Implemented classes for some missing interfaces needed to navigate device topology

NAudio.Wasapi/CoreAudioApi/AudioMute.cs

@@ -0,0 +1,31 @@
+using NAudio.CoreAudioApi.Interfaces;
+using NAudio.Wasapi.CoreAudioApi.Interfaces;
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace NAudio.CoreAudioApi
+{
+    public class AudioMute
+    {
+        private IAudioMute audioMuteInterface;
+        internal AudioMute(IAudioMute audioMute)
+        {
+            audioMuteInterface = audioMute;
+        }
+
+        public bool IsMuted
+        {
+            get
+            {
+                audioMuteInterface.GetMute(out var result);
+                return result;
+            }
+            set
+            {
+                var guid = Guid.Empty;
+                audioMuteInterface.SetMute(value, guid);
+            }
+        }
+    }
+}

NAudio.Wasapi/CoreAudioApi/AudioVolumeLevel.cs

@@ -0,0 +1,58 @@
+using NAudio.CoreAudioApi.Interfaces;
+using NAudio.Wasapi.CoreAudioApi.Interfaces;
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace NAudio.Wasapi.CoreAudioApi
+{
+    public class AudioVolumeLevel
+    {
+        private readonly IAudioVolumeLevel audioVolumeLevelInterface;
+        private bool isLevelRangeRead = false;
+        private float minLevelDb, maxLevelDb, stepping;
+
+        internal AudioVolumeLevel(IAudioVolumeLevel audioVolumeLevel)
+        {
+            audioVolumeLevelInterface = audioVolumeLevel;
+        }
+
+        public uint ChannelCount
+        {
+            get
+            {
+                audioVolumeLevelInterface.GetChannelCount(out uint result);
+                return result;
+            }
+        }
+
+        public void GetLevelRange(uint channel, out float minLevelDb, out float maxLevelDb, out float stepping)
+        {
+            audioVolumeLevelInterface.GetLevelRange(channel, out minLevelDb, out maxLevelDb, out stepping);
+        }
+
+        public float GetLevel(uint channel)
+        {
+            audioVolumeLevelInterface.GetLevel(channel, out float result);
+            return result;
+        }
+
+        public void SetLevel(uint channel, float value)
+        {
+            var guid = Guid.Empty;
+            audioVolumeLevelInterface.SetLevel(channel, value, ref guid);
+        }
+
+        public void SetLevelUniform(float value)
+        {
+            var guid = Guid.Empty;
+            audioVolumeLevelInterface.SetLevelUniform(value, ref guid);
+        }
+
+        public void SetLevelAllChannel(float[] values, uint channels)
+        {
+            var guid = Guid.Empty;
+            audioVolumeLevelInterface.SetLevelAllChannel(values, channels, ref guid);
+        }
+    }
+}

NAudio.Wasapi/CoreAudioApi/Connector.cs

@@ -100,6 +100,14 @@ namespace NAudio.CoreAudioApi
                 connectorInterface.GetDeviceIdConnectedTo(out var result);
                 return result;
             }
+        }
+
+        public Part Part
+        {
+            get
+            {
+                return new Part(connectorInterface as IPart);
+            }
         }
     }
 }

NAudio.Wasapi/CoreAudioApi/Interfaces/IAudioAutoGainControl.cs

@@ -0,0 +1,21 @@
+using System;
+using System.Collections.Generic;
+using System.Runtime.InteropServices;
+using System.Text;
+
+namespace NAudio.CoreAudioApi.Interfaces
+{
+    [Guid("85401FD4-6DE4-4b9d-9869-2D6753A82F3C"),
+        InterfaceType(ComInterfaceType.InterfaceIsIUnknown),
+        ComImport]
+    internal interface IAudioAutoGainControl
+    {
+        [PreserveSig]
+        int GetEnabled(
+            [Out, MarshalAs(UnmanagedType.Bool)] out bool enabled);
+
+        [PreserveSig]
+        int SetEnabled(
+            [In, MarshalAs(UnmanagedType.Bool)] bool enabled);
+    }
+}

