Mobile

public byte[] ClassToBytearray(object obj)
        {    
            int Length = Marshal.SizeOf(obj);       <----------This is where I get the error.
            byte[] bytearray = new byte[Length];     
            IntPtr ptr = Marshal.AllocHGlobal(Length);
            Marshal.StructureToPtr(obj, ptr, false);
            Marshal.Copy(ptr, bytearray, 0, Length);
            Marshal.FreeHGlobal(ptr);
            return bytearray;
        } 

[DllImport("coredll.dll")]
public static extern Wave.MMSYSERR waveInOpen(ref IntPtr phwi, uint uDeviceID, ref Wave.WAVEFORMATEX pwfx, IntPtr dwCallback, uint dwInstance, uint fdwOpen); 

[StructLayout(LayoutKind.Sequential)]
public class WAVEFORMATEX
{
   public ushort wFormatTag = 0;
   public ushort nChannels = 0;
   public uint nSamplesPerSec = 0;
   public uint nAvgBytesPerSec = 0;
}

[StructLayout(LayoutKind.Sequential)]
public class GSM610WAVEFORMAT
{
   public WAVEFORMATEX wfx;
   public ushort cbSize;
   public ushort wSamplesPerBlock;
}

Wave.GSM610WAVEFORMAT m_wfmt_gsm;
curDevice = Wave.WAVE_MAPPER;
m_wfmt_gsm = new Wave.GSM610WAVEFORMAT();
m_wfmt_gsm.wfx = new Wave.WAVEFORMATEX();
m_wfmt_gsm.wfx.wFormatTag = (ushort)0x31;
m_wfmt_gsm.wfx.nChannels = 1;
m_wfmt_gsm.wfx.nSamplesPerSec = 8000;
m_wfmt_gsm.wfx.nAvgBytesPerSec = 1625;
m_wfmt_gsm.nBlockAlign = 65;
m_wfmt_gsm.wBitsPerSample = 0;
m_wfmt_gsm.cbSize = 2;
m_wfmt_gsm.wSamplesPerBlock = 320;
result = WaveIn.waveInOpen(ref m_hwi, curDevice, m_wfmt_gsm.wfx, hwnd, 0, Wave.CALLBACK_WINDOW);