LEARNING AND INTERACTING IN DISTRIBUTED 3D VIRTUAL WORLDS (3D VIRTUAL MUSIC JUKE BOX)

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1 NUROP CONGRESS PAPER LEARNING AND INTERACTING IN DISTRIBUTED 3D VIRTUAL WORLDS (3D VIRTUAL MUSIC JUKE BOX) DU SICHAO 1 AND CHEE YAM SAN 2 School of Computing, National University of Singapore 3 Science Drive 2, Singapore Abstract 3D virtual music juke-box system constructs a 3D virtual community which allows users to upload, query, request, and listen to the music. The music requested by users is streamed to all the current users in the system with Java Media FrameWork (JMF) technology. Good uploading policy is adopted so that good music will be kept for a long time, while music that is not popular will be soon removed. This system provides an immersive 3D environment context. After users who are represented by avatars enter the system, they are free to socialize with others through the embedded text based chatting as well as the audio chatting tools while they are enjoying the music played by the music juke-box. Peaceful atmosphere and beautiful music will effectively enhance the socializing and interacting, while the two communication tools which are text chatting tool and audio chatting tool give the supports of rich media communication. 1 GENERAL INSTRUCTIONS Imagine when we are having lunch in a restaurant, a person takes out a one-dollar coin, walks towards the juke-box in the corner of the restaurant, inserts the coin, chooses a beautiful song, immediately beautiful music comes out from the juke-box. All the people are enjoying the beautiful music. This 3D virtual music juke-box project has simulated almost all the functions of the real music juke-box. Generally speaking, there is a 3D virtual room, in which there is a 3D virtual music juke-box. After the user logs into this system, it is like they have entered the restaurant. They can walk towards the juke-box, and request music that they like. After a user request a music in the juke-box, the requested music will be queued. If currently there is no other music in the queue, the user will immediately hear the music he/she requested. Alternatively, the user can bring his/her own music and upload it to the music juke-box. Or the user can query the music query, and all the music available in the music juke-box. All the users currently in the room will hear the same music simultaneously. 1 Student 2 Supervisor 1

2 2 Learning and Interacting in Distributed 3D Virtual Worlds 2.1 Objectives The objectives of this 3D virtual music juke-box are: Provide a 3D virtual environment for all the users to stay and enjoy the music and users are able to walk here and there in this room, to socialize with each other. Provide a 2D graphic user interface to let the user be able to upload, request, query music, and exit the room. Provide a music uploading policy so that those good and popular music will be kept in the juke-box for a long time, whereas those bad and less popular music will be removed from the juke-box in a short time. Provide the music streaming for the most common music audio formats which are wav file and mp3 file. 2.2 Technology in use The system conforms to object-oriented paradigm which is directly inherited from C-VISions system. The primary language is Java. The Java Media Framework(JMF) is used, since it provides a set of encoders and decoders for the streaming media formats, as well as an implementation of the RTP protocol. The rendering and animating of the 3D objects is implemented using Java 3D API. In addition, C-VISions system offers the platform called VTalk API for building new virtual world and virtual objects on top it. 2.3 protocol in use (Real-Time Transport Protocol (RTP)) Real-Time Transport Protocol (RTP) provides end-to-end network delivery services for the transmission of real-time data. RTP is network and transport-protocol independent, though it is often used over UDP. (See Figure 2) RTP can be used over both unicast and multicast network services. Over a unicast network service, separate copies of the data are sent from the source to each destination. Over a multicast network service, the data is sent from the source only once and the network is responsible for transmitting the data to multiple locations. Multicasting is more efficient for many multimedia applications, such as video conferences. 2.4 Multi-Unicast audio streaming system The Streaming Server StreamS uses the Multi-Unicast strategy, which opens a stream for a particular user. In order to do that, the StreamS knows the IP address of each current user. Using multi-unicast is because of some quality preservation concern. How does StreamS stream the music to each user? Specifically speaking, the StreamS will obtain the music file from the local disk., process it using the JMF facility, pass the processed version to the RTPManager. RTPManage is the central manager to manager the RTP streaming. The RTPManager will take 2

3 the processed music file as the input, come up with a sending stream, then this sending stream will be transmitted through the network. At the other end, the user part also has an initialized RTPManager. Once the new coming stream reached the user part, certain events will be triggered to inform the user, then the user will use the JMF facility to catch the received stream and play this received stream. 3 EQUATIONS, TABLES, AND FIGURES Figure 1: Media processing model. Figure 2: RTP architecture. 3

4 ServerManager RequestS QueryS StreamS UploadS Qslave Rslave Rslave Uslave Figure 3: Server-Client architecture 4

5 Figure 4: Music uploading Server A B C CPU Pentium4 Pentium3 Celeron Pentium4 1.6G 650M 500M 1.6G Memory 256MB 320MB 256MB 256MB Network 100Mbs 100Mbs 100Mbs 100Mbs connection Operating Windows-XP Windows-2000 Windows-2000 Windows-XP system Startup latency 3 s 4 s 2 s Table 1: Test results 4 Conclusion 5

6 The 3D Virtual Music Juke-Box system meets both functional requirements and usability requirements. The central music streaming makes users enjoy the music in a virtual fanciful style. In this system, I am able to use JMF to stream two most common music files which are WAV file and MP3 file successfully, and the quality of the original music file is preserved during the streaming. Moreover, a reasonable music uploading policy is embraced so that good music will be promoted while bad music will be removed. Interactive 2D and 3D user interfaces are presented so that learning and socializing becomes more convenient and interesting. 5 Reference [1] Chee, Y. S. (2001). Networked virtual environments for collaborative learning.invited speaker. In Proceedings of ICCE/SchoolNet 2001-Ninth International Conference on Computers in Education, Seoul, S. Korea, pp ICCE/SchoolNet [2] Learning Environment and Learning Science Laboratory. (2002). C-VISions, Collaborative Virtual Interactive Simulations. [3] Sandeep Singhal and Michael Zyda (1999). Networked virtual environments : design and implementation. Addison-Wesley, [4] Sun Microsystem. (1999). Java Media Framework API Guide, JMF 2.0 FCS, November 19, [5] Sun Microsystems, Inc. (2002). Archives of JMF-INTEREST@JAVA.SUN.COM. 6