Detect beat-per-minute value of specified file.
BPM value. If algorithm can't detect BPM value, return value is 0.
This function will open temporary stream and detect beat-per-minute. When detection process is done, stream will be closed.
Note: Detection process can take some time.
Warning: This function WILL NOT interfere with current playing.
BPM detection algorithm isn't 100 % accurate. Algorithm will stop when first valid BPM value is detected. If BPM value can't be detected, algorithm will try to search whole stream. If this fails, returned BPM value is 0.