To get ACTi cameras working you need the latest firmware for the camera.
Use the value in motion.conf:
replacing the IP with the IP of your camera.
- 17 Jul 2010
Also, the device's internal settings should be set to MJPEG, and the B2 Header (and in my case, the audio-in) should be disabled.(Tested ACTi ACM-3311 @ 720x480). Until I disabled the B2 header I was getting a "Could not decompress" error from Motion.
-DuffyWeber 15 Aug. 2012
I have an ACTi E32 camera, I am trying to use netcam_url http://192.168.1.118/cgi-bin/cmd/system?GET_STREAM
In my motion log I'm getting:
 [ALR] [NET] [Feb 22 19:05:50] netcam_start: Network Camera thread starting... for url (http://192.168.1.118/cgi-bin/cmd/system?GET_STREAM
 [CRT] [NET] [Feb 22 19:05:50] netcam_start: libjpeg decompression failure on first frame - giving up!
If I try to get the data with curl, It looks like this:
If I play this file with mplayer or VLC it plays fine and show MJPG as the codec type.
- 22 Feb 2013
Faced with same. Can't play video from ACTI E22 in browser also. Something wrong with ACTI camera stream.
- 06 Oct 2015