C# 有关系统音量的操作

public static class SystemVolume
{
#region Master Volume Manipulation

/// 

/// 返回系统音量(1~100)
/// 
public static float GetMasterVolume()
{
IAudioEndpointVolume masterVol = null;
try
{
    masterVol = GetMasterVolumeObject();
    if (masterVol == null)
        return -1;

    masterVol.GetMasterVolumeLevelScalar(out var volumeLevel);
    return volumeLevel * 100;
}
finally
{
    if (masterVol != null)
        Marshal.ReleaseComObject(masterVol);
}
}

/// 

/// 设置系统音量
/// 
public static void SetMasterVolume(float newLevel)
{
IAudioEndpointVolume masterVol = null;
try
{
    masterVol = GetMasterVolumeObject();
    if (masterVol == null)
        return;

    masterVol.SetMasterVolumeLevelScalar(newLevel / 100, Guid.Empty);
}
finally
{
    if (masterVol != null)
        Marshal.ReleaseComObject(masterVol);
}
}

/// 

/// 设置系统静音
/// 
/// 
public static void SetMasterVolumeMute(bool isMuted)
{
IAudioEndpointVolume masterVol = null;
try
{
    masterVol = GetMasterVolumeObject();
    if (masterVol == null)
        return;

    masterVol.SetMute(isMuted, Guid.Empty);
}
finally
{
    if (masterVol != null)
        Marshal.ReleaseComObject(masterVol);
}
}

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

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

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

#endregion
}

#region Abstracted 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
}



[Guid("E2F5BB11-0570-40CA-ACDD-3AA01277DEE8"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
internal interface IAudioSessionEnumerator
{
[PreserveSig]
int GetCount(out int SessionCount);

[PreserveSig]
int GetSession(int SessionCount, out IAudioSessionControl2 Session);
}



[Guid("bfb7ff88-7239-4fc9-8fa2-07c950be9c6d"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
internal interface IAudioSessionControl2
{
// IAudioSessionControl
[PreserveSig]
int NotImpl0();

[PreserveSig]
int GetDisplayName([MarshalAs(UnmanagedType.LPWStr)] out string pRetVal);

[PreserveSig]
int SetDisplayName([MarshalAs(UnmanagedType.LPWStr)]string Value, [MarshalAs(UnmanagedType.LPStruct)] Guid EventContext);

[PreserveSig]
int GetIconPath([MarshalAs(UnmanagedType.LPWStr)] out string pRetVal);

[PreserveSig]
int SetIconPath([MarshalAs(UnmanagedType.LPWStr)] string Value, [MarshalAs(UnmanagedType.LPStruct)] Guid EventContext);

[PreserveSig]
int GetGroupingParam(out Guid pRetVal);

[PreserveSig]
int SetGroupingParam([MarshalAs(UnmanagedType.LPStruct)] Guid Override, [MarshalAs(UnmanagedType.LPStruct)] Guid EventContext);

[PreserveSig]
int NotImpl1();

[PreserveSig]
int NotImpl2();

// IAudioSessionControl2
[PreserveSig]
int GetSessionIdentifier([MarshalAs(UnmanagedType.LPWStr)] out string pRetVal);

[PreserveSig]
int GetSessionInstanceIdentifier([MarshalAs(UnmanagedType.LPWStr)] out string pRetVal);

[PreserveSig]
int GetProcessId(out int pRetVal);

[PreserveSig]
int IsSystemSoundsSession();

[PreserveSig]
int SetDuckingPreference(bool optOut);
}

// 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();

/// 

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

/// 

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

/// 

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

/// 

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

/// 

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

/// 

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

/// 

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

/// 

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

/// 

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

/// 

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

/// 

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

/// 

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

/// 

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

/// 

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

/// 

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

/// 

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

#endregion