Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
2000-05-09
2004-01-20
Britton, Howard (Department: 2613)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
C375S240120
Reexamination Certificate
active
06680976
ABSTRACT:
BACKGROUND OF THE INVENTION
Transmitting digital video over the current Internet is difficult. There is a big gap between Internet bandwidth and video bit rate. The current Internet is a best effort, unreliable network with no Quality of Service (QoS) guarantees. These difficulties require that an effective Internet video coding and transmission scheme be low bit rate and robust. The conflicting requirements of low bit rate and robustness requires a delicate balance between them. Traditional coding methods are optimized for compression ratio and rely on transmission schemes to provide robustness. The current Internet environment cannot provide desired robustness without sacrificing low delay and other real time requirements. Traditional schemes dealing with packet loss and error recovery are not suitable for the Internet because they are designed for specific environments under specific assumptions.
The Internet and its most important application the World Wide Web(WWW) have experienced exponential growth and gained widespread recognition during the past few years. The Internet and the WWW show the promise of becoming a global platform for computing, communication and collaboration. One reason for the phenomenal success of the Internet and the WWW is the successful integration of textual and graphical data and transmission of these static data types. The value of real time media, like real time video and audio on the Internet and WWW has been widely recognized. See, for example, C. Adie, “A survey of distributed multimedia research, standards and products”, ftp://ftp.ed.ac.uk/pub/mmsurvey/, January 1993 (Adi93); C. Adie, “Network access to multimedia information”, ftp://ftp.ed.ac.uk/pub/mmsurvey/, February 1994 (Adi94); T. J. Berners-Lee, R. Cailliau, J. F. Groff, and B. Pollerman, “World Wide Web: The Information Universe”, Electronic Networking: Research, Applications and Policy, 2(1):52-58, 1992 (BLCGP92); F. Kappe and N. Sherbakov, “Hyper-G: A Universal Hypermedia System”, ftp://iicm.tu-graz.ac.at/pub/Hyper-G/doc/report333.txt.Z, March 1992 (KS92); Z. Chen, S. Tan, R. Campbell, and Y. Li, “Real time video and audio in the World Wide Web”, In Proc Fourth International World Wide Web Conference, 1995 (CTCL95); Vosaic LLC white paper, http://choices.cs.uiuc.edu/Papers/New/www5/www5.html, February 1996 (wp96a); VXtreme Inc white paper, “Enabling Interactive Video Over the Internet”, http://www.vxtreme.com/developers/wp960304.html, March 1996 (wp96b); and Progressive Networks Inc. RealVideo Technical White Paper, http://www.realaudio.com/products/realvideo/overview/index.html, 1997 (Inc97). Supporting dynamic real time media such as real time video and audio, on the Internet enables new applications like real time visual communication, entertainment and distance learning and training, while enhancing the capability of existing ones. Internet video delivery has shown great commercial potential and, therefore, has encouraged a substantial number of commercial developments, e.g., as described in Xing Technology Corporation, “StreamWorks”, http://www.xingtech.com/, 1996 (Cor96b); VDOnet Corporation, “VDOLive Internet Video Servers and Players”, http://www.vdolive.com/, 1996 (Cor96a); InterVU Inc., “Inervu Video Delivery Products”, http://www.intervu.com/, 1996 (Inc96a); Vivo Inc., “VivoActive Video Delivery Products”, http://www.vivo.com/, 1996 (Inc96c); and VXtreme Inc., “VXtreme Video Delivery Products”, http://www.vxtreme.com/, 1996 (Inc96d). However, because of the shortened Internet software development cycles, these commercial developments tend to rush to product development, often skipping or shortening the research phase. Unlike browser and push products, which require less planning, research-intensive video products are not suited to the shortened Internet software development cycle. Interesting research issues arise from a number of aspects of Internet video coding and transmissions. Solutions to these research problems cannot be found in traditional video compression and network transmission literature where the problems are often addressed in different environments under very different assumptions. The present invention is directed to the problem of how to effectively encode and transmit video over the Internet.
Supporting digital video on the Internet and WWW is very difficult. Unlike textual and image data, networked digital video requires efficient compression, large storage space, and sufficient bandwidth. Some of these requirements cannot be met in the current Internet environment. As a result, Internet video applications have suffered from poor transmission and playback quality. Of the many difficulties facing these applications, the two most significant are: (1) the gap between bit rate and bandwidth, and (2) the unreliable nature of the Internet.
Bit Rate and Bandwidth Gap A large gap exists between the compressed video bit rate and Internet bandwidth. Even with sophisticated video compression, the bit rate of digital video is often too high for most Internet connections. For example, a compressed full frame rate (30 f/s) broadcast quality (720×480) video runs at a bit rate of 3-8 Mbps using MPEG compression. See, V. Bhaskaran and K. Konstantinides.
Image and Video Compression Standards: Algorithms and Architectures
, Kluwer Academic Publications, 1995 (BK95). A good Internet connection with a shared Ti line has a maximum bandwidth of 1.5 Mbps. Even with compromised video frame rate, quality and frame size, the bit rate is often high for average and low bandwidth connections. For example, a 10/320×240 video typically has a bit rate of 100 Kbps to 400 Kbps with MPEG compression. Currently a home user with dial-up or ISDN service can get a typical bit rate in the range from 14 Kbps to 128 Kbps.
Unreliable Nature of the Internet The Internet is inherently a packet switched, best effort, unreliable network. Research is being conducted toward a network with guaranteed quality of service (QoS). See, D. D. Clark, S. Shenker, and L. Zhang. “Supporting real-time application in an integrated services packet network: Architecture and mechanism” In Proc. of SIGCOM′92, 1992 (CSZ92); H. T. Kung, T. Blackwell, and A. Chapman. “Credit-based ow control for ATM networks: Credit update protocol, adaptive credit allocation, and statistical multiplexing”, In Proc SIGCOM′94, 1994 (KBC94); C. Partridge. Gigabit Networking, Addison-Wesley, 1993 (Par93); and L. Zhang, S. Deering, D. Estrin, and D. Zappala. “RSVP: A New Resource ReSerVation Protocol”, IEEE Network, September 1993 (ZDEZ93). However, there is no QoS guarantee on the current Internet. Packets on the Internet can get delayed, duplicated, or lost during the delivery process. Existing flow control and error handling schemes like those implemented in TCP (See, e.g., D. Comer and D. Stevens.
Internetworking with TCP/IP Volume
1
Principles. Protocols. and Architecture
, Prentice Hall, Englewood Cliffs, N.J., 1991 (CS91); and [Jac88] V. Jacobson. Congestion Avoidance and Control. In Proc. ACM Sigcom′88, pages 314-329, Stanford, Calif., August 1988 (Jac88)) ensure 100% reliability; however, they do not consider timely delivery. Therefore, they are only suitable for reliable non-realtime text and image transmission. As discussed below, these flow control and error handling schemes cause an unnecessarily large delay for delivery and are not suitable for video and other media. Internet video transmission has to deal with delay, jitter and packet losses. While delay and jitter can be effectively dealt with for on-demand services (CTCL95), packet loss is the major source of problems for Internet video transmission and playback. Dealing with packet losses requires both robust video coding and efficient transmission.
Internet video transmission must overcome the difficulties caused by the bit rate bandwidth gap and the unreliable nature of the Internet. The bit rate and Internet bandwidth gap requires efficient video compression schemes with very low bit rate. The unreliable nature of the Inter
Campbell Roy H.
Chen Zhigang
Britton Howard
The Board of Trustees of the University of Illinois
Woodard Emhardt Moriarty McNett & Henry LLP
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