vhost.exe crashes when trying to make waveout work in C#.

Question

I tried to use waveout in C# to play more wav files simultaneously (at least the different ones). (SoundPlayer object only plays one in a time, and I don't want to use DirectSound and MediaPlayer objects or any other advenced technologies for this simple goal.)

I ported a working C++ code to C# and it works (after a research how to marshal and how to call native win32 dll-s and how to allocate and lock unmanaged memory) but it somehow make the vhost.exe crash and I have no clue why it does this. (It does not throw any exception only the standard windows error dialog appears and the program crashes and exit.)

Does anyone have any ideas?

Here is the source of that class:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using XiVo.PlayThrough;
using System.ComponentModel;
using System.Runtime.InteropServices;
using System.Timers;

namespace RTS
{
    class WaveObject
    {
        protected IntPtr wo;
        protected byte[] Adat=null;
        protected WaveNative.WaveHdr woh;
        protected int pgc;

        public class NotAWaveformFileException : Exception
        {
            public NotAWaveformFileException(string str) : base(str) { }
            public NotAWaveformFileException() { }
        }

        public class WaveFileIsCorruptedException : Exception
        {
            public WaveFileIsCorruptedException(string str) : base(str) { }
            public WaveFileIsCorruptedException() { }
        }

        public class WaveMapperCouldNotBeOpenedException : Exception
        {
            public WaveMapperCouldNotBeOpenedException(string str) : base(str) { }
            public WaveMapperCouldNotBeOpenedException() { }
        }

        public WaveObject() {}

        public WaveObject(string Fn) : this() { Load(Fn); }

        public void Load(string Fn)
        {
            IntPtr mmio;
            NativeMMIO.mmckInfo Main, Sub;

            WaveFormat wfx;
            StringBuilder str=new StringBuilder(Fn);
            int r;
            mmio = NativeMMIO.mmioOpen(str,IntPtr.Zero,NativeMMIO.MMIO_READ);
            if (mmio == IntPtr.Zero)
            {
                throw new FileNotFoundException(Fn + "not found!");
            }
            Main.fccType = NativeMMIO.mmioFOURCC('W', 'A', 'V', 'E');
            if (NativeMMIO.mmioDescend(mmio, out Main, IntPtr.Zero, NativeMMIO.MMIO_FINDRIFF) != 0)
            {
                throw new NotAWaveformFileException();
            }
            Sub.ckid = NativeMMIO.mmioFOURCC('f', 'm', 't', ' ');
            if (NativeMMIO.mmioDescend(mmio, out Sub, out Main, NativeMMIO.MMIO_FINDCHUNK) != 0)
            {
                throw new WaveFileIsCorruptedException("fmt chunk is not found!");
            }
            byte[] raw = new byte[Sub.cksize+2];
            NativeMMIO.mmioRead(mmio, raw, (int)Sub.cksize);
            GCHandle conv = GCHandle.Alloc(raw, GCHandleType.Pinned); // mapping a WaveFormat structure from the byte array
            wfx = (WaveFormat)Marshal.PtrToStructure(conv.AddrOfPinnedObject(), typeof(WaveFormat));
            conv.Free();
            Sub.ckid = NativeMMIO.mmioFOURCC('d', 'a', 't', 'a');
            if (NativeMMIO.mmioDescend(mmio, out Sub, out Main, NativeMMIO.MMIO_FINDCHUNK) != 0)
            {
                throw new WaveFileIsCorruptedException("data chunk is not found!");
            }
            Adat = new byte[Sub.cksize+2];
            NativeMMIO.mmioRead(mmio, Adat, (int)Sub.cksize);
            NativeMMIO.mmioClose(mmio, 0);
            wfx.cbSize = (short)Marshal.SizeOf(wfx);
            unchecked // WAVE_MAPPER is 0xFFFFFFFF and it does not let it convert to int otherwise
            {
                int res = WaveNative.waveOutOpen(out wo, (int)WaveNative.WAVE_MAPPER, wfx, null, 0, (int)WaveNative.CALLBACK_NULL);
                if (res != WaveNative.MMSYSERR_NOERROR)
                {
                    throw new WaveMapperCouldNotBeOpenedException();
                }
            }
            woh.lpData = Marshal.AllocHGlobal((int)Sub.cksize); // alloc memory for the buffer
            Marshal.Copy(Adat, 0, woh.lpData, (int)Sub.cksize);
            woh.dwBufferLength = (int)Sub.cksize;
            woh.dwBytesRecorded = 0;
            woh.dwUser = IntPtr.Zero;
            woh.dwFlags = 0;
            woh.dwLoops = 1000000;
            woh.reserved = 0;
            woh.lpNext = IntPtr.Zero;
            r = WaveNative.waveOutPrepareHeader(wo, ref woh, Marshal.SizeOf(woh));
            pgc = System.Environment.TickCount;
        }

        public void Play()
        {
            if (System.Environment.TickCount - pgc > 50)
            {
                if (wo == null) throw new Exception("wo somehow became null.");
                int res = WaveNative.waveOutReset(wo);
                if (res != WaveNative.MMSYSERR_NOERROR) throw new Exception(string.Format("waveOutReset {0}",res));
                res=WaveNative.waveOutWrite(wo, ref woh, Marshal.SizeOf(woh));
                if ((res != WaveNative.MMSYSERR_NOERROR) && (res!=33)) throw new Exception(string.Format("waveOutWrite {0}",res));
            }
        }

        ~WaveObject()
        {
            Marshal.FreeHGlobal(woh.lpData); // release memory
        }
    }
}

Answer 1

After a lot of googling I realized that the bug is in the winmm.dll itself. Under some circumstances its helper thread crashes and bring down the host application too.

citation