[Ardour-Users] Determine bpm of given audio

[fukked up]

Hi,
can you tell me an easy way to determine the bpm of audio that I record
with ardour? I will record a band that doesn't know how fast their songs
are. So I want to let them play it once and then record it with click at
the right tempo. I don't want them to go nuts, while I try to fumble out
the tempo by adjusting it manually. I have separate tracks for the
drums, so maybe bassdrum or snare are a suitable source.
thx.
/mn0