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using System;
using System.Runtime.InteropServices;
// ReSharper disable SuspiciousTypeConversion.Global
// ReSharper disable InconsistentNaming
namespace AudioController
{
/// <summary>
/// Controls audio using the Windows CoreAudio API
/// from: http://stackoverflow.com/questions/14306048/controling-volume-mixer
/// and: http://netcoreaudio.codeplex.com/
/// </summary>
public static class AudioManager
{
#region Master Volume Manipulation
/// <summary>
/// Gets the current master volume in scalar values (percentage)
/// </summary>
/// <returns>-1 in case of an error, if successful the value will be between 0 and 100</returns>
public static float GetMasterVolume()
{
IAudioEndpointVolume masterVol = null;
try
{
masterVol = GetMasterVolumeObject();
if (masterVol == null)
return -1;
float volumeLevel;
masterVol.GetMasterVolumeLevelScalar(out volumeLevel);
return volumeLevel*100;
}
finally
{
if (masterVol != null)
Marshal.ReleaseComObject(masterVol);
}
}
/// <summary>
/// Gets the mute state of the master volume.
/// While the volume can be muted the <see cref="GetMasterVolume"/> will still return the pre-muted volume value.
/// </summary>
/// <returns>false if not muted, true if volume is muted</returns>
public static bool GetMasterVolumeMute()
{
IAudioEndpointVolume masterVol = null;
try
{
masterVol = GetMasterVolumeObject();
if (masterVol == null)
return false;
bool isMuted;
masterVol.GetMute(out isMuted);
return isMuted;
}
finally
{
if (masterVol != null)
Marshal.ReleaseComObject(masterVol);
}
}
/// <summary>
/// Sets the master volume to a specific level
/// </summary>
/// <param name="newLevel">Value between 0 and 100 indicating the desired scalar value of the volume</param>
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);
}
}
/// <summary>
/// Increments or decrements the current volume level by the <see cref="stepAmount"/>.
/// </summary>
/// <param name="stepAmount">Value between -100 and 100 indicating the desired step amount. Use negative numbers to decrease
/// the volume and positive numbers to increase it.</param>
/// <returns>the new volume level assigned</returns>
public static float StepMasterVolume(float stepAmount)
{
IAudioEndpointVolume masterVol = null;
try
{
masterVol = GetMasterVolumeObject();
if (masterVol == null)
return -1;
float stepAmountScaled = stepAmount/100;
// Get the level
float volumeLevel;
masterVol.GetMasterVolumeLevelScalar(out volumeLevel);
// Calculate the new level
float newLevel = volumeLevel + stepAmountScaled;
newLevel = Math.Min(1, newLevel);
newLevel = Math.Max(0, newLevel);
masterVol.SetMasterVolumeLevelScalar(newLevel, Guid.Empty);
// Return the new volume level that was set
return newLevel*100;
}
finally
{
if (masterVol != null)
Marshal.ReleaseComObject(masterVol);
}
}
/// <summary>
/// Mute or unmute the master volume
/// </summary>
/// <param name="isMuted">true to mute the master volume, false to unmute</param>
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);
}
}
/// <summary>
/// Switches between the master volume mute states depending on the current state
/// </summary>
/// <returns>the current mute state, true if the volume was muted, false if unmuted</returns>
public static bool ToggleMasterVolumeMute()
{
IAudioEndpointVolume masterVol = null;
try
{
masterVol = GetMasterVolumeObject();
if (masterVol == null)
return false;
bool isMuted;
masterVol.GetMute(out isMuted);
masterVol.SetMute(!isMuted, Guid.Empty);
return !isMuted;
}
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 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);
}
}
#endregion
#region Individual Application Volume Manipulation