NAudio.Wasapi/CoreAudioApi/Interfaces/IAudioMute.cs

@@ -0,0 +1,22 @@
+using System;
+using System.Collections.Generic;
+using System.Runtime.InteropServices;
+using System.Text;
+
+namespace NAudio.CoreAudioApi.Interfaces
+{
+    [Guid("DF45AEEA-B74A-4B6B-AFAD-2366B6AA012E"),
+        InterfaceType(ComInterfaceType.InterfaceIsIUnknown),
+        ComImport]
+    internal interface IAudioMute
+    {
+        [PreserveSig]
+        int GetMute(
+            [Out, MarshalAs(UnmanagedType.Bool)] out bool mute);
+
+        [PreserveSig]
+        int SetMute(
+            [In, MarshalAs(UnmanagedType.Bool)] bool mute,
+            [In] ref Guid eventContext);
+    }
+}

NAudio.Wasapi/CoreAudioApi/Interfaces/IAudioVolumeLevel.cs

@@ -0,0 +1,15 @@
+using System;
+using System.Collections.Generic;
+using System.Runtime.InteropServices;
+using System.Text;
+
+namespace NAudio.CoreAudioApi.Interfaces
+{
+    [Guid("7FB7B48F-531D-44A2-BCB3-5AD5A134B3DC"),
+        InterfaceType(ComInterfaceType.InterfaceIsIUnknown),
+        ComImport]
+    internal interface IAudioVolumeLevel : IPerChannelDbLevel
+    {
+
+    }
+}

NAudio.Wasapi/CoreAudioApi/Interfaces/IControlChangeNotify.cs

@@ -0,0 +1,18 @@
+using System;
+using System.Collections.Generic;
+using System.Runtime.InteropServices;
+using System.Text;
+
+namespace NAudio.Wasapi.CoreAudioApi.Interfaces
+{
+    [Guid("9c2c4058-23f5-41de-877a-df3af236a09e"),
+        InterfaceType(ComInterfaceType.InterfaceIsIUnknown),
+        ComImport]
+    interface IControlChangeNotify
+    {
+        [PreserveSig]
+        int OnNotify(
+            [In] uint controlId,
+            [In] IntPtr context);
+    }
+}

NAudio.Wasapi/CoreAudioApi/Interfaces/IControlInterface.cs

@@ -0,0 +1,14 @@
+using System;
+using System.Collections.Generic;
+using System.Runtime.InteropServices;
+using System.Text;
+
+namespace NAudio.CoreAudioApi.Interfaces
+{
+    [Guid("45d37c3f-5140-444a-ae24-400789f3cbf3"),
+        InterfaceType(ComInterfaceType.InterfaceIsIUnknown),
+        ComImport]
+    public interface IControlInterface
+    {
+    }
+}

NAudio.Wasapi/CoreAudioApi/Interfaces/IKsJackDescription.cs

@@ -0,0 +1,17 @@
+using NAudio.Utils;
+using System;
+using System.Collections.Generic;
+using System.Runtime.InteropServices;
+using System.Text;
+
+namespace NAudio.CoreAudioApi.Interfaces
+{
+    [Guid("4509F757-2D46-4637-8E62-CE7DB944F57B"),
+        InterfaceType(ComInterfaceType.InterfaceIsIUnknown),
+        ComImport]
+    internal interface IKsJackDescription 
+    {
+        int GetJackCount([Out] out uint jacks);
+        int GetJackDescription([In] uint jack, [Out, MarshalAs(UnmanagedType.LPWStr)] out string description);
+    };
+}

