Comparison of shaping and buffering for video transmission.pdf

Comparison of Shaping and Buffering for Video Transmission Gyo?rgy Da?n and Vikto?ria Fodor Royal Institute of Technology, Department of Microelectronics and Information Technology P.O.Box Electrum 229, SE-16440 Kista, Sweden gyuri,viktoria
@it.kth.se Abstract Video communication over the Internet requires performance guarantees in terms of limited packet loss probability and end to end delay. This paper compares two possible net- work scenarios for transmitting video streams, source shaping combined with small buffers at the network nodes and delay limited buffering in the network. It is shown that due to its simplicity and performance comparable to buffering source shaping can provide the solution for efficient video transmission in the Internet. 1 Introduction The transmission of video traffic over large packet switched networks like the Internet is still a fundamental problem of network design. First, video applications require quality of service guarantees from the network, in terms of limited packet loss, end to end delay and delay vari- ation. The acceptable packet loss probability depends on the video coding scheme and is in the range of 10  5 –10  3 . The delay limitation depends on the application. While in the case of computer to human applications delay can be up to several seconds, in the case of human to human applications delay should be kept below 150 ms. Second, the provisioning of the required quality at a network utilization acceptable for the operator is a complex issue due to the characteristics of coded video streams. Considering the widely used MPEG coding, the transmission rate is changing in short and long time scales. Moreover, as a result of data compression the distribution of the packet losses affects the percepted visual quality: multiple packet loss in a single frame decreases the visual quality of the corresponding picture, and the effect of a packet loss in an I frame propagates to P and B frames. Research and developement effo