Merge branch 'develop'

* develop:
  Adding silence calculator utility.
  Asserting how silence maps in the hash domain.

Author: AddictedCS

src/SoundFingerprinting.Tests/Properties/AssemblyInfo.cs

@@ -11,5 +11,5 @@
 [assembly: AssemblyCulture("")]
 [assembly: ComVisible(false)]
 [assembly: Guid("4cac962e-ebc5-4006-a1e0-7ffb3e2483c2")]
-[assembly: AssemblyVersion("10.4.0.100")]
-[assembly: AssemblyInformationalVersion("10.4.0.100")]
+[assembly: AssemblyVersion("10.6.0.100")]
+[assembly: AssemblyInformationalVersion("10.6.0.100")]

src/SoundFingerprinting.Tests/Unit/LSH/LocalitySensitiveHashingAlgorithmTest.cs

@@ -123,15 +123,15 @@ public void FingerprintsCantMatchUniformlyAtRandom()
             for (int i = 0; i < 100; ++i)
             {
                 var schema = TestUtilities.GenerateRandomFingerprint(random, 200, 128, 32);
-                var hash = lshAlgorithm.Hash(new Fingerprint(schema, i * one, (uint)i, Array.Empty<byte>()), config);
+                var hash = lshAlgorithm.Hash(new Fingerprint(schema, i * one, (uint)i, []), config);
                 var subFingerprint = new SubFingerprintData(hash.HashBins, hash.SequenceNumber, hash.StartsAt, new ModelReference<uint>((uint)i), track);
                 storage.AddSubFingerprint(subFingerprint);
             }
 
             for (int i = 0; i < 10; ++i)
             {
                 var schema = TestUtilities.GenerateRandomFingerprint(random, 200, 128, 32);
-                var hash = lshAlgorithm.Hash(new Fingerprint(schema, i * one, (uint)i, Array.Empty<byte>()), config);
+                var hash = lshAlgorithm.Hash(new Fingerprint(schema, i * one, (uint)i, []), config);
                 for (int j = 0; j < 25; ++j)
                 {
                     var ids = storage.GetSubFingerprintsByHashTableAndHash(j, hash.HashBins[j], MediaType.Audio);
@@ -199,16 +199,16 @@ public void ShouldBeAbleToControlReturnedCandidatesWithThresholdParameter()
                     var fingerprints = TestUtilities.GenerateSimilarFingerprints(random, howSimilar, topWavelets, width * height * 2);
                     int hammingDistance = similarity.CalculateHammingDistance(fingerprints.Item1.ConvertToBooleans(), fingerprints.Item2.ConvertToBooleans());
                     hammingDistances.Add(hammingDistance);
-                    var hashed1 = lsh.HashImage(new Fingerprint(fingerprints.Item1, 0, 0, Array.Empty<byte>()), hashingConfig);
-                    var hashed2 = lsh.HashImage(new Fingerprint(fingerprints.Item2, 0, 0, Array.Empty<byte>()), hashingConfig);
+                    var hashed1 = lsh.HashImage(new Fingerprint(fingerprints.Item1, 0, 0, []), hashingConfig);
+                    var hashed2 = lsh.HashImage(new Fingerprint(fingerprints.Item2, 0, 0, []), hashingConfig);
                     int agreeCount = AgreeOn(hashed1.HashBins, hashed2.HashBins);
                     agreeOn.Add(agreeCount);
                 }
 
                 int requested = (int)((1 - howSimilar) * topWavelets * 2);
                 Assert.AreEqual(requested, hammingDistances.Average(), 1);
                 Assert.AreEqual(expectedThresholds[r], Math.Floor(agreeOn.Average()));
-                logger.LogInformation($"Similarity: {howSimilar: 0.00}, Avg. Table Matches {agreeOn.Average(): 0.000}");
+                logger.LogInformation("Similarity: {HowSimilar}, Avg. Table Matches {Average}", howSimilar, agreeOn.Average());
             });
         }
 

src/SoundFingerprinting.Tests/Unit/Math/SimilarityUtilityTest.cs

@@ -65,6 +65,16 @@ public void CalculateJaccardSimilarityCorrect()
             Assert.AreEqual(5f / 6, result, 0.0001);
         }
 
+        [Test]
+        public void SilenceShouldMapToNegativeOne()
+        {
+            byte[] minHashes = [255, 255, 255, 255];
+            int[] hashes = hashConverter.ToInts(minHashes, 1);
+            
+            Assert.AreEqual(1, hashes.Length);
+            Assert.AreEqual(-1, hashes[0]);
+        }
+
         private byte[] GenerateByteArray(int length)
         {
             var ran = new Random();

src/SoundFingerprinting.Tests/Unit/Utils/SilenceCalculatorTest.cs

@@ -0,0 +1,26 @@
+namespace SoundFingerprinting.Tests.Unit.Utils;
+
+using System.Linq;
+using NUnit.Framework;
+using SoundFingerprinting.Data;
+using SoundFingerprinting.Utils;
+
+[TestFixture]
+public class SilenceCalculatorTest
+{
+    [Test]
+    public void ShouldCalculateCorrectly()
+    {
+        var hashedFingerprints = Enumerable.Range(0, 10).Select(index =>
+        {
+            int[] hashBins = index % 2 == 0 ? Enumerable.Repeat(-1, 25).ToArray() : Enumerable.Repeat(1, 25).ToArray();
+            return new HashedFingerprint(hashBins, (uint)index, (float)index / 2, []);
+        }).ToArray();
+
+        var hashes = new Hashes(hashedFingerprints, 10, MediaType.Audio);
+
+        var timespan = SilenceCalculator.Calculate(hashes);
+        
+        Assert.That(timespan.TotalSeconds, Is.EqualTo(2.5).Within(0.1));
+    }
+}

