Now I'm using soundfiler (expr 44100 / sample size) to get the information of the playback speed. And I also use this to change the speed.

sound filer
|
expr 44100 / $f1
| (numberA)
|
phasor~

I wrote a patch about tap BPM calculator and I tapped with the soundtrack to get the BPM, and is there any connection between BPM and numberA (above)? or is there any possibility to change the playback speed by the BPM??

http://www.pdpatchrepo.info/hurleur/94C49BB8-8ECB-4C9F-A4DE-B4C9EC0D9D6D.png

they should be directly proportional? so if you double A the sound file will playback at double speed (and pitch). If you want to create a control with bpm, make a ratio between the bpm of the file and the bpm you want and then multiply A by that amount

Yeah, you'll need to know what the tempo of the original loop is, then figure out the tap tempo and divide it by the original tempo. This will give you a ratio of how much faster/slower the tap tempo is compared to the orginal. Multiply that by the output of [expr~ 44100/$f1].

Thanks guys, I'll try