System.AccessViolationExceptio...

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COM

audio

Hi All,

I am using Naudio to access audio device properties and receive device connected or removed notification.

i am using MMDeviceEnumerator's RegisterEndpointNotificationCallback(IMMNotificationClient) register for notifications.

The code compiles and runs but when is connect a jack device i recieve. the following errors.

System.AccessViolationException was unhandled
HResult=-2147467261
Message=Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
Source=mscorlib
StackTrace:
at System.Runtime.InteropServices.Marshal.AddRef(IntPtr pUnk)
at System.Management.SinkForEventQuery.Indicate(IntPtr pWbemClassObject)
InnerException:
FatalExecutionEngineError was detected
Message: The runtime has encountered a fatal error. The address of the error was at 0x6aab9017, on thread 0x1f10. The error code is 0xc0000005. This error may be a bug in the CLR or in the unsafe or non-verifiable portions of user code. Common sources of this bug include user marshaling errors for COM-interop or PInvoke, which may corrupt the stack.

Below is the class i have created that implements Naudio's IMMNotificationClient Interface

class NotificationClientImplementation : NAudio.CoreAudioApi.Interfaces.IMMNotificationClient
    {

public void OnDefaultDeviceChanged(DataFlow dataFlow, Role deviceRole, string defaultDeviceId)
        {
            Console.WriteLine("OnDefaultDeviceChanged --> {0}", dataFlow.ToString());
        }

        public void OnDeviceAdded(string deviceId)
        {
            Console.WriteLine("OnDeviceAdded -->");
        }

        public void OnDeviceRemoved(string deviceId)
        {
            Console.WriteLine("OnDeviceRemoved -->");
        }

        public void OnDeviceStateChanged(string deviceId, DeviceState newState)
        {
            Console.WriteLine("OnDeviceStateChanged\n Device Id -->{0} : Device State {1}", deviceId, newState);
        }

        public NotificationClientImplementation()
        {
            if (System.Environment.OSVersion.Version.Major < 6)
            {
                throw new NotSupportedException("This functionality is only supported on Windows Vista or newer.");
            }
        }

        public void OnPropertyValueChanged(string deviceId, PropertyKey propertyKey)
        {
            //  Console.WriteLine("OnPropertyValueChanged:  fmtid --> {0}  PID--> {1}", propertyKey.fmtid.ToString(), propertyKey.pid.ToString());
        }

    }

NAUDIO Enums ::::
public enum Role
    {
       Console,
       Multimedia,
       Communications,
    }
[Flags]
    public  enum DeviceState
    {
      Active = 0x00000001,
      Disabled = 0x00000002,
      NotPresent = 0x00000004,
      Unplugged = 0x00000008,
      All = 0x0000000F
    }

public enum DataFlow
    {
       Render,
       Capture,
       All
    };

NAudio IMMNotificationClient:::: 

    [Guid("7991EEC9-7E89-4D85-8390-6C703CEC60C0"),
    InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public partial interface IMMNotificationClient
    {
        void OnDeviceStateChanged(
            [MarshalAs(UnmanagedType.LPWStr)] string deviceId,
            [MarshalAs(UnmanagedType.U4)] DeviceState newState);

        void OnDeviceAdded(
            [MarshalAs(UnmanagedType.LPWStr)] string deviceId);

        void OnDeviceRemoved(
            [MarshalAs(UnmanagedType.LPWStr)] string deviceId);

void OnDefaultDeviceChanged(
            [MarshalAs(UnmanagedType.I4)] DataFlow dataFlow,
            [MarshalAs(UnmanagedType.I4)] Role deviceRole,
            [MarshalAs(UnmanagedType.LPWStr)] string defaultDeviceId);

        void OnPropertyValueChanged(
            [MarshalAs(UnmanagedType.LPWStr)] string deviceId, PropertyKey propertyKey);

    }

Ours is a Winforms application and my first encounter with COM . Please Help.
Thanks.