摘要
多媒体通信在日常工作和生活中扮演着越来越重要的角色。随着计算机硬件技术的飞速发展,多媒体数据处理的软件化已成为大势所趋。
通常的数据传输方式分为点对点、广播和组播三种。由于广播的技术局限性和组播的客观条件限制,本文的软件采用了点对点的传输方式。并且根据实际要求的不同,采用不同的网络拓扑模式来减轻点对点方式带来的负面效应。
本文实现了三个软件:基于卫星链路的双向视频音频实时传输软件、点对点模式多媒体会议软件和客户/服务器模式多媒体会议软件。
第一个软件结合一个工程实践,采用面向对象软件设计方法,实现了在卫星链路上的视频音频双向传输。其中视频编解码标准采用改进后的H.263,音频编解码标准采用G.711。由于面向对象方法是源代码级共享,软件结构复杂。
后两个软件在分析传统软件设计方法固有的缺陷后,引入了基于COM组件的软件设计思想,实现了二进制级的代码共享,使软件在功能扩展性、代码可维护性、结构开放性等方面都有显著改进。
在本文最后一章里,提出一种利用神经计算进行视频输出码率控制的算法。
Multimedia transportation has been playing a increasingly important role in our work and life . With the rapid progress of computer hardware technique , it is a trend to software-realize the data processing of multimedia .
Generally , there are three kind of method to transport data . Namely , point-to-point, broadcasting and multicasting . Considering the technique limitation of broadcasting and the practical limitation of multicasting , the point-to-point method is adopted in the applications of this paper .
This paper involves three software applications , the software in the duplex transmission system of video and audio based on satellite channel , multimedia conference software based on peer-to-peer network topology and multimedia conference software based on client-server network topology .
The object-oriented design method is adopted in the first application , which can send and receive video and audio data on satellite channel . The ITU-T recommendation of H.263 is improved and accepted as the video compression standard . G.711 is selected as the audio standard .
After the inherent limitation of OOD is analysed , the component object module is introduced and applied to design and develop the second and the third applications ,which have some obvious advantages in the aspects of function extension , code maintenance and structure flexibility .
In the last chapter , a neural computing algorithm for bit rate control is designed.
引文
[1] ITU-T Recommendation H.263,“Video coding for low bit rate communication”,Feb 1998
[2] ITU-T Recommendation H.261,“Video codec for audiovisual services at px64 kbit/s”,March 1993
[3] ITU-T Recommendation G.711,“Pulse code modulation (PCM) of voice frequencies”,Nov 1988
[4] MSDN Library,Platform SDK,Networking and Distributed Services,“Telephony Application Programming Interface (TAPI)”,2001
[5] MSDN Library,Platform SDK,Windows Base Services,“Files and I/O”,2001
[6] MSDN Library,Visual C++ Documentation,Reference,“Microsoft Foundation Classes Library and Templates”,2001
[7] MSDN Library,Platform SDK,Graphics and Multimedia Services,Multimedia Audio,“WaveForm Audio”,2001
[8] MSDN Library,Platform SDK,Graphics and Multimedia Services,DirectX,“DirectSound”,2001
[9] MSDN Library,Platform SDK,Graphics and Multimedia Services,Multimedia Audio,“Audio Mixers”,2001
[10] MSDN Library,Platform SDK,Graphics and Multimedia Services,Video for Windows,“Video Capture”,2001
[11] MSDN Library,Platform SDK,Graphics and Multimedia Services,Video for Windows,“DrawDib”,2001
[12] MSDN Library,Platform SDK,Graphics and Multimedia Services,DirectX,“DirectDraw”,2001
[13] MSDN Library,Platform SDK,COM and ActiveX Object Services,“COM”,2001
[14] MSDN Library,Platform SDK,Networking and Distributed Services,“Windows Sockets Version 2” ,2001
[15] William Stallings,“Operating Systems Internals and Design Principles”(影印版),清华大学出版社,1998.6
[16] Microsoft , “DirectX 8a SDK”,2000.10
[17] 李明峰,“基于卫星链路的双向实时数据和图象传输系统及接口电路研究”(学位论文),中科院空间中心,2001.6
[18] 张明德 等,“视频会议系统原理与应用”,北京:北京希望电子出版社,1999.8
[19] 鲁士文,“计算机网络原理与网络技术”,北京:机械工业出版社,1996.12
[20] 沈兰荪 等,“视频编码与低速率传输”,北京:电子工业出版社,2001.12
[21] 陈鸣,“多媒体技术”,北京:人民邮电出版社,1994.2
[22] 黎洪松,“数字视频技术及其应用”,北京:清华大学出版社,1997.5
[23] 钟玉琢等,“基于对象的多媒体数据压缩编码国际标准-MPEG-4及其校验模型”,北京:科学出版社,2000.10
[24] [美]Kenneth D. Reed 著,3Com公司译,“TCP/IP基础”,北京,电子工业出版社,2002.1
[25] [美]Olivier Hersent等著,邝坚等译“IP电话-基于分组的多媒体通信系统”,北京,人民邮电出版社,2000.11
[26] Tekalp A. M., “Digital Video Processing”,北京:清华大学出版社,1998.5
[27] [美]David J. Kruglinski著,潘爱民 王国印 译,“Visual C++技术内幕”,北京:清华大学出版社,1999.1
[28] 官章全 等,“Visual C++ 6.0类库大全”,电子工业出版社,1999.12
[29] 何斌 等,“Visual C++ 数字图象处理”,人民邮电出版社,2001.4
[30] [美]David J. Kruglinski 等,“Visual C++ 6.0技术内幕”,北京希望电子出版社,1999.5
[31] [美]Corry等著,刘云 等译,“COM/DCOM编程指南”,清华大学出版社,2001.1
[32] [美]Richard C.Leinecker, Tom Archer著,齐舒创作室 译,“Windows 98编程实用大全”,北京:中国水利水电出版社,1999.1
[33] 蒋东兴 等,“Windows Sockets网络程序设计大全”,北京:清华大学出版社,1999.4
[34] [美]Scott Stanfield, Ralph Arvesen著,华译工作室译,“Visual C++ 4.0开发人员指南”,北京:机械工业出版社,1997.4
[35] 蒋华 等,“Visual C++ 5.0编程技术”,北京:北京航空航天大学出版社,1998.3
[36] [美]Leinecker R.C.著,“Visual C++ 5开发人员参考手册”,北京:机械工业出版社,1998.6
[37] 木林森 等,“Visual C++ 5.0使用与开发”,北京:清华大学出版社,1997.10
[38] 潘爱民,“Visual C++5.0中的多线程编程技术”,电子&电脑,1998.4
[39] 吴云 等,“Windows 95 下多线程编程技术及其实现”,计算机世界,1997.9
[40] 胡守仁 主编,“神经网络导论”,长沙:国防科技大学出版社,1993.10
[41] 袁曾任,“人工神经元网络及其应用”,北京:清华大学出版社,1999.10
致谢