public static float? GetApplicationVolume(int pid)
{
{
IMMDeviceEnumerator deviceEnumerator = null;
IAudioSessionEnumerator sessionEnumerator = null;
IAudioSessionManager2 mgr = null;
IMMDevice speakers = null;
try
{
// get the speakers (1st render + multimedia) device
deviceEnumerator = (IMMDeviceEnumerator)(new MMDeviceEnumerator());
deviceEnumerator.GetDefaultAudioEndpoint(EDataFlow.eRender, ERole.eMultimedia, out speakers);
// activate the session manager. we need the enumerator
Guid IID_IAudioSessionManager2 = typeof(IAudioSessionManager2).GUID;
object o;
speakers.Activate(ref IID_IAudioSessionManager2, 0, IntPtr.Zero, out o);
mgr = (IAudioSessionManager2)o;
// enumerate sessions for on this device
mgr.GetSessionEnumerator(out sessionEnumerator);
int count;
sessionEnumerator.GetCount(out count);
// search for an audio session with the required process-id
ISimpleAudioVolume volumeControl = null;
float level;
for (int i = 0; i < count; ++i)
{
IAudioSessionControl2 ctl = null;
try
{
sessionEnumerator.GetSession(i, out ctl);
// NOTE: we could also use the app name from ctl.GetDisplayName()
int cpid;
ctl.GetProcessId(out cpid);
if (cpid == pid)
{
volumeControl = ctl as ISimpleAudioVolume;
volumeControl.GetMasterVolume(out level);
return level * 100;
}
}
finally
{
if (ctl != null) Marshal.ReleaseComObject(ctl);
}
}
return null;
}
finally
{
if (speakers != null) Marshal.ReleaseComObject(speakers);
if (mgr != null) Marshal.ReleaseComObject(mgr);
if (sessionEnumerator != null) Marshal.ReleaseComObject(sessionEnumerator);
if (deviceEnumerator != null) Marshal.ReleaseComObject(deviceEnumerator);
}
}
}
public static bool? GetApplicationMute(int pid)
{
{
IMMDeviceEnumerator deviceEnumerator = null;
IAudioSessionEnumerator sessionEnumerator = null;
IAudioSessionManager2 mgr = null;
IMMDevice speakers = null;
try
{
// get the speakers (1st render + multimedia) device
deviceEnumerator = (IMMDeviceEnumerator)(new MMDeviceEnumerator());
deviceEnumerator.GetDefaultAudioEndpoint(EDataFlow.eRender, ERole.eMultimedia, out speakers);
// activate the session manager. we need the enumerator
Guid IID_IAudioSessionManager2 = typeof(IAudioSessionManager2).GUID;
object o;
speakers.Activate(ref IID_IAudioSessionManager2, 0, IntPtr.Zero, out o);
mgr = (IAudioSessionManager2)o;
// enumerate sessions for on this device
mgr.GetSessionEnumerator(out sessionEnumerator);
int count;
sessionEnumerator.GetCount(out count);
// search for an audio session with the required process-id
ISimpleAudioVolume volumeControl = null;
bool mute;
for (int i = 0; i < count; ++i)
{
IAudioSessionControl2 ctl = null;
try
{
sessionEnumerator.GetSession(i, out ctl);
// NOTE: we could also use the app name from ctl.GetDisplayName()
int cpid;
ctl.GetProcessId(out cpid);
if (cpid == pid)
{
volumeControl = ctl as ISimpleAudioVolume;
volumeControl.GetMute(out mute);
return mute;
}
}
finally
{
if (ctl != null) Marshal.ReleaseComObject(ctl);
}
}
return null;
}
finally
{
if (speakers != null) Marshal.ReleaseComObject(speakers);
if (mgr != null) Marshal.ReleaseComObject(mgr);
if (sessionEnumerator != null) Marshal.ReleaseComObject(sessionEnumerator);
if (deviceEnumerator != null) Marshal.ReleaseComObject(deviceEnumerator);
}
}
}
public static void SetApplicationVolume(int pid, float? level)
{
if (level == null) return;
{
IMMDeviceEnumerator deviceEnumerator = null;
IAudioSessionEnumerator sessionEnumerator = null;
IAudioSessionManager2 mgr = null;
IMMDevice speakers = null;
try
{
// get the speakers (1st render + multimedia) device
deviceEnumerator = (IMMDeviceEnumerator)(new MMDeviceEnumerator());
deviceEnumerator.GetDefaultAudioEndpoint(EDataFlow.eRender, ERole.eMultimedia, out speakers);
