Add BandPassFilter, FrequencyModulator, update ButterworthFilter defaults, improve filter sound

ProjectObsidian/Components/Audio/BandPassFilter.cs

@@ -0,0 +1,86 @@
+using System;
+using FrooxEngine;
+using Elements.Assets;
+using System.Net;
+using ProtoFlux.Runtimes.Execution;
+
+namespace Obsidian.Components.Audio
+{
+    [Category(new string[] { "Obsidian/Audio" })]
+    public class BandPassFilter : Component, IAudioSource, IWorldElement
+    {
+        [Range(0.1f, 1.41f, "0.00")]
+        public readonly Sync<float> Resonance;
+
+        [Range(20f, 20000f, "0.00")]
+        public readonly Sync<float> LowFrequency;
+
+        [Range(20f, 20000f, "0.00")]
+        public readonly Sync<float> HighFrequency;
+
+        public readonly SyncRef<IAudioSource> Source;
+
+        private double lastTime;
+
+        private object lowFilter = null;
+        private object highFilter = null;
+
+        public bool IsActive
+        {
+            get => Source.Target != null && Source.Target.IsActive;
+        }
+
+        public int ChannelCount => Source.Target?.ChannelCount ?? 0;
+
+        public void Read<S>(Span<S> buffer) where S : unmanaged, IAudioSample<S>
+        {
+            if (!IsActive)
+            {
+                return;
+            }
+
+            Span<S> tempBuffer = stackalloc S[buffer.Length];
+            tempBuffer = buffer;
+            Source.Target.Read(tempBuffer);
+
+            if (lowFilter == null)
+            {
+                lowFilter = new ButterworthFilter.FilterButterworth<S>();
+            }
+            if (highFilter == null)
+            {
+                highFilter = new ButterworthFilter.FilterButterworth<S>();
+            }
+
+            ((ButterworthFilter.FilterButterworth<S>)lowFilter).UpdateCoefficients(HighFrequency, (int)(tempBuffer.Length / (Engine.Current.AudioSystem.DSPTime - lastTime)), ButterworthFilter.FilterButterworth<S>.PassType.Lowpass, Resonance);
+            ((ButterworthFilter.FilterButterworth<S>)highFilter).UpdateCoefficients(LowFrequency, (int)(tempBuffer.Length / (Engine.Current.AudioSystem.DSPTime - lastTime)), ButterworthFilter.FilterButterworth<S>.PassType.Highpass, Resonance);
+
+            for (int i = 0; i < tempBuffer.Length; i++)
+            {
+                ((ButterworthFilter.FilterButterworth<S>)lowFilter).Update(ref tempBuffer[i]);
+                ((ButterworthFilter.FilterButterworth<S>)highFilter).Update(ref tempBuffer[i]);
+            }
+
+            lastTime = Engine.Current.AudioSystem.DSPTime;
+        }
+
+        protected override void OnAwake()
+        {
+            base.OnAwake();
+            Resonance.Value = 1.41f;
+            LowFrequency.Value = 20f;
+            HighFrequency.Value = 20000f;
+            lastTime = Engine.Current.AudioSystem.DSPTime;
+        }
+
+        protected override void OnChanges()
+        {
+            base.OnChanges();
+            if (Source.GetWasChangedAndClear())
+            {
+                lowFilter = null;
+                highFilter = null;
+            }
+        }
+    }
+}

ProjectObsidian/Components/Audio/ButterworthFilter.cs

@@ -7,7 +7,7 @@ namespace Obsidian.Components.Audio;
 [Category(new string[] { "Obsidian/Audio" })]
 public class ButterworthFilter : Component, IAudioSource, IWorldElement
 {
-    [Range(0f, 10000f, "0.00")]
+    [Range(20f, 20000f, "0.00")]
     public readonly Sync<float> Frequency;
 
     [Range(0.1f, 1.41f, "0.00")]
@@ -19,6 +19,8 @@ public class ButterworthFilter : Component, IAudioSource, IWorldElement
 
     private double lastTime;
 
+    private object filter = null;
+
     public bool IsActive
     {
         get
@@ -30,7 +32,18 @@ public bool IsActive
     protected override void OnAwake()
     {
         base.OnAwake();
-        lastTime = -1;
+        lastTime = Engine.Current.AudioSystem.DSPTime;
+        Frequency.Value = 20f;
+        Resonance.Value = 1.41f;
+    }
+
+    protected override void OnChanges()
+    {
+        base.OnChanges();
+        if (Source.GetWasChangedAndClear())
+        {
+            filter = null;
+        }
     }
 
     public int ChannelCount => Source.Target?.ChannelCount ?? 0;
@@ -48,11 +61,16 @@ public void Read<S>(Span<S> buffer) where S : unmanaged, IAudioSample<S>
 