NAudio.Wasapi/CoreAudioApi/Interfaces/IPart.cs

@@ -1,19 +1,64 @@
-using System;
-using System.Collections.Generic;
-using System.Runtime.InteropServices;
-using System.Text;
-
-namespace NAudio.CoreAudioApi.Interfaces
-{
-    /// <summary>
-    /// Windows CoreAudio IPart interface
-    /// Defined in devicetopology.h
-    /// </summary>
-    [Guid("AE2DE0E4-5BCA-4F2D-AA46-5D13F8FDB3A9"),
-        InterfaceType(ComInterfaceType.InterfaceIsIUnknown),
-        ComImport]
-    internal interface IPart
-    {
-        // Stub, Not implemented
-    }
-}
+using NAudio.Wasapi.CoreAudioApi.Interfaces;
+using System;
+using System.Collections.Generic;
+using System.Runtime.InteropServices;
+using System.Text;
+
+namespace NAudio.CoreAudioApi.Interfaces
+{
+    /// <summary>
+    /// Windows CoreAudio IPart interface
+    /// Defined in devicetopology.h
+    /// </summary>
+    [Guid("AE2DE0E4-5BCA-4F2D-AA46-5D13F8FDB3A9"),
+        InterfaceType(ComInterfaceType.InterfaceIsIUnknown),
+        ComImport]
+    internal interface IPart
+    {
+        int GetName(
+            [Out, MarshalAs(UnmanagedType.LPWStr)] out string name);
+
+        int GetLocalId(
+            [Out] out uint id);
+
+        int GetGlobalId(
+            [Out, MarshalAs(UnmanagedType.LPWStr)] out string id);
+
+        int GetPartType(
+            [Out] out PartTypeEnum partType);
+
+        int GetSubType(
+            out Guid subType);
+
+        int GetControlInterfaceCount(
+            [Out] out uint count);
+
+        int GetControlInterface(
+            [In] uint index,
+            [Out, MarshalAs(UnmanagedType.IUnknown)] out IControlInterface controlInterface);
+
+        [PreserveSig]
+        int EnumPartsIncoming(
+            [Out] out IPartsList parts);
+
+        [PreserveSig]
+        int EnumPartsOutgoing(
+            [Out] out IPartsList parts);
+
+        int GetTopologyObject(
+            [Out] out object topologyObject);
+
+        [PreserveSig]
+        int Activate(
+            [In] ClsCtx dwClsContext,
+            [In] ref Guid refiid,
+            [MarshalAs(UnmanagedType.IUnknown)] out object interfacePointer);
+
+        int RegisterControlChangeCallback(
+            [In] ref Guid refiid,
+            [In] IControlChangeNotify notify);
+
+        int UnregisterControlChangeCallback(
+            [In] IControlChangeNotify notify);
+    }
+}

NAudio.Wasapi/CoreAudioApi/Interfaces/IPerChannelDbLevel.cs

@@ -0,0 +1,20 @@
+using System;
+using System.Collections.Generic;
+using System.Runtime.InteropServices;
+using System.Text;
+
+namespace NAudio.CoreAudioApi.Interfaces
+{
+    [Guid("7FB7B48F-531D-44A2-BCB3-5AD5A134B3DC"),
+       InterfaceType(ComInterfaceType.InterfaceIsIUnknown),
+       ComImport]
+    internal interface IPerChannelDbLevel
+    {
+        int GetChannelCount(out uint channels);
+        int GetLevelRange(uint channel, out float minLevelDb, out float maxLevelDb, out float stepping);
+        int GetLevel(uint channel, out float levelDb);
+        int SetLevel(uint channel, float levelDb, ref Guid eventGuidContext);
+        int SetLevelUniform(float levelDb, ref Guid eventGuidContext);
+        int SetLevelAllChannel(float[] levelsDb, uint channels, ref Guid eventGuidContext);
+    }
+}

NAudio.Wasapi/CoreAudioApi/Interfaces/PartType.cs

@@ -0,0 +1,17 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace NAudio.CoreAudioApi.Interfaces
+{
+    public enum PartTypeEnum
+    {
+        Connector = 0,
+        Subunit = 1,
+        HardwarePeriphery = 2,
+        SoftwareDriver = 3,
+        Splitter = 4,
+        Category = 5,
+        Other = 6
+    }
+}

NAudio.Wasapi/CoreAudioApi/KsJackDescription.cs

@@ -0,0 +1,35 @@
+using NAudio.CoreAudioApi.Interfaces;
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace NAudio.CoreAudioApi
+{
+    public class KsJackDescription
+    {
+        private readonly IKsJackDescription ksJackDescriptionInterface;
+
+        internal KsJackDescription(IKsJackDescription ksJackDescription)
+        {
+            ksJackDescriptionInterface = ksJackDescription;
+        }
+
+        public uint Count
+        {
+            get
+            {
+                ksJackDescriptionInterface.GetJackCount(out var result);
+                return result;
+            }
+        }
+
+        public string this[uint index]
+        {
+            get
+            {
+                ksJackDescriptionInterface.GetJackDescription(index, out var result);
+                return result;
+            }
+        }
+    }
+}

