Streaming Video Using Dynamic Rate Shaping and TCP Congestion Control
✍ Scribed by Stephen Jacobs; Alexandros Eleftheriadis
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 392 KB
- Volume
- 9
- Category
- Article
- ISSN
- 1047-3203
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✦ Synopsis
ously defined. The fixed delay assumption is allowed to be relaxed in practice, with the addition of extra buffering at
We present a new technique for streaming real time video on today's Internet, based on dynamic rate shaping and TCP the receiver. It is much more difficult to deviate from the congestion control. Dynamic rate shaping is a signal processing constant bandwidth requirement; solutions from the codec technique that adapts the rate of compressed video (MPEG-1, side include multiresolution or scalable coding, as well as MPEG-2, H.26x) to dynamically varying bandwidth conbuilt-in robustness measures that aid in error recovery and straints. This provides an interface (or filter) between the source concealment. From a networking standpoint, an approxiand the network, with which the encoder's output (either live mation to such an ideal communication system can be or stored) can be perfectly matched to the network's available provided using quality of service (QoS) guarantees. Such bandwidth. We couple this adaptation capability with the use guarantees can aid in fully or partially characterizing netof a new semi-reliable protocol that uses the TCP congestion work ''imperfections,'' and allow the implementation of window to pace the delivery of data into the network, but proactive measures to work around them. without using other TCP algorithms that are poorly suited to Our interest in this paper is focused on Internet-based real time media. Use of TCP congestion control ensures that the protocol competes fairly with all other TCP data and that delivery of real-time digital video, and in particular it optimally shares the available bandwidth. It also avoids the MPEG-1 [14, 19] and MPEG-2 video [13, 15]. Both obvilatency problems commonly associated with TCP. In addition, ously represent the most pervasive technical solutions in we describe a real application that uses this approach to stream their respective fields, and a successful solution that caters MPEG video on the Internet. We present several experiments, to their particular needs can have a significant impact. performed in both a controlled environment and the wide area The underlying technologies of today's Internet are not Internet, that were used to evaluate the effectiveness and fairsufficient to support QoS guarantees which would facilitate ness of the scheme. The results show that the proposed solution real-time services. The evolution of these technologies achieves superior video quality while at the same time providing could result in any number of possibilities, including ATM fairness by sharing bandwidth equally with other non-real-time backbones, IP switching, or fully deployed ATM networks.
connections.