Gscam can't find udpsrc, but gstreamer works fine

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Hi, I'm trying to use gscam ( http://wiki.ros.org/gscam ) with a camera connected via ethernet to my laptop running Ubuntu16.04, ROS kinetic and gstreamer 1.0.

I'm able to properly start gstreamer and see the stram window using the command:

gst-launch-1.0 udpsrc caps="application/x-rtp,media=video,clock-rate=90000,encoding-name=H264, payload=96" port=5002 ! rtph264depay  ! video/x-h264,framerate=24/1,width=640,height=480 ! queue ! avdec_h264 ! videoconvert ! autovideosink sync=FALSE

but following the gscam instuction, running the command:

export GSCAM_CONFIG="udpsrc caps="application/x-rtp,media=video,clock-rate=90000,encoding-name=H264,payload=96" port=5002 ! rtph264depay  ! video/x-h264,framerate=24/1,width=640,height=480 ! decodebin ! videoconvert"

and then:

rosrun gscam gscam

I get the error:

[FATAL] [1533651268.132080791]: no element "udpsrc"
[FATAL] [1533651268.132104353]: Failed to initialize gscam stream!

This happens both when installing gscam using:

sudo apt-get install ros-kinetic-gscam

and compiling it from source using catkin

Can anyone please help me?