// activate the session manager. we need the enumerator
Guid IID_IAudioSessionManager2 = typeof(IAudioSessionManager2).GUID;
object o;
speakers.Activate(ref IID_IAudioSessionManager2, 0, IntPtr.Zero, out o);
mgr = (IAudioSessionManager2)o;
// enumerate sessions for on this device
mgr.GetSessionEnumerator(out sessionEnumerator);
int count;
sessionEnumerator.GetCount(out count);
// search for an audio session with the required process-id
ISimpleAudioVolume volumeControl = null;
for (int i = 0; i < count; ++i)
{
IAudioSessionControl2 ctl = null;
try
{
sessionEnumerator.GetSession(i, out ctl);
// NOTE: we could also use the app name from ctl.GetDisplayName()
int cpid;
ctl.GetProcessId(out cpid);
if (cpid == pid)
{
Guid guid = Guid.Empty;
volumeControl = ctl as ISimpleAudioVolume;
volumeControl.SetMasterVolume(Convert.ToSingle(level) / 100, ref guid);
}
}
finally
{
if (ctl != null) Marshal.ReleaseComObject(ctl);
}
}
}
finally
{
if (speakers != null) Marshal.ReleaseComObject(speakers);
if (mgr != null) Marshal.ReleaseComObject(mgr);
if (sessionEnumerator != null) Marshal.ReleaseComObject(sessionEnumerator);
if (deviceEnumerator != null) Marshal.ReleaseComObject(deviceEnumerator);
}
}
}
public static void SetApplicationMute(int pid, bool? mute)
{
if (mute == null) return;
{
IMMDeviceEnumerator deviceEnumerator = null;
IAudioSessionEnumerator sessionEnumerator = null;
IAudioSessionManager2 mgr = null;
IMMDevice speakers = null;
try
{
// get the speakers (1st render + multimedia) device
deviceEnumerator = (IMMDeviceEnumerator)(new MMDeviceEnumerator());
deviceEnumerator.GetDefaultAudioEndpoint(EDataFlow.eRender, ERole.eMultimedia, out speakers);
// activate the session manager. we need the enumerator
Guid IID_IAudioSessionManager2 = typeof(IAudioSessionManager2).GUID;
object o;
speakers.Activate(ref IID_IAudioSessionManager2, 0, IntPtr.Zero, out o);
mgr = (IAudioSessionManager2)o;
// enumerate sessions for on this device
mgr.GetSessionEnumerator(out sessionEnumerator);
int count;
sessionEnumerator.GetCount(out count);
// search for an audio session with the required process-id
ISimpleAudioVolume volumeControl = null;
for (int i = 0; i < count; ++i)
{
IAudioSessionControl2 ctl = null;
try
{
sessionEnumerator.GetSession(i, out ctl);
// NOTE: we could also use the app name from ctl.GetDisplayName()
int cpid;
ctl.GetProcessId(out cpid);
if (cpid == pid)
{
Guid guid = Guid.Empty;
volumeControl = ctl as ISimpleAudioVolume;
volumeControl.SetMute(Convert.ToBoolean(mute), ref guid);
}
}
finally
{
if (ctl != null) Marshal.ReleaseComObject(ctl);
}
}
}
finally
{
if (speakers != null) Marshal.ReleaseComObject(speakers);
if (mgr != null) Marshal.ReleaseComObject(mgr);
if (sessionEnumerator != null) Marshal.ReleaseComObject(sessionEnumerator);
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("77AA99A0-1BD6-484F-8BC7-2C654C9A9B6F"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
internal interface IAudioSessionManager2
{
int NotImpl1();
int NotImpl2();
[PreserveSig]
int GetSessionEnumerator(out IAudioSessionEnumerator SessionEnum);
// 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("87CE5498-68D6-44E5-9215-6DA47EF883D8"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
internal interface ISimpleAudioVolume
{
[PreserveSig]
int SetMasterVolume(float fLevel, ref Guid EventContext);
[PreserveSig]
int GetMasterVolume(out float pfLevel);
[PreserveSig]
int SetMute(bool bMute, ref Guid EventContext);
[PreserveSig]
int GetMute(out bool pbMute);
}
[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();
/// <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);
}
#endregion
}
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