Maria Hong

Scalable mobile internet servers: selecting useful images from the web for mobile services

Mobile devices can be easily connected to network anywhere today. Therefore, there are many studies on a variety of contents for mobile devices. In order to provide mobile contents for personal computers in a ubiquitous environment. In this paper, the author propose a framework for obtaining Internet contents intended for personal computers on mobile devices. In other words, the primary concern of this paper is to select the best images for optimal performance and convert them into images that can be effectively reproduced on mobile devices. In case contents should be suitable to various platform devices for service, the load of the server is increased. For this, the performance of the server is to be optimized through selecting useful images among the many available images and converting them while considering the display pixel rates (DPR) and the image distribution areas

Transcoding pattern generation for adaptation of digital items containing multiple media streams in ubiquitous environment

Digital item adaptation (DIA) is one of main parts in MPEG21. The goal of the DIA is to achieve interoperable transparent access to multimedia contents by shielding users from network and terminal installation, management and implementation issues. In general, a digital item consists of multiple discrete or continuous media and adaptation process is to be applied to one of its multiple media. Therefore in the process of adapting the given digital item, the transcoding order of its media has great impact on the adaptation performance because the adaptation process may stop at the point of satisfying a adaptation QoS(Quality of Services). In order to reduce the transcoding time which result in reducing the initial delay time, we propose a pattern based transcoding model for DIA. Because the performance of the model is dependent on the pattern, we also suggest a EPOB based pattern generation method. Finally a sample pattern was suggested based on the experimental results of the method.

Using a transcode and prefetch method for playing XML contents containing multiple multimedia data on mobile terminals

With the recent development in mobile communication, Internet connection via mobile terminals became possible Therefore, in order for data exchange between mutually different terminal types, XML-based contents are widely being used However, there are limitations in using mobile terminals to achieve real-time playback of XML-based contents including various multimedia data Among them, two main limitations are discussed in this study The first limitation is the utilization of low communication bandwidth in mobile terminals That is, the bandwidth of mobile terminals is too low (24kbps ~ 1.2Mbps) to accommodate the high bandwidth required in multimedia data The second limitation is the restricted memory space in mobile terminals Playback of XML-based contents in such mobile terminals becomes restrictive when utilizing only the existing transcoding and prefetch technique Therefore, this study attempts at proposing the method of minimizing the initial delay time prior to playback when XML contents to be displayed in mobile terminals are consisted of a number of data In order for this, a stream selection policy was proposed to transcode data streams included in XML contents, rather than to transcode all of the data streams In addition, a technique has been suggested to reorganize the transcoded data streams, to evaluate whether it is possible to playback the reorganized data streams in the mobile terminal, thus to prefetch the data.

A transcode scheduling technique to reduce early-stage delay time in playing multimedia in mobile terminals

This paper proposes a new scheduling technique to play multimedia data streams in mobile terminals. The paper explores the characteristics of multimedia data streams , firstly. On basis of these characteristics, selection of specific data stream can be possible as well as transcoding protest. Our approach aims at reducing the early-stage delay time more effectively since it makes possible to select and transcodes some specific streams by employing a selection policy rather than transcoding all streams in the playing process Thus, this paper suggests a stream selection policy for the transcoding based on EPOB (End Point of Over Bandwidth). It aims to lower the required bandwidth of multimedia streams than the network bandwidth level and also to minimize early-stage delay time for multimedia streams, which is to be played in mobile terminals.

A Transcode and Prefetch Technique of Multimedia Presentations for Mobile Terminals

As mobile communication technologies are developing rapidly, this paper proposes a technique of playing multimedia presentation on mobile terminals in a more stable environment. To play multimedia presentation on mobile terminals in a stable way, there are problems. Since mobile terminals use low bandwidth, it is impossible to play multimedia presentation which has large amount of data. Even after prefetching, limited memory of mobile terminals prohibit stable play of the presentation. On this basis, the paper proposes a prefetching technique combined with transcoding method to solve these problems. For this aim, a multimedia presentation should be transcoded to be playable in mobile terminals. It is not that every stream existing in the presentation is transcoded, but that only the selected according to the stream selection policy, i.e. scheduling, are transcoded. This is to save transcoding time. By this way, the early delay time, which includes transcoding time in mobile terminals, can be minimized. Moreover, after undergoing transcode, the presentation is to be prefetched in compliance with the memory size of the mobile terminal. This process makes it possible for the presentation to be played in a more stable way. Through the experiments of 90 presentations, it becomes possible to select superior selection policy after applying prefetch and transcode. The presentation, which adopts more superior policy, shows more stable play as well as reduced early delay time.