public void Process(AudioRecord item, AudioInfo info)
{
var tempogram = new Tempogram();
var s = info.Samples;
s = new EnvelopeProcessor(factory).Build(info.Samples, 32, false);
var s2 = new Samples() { Values = new float[s.Values.Length], BitRate = s.BitRate };
var intensity = 0;
for (int i = 0; i < s.Values.Length - 1; i++)
{
var d = s.Values[i + 1] - s.Values[i];
var dd = d > 0 ? d : 0;
s.Values[i] = dd;
s2.Values[i] = d;
if (d > minAmplitudeChangeForIntensityRate)
intensity++;
}
s.Values[s.Values.Length - 1] = 0;
s2.Values[s.Values.Length - 1] = 0;
var time = s.Values.Length / s.BitRate;//time of sound
var maxShift = (int)(s.Values.Length * (maxRithmDuration / time));
var autoCorr1 = AutoCorr(s.Values, maxShift, 5);
var autoCorr2 = AutoCorr(s2.Values, maxShift, 2);
var l = (float)autoCorr1.Length;
var k = Math.Log(2);
var list1 = new List<KeyValuePair<float, float>>();
var list2 = new List<KeyValuePair<float, float>>();
for (int i = 0; i < l; i++)
{
var j = i / (float)l;
j = (float)(Math.Log(j + 1) / k);
list1.Add(new KeyValuePair<float, float>(j, autoCorr1[i]));
var v = autoCorr2[i];
list2.Add(new KeyValuePair<float, float>(j, v > 0 ? v : 0));
}
tempogram.LongTempogram.Build(list1);
tempogram.ShortTempogram.Build(list2);
tempogram.Intensity = (float)intensity / time;
CalcTempo(tempogram);
//save to audio item
item.Data.Add(tempogram);
}
public static void CalcTempo(Tempogram tempogram)
{
var step = 1f/tempogram.LongTempogram.Size;
var hist = tempogram.LongTempogram;
//find main frequency
var max = 0f;
var best = 0f;
for(float i=0;i<=1;i+=step)
{
var v = hist[i] * (1 - 0.8f * i);
if(v > max)
{
max = v;
best = i;
}
}
var k = Math.Log(2);
//j = (float)(Math.Log(j + 1) / k);
best = (float)Math.Exp(best*k) - 1;
tempogram.LongRhythm = 1/(best * maxRithmDuration);//hz
tempogram.LongRhythmLevel = max;
}