[DllImport("gstreamer-0.10.dll")]
    private static extern bool gst_pad_query_position(IntPtr raw, ref Format format, out long cur);

    public bool QueryPosition(Gst.Format format, out long current) 
    {
        return gst_pad_query_position(Handle, ref format, out current);
    }

    [DllImport("gstreamer-0.10.dll")]
    private static extern bool gst_pad_query_duration(IntPtr raw, ref Format format, out long duration);

    public bool QueryDuration(Gst.Format format, out long duration) 
    {
        return gst_pad_query_duration(Handle, ref format, out duration);
    }


	public delegate bool BufferProbeDelegate(Pad pad, Gst.Buffer buffer);
	internal delegate bool BufferProbeNativeDelegate(IntPtr pad, IntPtr buf, IntPtr data);

	internal class BufferProbeWrapper {
		internal BufferProbeNativeDelegate NativeFunc;
		BufferProbeDelegate managedFunc;

		public BufferProbeWrapper(BufferProbeDelegate func) 
		{
			managedFunc = func;
			if(func != null)
				NativeFunc = new BufferProbeNativeDelegate(BufferProbeMarshaller);
		}

		public bool BufferProbeMarshaller(IntPtr raw_pad, IntPtr buf, IntPtr data)
		{
			Pad pad = GLib.Object.GetObject(raw_pad) as Pad;
			Gst.Buffer buffer = GLib.Opaque.GetOpaque(buf, typeof(Gst.Buffer), false) as Gst.Buffer;
			return (bool) (managedFunc (pad, buffer));
		}
	}

	[DllImport("gstreamer-0.10.dll")]
	private static extern ulong gst_pad_add_buffer_probe(IntPtr pad, BufferProbeNativeDelegate func, IntPtr data); 

	public ulong AddBufferProbe(BufferProbeDelegate func)
	{
		BufferProbeWrapper func_wrapper;
		if(PersistentData["AddBufferProbe"] != null) {
			func_wrapper = PersistentData["AddBufferProbe"] as BufferProbeWrapper;
		}
		else 
		{
			func_wrapper = new BufferProbeWrapper(func);
			PersistentData["AddBufferProbe"] = func_wrapper;
		}	

		return gst_pad_add_buffer_probe(this.Handle, func_wrapper.NativeFunc, IntPtr.Zero);
	} 

	[DllImport("gstreamer-0.10.dll")]
	private static extern void gst_pad_remove_buffer_probe(IntPtr pad, uint handler_id);

	public void RemoveBufferProbe(uint handler_id)
	{
		gst_pad_remove_buffer_probe(this.Handle, handler_id);
		PersistentData["AddBufferProbe"] = null;
	}

	public delegate bool DataProbeDelegate (Pad pad, GLib.Opaque miniobject); 
	internal delegate bool DataProbeNativeDelegate(IntPtr pad, IntPtr miniobj, IntPtr data);

	internal class DataProbeWrapper {
		internal DataProbeNativeDelegate NativeFunc;
		DataProbeDelegate ManagedFunc;

		public DataProbeWrapper(DataProbeDelegate func)
		{
			ManagedFunc = func;
			if(func != null)
				NativeFunc = new DataProbeNativeDelegate(DataProbeMarshaller);
		}

		public bool DataProbeMarshaller (IntPtr raw_pad, IntPtr miniobj, IntPtr data)
		{
			Pad pad = GLib.Object.GetObject(raw_pad) as Pad;
			GLib.Opaque opaque = GLib.Opaque.GetOpaque(miniobj, typeof(GLib.Opaque), true);
			return ManagedFunc(pad, opaque);
		}
	}

	[DllImport("gstreamer-0.10.dll")]
	static extern uint gst_pad_add_data_probe(IntPtr pad, DataProbeNativeDelegate func, IntPtr data);

	public uint AddDataProbe(DataProbeDelegate func) 
	{
		DataProbeWrapper func_wrapper;
		if(PersistentData["AddDataProbe"] != null) {
			func_wrapper = PersistentData["AddDataProbe"] as DataProbeWrapper;
		} else {
			func_wrapper = new DataProbeWrapper(func);
			PersistentData["AddDataProbe"] = func_wrapper;
		}

		return gst_pad_add_data_probe(this.Handle, func_wrapper.NativeFunc, IntPtr.Zero);
	}

	[DllImport("gstreamer-0.10.dll")]
	static extern void gst_pad_remove_data_probe(IntPtr pad, uint handler_id);

	public void RemoveDataProbe(uint handler_id) 
	{
		gst_pad_remove_data_probe(this.Handle, handler_id);
		PersistentData["AddDataProbe"] = null;
	}