How to check if the system audio is muted?

Question

I found this answer which recommends using the "core audio.dll" API with the following code:

private function getmute() as boolean
    Dim devenum As New MMDeviceEnumerator
    Dim device As MMDevice = devenum.GetDefaultAudioEndpoint(EDataFlow.eRender, ERole.eMultimedia)
    If device.AudioEndpointVolume.Mute = True Then
        Return True
    Else
        Return False
    End If
End Function

I tried that code but it doesn't work and I could not leave a comment on the other question.

When I try the above code, the following line throws an exception:

If device.AudioEndpointVolume.Mute = True Then

Here's the exception message:

AudioEndpointVolume is not a member of device.

I have already imported CoreAudioAPI, what else could be wrong?

I'm looking for a VB.NET or a C# solution.

Answer 1

VB.Net rewriting (+ Bonus) of the CoreAudio API implementation γηράσκω δ' αεί πολλά διδασκόμε posted.

The code in wrapped in a Class (CoreAudio) and includes the original IsMuted() method, plus other methods I implemented on the fly (because, why not).

More information on the Windows CoreAudio APIs on MSDN.
GitHub NAudio CoreAudioApi implementation (C#).

Methods implemented:

IsMuted() As Integer
Return the Muted status of the default Audio Device.

SetMute(Boolean)
Sets the Muted status of the default Audio Device (True/False).

GetVolume() As Integer
Get the Volume status of the default Audio Device. Values range from 0 to 100.

SetVolume(Integer)
Set the Volume status of the default Audio Device to a values in the 0 to 100 range.

VolumeUp()
Increases the Volume of the default Audio Device by one step (usually 2 units).

VolumeDown()
Decreases the Volume of the default Audio Device by one step.

Usage:

 Public AudioDevice As CoreAudio = New CoreAudio()

 '0=False, 1=True, -1=Error
 Dim IsMuted As Integer = AudioDevice.IsMuted()

 'True=Mutes the Audio, False=Un-Mutes (?) it
 AudioDevice.SetMute(True)

 Dim Volume As Integer = AudioDevice.GetVolume()

 'Sets the Audio level to 50%
 AudioDevice.SetVolume(50)

 'Increases the Audio level by 1 Step
 AudioDevice.VolumeUp()

 'Decreases the Audio level by 1 Step
 AudioDevice.VolumeDown()

Declarations:

Imports System
Imports System.Runtime.InteropServices

Public Class CoreAudio

    Friend Enum EDataFlow
        eRender
        eCapture
        eAll
        EDataFlow_enum_count
    End Enum
    Friend Enum ERole
        eConsole
        eMultimedia
        eCommunications
        ERole_enum_count
    End Enum

    <Flags>
    Friend Enum CLSCTX As UInteger
        CLSCTX_INPROC_SERVER = &H1
        CLSCTX_INPROC_HANDLER = &H2
        CLSCTX_LOCAL_SERVER = &H4
        CLSCTX_INPROC_SERVER16 = &H8
        CLSCTX_REMOTE_SERVER = &H10
        CLSCTX_INPROC_HANDLER16 = &H20
        CLSCTX_RESERVED1 = &H40
        CLSCTX_RESERVED2 = &H80
        CLSCTX_RESERVED3 = &H100
        CLSCTX_RESERVED4 = &H200
        CLSCTX_NO_CODE_DOWNLOAD = &H400
        CLSCTX_RESERVED5 = &H800
        CLSCTX_NO_CUSTOM_MARSHAL = &H1000
        CLSCTX_ENABLE_CODE_DOWNLOAD = &H2000
        CLSCTX_NO_FAILURE_LOG = &H4000
        CLSCTX_DISABLE_AAA = &H8000
        CLSCTX_ENABLE_AAA = &H10000
        CLSCTX_FROM_DEFAULT_CONTEXT = &H20000
        CLSCTX_ACTIVATE_32_BIT_SERVER = &H40000
        CLSCTX_ACTIVATE_64_BIT_SERVER = &H80000
        CLSCTX_INPROC = CLSCTX_INPROC_SERVER Or CLSCTX_INPROC_HANDLER
        CLSCTX_SERVER = CLSCTX_INPROC_SERVER Or CLSCTX_LOCAL_SERVER Or CLSCTX_REMOTE_SERVER
        CLSCTX_ALL = CLSCTX_SERVER Or CLSCTX_INPROC_HANDLER
    End Enum

