examples:
rma test.rm
check integrity of test.rm
rma -f test.rm
try to fix errors in test.rm with default settings
rma -fb2n1 test.rm
try to fix errors in test.rm, seek two packets back
when broken packet is found, only fix first broken packet
rma -sx1 test.rm
extract stream 1 from test.rm
rma -j/audio.rm//video.rm/ test.rm
join streams from audio.rm and video.rm and write
multiplexed stream to test.rm.
