ISO/IEC 14478-4:1998

INTERNATIONAL ISOAEC
STANDARD 14478-4
First edition
1998-12-15
Information technology - Computer
graphics and image processing -
Presentation Environment for Jlultimedia
Objects (PREMO) -
Part 4:
Modelling, rendering and interac ion
component
Technologies de I’informa tion - lnfographie et traitement d ’images -
Environnement de prksentation d ’objets multimedia (PREMO) -
Partie 4: Composant pour Ia mod&ation, Ie rendu et I’interaction

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ISO/IEC 14478-4: 1998(E)
Contents
Foreword . . vii
...........................................
Introduction . Vlll
1 Scope.9
2 Normative references. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3 Definitions. . 10
..........................................
PREMO Part 1 definitions 10
3.1 .
PREMO Part 2 definitions .10
3.2 .
10
3.3 PREMO Part 3 definitions .
10
3.4 Additional Definitions .
.12
4 Symbols and abbreviations .
5 Conformance. . . 12
6 Overview of the Modelling, Rendering and Interaction Component. . .12
6.1 Introduction .12
.............................................
..12
6.2 Overview .
Devices for Modelling, Rendering, and Interaction . 16
6.3
Primitives and Coordinates. .17
6.4 .
17
6.4.1 Introduction
...................................................
0 ISO/IEC 1998
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Printed in Switzerland
ii

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ISO/IEC 14478-4: 1998(E)
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................................................... 17
6.4.2 Coordinates
............................... 17
6.4.3 The Primitive Hierarchy in PREMO
6.431 Overview.l 7
6.432 Captured Primitives. . 18
6.433 Form Primitives.~ 8
...............................................
6.434 Modifier Primitives. 18
6.435 Reference Primitives. . 19
6.436 Structured Primitives. . 19
6.437 Tracer Primitives. . 19
6.4.3.8 Wrapper Primitives. . 19
...................................... 19
6.4.4 Primitives and MRI Devices
Scene. 20
6.5
Interaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - . . . 21
6.6
6.7 Coordinators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
6.8 Dependencies on other Parts. . 23
........................................ 23
6.9 Subtyping Diagram.
23
7 Coordinates .
........................................ 23
7.1 General Coordinates
7.2 Colour. 24
7.3 TimeLocation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
8 Primitives. . . . . . . .
8.1 Introduction. 25
8.2 Captured Primitives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
8.3 Form Primitives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
8.3.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
8.3.2 Audio Primitives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
8.3.3 Geometrie Primitives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
.............................................. 28
8.3.4 Tactile Primitives
................................................ 28
8.3.5 Text Primitives
Modifier Primitives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
8.4
8.4.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . 28
8.4.2 Acoustic Modifiers . . . . . . . . . . . . . . . . . _ . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
8.4.3 Structural Modifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
8.4.4 TimeFrame Modifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
8.4.5 Visual Modifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
8.5 Reference Primitives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
8.5.1 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
8.5.2 The Name Object Type. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
8.6 Structured Primitives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1
8.6.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1
8.6.2 Aggregate.3 1
............................................... 32
8.6.3 TimeComposite.
.......................................... 35
8.7 Tracer Primitives.
Wrapper Primitives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
8.8
....................... 36
9 Modelling, Rendering and Interaction Device.
36
9.1 Introduction .
iii

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ISO/IEC 14478-4: 1998(E)
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9.2 MRI ForInat.3 6
-
9.3 E~~iciency.3 6
9.4 Behaviour . .37
10 Modeller.3 7
11 Renderer.3 8
12 MediaEngine.3 8
13 Scene.39
14 Interaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .~.42
14.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
14.2 InputDevice.42
14.3 Router.43
15 Coordinator . . . . . .~.~.~~~~. “.43
16 Functional Specification . . . . . o . . . . . e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
16.1 Introduction . . . e . S . . . . . . . D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
16.2 Non-Object data types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
16.3 Exceptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46
16.4 Objects for coordinate spaces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47
16.4.1 Coorchcrte Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
16.4.2 C&xlrobject. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48
16.43 Timehcntiorz Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
16.5 Name Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49
16.6
Objects for media primitives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49
16.6.1 Primi~iw Object. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
16.6.2 Cq~turd Object. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SO
16.63 Objects describing primitives with spatial and/or temporal form.
......... 50
16.631 Form Object
..................................................... SO
16.632 Ob.jects describing form primitives for audio media data
.................. SO
16.633 Ob.jects describing form primitives for geometric media data.
.............. 5 1
16.6.4 Objects describing primitives for the modification of media data
......... 52
16.6.4.1 Moclifkr.Object
................................................... 52
16.6.4.2 ObJet ’ ’ t* s d escribing modifier primitives for audio media data
............... 52
16.6.4.3
Ob.jects describing modifier primitives for structural aspects of media data. . 53
16.6.4.4 Tim Ft-twe ob-ject
................................................ 54
16.6.4.5 Ob-jects describing modifier primitives for visual aspects of media data.
...... S4
16.63 Refereuce Object
.............................................. .55
16.6.6 Objects for organising primitives into structures
...................... 56
16.6.6.1 Str.uctured ob.ject
................................................. 56
16.6.6.2 A,qyegclte ob-ject.
................................................. 56
16.6.6.3 Ob.jects for organising media data within time
.......................... 57
16.6.7 Tracer Object
.................................................. 58
16.6.8 Wrqyerobject
................................................ 59
16.7 Objects for describing properties of devices . . . . . . . . . . . . . . . . . . . . . .59
16.7.1
MRlJhrmat Object. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
16.7.2 l$fkierxyMeaswe Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
16.8 Processing devices for media data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60
16.8.1 MRCDevice Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60
IV

