Disklavier

Hi All,
Mark, you wrote of Pianodisc compatibility in your response; I have a
DCD1 and was wondering if there was a way of saving general midi files
to CDs for playback on the DCD1 without always involving my computer
connection. I've tried saving a few *.mid files to a CD and it doesn't
seem to work. Is it more complicated than that? If so, where can I
find the particulars on that? I've read in this forum of converting to
.wav files is this necessary?
Thanks
Fred