Added DecibelParameter and RangPower.

Author: mikeoliphant

AudioPlugSharp/AudioPluginParameter.cs

@@ -14,8 +14,9 @@ public class AudioPluginParameter : INotifyPropertyChanged
         public int ParameterIndex { get; internal set; }
         public string ID { get; set; }
         public string Name { get; set; }
-        public double MinValue { get; set; }
-        public double MaxValue { get; set; }
+        public virtual double MinValue { get; set; }
+        public virtual double MaxValue { get; set; }
+        public double RangePower { get; set; } = 0;
         public double DefaultValue { get; set; }
         public string ValueFormat { get; set; }
 
@@ -61,7 +62,7 @@ public double EditValue
             }
         }
 
-        public string DisplayValue { get { return String.Format(ValueFormat, editValue); } }
+        public virtual string DisplayValue { get { return String.Format(ValueFormat, editValue); } }
 
         public double NormalizedProcessValue
         {
@@ -83,19 +84,28 @@ public AudioPluginParameter()
             ValueFormat = "{0:0.0}";
         }
 
-        public static double DbToLinear(double db)
+        public static double DBToLinear(double db)
         {
             return Math.Pow(10.0, 0.05 * db);
         }
 
-        public double GetValueNormalized(double value)
+        public static double LinearToDB(double linear)
         {
-            return (value - MinValue) / (MaxValue - MinValue);
+            return 20.0 * Math.Log10(linear);
         }
 
-        public double GetValueDenormalized(double value)
+        public virtual double GetValueNormalized(double value)
         {
-            return MinValue + ((MaxValue - MinValue) * value);
+            double rangeVal = (value - MinValue) / (MaxValue - MinValue);
+
+            return (RangePower > 0) ? Math.Pow(rangeVal, RangePower) : rangeVal;
+        }
+
+        public virtual double GetValueDenormalized(double value)
+        {
+            double rangeVal = (RangePower > 0) ? Math.Pow(value, 1 / RangePower) : value;
+
+            return MinValue + ((MaxValue - MinValue) * rangeVal);
         }
 
         double prevParamValue;
@@ -161,4 +171,77 @@ public void OnPropertyChanged(string name)
             }
         }
     }
+
+    public class DecibelParameter : AudioPluginParameter
+    {
+        public override double MinValue
+        {
+            get => base.MinValue;
+            set
+            {
+                base.MinValue = value;
+
+                linearMin = DBToLinear(value);
+            }
+        }
+
+        public override double MaxValue
+        {
+            get => base.MaxValue;
+
+            set
+            {
+                base.MaxValue = value;
+
+                linearMax = DBToLinear(value);
+            }
+        }
+
+        double linearMin;
+        double linearMax;
+
+        public DecibelParameter()
+        {
+            MinValue = double.NegativeInfinity;
+            MaxValue = 0;
+            DefaultValue = 0;
+            RangePower = 1.0 / 4.0;
+            ValueFormat = "{0:0.0}dB";
+        }
+
+        public override string DisplayValue
+        {
+            get
+            {
+                if (double.IsNegativeInfinity(EditValue))
+                    return "-inf dB";
+
+                return base.DisplayValue;
+            }
+        }
+
+        public static double LinearToLog(double linear)
+        {
+            return Math.Pow(linear, .25);
+        }
+
+        public static double LogToLinear(double log)
+        {
+            return Math.Pow(log, 4);
+        }
+
+        public override double GetValueNormalized(double value)
+        {
+            double rangeVal = (DBToLinear(value) - linearMin) / (linearMax - linearMin);
+
+            return (RangePower > 0) ? Math.Pow(rangeVal, RangePower) : rangeVal;
+        }
+
+        public override double GetValueDenormalized(double value)
+        {
+            double rangeVal = (RangePower > 0) ? Math.Pow(value, 1 / RangePower) : value;
+
+            return LinearToDB(linearMin + ((linearMax - linearMin) * rangeVal));
+        }
+    }
 }

