/// <summary>
/// Retrieves an attribute at the specified index.
/// </summary>
/// <param name="attributes">A valid IMFAttributes instance.</param>
/// <param name="index">The index to retrieve.</param>
/// <param name="guidKey">The key of this attribute.</param>
/// <param name="value">The value of this attribute.</param>
/// <returns>If this function succeeds, it returns the S_OK member. Otherwise, it returns another HResult's member that describe the error.</returns>
public static HResult GetItemByIndex(this IMFAttributes attributes, int index, out Guid guidKey, out object value)
{
if (attributes == null)
{
throw new ArgumentNullException("attributes");
}
if (index < 0)
{
throw new ArgumentOutOfRangeException("index");
}
HResult hr = 0;
value = null;
using (PropVariant variant = new PropVariant())
{
hr = attributes.GetItemByIndex(index, out guidKey, variant);
if (hr.Succeeded())
{
value = variant.GetObject();
}
}
return(hr);
}
public static IEnumerable <KeyValuePair <Guid, _MF_ATTRIBUTE_TYPE> > Enumerate(this IMFAttributes obj)
{
if (obj == null)
{
yield break;
}
for (int i = 0; i < Count(obj); i++)
{
obj.GetItemByIndex((uint)i, out Guid guid, null).ThrowOnError();
obj.GetItemType(guid, out var type).ThrowOnError();
yield return(new KeyValuePair <Guid, _MF_ATTRIBUTE_TYPE>(guid, type));
}
}
private PropertySet PropSetFromAttributes(IMFAttributes attributes)
{
if (attributes == null)
{
return(null);
}
var retValue = new PropertySet();
uint cCount = 0;
attributes.GetCount(out cCount);
for (uint i = 0; i < cCount; i++)
{
Guid key;
Object item = null;
attributes.GetItemByIndex(i, out key, ref item);
retValue.Add(key.ToString(), item);
}
return(retValue);
}
public HResult GetItemByIndex(int unIndex,
out Guid pguidKey, PropVariant pValue)
{
return(m_Attribs.GetItemByIndex(unIndex, out pguidKey, pValue));
}
private string LogAttributeValueByIndex(IMFAttributes pAttr, int index, ref CaptureFormat capFormat)
{
//string pGuidName = null;
//string pGuidValName = null;
Guid guid = Guid.Empty;
PropVariant var = new PropVariant();
//PropVariantInit(&var);
int hr = pAttr.GetItemByIndex(index, out guid, var);
MFError.ThrowExceptionForHR(hr);
if (guid == MFAttributesClsid.MF_MT_FRAME_RATE)
{
//Trace.WriteLine("MF_MT_FRAME_RATE");
int lower = (int)var.GetULong();
//Trace.WriteLine("LogAttr1_1 = " + lower.ToString());
int upperbits = (int)(var.GetULong() >> 32);
//Trace.WriteLine("LogAttr1_2 = " + upperbits.ToString());
float fr = (float)upperbits / (float)lower;
capFormat.Framerate = fr;
Trace.WriteLine("FrameRate = " + fr.ToString());
return("Framerate=" + fr.ToString() + ", ");
}
else if (guid == MFAttributesClsid.MF_MT_FRAME_RATE_RANGE_MAX)
{
//Trace.WriteLine("MF_MT_FRAME_RATE_RANGE_MAX");
int lower = (int)var.GetULong();
//Trace.WriteLine("LogAttr1_1 = " + lower.ToString());
int upperbits = (int)(var.GetULong() >> 32);
//Trace.WriteLine("LogAttr1_2 = " + upperbits.ToString());
//return "MaxFramerate=" + fr.ToString() + ", ";
}
else if (guid == MFAttributesClsid.MF_MT_FRAME_RATE_RANGE_MIN)
{
//Trace.WriteLine("MF_MT_FRAME_RATE_RANGE_MIN");
int lower = (int)var.GetULong();
//Trace.WriteLine("LogAttr1_1 = " + lower.ToString());
int upperbits = (int)(var.GetULong() >> 32);
float fr = (float)upperbits / (float)lower;
//return "MinFramerate=" + fr.ToString() + ", ";
//Trace.WriteLine("LogAttr1_2 = " + upperbits.ToString());
}
else if (guid == MFAttributesClsid.MF_MT_FRAME_SIZE)
{
//Trace.WriteLine("MF_MT_FRAME_SIZE");
int lower = (int)var.GetULong();
// Trace.WriteLine("LogAttr1_1 = " + lower.ToString());
int upperbits = (int)(var.GetULong() >> 32);
//Trace.WriteLine("LogAttr1_2 = " + upperbits.ToString());
capFormat.Height = lower;
capFormat.Width = upperbits;
Trace.WriteLine("Resolution=" + lower.ToString() + "X" + upperbits.ToString());
return("Resolution=" + lower.ToString() + "X" + upperbits.ToString());
}
else if (guid == MFAttributesClsid.MF_MT_PIXEL_ASPECT_RATIO)
{
//Trace.WriteLine("MF_MT_PIXEL_ASPECT_RATIO");
int lower = (int)var.GetULong();
//Trace.WriteLine("LogAttr1_1 = " + lower.ToString());
int upperbits = (int)(var.GetULong() >> 32);
//Trace.WriteLine("LogAttr1_2 = " + upperbits.ToString());
}
else if (guid == MFAttributesClsid.MF_MT_GEOMETRIC_APERTURE)
{
//Trace.WriteLine("MF_MT_GEOMETRIC_APERTURE");
//Trace.WriteLine("LogAttr2 = " + var.ToString());
}
else if (guid == MFAttributesClsid.MF_MT_MINIMUM_DISPLAY_APERTURE)
{
//Trace.WriteLine("MF_MT_MINIMUM_DISPLAY_APERTURE");
//Trace.WriteLine("LogAttr2 = " + var.ToString());
}
else if (guid == MFAttributesClsid.MF_MT_PAN_SCAN_APERTURE)
{
//Trace.WriteLine("MF_MT_PAN_SCAN_APERTURE");
//Trace.WriteLine("LogAttr2 = " + var.ToString());
}
else if (guid == MFAttributesClsid.MF_MT_SUBTYPE)
{
capFormat.PixelFormat = var.GetGuid();
}
else
{
Trace.WriteLine("Unknown attr " + guid.ToString() + " val = " + var.ToString());
}
return("");
}