ffmpeg -f lavfi -i "movie=video.mpg[out0+subcc]" -map s output.srt

This is the exact command. It works perfectly, exactly as I'd expect.

In the command above, ffmpeg is opening a local file "video.mpg". My video source is a stream (udp://239.1.1.1:1234). How would I change the above command to use a UDP source instead of the local "video.mpg" file?