//-------------------------------------------------------------------
// LockBuffer
//
// Locks the buffer. Returns a pointer to scan line 0 and returns the stride.
//
// The caller must provide the default stride as an input parameter, in case
// the buffer does not expose IMF2DBuffer. You can calculate the default stride
// from the media type.
//-------------------------------------------------------------------
public int LockBuffer(
int lDefaultStride, // Minimum stride (with no padding).
int dwHeightInPixels, // Height of the image, in pixels.
out IntPtr ppbScanLine0, // Receives a pointer to the start of scan line 0.
out int plStride // Receives the actual stride.
)
{
int hr;
ppbScanLine0 = IntPtr.Zero;
plStride = 0;
// Use the 2-D version if available.
if (p2DBuffer != null)
{
hr = p2DBuffer.Lock2D(out ppbScanLine0, out plStride);
}
else
{
// Use non-2D version.
IntPtr pData;
int pcbMaxLength;
int pcbCurrentLength;
hr = pBuffer.Lock(out pData, out pcbMaxLength, out pcbCurrentLength);
if (Succeeded(hr))
{
plStride = lDefaultStride;
if (lDefaultStride < 0)
{
// Bottom-up orientation. Return a pointer to the start of the
// last row *in memory* which is the top row of the image.
ppbScanLine0 += lDefaultStride * (dwHeightInPixels - 1);
}
else
{
// Top-down orientation. Return a pointer to the start of the
// buffer.
ppbScanLine0 = pData;
}
}
}
bLocked = (Succeeded(hr));
return(hr);
}
private void Lockit(IMFMediaBuffer pOut, out IMF2DBuffer pOut2D, out int lDestStride, out IntPtr pDest)
{
MFError throwonhr;
pOut2D = pOut as IMF2DBuffer;
if (pOut2D != null)
{
throwonhr = pOut2D.Lock2D(out pDest, out lDestStride);
}
else
{
int ml;
int cb;
throwonhr = pOut.Lock(out pDest, out ml, out cb);
lDestStride = m_lStrideIfContiguous;
}
}