public virtual void  videoFrame(VideoFrame tag)
		{
		}
		public override void  videoFrame(VideoFrame tag)
		{
			tags.Add(tag);
		}
		private Tag decodeVideoFrame(int length)
		{
			VideoFrame t;
			t = new VideoFrame();
			int pos = r.Offset;
			
			int idref = r.readUI16();
			t.stream = (DefineVideoStream) dict.getTag(idref);
			t.frameNum = r.readUI16();
			
			length -= (r.Offset - pos);
			
			t.videoData = new byte[length];
			r.readFully(t.videoData);
			return t;
		}