Anaglyph ShaderEffect in WPF

///////////////////////////////////////////////////////////////////////////////
// CapHelper v1.1
//
// This software is released into the public domain.  You are free to use it
// in any way you like, except that you may not sell this source code.
//
// This software is provided "as is" with no expressed or implied warranty.
// I accept no liability for any damage or loss of business that this software
// may cause.
// 
// This source code is originally written by Tamir Khason (see http://blogs.microsoft.co.il/blogs/tamir
// or http://www.codeplex.com/wpfcap).
// 
// Modifications are made by Geert van Horrik (CatenaLogic, see http://blog.catenalogic.com) 
//
///////////////////////////////////////////////////////////////////////////////

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;

namespace CatenaLogic.Windows.Presentation.WebcamPlayer
{
    /// <summary>
    /// Class that helps finding the pins for a specific filter
    /// </summary>
    internal static class CapHelper
    {
        /// <summary>
        /// Gets a specific pin of a specific filter
        /// </summary>
        /// <param name="filter">Filter to retrieve the pin for (defines which object should make this method available)</param>
        /// <param name="dir">Direction</param>
        /// <param name="num">Number</param>
        /// <returns>IPin object or null</returns>
        public static IPin GetPin(this IBaseFilter filter, PinDirection dir, int num)
        {
            // Declare variables
            IPin[] pin = new IPin[1];
            IEnumPins pinsEnum = null;

            // Enumerator the pins
            if (filter.EnumPins(out pinsEnum) == 0)
            {
                // Get the pin direction
                PinDirection pinDir;
                int n = 0; ;

                // Loop the pins
                while (pinsEnum.Next(1, pin, out n) == 0)
                {
                    // Query the direction
                    pin[0].QueryDirection(out pinDir);

                    // Is the pin direction correct?
                    if (pinDir == dir)
                    {
                        // Yes, check the pins
                        if (num == 0)
                        {
                            return pin[0];
                        }
                        num--;
                    }

                    // Release the pin, this is not the one we are looking for
                    Marshal.ReleaseComObject(pin[0]);
                    pin[0] = null;
                }
            }

            // Not found
            return null;
        }
    }
}