/// <summary>
/// Amplitude envelope builder
/// Save maximum values
/// </summary>
public Samples Build(Samples source, int newBitrate = 20, bool differentiate = false)
{
float koeff = 1f * newBitrate /source.Bitrate;
var values = source.Values;
var resValues = new float[(int)(values.Length * koeff)+1];
for (var i = values.Length - 2; i >= 0; i--)
{
var newIndex = (int) (i*koeff);
var prevValue = resValues[newIndex];
var value = values[i];
if (differentiate)
{
value = values[i + 1] - value;
}
value = Math.Abs(value);
if (prevValue < value)
{
resValues[newIndex] = value;
}
}
return new Samples()
{
Bitrate = newBitrate, Values = resValues
};
}
public void DrawOneSide(Samples samples, Graphics gr, Rectangle bounds, bool normalize = false)
{
var kx = bounds.Width / samples.Values.Length;
var ky = bounds.Height;
var cy = bounds.Bottom;
var cx = bounds.Left;
var values = samples.Values;
if (normalize)
{
var s = samples.Clone();
s.Normalize();
values = s.Values;
}
using (var pen = new Pen(ForeColor))
for (int i = 0; i < values.Length; i++)
{
var x = i * kx;
var y = values[i];
if (y > 1) y = 1;
if (y < -1) continue;
y = y * ky;
gr.DrawLine(pen, cx + x, cy, cx + x, cy - y);
}
}
public Samples Clone()
{
var result = new Samples();
result.Bitrate = Bitrate;
result.Values = new float[Values.Length];
Array.Copy(Values, result.Values, Values.Length);
return result;
}
public void Process(Audio item, AudioInfo info)
{
var tempogram = new Tempogram();
//get maximum values
Samples samples = new EnvelopeProcessor(factory).Build(info.Samples, 32, false);
var newSamples = new Samples()
{
Values = new float[samples.Values.Length], Bitrate = samples.Bitrate
};
var intensity = 0;
for (int i = 0; i < samples.Values.Length - 1; i++)
{
var diff = samples.Values[i + 1] - samples.Values[i];
samples.Values[i] = diff > 0 ? diff : 0; //разница между всеми амплитудами
newSamples.Values[i] = diff;
if (diff > minAmplitudeChangeForIntensityRate)
{
intensity++;
}
}
samples.Values[samples.Values.Length - 1] = 0;
newSamples.Values[samples.Values.Length - 1] = 0;
var durationOfTrack = samples.Values.Length / samples.Bitrate;//time of sound
var maxShift = (int)(samples.Values.Length * (maxRithmDuration / durationOfTrack));
var autoCorr1 = AutoCorr(samples.Values, maxShift, 5);
var autoCorr2 = AutoCorr(newSamples.Values, maxShift, 2);
var lengthCorr1 = (float)autoCorr1.Length;
var log2 = Math.Log(2);
var list1 = new List<KeyValuePair<float, float>>();
var list2 = new List<KeyValuePair<float, float>>();
for (int i = 0; i < lengthCorr1; i++)
{
var j = i / (float)lengthCorr1;
j = (float)(Math.Log(j + 1) / log2);
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 / durationOfTrack;
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);
}
}