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;
}