/// <summary>
/// Retrieves a string from a header
/// </summary>
/// <param name="wma">WMA file instance being edited</param>
private static string GetStringTag(Win32.IWMHeaderInfo3 wma, string attribute)
{
ushort stream = 0; // Stream number
IntPtr ptData; // Data buffer pointer
ushort cbData = 0; // Length of data buffer
Win32.WMT_ATTR_DATATYPE type; // Attribute type
// Determine the size of the buffer we need to allocate and then go get the attribute
string ATTR = attribute + "\0";
try { wma.GetAttributeByName(ref stream, ATTR, out type, IntPtr.Zero, ref cbData); }
catch { return(null); }
if (type != Win32.WMT_ATTR_DATATYPE.WMT_TYPE_STRING)
{
return(null);
}
ptData = Marshal.AllocCoTaskMem((int)cbData);
try
{
wma.GetAttributeByName(ref stream, ATTR, out type, ptData, ref cbData);
return(Marshal.PtrToStringUni(ptData));
}
finally { Marshal.FreeCoTaskMem(ptData); } // Release allocated memory
}
/// <summary>
/// Retrieves the Duration from a header
/// </summary>
/// <param name="wma">WMA file instance being edited</param>
private static long GetTrackDuration(Win32.IWMHeaderInfo3 wma)
{
ushort stream = 0; // Stream number
IntPtr ptData; // Data buffer pointer
ushort cbData = 0; // Length of data buffer
Win32.WMT_ATTR_DATATYPE type; // Attribute type
// Determine the size of the buffer we need to allocate, and of course if the
// WM/TrackNumber attribute even exists in this header
const string ATTR = "Duration\0";
try { wma.GetAttributeByName(ref stream, ATTR, out type, IntPtr.Zero, ref cbData); }
catch { return(0); }
ptData = Marshal.AllocCoTaskMem((int)cbData);
try
{
wma.GetAttributeByName(ref stream, ATTR, out type, ptData, ref cbData);
switch (type)
{
case Win32.WMT_ATTR_DATATYPE.WMT_TYPE_DWORD:
return((long)Marshal.ReadInt32(ptData));
case Win32.WMT_ATTR_DATATYPE.WMT_TYPE_QWORD:
return(Marshal.ReadInt64(ptData));
case Win32.WMT_ATTR_DATATYPE.WMT_TYPE_STRING:
return(Convert.ToInt64(Marshal.PtrToStringUni(ptData)));
default:
throw new Exception("Unknown Duration data type detected");
}
}
finally { Marshal.FreeCoTaskMem(ptData); } // Release allocated memory
}