    <ComImport, Guid("BCDE0395-E52F-467C-8E3D-C4579291692E")>
    Friend Class MMDeviceEnumeratorComObject
    End Class

    <ComImport, Guid("A95664D2-9614-4F35-A746-DE8DB63617E6"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)>
    Friend Interface IMMDeviceEnumerator
        Function NotImpl1() As Integer
        Function GetDefaultAudioEndpoint(dataFlow As EDataFlow, role As ERole, ByRef ppDevice As IMMDevice) As Integer
    End Interface


    <ComImport, Guid("D666063F-1587-4E43-81F1-B948E807363F"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)>
    Friend Interface IMMDevice
        Function Activate(ByRef iid As Guid, dwClsCtx As CLSCTX, pActivationParams As IntPtr, <Out> ByRef ppInterface As IAudioEndpointVolume) As Integer
    End Interface

    <ComImport, Guid("5CDF2C82-841E-4546-9722-0CF74078229A"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)>
    Friend Interface IAudioEndpointVolume
        Function RegisterControlChangeNotify() As Integer
        Function UnregisterControlChangeNotify() As Integer
        Function GetChannelCount(ByRef channelCount As Integer) As Integer
        Function SetMasterVolumeLevel() As Integer
        Function SetMasterVolumeLevelScalar(level As Single, eventContext As Guid) As Integer
        Function GetMasterVolumeLevel(<Out> ByRef level As Single) As Integer
        Function GetMasterVolumeLevelScalar(<Out> ByRef level As Single) As Integer
        Function SetChannelVolumeLevel(channelNumber As Integer, level As Single, eventContext As Guid) As Integer
        Function SetChannelVolumeLevelScalar(channelNumber As Integer, level As Single, eventContext As Guid) As Integer
        Function GetChannelVolumeLevel(channelNumber As Integer, <Out> ByRef level As Single) As Integer
        Function GetChannelVolumeLevelScalar(channelNumber As Integer, <Out> ByRef level As Single) As Integer
        Function SetMute(<MarshalAs(UnmanagedType.Bool)> isMuted As Boolean, eventContext As Guid) As Integer
        Function GetMute(<Out> ByRef isMuted As Boolean) As Integer
        Function GetVolumeStepInfo(<Out> ByRef pnStep As Integer, ByRef pnStepCount As Integer) As Integer
        Function VolumeStepUp(eventContext As Guid) As Integer
        Function VolumeStepDown(eventContext As Guid) As Integer
        Function QueryHardwareSupport(<Out> ByRef hardwareSupportMask As Integer) As Integer
        Function GetVolumeRange(<Out> ByRef volumeMin As Single, <Out> ByRef volumeMax As Single, <Out> ByRef volumeStep As Single) As Integer
    End Interface

    Public Function IsMuted() As Integer
        Dim masterVol As IAudioEndpointVolume = Nothing
        Try
            masterVol = GetMasterVolumeObject()
            If masterVol Is Nothing Then
                Return -1
            End If

            Dim isAudioMuted As Boolean
            masterVol.GetMute(isAudioMuted)

            Return Convert.ToInt32(isAudioMuted)
        Finally
            If masterVol IsNot Nothing Then
                Marshal.ReleaseComObject(masterVol)
            End If
        End Try
    End Function

    Public Sub SetMute(IsMute As Boolean)
        Dim masterVol As IAudioEndpointVolume = Nothing
        Try
            masterVol = GetMasterVolumeObject()
            masterVol.SetMute(IsMute, Guid.Empty)
        Finally
            If masterVol IsNot Nothing Then
                Marshal.ReleaseComObject(masterVol)
            End If
        End Try
    End Sub


    Public Function GetVolume() As Integer
        Dim fVolume As Single
        Dim masterVol As IAudioEndpointVolume = Nothing
        Try
            masterVol = GetMasterVolumeObject()
            masterVol.GetMasterVolumeLevelScalar(fVolume)
            Return CType(fVolume * 100, Integer)
        Finally
            Marshal.ReleaseComObject(masterVol)
        End Try
    End Function

    Public Sub SetVolume(Volume As Integer)
        Volume = Math.Max(Math.Min(Volume, 100), 0)
        Dim masterVol As IAudioEndpointVolume = Nothing
        Try
            masterVol = GetMasterVolumeObject()
            masterVol.SetMasterVolumeLevelScalar((CType(Volume, Single) / 100), Guid.Empty)
        Finally
            Marshal.ReleaseComObject(masterVol)
        End Try
    End Sub

