Muxing udpsrc with videotestsrc?

Hello, I have an Audio only multicast stream that I am trying to combine a dummy video screen over. I’m trying to pass this into kvssink so I cannot only stream the audio. The video needs to be in H264 and the audio in AAC as I am trying to pass this to AWS using the kvssink plugin.

Here is the stream properties (via gst-discoverer-1.0) if it helps!

Properties:
  Duration: 99:99:99.999999999
  Seekable: no
  Live: yes
  container #0: application/rtp
    unknown #2: application/x-rtp
      container #-1: MPEG-2 Transport Stream
        audio #1: MPEG-4 AAC

Here is the most recent attempt at a pipeline that errored as Mux could not link to Kvssink

gst-launch-1.0 udpsrc address=239.0.0.7 port=5004 ! audioconvert ! avenc_aac ! aacparse ! queue ! mux. videotestsrc pattern=black is-live=true ! x264enc ! queue ! mp4mux name=mux ! kvssink