Correct dBFS calculation.

keijiro · Jul 19, 2017 · 477c01a · 477c01a
1 parent d78cc66
commit 477c01a
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Showing 4 changed files with 27 additions and 15 deletions.
diff --git a/Assets/Lasp/AudioInput.cs b/Assets/Lasp/AudioInput.cs
@@ -21,7 +21,8 @@ public static float GetPeakLevel(FilterType filter)
         // Returns the peak level during the last frame in dBFS.
         public static float GetPeakLevelDecibel(FilterType filter)
         {
-            return Mathf.Log10(GetPeakLevel(filter)) * 10;
+            // Full scale square wave = 0 dBFS : refLevel = 1
+            return ConvertToDecibel(GetPeakLevel(filter), 1);
         }
 
         // Calculates the RMS level of the last frame.
@@ -34,7 +35,8 @@ public static float CalculateRMS(FilterType filter)
         // Calculates the RMS level of the last frame in dBFS.
         public static float CalculateRMSDecibel(FilterType filter)
         {
-            return Mathf.Log10(CalculateRMS(filter)) * 10;
+            // Full scale sin wave = 0 dBFS : refLevel = 1/sqrt(2)
+            return ConvertToDecibel(CalculateRMS(filter), 0.7071f);
         }
 
         // Retrieve and copy the waveform.
@@ -52,6 +54,12 @@ public static void RetrieveWaveform(FilterType filter, float[] dest)
         static FilterBlock[] _filterBank;
         static int _lastUpdateFrame;
 
+        static float ConvertToDecibel(float level, float refLevel)
+        {
+            const float zeroOffset = 1.5849e-13f;
+            return 20 * Mathf.Log10(level / refLevel + zeroOffset);
+        }
+
         static void Initialize()
         {
             _stream = new Lasp.LaspStream();

diff --git a/Assets/Test/Particles.unity b/Assets/Test/Particles.unity
@@ -138,7 +138,7 @@ MonoBehaviour:
   m_Name: 
   m_EditorClassIdentifier: 
   _filterType: 3
-  _amplify: 12
+  _amplify: 20
 --- !u!199 &144958675
 ParticleSystemRenderer:
   serializedVersion: 4
@@ -250,7 +250,7 @@ ParticleSystem:
   moveWithTransform: 0
   moveWithCustomTransform: {fileID: 0}
   scalingMode: 1
-  randomSeed: -1897777151
+  randomSeed: -240977648
   InitialModule:
     serializedVersion: 3
     enabled: 1
@@ -3607,7 +3607,7 @@ ParticleSystem:
   moveWithTransform: 0
   moveWithCustomTransform: {fileID: 0}
   scalingMode: 1
-  randomSeed: 1531819271
+  randomSeed: 949519521
   InitialModule:
     serializedVersion: 3
     enabled: 1
@@ -6847,7 +6847,7 @@ MonoBehaviour:
   m_Name: 
   m_EditorClassIdentifier: 
   _filterType: 1
-  _amplify: 4
+  _amplify: 8
 --- !u!1 &739515039
 GameObject:
   m_ObjectHideFlags: 0
@@ -7032,7 +7032,7 @@ ParticleSystem:
   moveWithTransform: 0
   moveWithCustomTransform: {fileID: 0}
   scalingMode: 1
-  randomSeed: -87322421
+  randomSeed: 1170090217
   InitialModule:
     serializedVersion: 3
     enabled: 1

diff --git a/Assets/Test/Test.unity b/Assets/Test/Test.unity
@@ -210,7 +210,7 @@ MonoBehaviour:
   m_Name: 
   m_EditorClassIdentifier: 
   _filterType: 3
-  _amplify: 10
+  _amplify: 16
   _peakIndicator: {fileID: 182632196}
   _rmsIndicator: {fileID: 462222369}
   _lineMaterial: {fileID: 10306, guid: 0000000000000000f000000000000000, type: 0}
@@ -346,7 +346,7 @@ MonoBehaviour:
   m_Name: 
   m_EditorClassIdentifier: 
   _filterType: 2
-  _amplify: 5
+  _amplify: 4
   _peakIndicator: {fileID: 2026675033}
   _rmsIndicator: {fileID: 1680186477}
   _lineMaterial: {fileID: 10306, guid: 0000000000000000f000000000000000, type: 0}
@@ -1140,7 +1140,7 @@ MonoBehaviour:
   m_Name: 
   m_EditorClassIdentifier: 
   _filterType: 1
-  _amplify: 5
+  _amplify: 8
   _peakIndicator: {fileID: 1106074908}
   _rmsIndicator: {fileID: 1070605825}
   _lineMaterial: {fileID: 10306, guid: 0000000000000000f000000000000000, type: 0}

diff --git a/Assets/Test/Tester.cs b/Assets/Test/Tester.cs
@@ -4,11 +4,12 @@
 public class Tester : MonoBehaviour
 {
     [SerializeField] Lasp.FilterType _filterType;
-    [SerializeField] float _amplify = 1;
     [SerializeField] Transform _peakIndicator;
     [SerializeField] Transform _rmsIndicator;
     [SerializeField] Material _lineMaterial;
 
+    const float kSilence = -40; // -40 dBFS = silence
+
     float[] _waveform;
     List<Vector3> _vertices;
     Mesh _mesh;
@@ -30,12 +31,15 @@ void OnDestroy()
 
     void Update()
     {
-        var peak = Lasp.AudioInput.GetPeakLevelDecibel(_filterType) + _amplify;
-        var rms = Lasp.AudioInput.CalculateRMSDecibel(_filterType) + _amplify;
+        var peak = Lasp.AudioInput.GetPeakLevelDecibel(_filterType);
+        var rms = Lasp.AudioInput.CalculateRMSDecibel(_filterType);
         Lasp.AudioInput.RetrieveWaveform(_filterType, _waveform);
 
-        _peakIndicator.localScale = new Vector3(1, Mathf.Clamp01(1 + peak / 10), 1);
-        _rmsIndicator.localScale = new Vector3(1, Mathf.Clamp01(1 + rms / 10), 1);
+        peak = Mathf.Clamp01(1 - peak / kSilence);
+        rms = Mathf.Clamp01(1 - rms / kSilence);
+
+        _peakIndicator.localScale = new Vector3(1, peak, 1);
+        _rmsIndicator.localScale = new Vector3(1, rms, 1);
 
         UpdateMeshWithWaveform();
         Graphics.DrawMesh(_mesh, transform.localToWorldMatrix, _lineMaterial, gameObject.layer);