	var uploadedSize = evt.loaded + start_offset; 
			var percentComplete = Math.round(uploadedSize * 100 / totalFilesize);

			var timestamp = (new Date()).valueOf();
			var isFinish = evt.loaded == evt.total;

			if (timestamp > oldTimestamp || isFinish) {
				var duration = timestamp - oldTimestamp;
				if (duration > 500 || isFinish) {
					var size = evt.loaded - oldLoadsize;

					var bitrate = (size * 8 / duration /1024) * 1000; //kbps
					if (bitrate > 1000)
						bitrate = Math.round(bitrate / 1000) 