I am just starting with MJPEG also (and gstreamer, for that matter) and am trying to learn the various pipe stages that work with MJPEG. I think I can say for sure that these bits work well:
(Remember, your URIs will differ)
gst-launch -e souphttpsrc location="
http://10.1.2.3/axis-cgi/mjpg/video.cgi?camera=3" is_live=true ! fakesink
gst-launch -e souphttpsrc location="
http://10.1.2.3/axis-cgi/mjpg/video.cgi?camera=3" is_live=true ! multipartdemux ! decodebin ! ffmpegcolorspace ! dshowvideosink
Not sure what file extension to use here. They are jpeg pictures, but perhaps .mjpg is more dorrect?
gst-launch -e souphttpsrc location="
http://10.1.2.3/axis-cgi/mjpg/video.cgi?camera=3" is_live=true ! filesink location="z.jpg"
gst-launch filesrc location="z.jpg" ! multipartdemux ! decodebin ! ffmpegcolorspace ! dshowvideosink
Wes