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ISO/IEC 14478-4: 1998(E)
.............. . . . . . . . ” . . . . . . . . . . . . . . . . . . . . . . . 60
16.8.2 Modeller Object.
16.83 Reizderer Object. . . . * . . . . . . . . . . . . . . . . 61
. . . . . . . . . . . . . . . . .
16.8.4 MdiaEqine Object . . . 61
. . . 63
16.9 Seeuze Object. .
. . . 65
16.10 Objects for supporting interaction.
. . . 65
16.10.1 ItxputDevice Object .
. . . 66
16.10.2 Router Object. .
...............
16.11 Coordinator Object . . . 67
17 Component Specifkation. . a . I . < . . . . . . . . . . .a.* 69
A Overview of PREMO Modelling, Rendering and Interaction Object I ’ypes .
70
73
B Diagrammatic Conventions. .
............................................... 73
B.1 Introduction
General Graphical Signatures 73
B.2 .
Conventions for Devices and Communication . 74
B.3
........................ 75
C Relationship between Part 4 and the CGRM
............................................... 75
C.1 Introduction
C.2 Architectural Links. 75
........................................
C.3 Processing Links. 76
..........................................
C.4 Input and Output Primitives . 76
C.5 Storage . 76
A typical example scenario of MRI usage . . . . . . . . . . . . . . . . . . o . . . . . . . . 77
D

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0 ISO/IEC
ISO/IEC 14478-4: 1998(E)
Foreword
ISO (the International Organization for Standardization) and IEC (the International
Electrotechnical Commission) form the specialized System for worldwide standardi-
zation. National bodies that are members of ISO or IEC participate in the development
of International Standards through technical committees established by the respective
organization to deal with particular fields of technical activity. ISO and IEC technical
committees collaborate in fields of mutual interest. Other international organizations,
government and non-governmental, in liaison with ISO and IEC, also take part in the
work.
‘In the field of information technology, ISO and IEC have established a joint technical
committee: ISO/IEC JTC 1. Draft International Standards adopted by the joint techni-
cal committees are circulated to the national bodies for voting. Publication as an Inter-
national Standard requires approval by at least 75% of the national bodies casting a
vote.
ISO/IEC 144784 was prepared by Joint Technical Committee ISO/IEC JTCl, hfor-
mation techology, Subcommittee SC24, Conzyuter graphics and image processing.
ISO/IEC 14478 consists of the following Parts under the general title Injkwzation
technology - Computer graphics and image processing - Presentation Environment
for Multimedia Objects (PREMO).
- Pm-t 1: Fundumen.tals of PREMO
- Part 2: Foundation component
- Part 3: Multimedia systerns Services
- Part 4: Modelling, rendering, und interaction component
Annex A forms an integral part of this part of ISO/IEC 14478. Annexes B to D arc for
information only.
vi

