MPEG-4 Scene Description Optimization for Interactive Terrestrial DMB Content

摘要

The Digital Multimedia Broadcasting (DMB) system was developed to provide high-quality multimedia contents in the mobile environment. The system adopts the MPEG-4 standard for its main video, audio and other media formats. It also adopts MPEG-4 scene description for its interactive multimedia contents. Its animated and interactive contents are based on BIFS (Binary Format for Scenes), which refers to the spatio-temporal specifications and behavior of the individual objects. The more interactive contents are, the more high-bitrate the scene description should be. However, the bandwidth for allocating meta-data such as those in scene descriptions is restrictive in the mobile environment. On one hand, the DMB terminal starts demultiplexing contents and decoding individual media with its own decoder. After decoding each medium, the rendering module presents each media stream according to the scene description. Thus, the BIFS stream corresponding to the scene description should be decoded and parsed before the audio or visual object is presented. For these reasons, the transmission delay of the BIFS stream causes the delay in the entire audio-visual scene presentation, although the audio or video streams are en-coded in very low bitrate. This paper presents the effective optimization technique for adapting the BIFS stream into an expected MPEG-2 TS bitrate with-out bandwidth waste and for avoiding delay in the transmission of the initial scene description for interactive DMB contents.