static void Main(string[] args)
{
if(args.Length<1){
Console.WriteLine("Usage: BPMAnalyzer <filename>.wav");
return;
}
var waveFile=new WaveFile(args[0]);
const int frameSize=1024;
var frameCount=(double)waveFile.FormatChunk.SamplesPerSecond/frameSize;
var dataLength=waveFile.Data.Length;
var sampleCount=dataLength/frameSize/2;
var data=waveFile.Data.ToList();
var volume=(from index in Enumerable.Range(0,sampleCount)
let sum=data.GetRange(frameSize*index,frameSize).Sum(d=>(double)d*d)
select Math.Sqrt(sum/frameSize)).ToArray();
waveFile.Dispose();
var prev=0.0;
var diff=(from v in volume let temp=prev select Math.Max((prev=v)-temp,0.0)).ToArray();
var indices=Enumerable.Range(0,diff.Length).AsParallel();
var r=(from i in Enumerable.Range(0,181)
let freq=(i+60)/60.0
let theta=2.0*Math.PI*freq/frameCount
let cosSum=indices.Sum(index=>HannWindow(index,diff.Length)*Math.Cos(theta*index)*diff[index])/sampleCount
let sinSum=indices.Sum(index=>HannWindow(index,diff.Length)*Math.Sin(theta*index)*diff[index])/sampleCount
select new{A=cosSum,B=sinSum,R=Math.Sqrt(cosSum*cosSum+sinSum*sinSum)}).ToArray();
var peaks=FindPeak(r.Select(obj=>obj.R).ToArray(),3);
for(int i=0;i<peaks.Length;i++){
Console.WriteLine("[{0}]",i+1);
int bpm=peaks[i]+60;
Console.WriteLine("Peak BPM: {0}",bpm);
var theta=Math.Atan2(r[peaks[i]].B,r[peaks[i]].A);
if(theta<0) theta+=2.0*Math.PI;
var peakFreq=(double)bpm/60;
var startTime=theta/(2.0*Math.PI*peakFreq);
var startBeat=theta/(2.0*Math.PI);
Console.WriteLine("First beat time: {0} sec",startTime);
Console.WriteLine("First beat: {0} beat",startBeat);
}
}