    Public Sub VolumeUp()
        Dim masterVol As IAudioEndpointVolume = Nothing
        Try
            masterVol = GetMasterVolumeObject()
            masterVol.VolumeStepUp(Guid.Empty)
        Finally
            Marshal.ReleaseComObject(masterVol)
        End Try
    End Sub

    Public Sub VolumeDown()
        Dim masterVol As IAudioEndpointVolume = Nothing
        Try
            masterVol = GetMasterVolumeObject()
            masterVol.VolumeStepDown(Guid.Empty)
        Finally
            Marshal.ReleaseComObject(masterVol)
        End Try
    End Sub

    Friend Function GetMasterVolumeObject() As IAudioEndpointVolume
        Dim deviceEnumerator As IMMDeviceEnumerator = Nothing
        Dim MediaDevice As IMMDevice = Nothing
        Try
            deviceEnumerator = TryCast(New MMDeviceEnumeratorComObject(), IMMDeviceEnumerator)
            deviceEnumerator.GetDefaultAudioEndpoint(EDataFlow.eRender, ERole.eMultimedia, MediaDevice)
            Dim EndPointVolID As Guid = GetType(IAudioEndpointVolume).GUID
            Dim ppEndpoint As IAudioEndpointVolume = Nothing
            MediaDevice.Activate(EndPointVolID, CLSCTX.CLSCTX_ALL, IntPtr.Zero, ppEndpoint)
            Return ppEndpoint
        Finally
            Marshal.ReleaseComObject(deviceEnumerator)
            Marshal.ReleaseComObject(MediaDevice)
        End Try
    End Function
End Class

Answer 2

Using C/C++ and having some knowledge with directshow is quite straight forward but with C# you need some kind of wrapper to make the calls. To be honest I don't use managed languages to use low level libraries but likely I found code for your case:

    private int IsMuted() {
        IAudioEndpointVolume masterVol = null;

        try {
            masterVol = GetMasterVolumeObject();
            if( masterVol == null )
                return -1; //error

            bool isMuted;
            masterVol.GetMute( out isMuted );

            return Convert.ToInt32( isMuted );
        }
        finally {
            if( masterVol != null )
                Marshal.ReleaseComObject( masterVol );
        }
    }

    private IAudioEndpointVolume GetMasterVolumeObject() {
        IMMDeviceEnumerator deviceEnumerator = null;
        IMMDevice speakers = null;
        try {
            deviceEnumerator = (IMMDeviceEnumerator)( new MMDeviceEnumerator() );
            deviceEnumerator.GetDefaultAudioEndpoint( EDataFlow.eRender, ERole.eMultimedia, out speakers );

            Guid IID_IAudioEndpointVolume = typeof( IAudioEndpointVolume ).GUID;
            object o;
            speakers.Activate( ref IID_IAudioEndpointVolume, 0, IntPtr.Zero, out o );
            IAudioEndpointVolume masterVol = (IAudioEndpointVolume)o;

            return masterVol;
        }
        finally {
            if( speakers != null ) Marshal.ReleaseComObject( speakers );
            if( deviceEnumerator != null ) Marshal.ReleaseComObject( deviceEnumerator );
        }
    }

COM interfaces from Windows CoreAudio API:

    [ComImport]
    [Guid( "BCDE0395-E52F-467C-8E3D-C4579291692E" )]
    internal class MMDeviceEnumerator {
    }

    internal enum EDataFlow {
        eRender,
        eCapture,
        eAll,
        EDataFlow_enum_count
    }

    internal enum ERole {
        eConsole,
        eMultimedia,
        eCommunications,
        ERole_enum_count
    }

    [Guid( "A95664D2-9614-4F35-A746-DE8DB63617E6" ), InterfaceType( ComInterfaceType.InterfaceIsIUnknown )]
    internal interface IMMDeviceEnumerator {
        int NotImpl1();

        [PreserveSig]
        int GetDefaultAudioEndpoint( EDataFlow dataFlow, ERole role, out IMMDevice ppDevice );

        // the rest is not implemented
    }

    [Guid( "D666063F-1587-4E43-81F1-B948E807363F" ), InterfaceType( ComInterfaceType.InterfaceIsIUnknown )]
    internal interface IMMDevice {
        [PreserveSig]
        int Activate( ref Guid iid, int dwClsCtx, IntPtr pActivationParams, [MarshalAs( UnmanagedType.IUnknown )] out object ppInterface );

