Synchronization in MPEG-4 systems

The MPEG-4 standard was defined in the early days of broadband Internet, after successful deployments of digital television networks, with the goal of unifying both broadcast and broadband media architectures and protocols in a single standard, tackling natural media (audio, video, images) as well as synthetic 2D or 3D graphics and audio. As such MPEG-4 can be seen as one of the first attempt at building the so-called convergence of Web and TV. Some parts of the standard have changed the media world forever (AAC audio and AVC|H264 video compression, MP4 file format), and while other parts have not always met their markets in successful way, they paved the way for more recent works, including HTML5 media. In this chapter, we explain how the MPEG-4 standard manages playback and synchronization of audio-visual streams and graphics animations and how multiple timelines can be used to provide rich interactive presentation over broadband and broadcast.