/// <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);
}
/// <summary>Create the stream and initialize settings</summary>
/// <param name="file">file name</param>
/// <returns>SND_RESULT</returns>
public SND_RESULT Create(string file)
{
if (!IsValidFile(file))
{
return(SND_RESULT.SND_ERR_INVALID_SOURCE);
}
// find wav chunks data and fmt
_ckData = GetChunkPos(file, "data");
_ckInfo = GetChunkPos(file, "fmt ");
DataLength = _ckData.Length;
// valid chunks?
if (_ckData.Start == 0)
{
return(SND_RESULT.SND_ERR_INVALID_SOURCE);
}
if (_ckInfo.Start == 0)
{
return(SND_RESULT.SND_ERR_INVALID_SOURCE);
}
if (_ckInfo.Length < 16)
{
return(SND_RESULT.SND_ERR_INVALID_SOURCE);
}
// open file
_waveHandle = FileOpen(file, FILE_ACCESS.GENERIC_READ, FILE_SHARE.FILE_SHARE_READ, FILE_METHOD.OPEN_EXISTING);
if (_waveHandle == INVALID_HANDLE)
{
return(SND_RESULT.SND_ERR_INVALID_SOURCE);
}
// shrink data chunks with ilegal length to file length
if (FileLength(_waveHandle) < (_ckData.Start + _ckData.Length))
{
_ckData.Length = FileLength(_waveHandle) - _ckData.Start;
}
// read info chunk
_btWfx = new byte[_ckInfo.Length];
FileSeek(_waveHandle, (int)_ckInfo.Start, (uint)SEEK_METHOD.FILE_BEGIN);
fixed(byte *pBt = _btWfx)
{
FileRead(_waveHandle, pBt, _ckInfo.Length);
}
// copy the header
uint size = (uint)sizeof(WAVEFORMATEX);
fixed(byte *pBt = _btWfx) fixed(WAVEFORMATEX * pWv = &_tWFXIn)
{
{ RtlMoveMemory(pWv, pBt, size); }
}
// seek to the beginning of the audio data
FileSeek(_waveHandle, (int)_ckData.Start, (uint)SEEK_METHOD.FILE_BEGIN);
// init the Audio Compression Manager
if (InitConversion() != MMSYSERR.NOERROR)
{
Close();
return(SND_RESULT.SND_ERR_INTERNAL);
}
return(SND_RESULT.SND_ERR_SUCCESS);
}
