public unsafe Samples Resample(Samples source, float targetBitrate)
{
var values = source.Values;
var k = targetBitrate / source.BitRate;
var newLength = (int)Math.Round(k * source.Values.Length);
var resValues = new float[newLength];
var l = values.Length;
fixed (float* valuesPtr = values)
{
var ptr = valuesPtr;
for (int i = 0; i < l; i++)
{
var j = (int)(k * i);
resValues[j] += *ptr;
ptr++;
}
}
l = resValues.Length;
fixed (float* valuesPtr = resValues)
{
var ptr = valuesPtr;
for (int i = 0; i < l; i++)
{
*ptr *= k;
ptr++;
}
}
return new Samples() { Values = resValues, BitRate = targetBitrate };
}
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 Envelope(Samples samples)
{
var values = samples.Values;
//pack
packedValues = new byte[values.Length / 2];
for (int i = 0; i < values.Length; i += 2)
{
var v1 = (int)(16 * values[i]);
var v2 = (int)(16 * values[i + 1]);
if (v1 > 15) v1 = 15;
if (v2 > 15) v2 = 15;
packedValues[i / 2] = (byte)((v1 << 4) + v2);
}
}
/// <summary>
/// Amplitude envelope builder
/// </summary>
public Samples Build(Samples source, int targetBitRate = 20, bool differentiate = false)
{
float k = 1f * targetBitRate / source.BitRate;
var values = source.Values;
var resValues = new float[(int)(values.Length * k) + 1];
for (int i = values.Length - 2; i >= 0; i--)
{
var ii = (int)(i * k);
var prev = resValues[ii];
var f = values[i];
if (differentiate) f = values[i + 1] - f;
if (f < 0) f = -f;
if (prev < f) resValues[ii] = f;
}
return new Samples() { BitRate = targetBitRate, Values = resValues };
}