble it crashed and closed the video playback window so you knew something was wrong.

I set up a simple shell script that loops indefinitely starting mplayer then when mplayer exits it re-boots the ip camera, waits for 30 seconds and starts mplayer again.
This approach worked pretty well - the 30 second interruptions during the re-boot were not usually too troublesome.

We did find some problems when the video stream only worked for a few seconds before mplayer exited and the re-boot sequence started again, which was no good at all. The only way I found to cure this was to power off the camera all together - a software re-boot via the web interface did not cure it. I'll set up a little test at home now to see how long it takes to get into this state, and whether it makes a difference if you use wireless or wired networking.

The code to achieve this is stored at http://code.google.com/p/ntmisc/source/browse/bentv/.

The most up to date information I have on using this camera with linux can be found at http://ic-3010wg.webhop.net.

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