/// <summary>
/// Creates a lookup dictionary from the fingerprintsignature. Key is the hash an value is an array of int
/// pointing (index) to where the hash can be found using "SubFingerprint(int index)"
/// </summary>
public static Dictionary <uint, int[]> CreateLookupDictionary(FingerprintSignature fs, bool filterNoneRandomHashes = true)
{
Dictionary <uint, int[]> subFingerLookup = new Dictionary <uint, int[]>(fs.SubFingerprintCount);
for (int index = 0; index < fs.SubFingerprintCount; index++)
{
uint h = BitConverter.ToUInt32(fs.Signature, index * 4);
if (filterNoneRandomHashes)
{
int bits = AudioFingerprint.Math.SimilarityUtility.HammingDistance(h, 0);
if (bits < 10 || bits > 22) // 5 27 (10 22)
{
// try further in the fingerprint
continue;
}
}
int[] data = new int[1] {
index
};
if (subFingerLookup.ContainsKey(h))
{
subFingerLookup[h] = CombineArrays(subFingerLookup[h], data);
}
else
{
subFingerLookup.Add(h, data);
}
} //foreach
return(subFingerLookup);
}
public static MMHashtable CreateMMHashtable(FingerprintSignature fs, bool filterNoneRandomHashes = true)
{
Dictionary <uint, int[]> dict = CreateLookupDictionary(fs, filterNoneRandomHashes);
MMHashtable mh = new MMHashtable(fs.SubFingerprintCount, fs.SubFingerprintCount);
foreach (KeyValuePair <uint, int[]> entry in dict)
{
mh.Add(entry.Key, entry.Value);
} //foreach
byte[] byteArray = mh.HashtableAsByteArray;
return(mh);
}
/// <summary>
/// Calculate the BER between 2 fingerprints
/// </summary>
public static int BER(FingerprintSignature f1, FingerprintSignature f2)
{
if (f1.SubFingerprintCount != f2.SubFingerprintCount)
{
return(-1);
}
// length of both needs to be equal!
int BER = 0; // Bit Error Rate
for (int i = 0; i < f1.SubFingerprintCount; i++)
{
int bits = AudioFingerprint.Math.SimilarityUtility.HammingDistance(f1.SubFingerprint(i), f2.SubFingerprint(i));
if (bits > 0)
{
BER += bits;
}
} // for i
return(BER);
}
/// <summary>
/// Creates a lookup dictionary from the fingatprintsignature. Key is the hash an value is an array of int
/// pointing (index) to where the hash can be found using "SubFingerprint(int index)"
/// </summary>
public static Dictionary <uint, int[]> CreateLookupDictionary(FingerprintSignature fs)
{
Dictionary <uint, int[]> subFingerLookup = new Dictionary <uint, int[]>(fs.SubFingerprintCount);
for (int index = 0; index < fs.SubFingerprintCount; index++)
{
uint h = BitConverter.ToUInt32(fs.Signature, index * 4);
int[] data = new int[1] {
index
};
if (subFingerLookup.ContainsKey(h))
{
subFingerLookup[h] = CombineArrays(subFingerLookup[h], data);
}
else
{
subFingerLookup.Add(h, data);
}
} //foreach
return(subFingerLookup);
}
public static FingerprintSignature ReadHashFromText(string filename)
{
filename = System.IO.Path.Combine(System.IO.Path.GetDirectoryName(filename), System.IO.Path.GetFileNameWithoutExtension(filename));
List <uint> data = new List <uint>();
List <byte[]> r = new List <byte[]>();
using (System.IO.StreamReader reader = new System.IO.StreamReader(System.IO.File.Open(filename + ".hash", System.IO.FileMode.Open)))
{
bool doHash = true;
long countR = 0;
byte[] tmpR = new byte[32];
while (!reader.EndOfStream)
{
string line = reader.ReadLine();
if (line.Length > 0)
{
if (line == "---")
{
doHash = false;