NAudio.Wasapi/CoreAudioApi/Part.cs

@@ -0,0 +1,150 @@
+using NAudio.CoreAudioApi.Interfaces;
+using NAudio.Wasapi.CoreAudioApi;
+using NAudio.Wasapi.CoreAudioApi.Interfaces;
+using System;
+using System.Collections.Generic;
+using System.Runtime.InteropServices;
+using System.Text;
+
+namespace NAudio.CoreAudioApi
+{
+    public class Part
+    {
+        private const int E_NOTFOUND = unchecked((int)0x80070490);
+        private readonly IPart partInterface;
+        private DeviceTopology deviceTopology;
+        private static Guid IID_IAudioVolumeLevel = new Guid("7FB7B48F-531D-44A2-BCB3-5AD5A134B3DC");
+        private static Guid IID_IAudioMute = new Guid("DF45AEEA-B74A-4B6B-AFAD-2366B6AA012E");
+        private static Guid IID_IAudioEndpointVolume = new Guid("5CDF2C82-841E-4546-9722-0CF74078229A");
+        private static Guid IID_IKsJackDescription = new Guid("4509F757-2D46-4637-8E62-CE7DB944F57B");
+
+        internal Part(IPart part)
+        {
+            partInterface = part;
+        }
+
+        public string Name
+        {
+            get
+            {
+                partInterface.GetName(out var result);
+                return result;
+            }
+        }
+
+        public uint LocalId
+        {
+            get
+            {
+                partInterface.GetLocalId(out var result);
+                return result;
+            }
+        }
+
+        public string GlobalId
+        {
+            get
+            {
+                partInterface.GetGlobalId(out var result);
+                return result;
+            }
+        }
+
+        public PartTypeEnum PartType
+        {
+            get
+            {
+                partInterface.GetPartType(out var result);
+                return result;
+            }
+        }
+
+        public Guid GetSubType
+        {
+            get
+            {
+                partInterface.GetSubType(out var result);
+                return result;
+            }
+        }
+
+        public uint ControlInterfaceCount
+        {
+            get
+            {
+                partInterface.GetControlInterfaceCount(out var result);
+                return result;
+            }
+        }
+
+        public IControlInterface GetControlInterface(uint index)
+        {
+            partInterface.GetControlInterface(index, out var result);
+            return result;
+        }
+
+        public PartsList PartsIncoming
+        {
+            get
+            {
+                var hr = partInterface.EnumPartsIncoming(out var result);
+                return hr == 0 ? new PartsList(result) : hr == E_NOTFOUND ? new PartsList(null) : throw new COMException(nameof(IPart.EnumPartsIncoming), hr);
+            }
+        }
+
+        public PartsList PartsOutgoing
+        {
+            get
+            {
+                var hr = partInterface.EnumPartsOutgoing(out var result);
+                return hr == 0 ? new PartsList(result) : hr == E_NOTFOUND ? new PartsList(null) : throw new COMException(nameof(IPart.EnumPartsOutgoing), hr);
+            }
+        }
+
+        public DeviceTopology DeviceTopology
+        {
+            get
+            {
+                if (deviceTopology == null)
+                {
+                    GetDeviceTopology();
+                }
+
+                return deviceTopology;
+            }
+        }
+
+        public AudioVolumeLevel AudioVolumeLevel
+        {
+            get
+            {
+                var hr = partInterface.Activate(ClsCtx.ALL, ref IID_IAudioVolumeLevel, out var result);
+                return hr == 0 ? new AudioVolumeLevel(result as IAudioVolumeLevel) : null;
+            }
+        }
+
+        public AudioMute AudioMute
+        {
+            get
+            {
+                var hr = partInterface.Activate(ClsCtx.ALL, ref IID_IAudioMute, out var result);
+                return hr == 0 ? new AudioMute(result as IAudioMute) : null;
+            }
+        }
+
+        public KsJackDescription JackDescription
+        {
+            get
+            {
+                var hr = partInterface.Activate(ClsCtx.ALL, ref IID_IKsJackDescription, out var result);
+                return hr == 0 ? new KsJackDescription(result as IKsJackDescription) : null;
+            }
+        }
+
+        private void GetDeviceTopology()
+        {
+            Marshal.ThrowExceptionForHR(partInterface.GetTopologyObject(out var result));
+            deviceTopology = new DeviceTopology(result as IDeviceTopology);
+        }
+    }
+}

