Tested with UE4 4.21 and GStreamer 1.14.4
Download and install GStreamer binaries and dev files
Edit Plugins\GStreamer\Source\GStreamer\GStreamer.Build.cs
Modify const string GStreamerRoot = @"d:\dev\gstreamer1.14.4\1.0\x86_64" to path where GStreamer installed
Launch project and hit play.
Pipeline:
appsrc name=src caps=video/x-raw,width=(int)1920,height=(int)1080,format=(string)BGRA,framerate=(fraction)60/1 ! tcpserversink port=5000 sync=false
Consuming pipeline:
gst-launch-1.0 -v tcpclientsrc host=127.0.0.1 port=5000 ! pngdec ! video/x-raw,format=RGBA ! videoconvert ! videorate ! video/x-raw,framerate=60/1 ! videoscale ! video/x-raw,width=640,height=480 ! fpsdisplaysink
Test pattern:
videotestsrc pattern=snow ! video/x-raw,width=(int)512,height=(int)512,format=(string)RGBA,framerate=(fraction)30/1 ! appsink name=sink
Play a local file:
filesrc location=d:/video/doom.mp4 ! decodebin ! videoconvert ! video/x-raw,format=(string)RGBA ! videoconvert ! appsink name=sink
Play URI:
uridecodebin uri=http://images.nvidia.com/geforce-com/international/videos/doom/doom-nvidia-geforce-gtx-geforce-dot-com-vulkan-graphics-api-gameplay-video.mp4 ! videoconvert ! video/x-raw,format=(string)RGBA ! videoconvert ! appsink name=sink