continue; // op naar volgende regel voor reliabilty
}
if (doHash)
{
data.Add(Convert.ToUInt32(line));
}
else
{
if (countR >= 32)
{
r.Add(tmpR);
tmpR = new byte[32];
countR = 0;
}
tmpR[countR] = Convert.ToByte(line);
countR++;
}
}
} //while
if (countR > 0)
{
r.Add(tmpR);
tmpR = null;
countR = 0;
}
} //using
byte[] signature = new byte[data.Count * sizeof(uint)];
for (int i = 0; i < data.Count; i++)
{
byte[] b = BitConverter.GetBytes(data[i]);
Buffer.BlockCopy(b, 0, signature, i * sizeof(uint), b.Length);
} //for i
byte[] reliabilities = new byte[r.Count * 32];
for (int i = 0; i < r.Count; i++)
{
Buffer.BlockCopy(r[i], 0, reliabilities, i * 32, r[i].Length);
} //for i
FingerprintSignature fs = new FingerprintSignature(System.IO.Path.GetFileNameWithoutExtension(filename), 0, signature, (long)(signature.Length * 11.6));
fs.reliabilities = reliabilities;
return(fs);
}
public FingerprintSignature CreateFingerprint(AudioSamples audioSamples, SpectrogramConfig configuration)
{
absEnergy = new double[(Frequencies.Length - 1) * 4]; // number of frequencies bands (33)
lowpassFilters = new LowpassFilters(Frequencies.Length - 1); // 33 bands
try
{
int width = (audioSamples.Samples.Length - configuration.WdftSize) / configuration.Overlap; // WdftSize=2048 / Overlap=64
if (width < 1)
{
return(null);
}
// reserve memory for 32 bit fingerprint hashes
byte[] hashes = new byte[width * sizeof(uint)];
byte[] reliabilities = new byte[width * 32]; // elke subfinger (32 bits) heeft voor elke bit een waarde tussen 0 en 31 voor relibility (dus 5 bits), we ronden dit af naar 1 byte
FingerprintSignature fingerprintSignature = new FingerprintSignature(null, 0, hashes, (long)(width * 11.6));
fingerprintSignature.Reliabilities = reliabilities;
// Calculate a hamming windows
float[] hammingWindow = new float[configuration.WdftSize];
for (int i = 0; i < hammingWindow.Length; i++)
{
// Hamming (watch it peak is at beginning not as in real hamming in the middle)
hammingWindow[i] = 0.54f + 0.46f * (float)System.Math.Cos((6.283f * (float)i / hammingWindow.Length));
//hammingWindow[i] = 0.54f - (0.46f * (float)System.Math.Cos(((6.283f * (float)i) / (hammingWindow.Length - 1)))); // real hamming window
} //for
int[] frequenciesRange = Frequencies; // 34 freqencies
float[] samples = new float[configuration.WdftSize];
for (int i = 0; i < width; i++)
{
if (((samples.Length - 1) + (i * configuration.Overlap)) >= audioSamples.Samples.Length)
{
// we hebben niet voldoende data meer!
// dus we stoppen nu en nemen het "laaste" stukje niet mee!
break;
}
for (int j = 0; j < samples.Length; j++)
{
samples[j] = audioSamples.Samples[j + (i * configuration.Overlap)] * hammingWindow[j];
} // for j
float[] complexSignal = fftService.FFTForward(samples, 0, configuration.WdftSize);
byte[] reliability;
uint subFingerprint = CalculateSubFingerprint(complexSignal, frequenciesRange, 5512, out reliability);
Buffer.BlockCopy(BitConverter.GetBytes(subFingerprint), 0, hashes, i * sizeof(uint), sizeof(uint));
Buffer.BlockCopy(reliability, 0, reliabilities, i * reliability.Length, reliability.Length);
// sequencenumber = i;
// timestamp = (i / audioSamples.Samples.Length) * configuration.SampleRate
} //for
return(fingerprintSignature);
}
finally
{
absEnergy = null;
lowpassFilters = null;
}
}
