Add DmoEffectWaveProvider and Tests

NAudio/NAudio.csproj

@@ -476,6 +476,7 @@
     <Compile Include="Wave\SampleProviders\SampleToWaveProvider.cs" />
     <Compile Include="Wave\WaveProviders\BufferedWaveProvider.cs" />
     <Compile Include="Wave\SampleProviders\MonoToStereoSampleProvider.cs" />
+    <Compile Include="Wave\WaveProviders\DmoEffectWaveProvider.cs" />
     <Compile Include="Wave\WaveProviders\MediaFoundationResampler.cs" />
     <Compile Include="MediaFoundation\MediaFoundationTransform.cs" />
     <Compile Include="Wave\WaveProviders\MixingWaveProvider32.cs" />

NAudio/Wave/WaveProviders/DmoEffectWaveProvider.cs

@@ -0,0 +1,99 @@
+using System;
+using NAudio.Dmo;
+using NAudio.Dmo.Effect;
+
+// ReSharper disable once CheckNamespace
+namespace NAudio.Wave
+{
+    /// <summary>
+    /// Provide WaveProvider that can apply effects in real time using DMO.
+    /// 
+    /// If the audio thread is running on the STA thread, please generate and operate from the same thread.
+    /// If the audio thread is running on the MTA thread, please operate on any MTA thread.
+    /// </summary>
+    /// <typeparam name="TDmoEffector">Types of DMO effectors to use</typeparam>
+    /// <typeparam name="TEffectorParam">Parameters of the effect to be used</typeparam>
+    public class DmoEffectWaveProvider<TDmoEffector, TEffectorParam> : IWaveProvider, IDisposable
+        where TDmoEffector : IDmoEffector<TEffectorParam>, new()
+    {
+        private readonly IWaveProvider inputProvider;
+        private readonly IDmoEffector<TEffectorParam> effector;
+
+        /// <summary>
+        /// Create a new DmoEffectWaveProvider
+        /// </summary>
+        /// <param name="inputProvider">Input Stream</param>
+        public DmoEffectWaveProvider(IWaveProvider inputProvider)
+        {
+            this.inputProvider = inputProvider;
+            effector = new TDmoEffector();
+
+            var mediaObject = effector.MediaObject;
+
+            if (mediaObject == null)
+            {
+                throw new NotSupportedException(@"Dmo Effector Not Supported: " + nameof(TDmoEffector));
+            }
+
+            if (!mediaObject.SupportsInputWaveFormat(0, inputProvider.WaveFormat))
+            {
+                throw new ArgumentException(@"Unsupported Input Stream format", nameof(inputProvider));
+            }
+
+            mediaObject.AllocateStreamingResources();
+            mediaObject.SetInputWaveFormat(0, this.inputProvider.WaveFormat);
+            mediaObject.SetOutputWaveFormat(0, this.inputProvider.WaveFormat);
+        }
+
+        /// <summary>
+        /// Stream Wave Format
+        /// </summary>
+        public WaveFormat WaveFormat => inputProvider.WaveFormat;
+
+        /// <summary>
+        /// Reads data from input stream
+        /// </summary>
+        /// <param name="buffer">buffer</param>
+        /// <param name="offset">offset into buffer</param>
+        /// <param name="count">Bytes required</param>
+        /// <returns>Number of bytes read</returns>
+        public int Read(byte[] buffer, int offset, int count)
+        {
+            var readNum = inputProvider.Read(buffer, offset, count);
+
+            if (effector == null)
+            {
+                return readNum;
+            }
+
+            if (effector.MediaObjectInPlace.Process(readNum, offset, buffer, 0, DmoInPlaceProcessFlags.Normal)
+                == DmoInPlaceProcessReturn.HasEffectTail)
+            {
+                var effectTail = new byte[readNum];
+                while (effector.MediaObjectInPlace.Process(readNum, 0, effectTail, 0, DmoInPlaceProcessFlags.Zero) ==
+                       DmoInPlaceProcessReturn.HasEffectTail)
+                {
+                }
+            }
+
+            return readNum;
+        }
+
+        /// <summary>
+        /// Get Effector Parameters
+        /// </summary>
+        public TEffectorParam EffectParams => effector.EffectParams;
+
+        /// <summary>
+        /// Dispose
+        /// </summary>
+        public void Dispose()
+        {
+            if (effector != null)
+            {
+                effector.MediaObject.FreeStreamingResources();
+                effector.Dispose();
+            }
+        }
+    }
+}