        // the rest is not implemented
    }

    // http://netcoreaudio.codeplex.com/SourceControl/latest#trunk/Code/CoreAudio/Interfaces/IAudioEndpointVolume.cs
    [Guid( "5CDF2C82-841E-4546-9722-0CF74078229A" ), InterfaceType( ComInterfaceType.InterfaceIsIUnknown )]
    public interface IAudioEndpointVolume {
        [PreserveSig]
        int NotImpl1();

        [PreserveSig]
        int NotImpl2();

        /// <summary>
        /// Gets a count of the channels in the audio stream.
        /// </summary>
        /// <param name="channelCount">The number of channels.</param>
        /// <returns>An HRESULT code indicating whether the operation passed of failed.</returns>
        [PreserveSig]
        int GetChannelCount(
            [Out] [MarshalAs( UnmanagedType.U4 )] out UInt32 channelCount );

        /// <summary>
        /// Sets the master volume level of the audio stream, in decibels.
        /// </summary>
        /// <param name="level">The new master volume level in decibels.</param>
        /// <param name="eventContext">A user context value that is passed to the notification callback.</param>
        /// <returns>An HRESULT code indicating whether the operation passed of failed.</returns>
        [PreserveSig]
        int SetMasterVolumeLevel(
            [In] [MarshalAs( UnmanagedType.R4 )] float level,
            [In] [MarshalAs( UnmanagedType.LPStruct )] Guid eventContext );

        /// <summary>
        /// Sets the master volume level, expressed as a normalized, audio-tapered value.
        /// </summary>
        /// <param name="level">The new master volume level expressed as a normalized value between 0.0 and 1.0.</param>
        /// <param name="eventContext">A user context value that is passed to the notification callback.</param>
        /// <returns>An HRESULT code indicating whether the operation passed of failed.</returns>
        [PreserveSig]
        int SetMasterVolumeLevelScalar(
            [In] [MarshalAs( UnmanagedType.R4 )] float level,
            [In] [MarshalAs( UnmanagedType.LPStruct )] Guid eventContext );

        /// <summary>
        /// Gets the master volume level of the audio stream, in decibels.
        /// </summary>
        /// <param name="level">The volume level in decibels.</param>
        /// <returns>An HRESULT code indicating whether the operation passed of failed.</returns>
        [PreserveSig]
        int GetMasterVolumeLevel(
            [Out] [MarshalAs( UnmanagedType.R4 )] out float level );

        /// <summary>
        /// Gets the master volume level, expressed as a normalized, audio-tapered value.
        /// </summary>
        /// <param name="level">The volume level expressed as a normalized value between 0.0 and 1.0.</param>
        /// <returns>An HRESULT code indicating whether the operation passed of failed.</returns>
        [PreserveSig]
        int GetMasterVolumeLevelScalar(
            [Out] [MarshalAs( UnmanagedType.R4 )] out float level );

        /// <summary>
        /// Sets the volume level, in decibels, of the specified channel of the audio stream.
        /// </summary>
        /// <param name="channelNumber">The channel number.</param>
        /// <param name="level">The new volume level in decibels.</param>
        /// <param name="eventContext">A user context value that is passed to the notification callback.</param>
        /// <returns>An HRESULT code indicating whether the operation passed of failed.</returns>
        [PreserveSig]
        int SetChannelVolumeLevel(
            [In] [MarshalAs( UnmanagedType.U4 )] UInt32 channelNumber,
            [In] [MarshalAs( UnmanagedType.R4 )] float level,
            [In] [MarshalAs( UnmanagedType.LPStruct )] Guid eventContext );

        /// <summary>
        /// Sets the normalized, audio-tapered volume level of the specified channel in the audio stream.
        /// </summary>
        /// <param name="channelNumber">The channel number.</param>
        /// <param name="level">The new master volume level expressed as a normalized value between 0.0 and 1.0.</param>
        /// <param name="eventContext">A user context value that is passed to the notification callback.</param>
        /// <returns>An HRESULT code indicating whether the operation passed of failed.</returns>
        [PreserveSig]
        int SetChannelVolumeLevelScalar(
            [In] [MarshalAs( UnmanagedType.U4 )] UInt32 channelNumber,
            [In] [MarshalAs( UnmanagedType.R4 )] float level,
            [In] [MarshalAs( UnmanagedType.LPStruct )] Guid eventContext );

