We present a modification of the new edge-directed interpolation method that eliminates the prediction error accumulation problem by adopting a modified training window structure, and extending the covariance matching into multiple directions to suppress the covariance mismatch problem. Simulation results show that the proposed method achieves remarkable subjective performance in preserving the edge smoothness and sharpness among other methods in the literaturé. It also demonstrates consistent objective performance among a variety of images.
A flow control for streaming multimedia data over UDP on IP network is presented. The bitrate adaptation algorithm embedded in the protocol is considered to be an end-to-end mechanism in the application level. The flow control system constantly maintains the streaming buffer at a prescribed capacity even with bursty network losses by adapting the multimedia bitrate B from the streaming codec. A congestion control algorithm which is considered to be located in a lower level than that of the flow control mechanism is presented. It works together with the presented flow control to resolve network congestion problems while maintaining a degree of TCP-friendliness by changing the sending rate R at the server. Simulation results obtained from NS2 have shown better resource allocation can be obtained, and an overall incrase in the average sending rate and hence better quality of streaming media is observed.
This paper investigates a novel active buffer management scheme, "Jitter Detection" (JD) for gateway-based congestion control to stream multimedia traffics in packet-switched networks. The quality of multimedia presentation can be greatly degraded due to network delay variation or jitter when transported over packet-switched network. Jitter degrades the timing relationship among packets in a single media stream and between packets from different media streams and hence creates multimedia synchronization problems. Moreover, too much jitter will also degrade the performance of the streaming buffer in the client. Packets received by client will render useless if they have accumulated a large enough jitter. The proposed active buffer management scheme will improve the quality of service in multimedia networking by detecting and discarding useless packets that accumulated large enough jitter. Such as to maintain a high bandwidth for packets within the multimedia stream's jitter
tolerance. Simulation results have shown that the proposed scheme can effectively lower the average received packet jitter and increase the goodput of the received packets when compared to random early detection (RED), and Droptail used in gateway-based congestion control. Furthermore, simulation results have also revealed that
the proposed scheme can maintain the same TCP-friendliness when compared to that of RED and Droptail used for multimedia streams.