Media synchronization may be disturbed owing to network delays and skews, which are caused by many reasons such as the difference of time in capturing media among terminals, the difference of time in protocol processing, media interleaving, network delay jitter, packet loss, the difference of decoding time at the playout process, and clock difference. Media synchronization control is carried out to compensate for the network delay jitter. We can identify two types of media synchronization control: Object (or event-driven) and continuous synchronization control (Campbell et al., 1992). Object synchronization control means synchronization control among multimedia objects. The control adjusts the beginning output timings of media according to a scenario. Under continuous synchronization control, the output timings (e.g., output times and speeds) among media streams can be synchronized with each other. In this chapter, we focus on continuous synchronization control. Media synchronization control is categorized into three types:
Intra-stream
Inter-stream (Blalowski & Steinmetz, 1995; Ehley et al., 1994; Ishibashi & Tasaka, 1995, 2000; Huang et al., 2013; Boronat et al., 2009, Ishibashi et al., 2003), and
Group (or inter-destination) synchronization control (Ishibashi et al., 1997; Ishibashi & Tasaka, 1997, 1999).