NAudio.Wasapi/CoreAudioApi/PartsList.cs

@@ -0,0 +1,45 @@
+using NAudio.CoreAudioApi.Interfaces;
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace NAudio.CoreAudioApi
+{
+    public class PartsList
+    {
+        private IPartsList partsListInterface;
+
+        internal PartsList(IPartsList partsList)
+        {
+            partsListInterface = partsList;
+        }
+
+        public uint Count
+        {
+            get
+            {
+                uint result = 0;
+                if (partsListInterface != null)
+                {
+                    partsListInterface.GetCount(out result);
+                }
+
+                return result;
+            }
+        }
+
+        public Part this[uint index]
+        {
+            get
+            {
+                if (partsListInterface == null)
+                {
+                    throw new IndexOutOfRangeException();
+                }
+
+                partsListInterface.GetPart(index, out IPart part);
+                return new Part(part);
+            }
+        }
+    }
+}

NAudioDemo/DeviceTopology/DeviceTopologyPanel.Designer.cs

@@ -0,0 +1,87 @@
+namespace NAudioDemo.DeviceTopology
+{
+    partial class DeviceTopologyPanel
+    {
+        /// <summary> 
+        /// Required designer variable.
+        /// </summary>
+        private System.ComponentModel.IContainer components = null;
+
+        /// <summary> 
+        /// Clean up any resources being used.
+        /// </summary>
+        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
+        protected override void Dispose(bool disposing)
+        {
+            if (disposing && (components != null))
+            {
+                components.Dispose();
+            }
+            base.Dispose(disposing);
+        }
+
+        #region Component Designer generated code
+
+        /// <summary> 
+        /// Required method for Designer support - do not modify 
+        /// the contents of this method with the code editor.
+        /// </summary>
+        private void InitializeComponent()
+        {
+            this.lblSelectDevice = new System.Windows.Forms.Label();
+            this.cbDevices = new System.Windows.Forms.ComboBox();
+            this.tbTopology = new System.Windows.Forms.TextBox();
+            this.SuspendLayout();
+            // 
+            // lblSelectDevice
+            // 
+            this.lblSelectDevice.AutoSize = true;
+            this.lblSelectDevice.Dock = System.Windows.Forms.DockStyle.Top;
+            this.lblSelectDevice.Location = new System.Drawing.Point(0, 0);
+            this.lblSelectDevice.Name = "lblSelectDevice";
+            this.lblSelectDevice.Size = new System.Drawing.Size(111, 15);
+            this.lblSelectDevice.TabIndex = 0;
+            this.lblSelectDevice.Text = "Select audio device:";
+            // 
+            // cbDevices
+            // 
+            this.cbDevices.Dock = System.Windows.Forms.DockStyle.Top;
+            this.cbDevices.DropDownStyle = System.Windows.Forms.ComboBoxStyle.DropDownList;
+            this.cbDevices.FormattingEnabled = true;
+            this.cbDevices.Location = new System.Drawing.Point(0, 15);
+            this.cbDevices.Name = "cbDevices";
+            this.cbDevices.Size = new System.Drawing.Size(1013, 23);
+            this.cbDevices.TabIndex = 1;
+            this.cbDevices.SelectedValueChanged += new System.EventHandler(this.cbDevices_SelectedValueChanged);
+            // 
+            // tbTopology
+            // 
+            this.tbTopology.Dock = System.Windows.Forms.DockStyle.Fill;
+            this.tbTopology.Location = new System.Drawing.Point(0, 38);
+            this.tbTopology.Multiline = true;
+            this.tbTopology.Name = "tbTopology";
+            this.tbTopology.ScrollBars = System.Windows.Forms.ScrollBars.Both;
+            this.tbTopology.Size = new System.Drawing.Size(1013, 483);
+            this.tbTopology.TabIndex = 2;
+            // 
+            // DeviceTopologyPanel
+            // 
+            this.AutoScaleDimensions = new System.Drawing.SizeF(7F, 15F);
+            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
+            this.Controls.Add(this.tbTopology);
+            this.Controls.Add(this.cbDevices);
+            this.Controls.Add(this.lblSelectDevice);
+            this.Name = "DeviceTopologyPanel";
+            this.Size = new System.Drawing.Size(1013, 521);
+            this.ResumeLayout(false);
+            this.PerformLayout();
+
+        }
+
+        #endregion
+
+        private System.Windows.Forms.Label lblSelectDevice;
+        private System.Windows.Forms.ComboBox cbDevices;
+        private System.Windows.Forms.TextBox tbTopology;
+    }
+}

