An Architecture for Multimedia Systems

The architecure of multimedia system may be described as a four-level hierarchy. In line with concepts developed in conventional layered systems such as the OSI and Internet (Chapter 6) each layer performs a specific function and supports the function performed in the layer above. The four-layers (lowest (bottom) layer first) of the archiotecture, known as the RT architecture (Real-time information handling), are:

Network Subsystem (Layer 1)

-- This layer takes care of the functionalities up layer 3 in the OSI model (Chapter 6). Network specific funstions depend on the technolgy used in this layer (see Section refsec:mmnetwork below). Essentially this level provides a possible connection through a network with a specified bandwidth and error probability as supported by the underlying technology.

End-to-End QoS Control(Layer 2)

-- This layer maintains the connection between the source and destination and can be conceptually viewed as a single connection -- even though there may be physically many more. Each connection is managed to ensure that a given Quality of Service (Qos) (Section 24.4) is maintained.

Media Management (layer 3)

- This layer provides generic services to applications ihn so far as media management is concerned. A primary functions is synchronisation across the media (Section 24.4).

Application (Layer 4)

-- The direct interface with the user. The applciation wil also interface with the operating system, if required -- for example calls to stroage media or specific library functions (subroutines).