ios - How can I normalized decibel value and make it between 0 and 1 -

i trying power of audio looping on audio samples , getting average power per channel.

i want value between 0 , 1 reflect intensity of audio being played. right getting db (decibel value) float value -160 (near silent) 0 (very loud).

here code written in swift:

func configureaudio() {     audiocontroller.play()     avaudiosession.sharedinstance().setcategory(avaudiosessioncategoryplayback, error: nil)     audiocontroller.numberofloops = 0     audiocontroller.meteringenabled = true     var audtimer = cadisplaylink(target: self, selector: "monitoraudio")     audtimer.addtorunloop(nsrunloop.currentrunloop(), formode: nsrunloopcommonmodes) }  func monitoraudio() {     audiocontroller.updatemeters()      var db = float(0)     in 0..<audiocontroller.numberofchannels {         db += audiocontroller.averagepowerforchannel(i)     }      db /= float(audiocontroller.numberofchannels) //code copied website not normalization     var power = (int(log10(db+161)/log10(1.5) * 100) - 1220) * 6     if power < 0 {         power = 0     }     println(power) } 

i not sure if db value getting accurate or doing wrong?

right getting values between 0-190 using code found doesn't make sense me.

what need normalize db values getting between 0 - 1

edit - feel free write code in obective-c

averagepowerforchannel returns db value 0 db represents digital full scale. if want value between 0 , 1 db not right scale you.

as code kind of hinting @ function turning digital level db

db = 20 * log10(ffs); 

so when ffs = 1.0, db 0 , when ffs == 0 db -inf.

you need go other way.

var power = exp(10, db/20);