NAudioDemo/DeviceTopology/DeviceTopologyPanel.cs

@@ -0,0 +1,189 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Data;
+using System.Diagnostics;
+using System.Drawing;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Forms;
+
+using NAudio.CoreAudioApi;
+using NAudio.CoreAudioApi.Interfaces;
+using NAudio.Wasapi.CoreAudioApi;
+
+namespace NAudioDemo.DeviceTopology
+{
+    public partial class DeviceTopologyPanel : UserControl
+    {
+        class AudioVolumeWrapper
+        {
+            public uint Channel { get; set; }
+            public AudioVolumeLevel AudioVolumeLevel { get; set; }
+        }
+
+        public DeviceTopologyPanel()
+        {
+            InitializeComponent();
+
+            foreach (var device in GetCaptureDevices())
+            {
+                cbDevices.Items.Add(device);
+            }
+
+            foreach (var device in GetRenderDevices())
+            {
+                cbDevices.Items.Add(device);
+            }
+
+            if (cbDevices.Items.Count > 0)
+            {
+                cbDevices.SelectedIndex = 0;
+            }
+        }
+
+        public IEnumerable<MMDevice> GetCaptureDevices()
+        {
+            using (var enumerator = new MMDeviceEnumerator())
+            {
+                var audioEndPoints = enumerator.EnumerateAudioEndPoints(DataFlow.Capture, DeviceState.Active);
+
+                foreach (var device in audioEndPoints)
+                {
+                    yield return device;
+                }
+            }
+        }
+
+        public IEnumerable<MMDevice> GetRenderDevices()
+        {
+            using (var enumerator = new MMDeviceEnumerator())
+            {
+                var audioEndPoints = enumerator.EnumerateAudioEndPoints(DataFlow.Render, DeviceState.Active);
+
+                foreach (var device in audioEndPoints)
+                {
+                    yield return device;
+                }
+            }
+        }
+
+        private void cbDevices_SelectedValueChanged(object sender, EventArgs e)
+        {
+            var device = (MMDevice)cbDevices.SelectedItem;
+            var topology = device.DeviceTopology;
+            var connector = topology.GetConnector(0);
+
+            var deviceConnector = connector.ConnectedTo;
+            tbTopology.Text = "";
+            _superMixBox = null;
+            WalkParts(deviceConnector.Part, device.DataFlow == DataFlow.Render, "");
+        }
+
+        private bool HasVolumeOrMuteParts(Part part)
+        {
+            if (part.Name == "Volume" || part.Name == "Mute")
+            {
+                return true;
+            }
+
+            for (uint i = 0; i < part.PartsIncoming.Count; i++)
+            {
+                if (HasVolumeOrMuteParts(part.PartsIncoming[i]))
+                {
+                    return true;
+                }
+            }
+
+            return false;
+        }
+
+        private void WalkParts(Part part, bool isRenderDevice, string indent)
+        {
+            var audioVolumeLevel = part.AudioVolumeLevel;
+            var audioMute = part.AudioMute;
+            var jackDescription = part.JackDescription;
+
+            var s = "\r\n";
+            if (audioVolumeLevel != null)
+            {
+                s = $" (audio volume level)\r\n";
+                for (uint i = 0; i < audioVolumeLevel.ChannelCount; i++)
+                {
+                    audioVolumeLevel.GetLevelRange(i, out var minLevelDb, out var maxLevelDb, out var stepping);
+                    var volume = audioVolumeLevel.GetLevel(i);
+                    s += $"{indent}Channel: {i}, Min {minLevelDb:0.##} dB, Max {maxLevelDb:0.##} dB, stepping {stepping:0.##} dB: {volume:0.##} dB\r\n";
+                }
+            }
+            else if (audioMute != null)
+            {
+                s = $" (audio mute. Muted: {audioMute.IsMuted})\r\n";
+            } if (jackDescription != null)
+            {
+                s = $" (Jacks: {jackDescription.Count})\r\n";
+            }
+
+            tbTopology.AppendText($"{indent}{part.PartType}: {part.Name}{s}");
+            if (part.Name.ToLowerInvariant() == "supermix")
+            {
+                if (isRenderDevice && HasVolumeOrMuteParts(part))
+                {
+                    _superMixBox = new GroupBox
+                    {
+                        Text = $"Supermix",
+                        Dock = DockStyle.Top
+                    };
+                }
+            }
+
+            var parts = isRenderDevice ? part.PartsIncoming : part.PartsOutgoing;
+            for (uint i = 0; i < parts.Count; i++)
+            {
+                var outgoingPart = parts[i];
+                WalkParts(outgoingPart, isRenderDevice, indent + "  ");
+            }
+        }
+
+        private void Tb_ValueChanged(object sender, EventArgs e)
+        {
+            var trackBar = (TrackBar)sender;
+            var wrapper = (AudioVolumeWrapper)trackBar.Tag;
+
+            wrapper.AudioVolumeLevel.GetLevelRange(wrapper.Channel, out var minLevelDb, out float maxLevelDb, out float _);
+            wrapper.AudioVolumeLevel.SetLevel(wrapper.Channel, (float)LinearToDecibels(trackBar.Value, minLevelDb, maxLevelDb));
+        }
+
+        private static double LinearToDecibels(double linearValue, double minDb, double maxDb)
+        {
+            // Calculate the minimum and maximum values in linear scale
+            double minLinearValue = Math.Pow(10, minDb / 10.0);
+            double maxLinearValue = Math.Pow(10, maxDb / 10.0);
+
+            // Convert the percentage to a linear value within the given range
+            double linearRangeValue = (linearValue / 100.0) * (maxLinearValue - minLinearValue) + minLinearValue;
+
+            // Convert the linear value to decibels
+            return 10.0 * Math.Log10(linearRangeValue);
+        }
+
+        private static double DecibelsToLinear(double valueInDb, double minDb, double maxDb)
+        {
+            // Convert the value from decibels to linear scale
+            double linearValue = Math.Pow(10, valueInDb / 10.0);
+
+            // Calculate the minimum and maximum values in linear scale
+            double minLinearValue = Math.Pow(10, minDb / 10.0);
+            double maxLinearValue = Math.Pow(10, maxDb / 10.0);
+
+            // Convert the linear value to a percentage within the given range
+            double percentage = (linearValue - minLinearValue) / (maxLinearValue - minLinearValue) * 100.0;
+
+            // Ensure the percentage is within the valid range from 0 to 100
+            return Math.Max(Math.Min(percentage, 100.0), 0.0);
+
+        }
+
+        private GroupBox _superMixBox;
+    }
+}

