(1.Department of Computer Science and Information Technology,Guangzhou Maritime Collge,Guangzhou 510725,China;2.College of Computer Science and Engineering,South China University of Technology,Guangzhou 510641,China;3.Center of Research and Development,Nanwang Multimedia Technology Group CO.,LTD.,Hangzhou 310002,China;4.College of Mechanical Engineering,South China University of Technology,Guangzhou 510640,China)