VLC cannot open and play a sdp file that ffmpeg created and ffplay can play
Assuming you have a movie "test_input.mp4", you can broadcast it to rtp using ffmpeg like this :
ffmpeg -re -thread_queue_size 4 -i test_input.mp4 -strict -2 -an -vcodec mpeg2video -f rtp rtp://<some ip>:<some port> -sdp_file ffmpeg-broadcast-to-rtp.sdp
That command also creates a SDP file you can use for playing in a client. It can then be opened with ffplay :
ffplay -protocol_whitelist "file,rtp,udp" -strict -2 -i ffmpeg-broadcast-to-rtp.sdp
VLC fails at opening the sdp file