1 Scope
This part of ISO/IEC 14478 defines a standard set of multimedia system services that can be used by multimedia
application developers in a variety of computing environments. The focus is on enabling
multimedia applications in a heterogeneous, distributed computing environment. Throughout
this part of ISO/IEC 14478, this component will also be referred to as “Multimedia Systems Services”, and abbreviated
as MSS.
The Multimedia Systems Services constitutes a framework of “middleware” — system software
components lying in the region between the generic operating system and specific applications.
As middleware, the Multimedia Systems Services marshals lower-level system resources
to the task of supporting multimedia processing, providing a set of common services
which can be used by multimedia application developers.
The Multimedia Systems Services encompasses the following characteristics:
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a) provision of an abstract type for a media processing node, extensible through subtyping
to support abstractions of real media processing hardware or software;
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b) provision of an abstract type for the data flow path or the connection between media
processing nodes, encapsulating low-level connection and transport semantics;
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c) grouping of multiple processing nodes and connections into a single unit for purposes
of resource reservation and stream control;
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d) provision of a media dataflow abstraction, with support for a variety of position,
time and/or synchronization capabilities;
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e) separation of the media format abstractions from the dataflow abstraction;
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f) synchronous exceptions and asynchronous events;
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g) application visible characterization of object capabilities;
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h) registration of objects in a distributed environment by location and capabilities;
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i) retrieval of objects in a distributed environment by location and constraints;
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j) definition of a Media Stream Protocol to support media independent transport and synchronization.
The Multimedia Systems Services rely on the object model of ISO/IEC 14478‑1 (Fundamentals of PREMO) and the object types and non-object data types defined in
ISO/IEC 14478‑2 (PREMO Foundation Component).