//-----------------------------------------------------------------------------
// GetDefaultStride
//
// Gets the default stride for a video frame, assuming no extra padding bytes.
//
//-----------------------------------------------------------------------------
private static int GetDefaultStride(IMFMediaType pType, out int plStride)
{
int lStride;
plStride = 0;
// Try to get the default stride from the media type.
var hr = pType.GetUINT32(MFAttributesClsid.MF_MT_DEFAULT_STRIDE, out lStride);
if (Failed(hr))
{
// Attribute not set. Try to calculate the default stride.
Guid subtype;
var width = 0;
// ReSharper disable once TooWideLocalVariableScope
// ReSharper disable once RedundantAssignment
var height = 0;
// Get the subtype and the image size.
hr = pType.GetGUID(MFAttributesClsid.MF_MT_SUBTYPE, out subtype);
if (Succeeded(hr))
{
hr = CProcess.MfGetAttributeSize(pType, out width, out height);
}
if (Succeeded(hr))
{
var f = new FourCC(subtype);
hr = MFExtern.MFGetStrideForBitmapInfoHeader(f.ToInt32(), width, out lStride);
}
// Set the attribute for later reference.
if (Succeeded(hr))
{
hr = pType.SetUINT32(MFAttributesClsid.MF_MT_DEFAULT_STRIDE, lStride);
}
}
if (Succeeded(hr))
{
plStride = lStride;
}
return(hr);
}
//-------------------------------------------------------------------
// SetVideoType
//
// Set the video snapFormat.
//-------------------------------------------------------------------
public int SetVideoType(IMFMediaType pType)
{
Guid subtype;
var PAR = new MFRatio();
// Find the video subtype.
var hr = pType.GetGUID(MFAttributesClsid.MF_MT_SUBTYPE, out subtype);
try
{
if (Failed(hr))
{
throw new Exception();
}
// Choose a conversion function.
// (This also validates the snapFormat type.)
hr = SetConversionFunction(subtype);
if (Failed(hr))
{
throw new Exception();
}
//
// Get some video attributes.
//
// Get the frame size.
hr = CProcess.MfGetAttributeSize(pType, out width, out height);
if (Failed(hr))
{
throw new Exception();
}
// Get the image stride.
hr = GetDefaultStride(pType, out lDefaultStride);
if (Failed(hr))
{
throw new Exception();
}
// Get the pixel aspect ratio. Default: Assume square pixels (1:1)
hr = CProcess.MfGetAttributeRatio(pType, out PAR.Numerator, out PAR.Denominator);
if (Succeeded(hr))
{
pixelAR = PAR;
}
else
{
pixelAR.Numerator = pixelAR.Denominator = 1;
}
var f = new FourCC(subtype);
format = (Format)f.ToInt32();
// Create Direct3D swap chains.
hr = CreateSwapChains();
if (Failed(hr))
{
throw new Exception();
}
// Update the destination rectangle for the correct
// aspect ratio.
UpdateDestinationRect();
}
finally
{
if (Failed(hr))
{
format = Format.Unknown;
m_convertFn = null;
}
}
return(hr);
}