Adding SilenceProvider

NAudio/NAudio.csproj

@@ -453,6 +453,7 @@
     <Compile Include="MediaFoundation\MediaFoundationTransform.cs" />
     <Compile Include="Wave\WaveProviders\MixingWaveProvider32.cs" />
     <Compile Include="Wave\WaveProviders\MultiplexingWaveProvider.cs" />
+    <Compile Include="Wave\WaveProviders\SilenceWaveProvider.cs" />
     <Compile Include="Wave\WaveProviders\StereoToMonoProvider16.cs" />
     <Compile Include="Wave\WaveProviders\MonoToStereoProvider16.cs" />
     <Compile Include="Wave\WaveProviders\VolumeWaveProvider16.cs" />

NAudio/Wave/WaveProviders/SilenceWaveProvider.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Linq;
+
+// ReSharper disable once CheckNamespace
+namespace NAudio.Wave
+{
+    /// <summary>
+    /// Silence producing wave provider
+    /// Useful for playing silence when doing a WASAPI Loopback Capture
+    /// </summary>
+    public class SilenceProvider : IWaveProvider
+    {
+        /// <summary>
+        /// Creates a new silence producing wave provider
+        /// </summary>
+        /// <param name="wf">Desired WaveFormat (should be PCM / IEE float</param>
+        public SilenceProvider(WaveFormat wf) { WaveFormat = wf; }
+
+        /// <summary>
+        /// Read silence from into the buffer
+        /// </summary>
+        public int Read(byte[] buffer, int offset, int count)
+        {
+            var end = offset + count;
+            for (var pos = offset; pos < end; pos++)
+            {
+                buffer[pos] = 0;
+            }
+            return count;
+        }
+
+        /// <summary>
+        /// WaveFormat of this silence producing wave provider
+        /// </summary>
+        public WaveFormat WaveFormat { get; private set; }
+    }
+}

NAudioTests/NAudioTests.csproj

@@ -120,6 +120,7 @@
     <Compile Include="WaveStreams\MultiplexingWaveProviderTests.cs" />
     <Compile Include="WaveStreams\OffsetSampleProviderTests.cs" />
     <Compile Include="WaveStreams\SampleToWaveProvider24Tests.cs" />
+    <Compile Include="WaveStreams\SilenceProviderTests.cs" />
     <Compile Include="WaveStreams\StereoToMonoProvider16Tests.cs" />
     <Compile Include="WaveStreams\StereoToMonoSampleProviderTests.cs" />
     <Compile Include="WaveStreams\TestSampleProvider.cs" />

NAudioTests/WaveStreams/SilenceProviderTests.cs

@@ -0,0 +1,33 @@
+using System;
+using System.Linq;
+using NAudio.Wave;
+using NUnit.Framework;
+
+namespace NAudioTests.WaveStreams
+{
+    [TestFixture]
+    public class SilenceProviderTests
+    {
+        [Test]
+        public void CanReadSilence()
+        {
+            var sp = new SilenceProvider(new WaveFormat(44100, 2));
+            var length = 1000;
+            var b = Enumerable.Range(1, length).Select(n => (byte) 1).ToArray();
+            var read = sp.Read(b, 0, length);
+            Assert.AreEqual(length, read);
+            Assert.AreEqual(new byte[length], b);
+        }
+
+        [Test]
+        public void RespectsOffsetAndCount()
+        {
+            var sp = new SilenceProvider(new WaveFormat(44100, 2));
+            var length = 10;
+            var b = Enumerable.Range(1, length).Select(n => (byte)1).ToArray();
+            var read = sp.Read(b, 2, 4);
+            Assert.AreEqual(4, read);
+            Assert.AreEqual(new byte[] { 1, 1, 0, 0, 0, 0, 1, 1, 1, 1}, b);
+        }
+    }
+}