src/SoundFingerprinting/Data/AVHashes.cs

@@ -135,7 +135,7 @@ public AVHashes WithStreamId(string streamId)
         }
 
         /// <summary>
-        ///  Add an additional property to the Audio/Video hashes object.
+        ///  Add a property to the Audio/Video hashes object.
         /// </summary>
         /// <param name="key">Property key.</param>
         /// <param name="value">Property value.</param>

src/SoundFingerprinting/FingerprintService.cs

@@ -86,7 +86,7 @@ internal IEnumerable<Fingerprint> CreateOriginalFingerprintsFromFrames(IEnumerab
             var images = normalized.ToList();
             if (!images.Any())
             {
-                return Enumerable.Empty<Fingerprint>();
+                return [];
             }
 
             var fingerprints = new ConcurrentBag<Fingerprint>();

src/SoundFingerprinting/Properties/AssemblyInfo.cs

@@ -19,5 +19,5 @@
 [assembly: InternalsVisibleTo("SoundFingerprinting.FFT.FFTW")]
 [assembly: InternalsVisibleTo("SoundFingerprinting.FFT.FFTW.Tests")]
 
-[assembly: AssemblyVersion("10.4.0.100")]
-[assembly: AssemblyInformationalVersion("10.4.0.100")]
+[assembly: AssemblyVersion("10.6.0.100")]
+[assembly: AssemblyInformationalVersion("10.6.0.100")]

src/SoundFingerprinting/SoundFingerprinting.csproj

@@ -4,7 +4,7 @@
 	<AllowUnsafeBlocks>true</AllowUnsafeBlocks>
 	<GenerateAssemblyInfo>false</GenerateAssemblyInfo>
 	<Nullable>enable</Nullable>
-	<PackageVersion>10.4.0</PackageVersion>
+	<PackageVersion>10.6.0</PackageVersion>
 	<Authors>Sergiu Ciumac</Authors>
 	<PackageDescription>SoundFingerprinting is a C# framework that implements an efficient algorithm of audio fingerprinting and identification. Designed for developers, enthusiasts, researchers in the fields of audio processing, data mining, digital signal processing.</PackageDescription>
 	<PackageProjectUrl>https://github.com/addictedcs/soundfingerprinting</PackageProjectUrl>

src/SoundFingerprinting/Utils/SilenceCalculator.cs

@@ -0,0 +1,63 @@
+namespace SoundFingerprinting.Utils;
+
+using System;
+using System.Linq;
+using SoundFingerprinting.Data;
+
+/// <summary>
+///  Silence calculator.
+/// </summary>
+/// <remarks>
+///  A utility class allowing to calculate silence contained within audio and video hashes. <br />
+///  It only makes sense to calculate silence for hashes if TreatAsSilence flag is set to true during fingerprinting. <br />
+///  Do not set the flag to true unless you've explicitly arrived to the conclusion you need it.
+/// </remarks>
+public static class SilenceCalculator
+{
+    /// <summary>
+    ///  Silence value, derived from the fact that an array of [255, 255, 255, 255] min hashes will map to -1 during hashes conversion.
+    /// </summary>
+    private const int Silence = -1;
+    
+    /// <summary>
+    ///  Calculate silence contained within audio and video hashes.
+    /// </summary>
+    /// <param name="avHashes">AVHashes to analyze.</param>
+    /// <returns>
+    ///  Tuple containing audio and video silence. For video hashes silence means black frames.
+    /// </returns>
+    public static (TimeSpan, TimeSpan) Calculate(AVHashes avHashes)
+    {
+        var audioSilence = Calculate(avHashes.Audio);
+        var videoSilence = Calculate(avHashes.Video);
+        return (audioSilence, videoSilence);
+    }
+    
+    /// <summary>
+    ///  Calculate contained silence within hashes.
+    /// </summary>
+    /// <param name="hashes">Hashes to analyze.</param>
+    /// <returns>Timespan.</returns>
+    /// <remarks>
+    ///  It only makes sense to calculate silence for hashes if TreatAsSilence flag is set to true during fingerprinting.
+    /// </remarks>
+    public static TimeSpan Calculate(Hashes? hashes)
+    {
+        if (hashes == null || hashes.IsEmpty)
+        {
+            return TimeSpan.Zero;
+        }
+
+        var items = hashes.OrderBy(_ => _.SequenceNumber).ToArray();
+        double silence = 0;
+        for (int i = 1; i < items.Length; i++)
+        {
+            if (hashes[i - 1].HashBins.All(_ => _ == Silence))
+            {
+                silence += items[i].StartsAt - items[i - 1].StartsAt;
+            }
+        }
+
+        return TimeSpan.FromSeconds(silence);
+    }
+}