NAudioDemo/DeviceTopology/DeviceTopologyPanel.resx

@@ -0,0 +1,60 @@
+<root>
+  <xsd:schema id="root" xmlns="" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
+    <xsd:import namespace="http://www.w3.org/XML/1998/namespace" />
+    <xsd:element name="root" msdata:IsDataSet="true">
+      <xsd:complexType>
+        <xsd:choice maxOccurs="unbounded">
+          <xsd:element name="metadata">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" />
+              </xsd:sequence>
+              <xsd:attribute name="name" use="required" type="xsd:string" />
+              <xsd:attribute name="type" type="xsd:string" />
+              <xsd:attribute name="mimetype" type="xsd:string" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="assembly">
+            <xsd:complexType>
+              <xsd:attribute name="alias" type="xsd:string" />
+              <xsd:attribute name="name" type="xsd:string" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="data">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+                <xsd:element name="comment" type="xsd:string" minOccurs="0" msdata:Ordinal="2" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" msdata:Ordinal="1" />
+              <xsd:attribute name="type" type="xsd:string" msdata:Ordinal="3" />
+              <xsd:attribute name="mimetype" type="xsd:string" msdata:Ordinal="4" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="resheader">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" />
+            </xsd:complexType>
+          </xsd:element>
+        </xsd:choice>
+      </xsd:complexType>
+    </xsd:element>
+  </xsd:schema>
+  <resheader name="resmimetype">
+    <value>text/microsoft-resx</value>
+  </resheader>
+  <resheader name="version">
+    <value>2.0</value>
+  </resheader>
+  <resheader name="reader">
+    <value>System.Resources.ResXResourceReader, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <resheader name="writer">
+    <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+</root>

NAudioDemo/DeviceTopology/DeviceTopologyPlugin.cs

@@ -0,0 +1,22 @@
+using NAudioDemo.FadeInOutDemo;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace NAudioDemo.DeviceTopology
+{
+    class DeviceTopologyPlugin : INAudioDemoPlugin
+    {
+        public string Name
+        {
+            get { return "Device Topology"; }
+        }
+
+        public System.Windows.Forms.Control CreatePanel()
+        {
+            return new DeviceTopologyPanel();
+        }
+    }
+}