//-------------------------------------------------------------------
// Name: ReadRiffHeader
// Description:
// Read the container header section. (The 'RIFF' or 'LIST' header.)
//
// This method verifies the header is well-formed and caches the
// container's FOURCC type.
//-------------------------------------------------------------------
private void ReadRiffHeader()
{
int hr;
int iRiffSize = Marshal.SizeOf(typeof(RIFFLIST));
// Riff chunks must be WORD aligned
if (!Utils.IsAligned(m_llContainerOffset, 2))
{
throw new COMException("bad alignment", E_InvalidArgument);
}
// Offset must be positive.
if (m_llContainerOffset < 0)
{
throw new COMException("negative offset", E_InvalidArgument);
}
// Offset + the size of header must not overflow.
if (long.MaxValue - m_llContainerOffset <= iRiffSize)
{
throw new COMException("overflow chunk", E_InvalidArgument);
}
RIFFLIST header = new RIFFLIST();
int cbRead = 0;
// Seek to the start of the container.
hr = m_pStream.SetCurrentPosition(m_llContainerOffset);
MFError.ThrowExceptionForHR(hr);
// Read the header.
IntPtr ip = Marshal.AllocCoTaskMem(iRiffSize);
try
{
hr = m_pStream.Read(ip, iRiffSize, out cbRead);
MFError.ThrowExceptionForHR(hr);
// Make sure we read the number of bytes we expected.
if (cbRead == iRiffSize)
{
Marshal.PtrToStructure(ip, header);
}
else
{
throw new COMException("read riff failure", E_InvalidArgument);
}
}
finally
{
Marshal.FreeCoTaskMem(ip);
}
// Make sure the header ID matches what the caller expected.
if (header.fcc != m_fccID)
{
throw new COMException("bad header id", E_InvalidArgument);
}
// The size given in the RIFF header does not include the 8-byte header.
// However, our m_llContainerOffset is the offset from the start of the
// header. Therefore our container size = listed size + size of header.
m_dwContainerSize = header.cb + Marshal.SizeOf(typeof(RIFFCHUNK));
m_fccType = header.fccListType;
// Start of the first chunk = start of container + size of container header
m_llCurrentChunkOffset = m_llContainerOffset + iRiffSize;
ReadChunkHeader();
}
//-------------------------------------------------------------------
// Name: ReadRiffHeader
// Description:
// Read the container header section. (The 'RIFF' or 'LIST' header.)
//
// This method verifies the header is well-formed and caches the
// container's FOURCC type.
//-------------------------------------------------------------------
private void ReadRiffHeader()
{
HResult hr;
int iRiffSize = Marshal.SizeOf(typeof(RIFFLIST));
// Riff chunks must be WORD aligned
if (!Utils.IsAligned(m_llContainerOffset, 2))
{
throw new COMException("bad alignment", (int)HResult.E_INVALIDARG);
}
// Offset must be positive.
if (m_llContainerOffset < 0)
{
throw new COMException("negative offset", (int)HResult.E_INVALIDARG);
}
// Offset + the size of header must not overflow.
if (long.MaxValue - m_llContainerOffset <= iRiffSize)
{
throw new COMException("overflow chunk", (int)HResult.E_INVALIDARG);
}
RIFFLIST header = new RIFFLIST();
int cbRead = 0;
// Seek to the start of the container.
hr = m_pStream.SetCurrentPosition(m_llContainerOffset);
MFError.ThrowExceptionForHR(hr);
// Read the header.
IntPtr ip = Marshal.AllocCoTaskMem(iRiffSize);
try
{
hr = m_pStream.Read(ip, iRiffSize, out cbRead);
MFError.ThrowExceptionForHR(hr);
// Make sure we read the number of bytes we expected.
if (cbRead == iRiffSize)
{
Marshal.PtrToStructure(ip, header);
}
else
{
throw new COMException("read riff failure", (int)HResult.E_INVALIDARG);
}
}
finally
{
Marshal.FreeCoTaskMem(ip);
}
// Make sure the header ID matches what the caller expected.
if (header.fcc != m_fccID)
{
throw new COMException("bad header id", (int)HResult.E_INVALIDARG);
}
// The size given in the RIFF header does not include the 8-byte header.
// However, our m_llContainerOffset is the offset from the start of the
// header. Therefore our container size = listed size + size of header.
m_dwContainerSize = header.cb + Marshal.SizeOf(typeof(RIFFCHUNK));
m_fccType = header.fccListType;
// Start of the first chunk = start of container + size of container header
m_llCurrentChunkOffset = m_llContainerOffset + iRiffSize;
ReadChunkHeader();
}
