Why can't I receive an RTP video stream produced by appsrc?

[Daniel Koch - external]

Hi, there.

I'm trying to use the appsrc element with rtpbin and udpsink to create an RTP sender using the VP8 codec (vp8enc).

This program creates a fake video stream by switching black and white frames every 100 milliseconds. You can see the video by uncommenting the macro USE_AUTOVIDEOSINK.

broadcaster.c:
https://pastebin.com/raw/5w2UaBgP

receiver.sh (using gst-launch-1.0): 
https://pastebin.com/raw/s1YG4DPa

When I run the receiver, I only get the first frame. It doesn't blink. What am I doing wrong?

PS: I'm using libgstreamer 1.20.3 from Ubuntu 22.04.

Thank you,
Daniel Koch