/// <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 <int, int[]> CreateLookupDictionary(FingerprintAcoustID fs)
{
int[] hashes = fs.SignatureInt32;
Dictionary <int, int[]> subFingerLookup = new Dictionary <int, int[]>(hashes.Length);
for (int index = 0; index < hashes.Length; index++)
{
int h = hashes[index] & unchecked ((int)0xfffffff0);
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 float MatchFingerprint(FingerprintAcoustID finger1, FingerprintAcoustID finger2, int maxoffset = 0)
{
float score = 0.0f;
int[] f1 = finger1.SignatureInt32;
int f1size = f1.Length;
int[] f2 = finger2.SignatureInt32;
int f2size = f2.Length;
int numcounts = f1size + f2size + 1;
ushort[] aoffsets = new ushort[MATCH_MASK + 1];
ushort[] boffsets = new ushort[MATCH_MASK + 1];
// Zorg dat er een limiet is
if (f1size > aoffsets.Length)
{
f1size = aoffsets.Length;
}
if (f2size > boffsets.Length)
{
f2size = boffsets.Length;
}
// ------------------------------------------------------------
// YN aanpassing 2015-11-02 gedaan (zoeken duurt anders te lang
// zie titelnummer_id=944086
// Lookup tabel aanmaken ????
for (ushort i = 0; i < f1size; i++)
{
aoffsets[MatchStrip(f1[i])] = i;
}
for (ushort i = 0; i < f2size; i++)
{
boffsets[MatchStrip(f2[i])] = i;
}
// ------------------------------------------------------------
int topcount = 0;
int topoffset = 0;
ushort[] counts = new ushort[numcounts];
for (int i = 0; i < MATCH_MASK; i++)
{
if (aoffsets[i] != 0 && boffsets[i] != 0)
{
int offset = aoffsets[i] - boffsets[i];
if (maxoffset == 0 || (-maxoffset <= offset && offset <= maxoffset))
{
offset += f2size;
counts[offset]++;
if (counts[offset] > topcount)
{
topcount = counts[offset];
topoffset = offset;
}
}
}
} //for i
topoffset -= f2size;
int f1Offset = 0;
int f2Offset = 0;
int minsize = Math.Min(f1size, f2size) & ~1;
if (topoffset < 0)
{
f2Offset -= topoffset;
f2size = Math.Max(0, f2size + topoffset);
}
else
{
f1Offset += topoffset;
f1size = Math.Max(0, f1size - topoffset);
}
int size = Math.Min(f1size, f2size) / 2;
if (size == 0 || minsize == 0)
{
System.Diagnostics.Trace.WriteLine("acoustid_compare2: empty matching subfingerprint");
return(0.0f);
}
ushort[] seen = aoffsets;
int f1unique = 0;
// clear
for (int i = 0; i < UNIQ_MASK; i++)
{
seen[i] = 0;
}
for (int i = 0; i < f1size; i++)
{
int key = UniqueStrip(f1[i]);
if (seen[key] == 0)
{
f1unique++;
seen[key] = 1;
}
}
int f2unique = 0;
// clear
for (int i = 0; i < UNIQ_MASK; i++)
{
seen[i] = 0;
}
for (int i = 0; i < f2size; i++)
{
int key = UniqueStrip(f2[i]);
if (seen[key] == 0)
{
f2unique++;
seen[key] = 1;
}
}
float diversity = (float)Math.Min(Math.Min(1.0f, (float)(f1unique + 10) / f1size + 0.5f), Math.Min(1.0, (float)(f2unique + 10) / f2size + 0.5f));
int BER = 0;
for (int i = 0; i < size; i++)
{
int bits = AudioFingerprint.Math.SimilarityUtility.HammingDistance(unchecked ((uint)f1[i]), unchecked ((uint)f2[i]));
if (bits > 0)
{
BER += bits;
}
} //for i
score = (size * 2.0f / minsize) * (1.0f - 2.0f * (float)BER / (64 * size));
if (score < 0.0f)
{
score = 0.0f;
}
if (diversity < 1.0)
{
float newscore = (float)Math.Pow(score, 8.0f - 7.0f * diversity);
System.Diagnostics.Trace.WriteLine(string.Format("acoustid_compare2: scaling score because of duplicate items, {0:#0:00} => {1:#0:00}", score, newscore));
score = newscore;
}
return(score);
}