         Source.Target.Read(span);
 
-        var filter = new FilterButterworth<S>(Frequency, (int)(span.Length / (Engine.Current.AudioSystem.DSPTime - lastTime)), LowPass ? FilterButterworth<S>.PassType.Lowpass : FilterButterworth<S>.PassType.Highpass, Resonance);
+        if (filter == null)
+        {
+            filter = new FilterButterworth<S>();
+        }
+
+        ((FilterButterworth<S>)filter).UpdateCoefficients(Frequency, (int)(span.Length / (Engine.Current.AudioSystem.DSPTime - lastTime)), LowPass ? FilterButterworth<S>.PassType.Lowpass : FilterButterworth<S>.PassType.Highpass, Resonance);
 
         for (int i = 0; i < span.Length; i++)
         {
-            filter.Update(ref span[i]);
+            ((FilterButterworth<S>)filter).Update(ref span[i]);
         }
 
         lastTime = Engine.Current.AudioSystem.DSPTime;
@@ -69,7 +87,7 @@ public class FilterButterworth<S> where S: unmanaged, IAudioSample<S>
         private readonly int sampleRate;
         private readonly PassType passType;
 
-        private readonly float c, a1, a2, a3, b1, b2;
+        private float c, a1, a2, a3, b1, b2;
 
         /// <summary>
         /// Array of input values, latest are in front
@@ -81,13 +99,8 @@ public class FilterButterworth<S> where S: unmanaged, IAudioSample<S>
         /// </summary>
         private S[] outputHistory = new S[3];
 
-        public FilterButterworth(float frequency, int sampleRate, PassType passType, float resonance)
+        public void UpdateCoefficients(float frequency, int sampleRate, PassType passType, float resonance)
         {
-            this.resonance = resonance;
-            this.frequency = frequency;
-            this.sampleRate = sampleRate;
-            this.passType = passType;
-
             switch (passType)
             {
                 case PassType.Lowpass:

ProjectObsidian/Components/Audio/FrequencyModulator.cs

@@ -0,0 +1,79 @@
+using System;
+using FrooxEngine;
+using Elements.Assets;
+
+namespace Obsidian.Components.Audio
+{
+    [Category(new string[] { "Obsidian/Audio" })]
+    public class FrequencyModulator : Component, IAudioSource, IWorldElement
+    {
+        [Range(0f, 1000f, "0.00")]
+        public readonly Sync<float> ModulationIndex;
+
+        public readonly SyncRef<IAudioSource> CarrierSource;
+        public readonly SyncRef<IAudioSource> ModulatorSource;
+
+        public bool IsActive
+        {
+            get
+            {
+                return CarrierSource.Target != null &&
+                       ModulatorSource.Target != null &&
+                       CarrierSource.Target.IsActive &&
+                       ModulatorSource.Target.IsActive;
+            }
+        }
+
+        public int ChannelCount
+        {
+            get
+            {
+                return CarrierSource.Target?.ChannelCount ?? 0;
+            }
+        }
+
+        protected override void OnAwake()
+        {
+            base.OnAwake();
+            ModulationIndex.Value = 100f; // Default modulation index
+        }
+
+        public void Read<S>(Span<S> buffer) where S : unmanaged, IAudioSample<S>
+        {
+            if (!IsActive)
+            {
+                return;
+            }
+
+            int channelCount = ChannelCount;
+            if (channelCount == 0)
+            {
+                return;
+            }
+
+            // Temporary buffers for carrier and modulator sources
+            Span<S> carrierBuffer = stackalloc S[buffer.Length];
+            Span<S> modulatorBuffer = stackalloc S[buffer.Length];
+
+            // Read data from sources
+            CarrierSource.Target.Read(carrierBuffer);
+            ModulatorSource.Target.Read(modulatorBuffer);
+
+            float modulationIndex = ModulationIndex.Value;
+
+            // Apply FM synthesis
+            for (int i = 0; i < buffer.Length; i++)
+            {
+                // Get carrier and modulator values
+                float carrierValue = carrierBuffer[i].AbsoluteAmplitude;
+                float modulatorValue = modulatorBuffer[i].AbsoluteAmplitude;
+
+                // Compute frequency modulation
+                float modulatedValue = (float)(carrierValue * Math.Sin(2 * Math.PI * modulationIndex * modulatorValue));
+
+                // Write modulated value to the buffer
+                buffer[i] = buffer[i].Bias(buffer[i].AbsoluteAmplitude -  modulatedValue);
+            }
+        }
+    }
+}