I tried your app STrumPact pre-compiled win 64, this detect bpm ok.
If I replace the 64bitdll's ( all of them ) with the ones downloaded from latest svn
Then it does not detect BPM and errors, other strange thing happen on one of the songs I tested the generated wave of the track was fine, but when with new dlls' it maxed out as a solid bar.
Just a thought.
When I was using bass i created a routine that took 2 seconds samples throughout the length of the song (starting from 10 seconds in, finishing 10 seconds before end ; this got rid of a lot of the start end silence); it took 10 of these bpm reading, discarded the top and lowest 2 to leave 6 then bpm was avaerage of these 6; this produced a pretty accurate reading.
I am not familiar enough with soundtouch, but you probably knwo how to send these 2 second sample block to be ananlyzed by soundtouch bpm algorithims.
unfortunately I cant find my code at the moment, so going from memory on the 2 second samples; it might have been 3 or 4 seconds samples.
The start and end points were 10 seconds from the start or end of sound.
On normal files the spped was pretty fast; as most pc could handle the whole mp3 in memory, when using a large 4 hour mp3, it would take much longer as scanning and skipping a the file was much slower due to buffering in the data samples.