Hello all.

I am invoking waveOutPrepareHeader in Vista x64.
I am getting the following error:
"An invalid parameter was passed to a system function."
Here is the code:


using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
using System.Diagnostics;

namespace ConsoleApplication1
{
class Program
{
[StructLayout(LayoutKind.Sequential)]
internal struct WAVEFORMATEX
{
internal ushort wFormatTag; /* format type */
internal ushort nChannels; /* number of channels (i.e.
mono, stereo...) */
internal uint nSamplesPerSec; /* sample rate */
internal uint nAvgBytesPerSec; /* for buffer estimation */
internal ushort nBlockAlign; /* block size of data */
internal ushort wBitsPerSample; /* number of bits per sample
of mono data */
internal ushort cbSize; /* the count in bytes of the
size of */
/* extra information (after cbSize) */
}

internal enum Callbacks
{
EVENT = 0x00050000,
NULL = 0x00000000, /* no callback */
WINDOW = 0x00010000, /* dwCallback is a HWND */
TASK = 0x00020000, /* dwCallback is a HTASK */
FUNCTION = 0x00030000 /* dwCallback is a FARPROC */
}

[DllImport("winmm")]
internal static extern
uint waveOutOpen(
out int phwi,
uint uDeviceID,
ref WAVEFORMATEX pwfx,
uint threadId,
int dwCallbackInstance,
Callbacks fdwOpen
);

[DllImport("kernel32")]
internal static extern
int GetCurrentThreadId();

[DllImport("Winmm")]
internal static extern
uint waveOutGetErrorTextA(
uint mmrError,
byte[] pszText,
int cchText
);

private static void Assert(uint res)
{
if (res != 0)
{
byte[] buff = new byte[1000];
res = waveOutGetErrorTextA(res, buff, buff.Length);
Assert(res);

int c = Array.IndexOf<byte>(buff, 0);
string s = ASCIIEncoding.ASCII.GetString(buff, 0, c);
throw new ApplicationException(s);
}
}

[DllImport("winmm")]
internal static extern
uint waveOutPrepareHeader(
int hwi,
ref WAVEHDR pwh,
int cbwh
);

[StructLayout(LayoutKind.Sequential)]
internal struct WAVEHDR
{
internal uint lpData; /* 32-bit pointer to
locked data buffer */
internal uint dwBufferLength; /* length of data buffer
*/
internal uint dwBytesRecorded; /* used for input only */
internal int dwUser; /* for client's use */
internal uint dwFlags; /* assorted flags (see
defines) */
internal uint dwLoops; /* loop control counter */
int lpNext; /* reserved for driver */
int reserved; /* reserved for driver */
}

[DllImport("winmm")]
internal static extern
uint waveOutWrite(
int hwi,
ref WAVEHDR pwh,
int cbwh
);

[DllImport("winmm")]
internal static extern
uint waveOutClose(
int hwi
);

static void Main(string[] args)
{
int hWaveIn;

WAVEFORMATEX wf;
wf.cbSize = 0;
wf.nAvgBytesPerSec = 8000;
wf.nBlockAlign = 1;
wf.nChannels = 1;
wf.nSamplesPerSec = 8000;
wf.wBitsPerSample = 8;
wf.wFormatTag = 1;

uint Id = (uint)GetCurrentThreadId();

uint res = waveOutOpen(out hWaveIn, 0, ref wf, Id, 0,
Callbacks.TASK);
Assert(res);

uint size = 1000;
WAVEHDR wh = new WAVEHDR();
wh.dwUser = 0;
wh.dwBufferLength = size;
wh.dwBytesRecorded = 0;
wh.dwFlags=0;
wh.dwLoops=0;
IntPtr i = Marshal.AllocHGlobal((int)size);
Debug.Assert( (long)i <= uint.MaxValue, "(long)i >
uint.MaxValue");
wh.lpData = (uint)i;

int whSize = Marshal.SizeOf(wh);

res = waveOutPrepareHeader(hWaveIn, ref wh, whSize);
Assert(res); // An invalid parameter was passed to a system
function.

res = waveOutWrite(hWaveIn, ref wh, whSize);
Assert(res);

res = waveOutClose(hWaveIn);
Assert(res);
}
}
}