JackHostTest/Program.cs

@@ -8,6 +8,19 @@ internal class Program
     {
         static void Main(string[] args)
         {
+            var dec = new DecibelParameter
+            {
+                ID = "gain",
+                Name = "Gain",
+                //MinValue = -20,
+                //MaxValue = 20,
+                DefaultValue = 0,
+                ValueFormat = "{0:0.0}dB"
+            };
+
+            double denorm = dec.GetValueDenormalized(0.5);
+
+
             JackHost<SimpleExamplePlugin> host = new JackHost<SimpleExamplePlugin>(new SimpleExamplePlugin());
 
             host.Run();

MidiExample/MidiExamplePlugin.cs

@@ -70,7 +70,7 @@ public override void Process()
         {
             base.Process();
 
-            linearGain = AudioPluginParameter.DbToLinear(gainParameter.ProcessValue);
+            linearGain = AudioPluginParameter.DBToLinear(gainParameter.ProcessValue);
 
             Span<double> outSamples = monoOutput.GetAudioBuffer(0);
 
@@ -96,7 +96,7 @@ public override void Process()
                     // If we need to update our gain paramter, get the sample-accurate interpolated value
                     if (needGainUpdate)
                     {
-                        linearGain = AudioPluginParameter.DbToLinear(gainParameter.GetInterpolatedProcessValue(i));
+                        linearGain = AudioPluginParameter.DBToLinear(gainParameter.GetInterpolatedProcessValue(i));
                     }
 
                     outSamples[i] = Math.Sin(((double)samplesSoFar * 2 * Math.PI * freq) / Host.SampleRate) * noteVolume * linearGain;

SimpleExample/SimpleExamplePlugin.cs

@@ -30,13 +30,14 @@ public override void Initialize()
             InputPorts = new AudioIOPort[] { monoInput = new FloatAudioIOPort("Mono Input", EAudioChannelConfiguration.Mono) };
             OutputPorts = new AudioIOPort[] { monoOutput = new FloatAudioIOPort("Mono Output", EAudioChannelConfiguration.Mono) };
 
-            AddParameter(new AudioPluginParameter
+            AddParameter(new DecibelParameter
             {
                 ID = "gain",
                 Name = "Gain",
-                MinValue = -20,
-                MaxValue = 20,
-                DefaultValue = 0,
+                MaxValue = 12,
+                //MinValue = -20,
+                //MaxValue = 20,
+                //DefaultValue = 0,
                 ValueFormat = "{0:0.0}dB"
             });
         }
@@ -50,7 +51,7 @@ public override void Process()
             Host.ProcessAllEvents();
 
             double gainDb = GetParameter("gain").ProcessValue;
-            float linearGain = (float)AudioPluginParameter.DbToLinear(gainDb);
+            float linearGain = (float)AudioPluginParameter.DBToLinear(gainDb);
 
             ReadOnlySpan<float> inSamples = monoInput.GetAudioBuffer(0);
             Span<float> outSamples = monoOutput.GetAudioBuffer(0);

WPFExample/WPFExamplePlugin.cs

@@ -70,7 +70,7 @@ public override void Process()
             int currentSample = 0;
             int nextSample = 0;
 
-            double linearGain = AudioPluginParameter.DbToLinear(gainParameter.ProcessValue);
+            double linearGain = AudioPluginParameter.DBToLinear(gainParameter.ProcessValue);
             double pan = panParameter.ProcessValue;
 
             do
@@ -84,7 +84,7 @@ public override void Process()
                 {
                     if (needGainUpdate)
                     {
-                        linearGain = AudioPluginParameter.DbToLinear(gainParameter.GetInterpolatedProcessValue(i));
+                        linearGain = AudioPluginParameter.DBToLinear(gainParameter.GetInterpolatedProcessValue(i));
                     }
 
                     if (needPanUpdate)