private void WriteFormatBlock()
{
MMCKINFO mmckinfoParentIn = new MMCKINFO();
// Get format info
mmckinfoParentIn.ckid = new FourCC("fmt ");
mmckinfoParentIn.ckSize = FORMATBLOCKSIZE;
MMIOError rc = MMIO.CreateChunk(m_OutputFile, mmckinfoParentIn, RiffChunkFlags.None);
MMIO.ThrowExceptionForError(rc);
IntPtr ip = Marshal.AllocCoTaskMem(FORMATBLOCKSIZE);
try
{
Marshal.StructureToPtr(m_wfe, ip, false);
int iBytes = MMIO.Write(m_OutputFile, ip, FORMATBLOCKSIZE);
if (iBytes < 0)
{
throw new Exception("mmioWrite failed");
}
}
finally
{
Marshal.FreeCoTaskMem(ip);
}
rc = MMIO.Ascend(m_OutputFile, mmckinfoParentIn, 0);
MMIO.ThrowExceptionForError(rc);
}
/// <summary>
/// Read the WaveFormatEx from the input file and find the place to start
/// writing data.
/// </summary>
private void LoadWFE()
{
MMCKINFO mmckinfoParentIn = new MMCKINFO();
MMCKINFO mmckinfoSubchunkIn = new MMCKINFO();
int mm = MMIO.Seek(m_OutputFile, 0, MMIOSeekFlags.Set);
if (mm < 0)
{
throw new Exception("seek failure");
}
// Check if this is a wave file
mmckinfoParentIn.fccType = new FourCC("WAVE");
MMIOError rc = MMIO.Descend(m_OutputFile, mmckinfoParentIn, null, RiffChunkFlags.FindRiff);
MMIO.ThrowExceptionForError(rc);
// Get format info
mmckinfoSubchunkIn.ckid = new FourCC("fmt ");
rc = MMIO.Descend(m_OutputFile, mmckinfoSubchunkIn, mmckinfoParentIn, RiffChunkFlags.FindChunk);
MMIO.ThrowExceptionForError(rc);
// Read the data format from the file (WaveFormatEx)
IntPtr ip = Marshal.AllocCoTaskMem(Marshal.SizeOf(typeof(WaveFormatEx)));
try
{
rc = MMIO.Read(m_OutputFile, ip, mmckinfoSubchunkIn.ckSize);
if (rc < 0)
{
throw new Exception("Read failed");
}
m_wfe = new WaveFormatEx();
Marshal.PtrToStructure(ip, m_wfe);
}
finally
{
Marshal.FreeCoTaskMem(ip);
}
rc = MMIO.Ascend(m_OutputFile, mmckinfoSubchunkIn, 0);
MMIO.ThrowExceptionForError(rc);
// Find the data subchunk
mmckinfoSubchunkIn.ckid = new FourCC("data");
rc = MMIO.Descend(m_OutputFile, mmckinfoSubchunkIn, mmckinfoParentIn, RiffChunkFlags.FindChunk);
MMIO.ThrowExceptionForError(rc);
// Here is where data gets written
m_DataOffset = MMIO.Seek(m_OutputFile, 0, MMIOSeekFlags.Cur);
// Get the length of the audio
m_AudioLength = mmckinfoSubchunkIn.ckSize;
}
private void WriteDataBlock()
{
MMCKINFO mmckinfoSubchunkIn = new MMCKINFO();
mmckinfoSubchunkIn.ckid = new FourCC("data");
mmckinfoSubchunkIn.ckSize = m_AudioLength;
MMIOError rc = MMIO.CreateChunk(m_OutputFile, mmckinfoSubchunkIn, 0);
MMIO.ThrowExceptionForError(rc);
}
private void WriteWaveHeader()
{
MMCKINFO mmckinfoParentIn = new MMCKINFO();
mmckinfoParentIn.fccType = new FourCC("WAVE");
mmckinfoParentIn.ckSize = m_AudioLength + m_DataOffset - 8;
MMIOError rc = MMIO.CreateChunk(m_OutputFile, mmckinfoParentIn, RiffChunkFlags.CreateRiff);
MMIO.ThrowExceptionForError(rc);
}
/// <summary>Get the named position in a RIFF</summary>
/// <param name="file">file name</param>
/// <param name="name">named position</param>
/// <returns>CHUNKINFO</returns>
private CHUNKINFO GetChunkPos(string file, string name)
{
int ret;
IntPtr hMmioIn;
CHUNKINFO ck = new CHUNKINFO();
MMCKINFO mmckinfoParentIn = new MMCKINFO();
MMCKINFO mmckinfoSubchunkIn = new MMCKINFO();
// open for read
hMmioIn = mmioOpen(file, IntPtr.Zero, MMIO_READ);
if (hMmioIn == IntPtr.Zero)
{
return(ck);
}
// convert string to code
mmckinfoParentIn.fccType = mmioStringToFOURCC("WAVE", 0);
ret = mmioDescendParent(hMmioIn, &mmckinfoParentIn, IntPtr.Zero, MMIO_FINDRIFF);
if (ret != 0)
{
mmioClose(hMmioIn, 0);
return(ck);
}
// get named location
mmckinfoSubchunkIn.ckid = mmioStringToFOURCC(name, 0);
ret = mmioDescend(hMmioIn, &mmckinfoSubchunkIn, &mmckinfoParentIn, MMIO_FINDCHUNK);
if (ret != 0)
{
mmioClose(hMmioIn, 0);
return(ck);
}
// return position and size
ck.Start = (uint)mmioSeek(hMmioIn, 0, SEEK_CUR);
ck.Length = mmckinfoSubchunkIn.ckSize;
mmioClose(hMmioIn, 0);
return(ck);
}
internal static extern int mmioDescend(IntPtr hMIO,
[MarshalAs(UnmanagedType.LPStruct)] MMCKINFO lpck,
[MarshalAs(UnmanagedType.LPStruct)] MMCKINFO lcpkParent,
int flags);
internal static extern int mmioAscend(IntPtr hMIO, MMCKINFO lpck, int flags);
