AForge.Video.DirectShow.FilterInfoCollection.CollectFilters C# (CSharp) Method

		private void CollectFilters( Guid category )
		{
			object			comObj = null;
			ICreateDevEnum	enumDev = null;
			IEnumMoniker	enumMon = null;
			IMoniker[]		devMon = new IMoniker[1];
			int				hr;

            try
            {
                // Get the system device enumerator
                Type srvType = Type.GetTypeFromCLSID( Clsid.SystemDeviceEnum );
                if ( srvType == null )
                    throw new ApplicationException( "Failed creating device enumerator" );

                // create device enumerator
                comObj = Activator.CreateInstance( srvType );
                enumDev = (ICreateDevEnum) comObj;

                // Create an enumerator to find filters of specified category
                hr = enumDev.CreateClassEnumerator( ref category, out enumMon, 0 );
                if ( hr != 0 )
                    throw new ApplicationException( "No devices of the category" );

                // Collect all filters
                IntPtr n = IntPtr.Zero;
                while ( true )
                {
                    // Get next filter
                    hr = enumMon.Next( 1, devMon, n );
                    if ( ( hr != 0 ) || ( devMon[0] == null ) )
                        break;

                    // Add the filter
                    FilterInfo filter = new FilterInfo( devMon[0] );
                    InnerList.Add( filter );

                    // Release COM object
                    Marshal.ReleaseComObject( devMon[0] );
                    devMon[0] = null;
                }

                // Sort the collection
                InnerList.Sort( );
            }
            catch
            {
            }
			finally
			{
				// release all COM objects
				enumDev = null;
				if ( comObj != null )
				{
					Marshal.ReleaseComObject( comObj );
					comObj = null;
				}
				if ( enumMon != null )
				{
					Marshal.ReleaseComObject( enumMon );
					enumMon = null;
				}
				if ( devMon[0] != null )
				{
					Marshal.ReleaseComObject( devMon[0] );
					devMon[0] = null;
				}
			}
		}
    }