Implementation of Mobile Strea

Implementation of Mobile Streaming Media
Player Based on BREW*
WANG Zhong-rong, LIU Zhao
School of Electronic Engineering, University of Electronic Science and Technology of China Chengdu 610054 China
Abstract Nowadays mobile streaming service through cell phone is becoming the highlight of new value-added mobile services. Based on the present CDMA1x wireless data network and Binary Runtime Environment for Wireless (BREW) platform, adopting compression technologies of H.264 and QCP, a set of streaming media players are designed and implemented, and the principle, structure, key technologies and performance analysis of this system are introduced. This player works well in practice.
Key Words streaming media; Binary Runtime Environment for Wireless (BREW); Real-time Transport Protocol (RTP); Real-time Streaming Protocol (RTSP)

There are two major methods for audio/video files transfer through the network, downloading and streaming. The volume of storage and network bandwidth restricts transferring big audio/video files. Downloading needs minutes or hours while streaming only takes several seconds in starting and buffering. Streaming server will continuously send real-time packets to clients and the users don¡¯t need to wait for the whole file to be downloaded. They can play and receive simultaneously without big cache. Streaming is certainly a better choice for the limited working space of cell phone and PDA, etc[1-2].
The expanded bandwidth for air interfaces has made a solid ground for streaming media application on wireless networks. With the advantages of wireless system in time and place, mobile streaming media service is very attractive. The China Unicom¡¯s CDMA1x data network has an average steady rate of 70-80 kbps and is capable of running streaming media business. This paper will introduce the implementation of a mobile streaming client player based on BREW platform.
1 Mobile Streaming Media System
Fig.1 shows the structure of the mobile streaming media system, including four basic parts: the server, the client, the transmission channel and the content source. The server adopts concurrent server of cluster; the client is a cell phone supporting BREW application; the transmission channel uses CDMA1x wireless network of China Unicom; and the content source are the streaming type documents or real-time audio/video data. In addition to providing the basic streaming service, the server deals with the additional function such as file management, access certification, and charging[3-4].
Fig.1 Mobile streaming media system structure diagram
2 Implementation of the Client
This client is based on the platform of Binary Runtime Environment for Wireless (BREW) which is a point-to-point solution for wireless data application released by QUALCOMM in 2001. It¡¯s a basic platform for the development and operation of value-added services on CDMA wireless internet radio platform. BREW API provides a high-efficiency, low-cost, expansible Application-Executing Environment (AEE), customized to the development of hand-held device application. For developers, BREW AEE is an abstract layer above the operation system on embedded chips, with the characteristics of small volume, fast speed, extensiveness, stability and safety, and with abundant developing interfaces and strong support to multimedia applications such as audio,picture, animation and access to wireless networks.
BREW applications can be programmed in various computer languages, but the efficiency in C/C++ is of the highest. The BREW SDK is integrated in Visual C++ environment. After successful setup, there will appear a new menu item of BREW Application Wizard under New->Projects. It¡¯s easy to establish a new project with this wizard. The unit of developing and deploying a BREW application is called Module, allowed with several Applets in one Module, but there is only one active Applet each time regardless of the number of Applets in a Module. BREW is a single-thread environment, and it is difficult to resolve the problems about synchrony and efficiency of multitask such as network telecommunication, data processing and audio/video displaying.