[CM] detecting when the DJ drops the beat

[David O'Toole]

I'll soon be feeding 100 gigabytes of classic and contemporary
dance/dj/hiphop music mp3's into my concatenative synthesis system based on
Snd, called SchemeMosaic.

I can do decent tempo (BPM) detection with the external Soundstretch
command line utility, however SchemeMosaic currently assumes that the
beginning of the input mp3 is the first beat. What I need to do is
automatically find the sample offset of the first actual kick drum beat,
"when the DJ drops the beat" :)

What might be the best way to discover the position of the first time a
kick drum is hit in a recording, using Snd Scheme? Would it be sufficient
to look for RMS peak amplitude beyond a certain threshold in the sub 200 hz
area? Thanks so much in advance for any advice you can offer. The result
doesn't have to be perfect, but as the first kick drum occurrence in this
kind of music tends to be accentuated, I bet I will be able to get good
overall results with something relatively simple.
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