public AudioInfo Decode(System.IO.Stream stream, float targetBitrate, string fileExt)
{
var length = stream.Length;
byte[] source = new byte[length];
// read the file into the buffer
stream.Read(source, 0, (int)length);
// now create a pinned handle, so that the Garbage Collector will not move this object
var _hGCFile = GCHandle.Alloc(source, GCHandleType.Pinned);
try
{
var buffer = ReadMonoFromStream(_hGCFile.AddrOfPinnedObject(), source.Length, (int) targetBitrate, -1, 0);
var result = new AudioInfo();
result.Samples = new Samples() { Values = buffer, BitRate = (int)targetBitrate };
return result;
}
catch(Exception E)
{
//TODO: add logging
return null;
}
finally
{
_hGCFile.Free();
}
}
public virtual void Process(AudioRecord item, AudioInfo info)
{
//build amplitude envelope
var s = Build(info.Samples);
//resample
var resampler = factory.CreateResampler();
var resampled = resampler.Resample(s, info.Samples.BitRate * ((float)EnvelopeLength / info.Samples.Values.Length));
//build packed array
var envelope = new Envelope(resampled);
//save into audio item
item.Data.Add(envelope);
}
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);
}