        /// <summary>
        /// Gets the volume level, in decibels, of the specified channel in the audio stream.
        /// </summary>
        /// <param name="channelNumber">The zero-based channel number.</param>
        /// <param name="level">The volume level in decibels.</param>
        /// <returns>An HRESULT code indicating whether the operation passed of failed.</returns>
        [PreserveSig]
        int GetChannelVolumeLevel(
            [In] [MarshalAs( UnmanagedType.U4 )] UInt32 channelNumber,
            [Out] [MarshalAs( UnmanagedType.R4 )] out float level );

        /// <summary>
        /// Gets the normalized, audio-tapered volume level of the specified channel of the audio stream.
        /// </summary>
        /// <param name="channelNumber">The zero-based channel number.</param>
        /// <param name="level">The volume level expressed as a normalized value between 0.0 and 1.0.</param>
        /// <returns>An HRESULT code indicating whether the operation passed of failed.</returns>
        [PreserveSig]
        int GetChannelVolumeLevelScalar(
            [In] [MarshalAs( UnmanagedType.U4 )] UInt32 channelNumber,
            [Out] [MarshalAs( UnmanagedType.R4 )] out float level );

        /// <summary>
        /// Sets the muting state of the audio stream.
        /// </summary>
        /// <param name="isMuted">True to mute the stream, or false to unmute the stream.</param>
        /// <param name="eventContext">A user context value that is passed to the notification callback.</param>
        /// <returns>An HRESULT code indicating whether the operation passed of failed.</returns>
        [PreserveSig]
        int SetMute(
            [In] [MarshalAs( UnmanagedType.Bool )] Boolean isMuted,
            [In] [MarshalAs( UnmanagedType.LPStruct )] Guid eventContext );

        /// <summary>
        /// Gets the muting state of the audio stream.
        /// </summary>
        /// <param name="isMuted">The muting state. True if the stream is muted, false otherwise.</param>
        /// <returns>An HRESULT code indicating whether the operation passed of failed.</returns>
        [PreserveSig]
        int GetMute(
            [Out] [MarshalAs( UnmanagedType.Bool )] out Boolean isMuted );

        /// <summary>
        /// Gets information about the current step in the volume range.
        /// </summary>
        /// <param name="step">The current zero-based step index.</param>
        /// <param name="stepCount">The total number of steps in the volume range.</param>
        /// <returns>An HRESULT code indicating whether the operation passed of failed.</returns>
        [PreserveSig]
        int GetVolumeStepInfo(
            [Out] [MarshalAs( UnmanagedType.U4 )] out UInt32 step,
            [Out] [MarshalAs( UnmanagedType.U4 )] out UInt32 stepCount );

        /// <summary>
        /// Increases the volume level by one step.
        /// </summary>
        /// <param name="eventContext">A user context value that is passed to the notification callback.</param>
        /// <returns>An HRESULT code indicating whether the operation passed of failed.</returns>
        [PreserveSig]
        int VolumeStepUp(
            [In] [MarshalAs( UnmanagedType.LPStruct )] Guid eventContext );

        /// <summary>
        /// Decreases the volume level by one step.
        /// </summary>
        /// <param name="eventContext">A user context value that is passed to the notification callback.</param>
        /// <returns>An HRESULT code indicating whether the operation passed of failed.</returns>
        [PreserveSig]
        int VolumeStepDown(
            [In] [MarshalAs( UnmanagedType.LPStruct )] Guid eventContext );

        /// <summary>
        /// Queries the audio endpoint device for its hardware-supported functions.
        /// </summary>
        /// <param name="hardwareSupportMask">A hardware support mask that indicates the capabilities of the endpoint.</param>
        /// <returns>An HRESULT code indicating whether the operation passed of failed.</returns>
        [PreserveSig]
        int QueryHardwareSupport(
            [Out] [MarshalAs( UnmanagedType.U4 )] out UInt32 hardwareSupportMask );

        /// <summary>
        /// Gets the volume range of the audio stream, in decibels.
        /// </summary>
        /// <param name="volumeMin">The minimum volume level in decibels.</param>
        /// <param name="volumeMax">The maximum volume level in decibels.</param>
        /// <param name="volumeStep">The volume increment level in decibels.</param>
        /// <returns>An HRESULT code indicating whether the operation passed of failed.</returns>
        [PreserveSig]
        int GetVolumeRange(
            [Out] [MarshalAs( UnmanagedType.R4 )] out float volumeMin,
            [Out] [MarshalAs( UnmanagedType.R4 )] out float volumeMax,
            [Out] [MarshalAs( UnmanagedType.R4 )] out float volumeStep );
    }

AudioManager.cs