mplayer -dumpstream rtsp://rmv8.bbc.net.uk/radio4/comedy/thu2300.ra
(Time passes while mplayer writes a file named “stream.dump”.)
Now convert the stream.dump file to pcm/wave:
mplayer -ao pcm stream.dump
(Time passes while mplayer writes a file named “audiodump.wav”.)
Convert that wave file into mp3:
lame --preset standard --tt "Episode 1" --ta "BBC Radio 4" --tl "The Hitchhiker's Guide to the Galaxy, Tertiary Phase" --ty "2004" --tn 1 audiodump.wav episode1.mp3
Hooray! One down side I’ve seen so far: the stream.dump RealAudio file is just under 10Mb, while the mp3 produced by this process is over 37Mb. I should probably use different options when running lame.