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ISO/IEC 14478-4: 1998(E)
0 ISO/IEC
Introduction
The Modelling, Rendering and Interaction component of PREMO describes facilities
for the modelling and presentation of, and interaction with, multidimensional data that
utilises multiple media in an integrated way. That is, the data may be composed ofen-
tities that tan be rendered using graphics, Sound, Video or other media, and which may
be interrelated through both spatial coordinates and time.
The objective of this component is to provide developers and users of modelling and
rendering applications with a framework for supporting the definition and use of inter-
operable devices within a distributed setting. It achieves this by:
a) providing an extensible framework of primitives for use in modelling, render-
ing and interaction which encompass multiple media, and which tan be organized
into larger structures and embedded into Scenes.
b) extending the resource and device hierarchies of the PREMO Part 3 (Multi-
media Systems Services) Component to allow modelling, rendering and interac-
tion to be uniformally integrated into a network of objects for managing the
production and utilization of multimedia data.
c) utilizing the property and capability management Services of PREMO Part 3
to characterize the behaviour of modelling, rendering and interaction devices,
allowing an application to be configured from such devices such that constraints
on Performance and functionality are satisfied.
d) building on the Object model and foundation objects of PREMO Part 1 and
Part 2 to allow subsequent components to realize and extend specific modelling,
rendering and interaction functionality.
This component follows PREMO Part3 in describing the external interface of Object
types and other entities involved in modelling, presentation and interaction, but not the
internal structures needed to implement these. That is, it is not the purpose of this com-
ponent to provide a set of building blocks that tan be assembled into a modeller or a
renderer. Rather, the component provides facilities to enable devices, built with vari-
ous applications or Performance trade-offs in mind, to interoperate in a heterogenous
presentation environment.
vii

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ISO/IEC 14478-4: 1998(E)
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viii

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INTERNATIONAL STANDARD 0 ISO/IEC ISO/IEC 14478-4: 1998(E)
Information technology - Computer graphics and image
processing - Presentation Environment for Multimedia Objects
(PREMO) -
Part 4: Modelling, Rendering, and Interaction Component S
1 Scope
This part of ISO/IEC 14478 describes a set of Object types and non-Object types to provide the construction of, presentation of,
and the interaction with Multimedia information. The multimedia information tan be graphics, Video, audio, or other types of
presentable media. This information tan be enhanced by time aspects. Throughout this document this part of ISO/IEC 14478 will
also be referred to as “Modelling, Rendering and Interaction ”, and abbreviated as MRI.
The Modelling, Rendering and Interaction Component constitutes a framework of ‘Middleware ’, System Software components
lying between the generic operating System and computing environment, and a specific application operating as a client of the
Services and type definitions provided by this component. It provides a framework over the foundation objects and multimedia
Systems Services defined in other Parts of the international Standard for the development of a distributed and heterogeneous net-
work of devices for creating multimedia models, rendering these models, and interacting with this process.
The Modelling, Rendering and Interaction Component encompasses the following characteristics:
a ) Provision of a hierarchy of multimedia primitives as an abstract framework for describing the capabilities of modelling
and rendering devices, and for enabling their interoperation;
b) within the primitive hierarchy, specific Provision for describing the temporal structure of multimedia data through the
stepwise construction of structured primitives from component data;
c) Provision of abstract types for modellers, renderers and other supporting devices, enabling the integration of such devices
or any future subtypes representing real Software or hardware, into a processing network of such devices;
d) provision of an Object type to map synchronization requirements expressed within multimedia primitives into control of
the stream and synchronization mechanisms provided by ISO/IEC 14478-2 and ISO/IEC 14478-3.
The Modelling, Rendering and Interaction Component relies on the Object types and Services defined in PREMO Part 2: Foun-
dation Components (ISO/IEC 1447%2), and PREMO Part 3: Multimedia Systems Services (ISO/IEC 14478-3).
2 Normative references
The following Standards contain provisions which, through reference in this text, constitute provisions of this part of ISO/IEC
14478. At the time of publication, the editions indicated were valid. All Standards are subject to revision, and Parties to agree-
ments based on this part of ISO/IEC 14478 are encouraged to investigate the possibility of applying the most recent editions of
the Standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards.
ISO/IEC 1 1072: 1992, Information technology - Computer graphics - Computer Graphits Reference Model (CGRM).
ISO/IEC 7942- 1: 1994, Ir$ormation technology - Computer graphics and image processing - Graphical Kernal System (GKS)
- Part 1: Functional description.
ISO/IEC 9592: 1997, Information technology - Computer graphics and image processing - Programmerk Hierarchical Inter-
active Graphits System (PHIGS).

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0 ISOIIEC
ISO/IEC 14478=4:1998(E)
ISO/IEC 14478- 1: 1998, btformation technology - Computer graphics and image processing - Presentation Environment for
Multimedia Objects (PREMO) -Part 1: Fundamentals of PREMO
Computer graphics and image processing - Presentation Environment for
ISOIIEC 14478-2: 1998, Information technology -
- Part 2: Foundation component
Multimedia Objects (PREMO)
Computer graphics and image processing - Presentation Environment for
ISOIIEC 14478-3: 1998, Information technology -
- Part 3: Multimedia Systems Services
Multimedia Objects (PREMO)
3 Definitions
31 l PREMO Part 1 definitions
This part of ISO/IEC 14478 makes use of all terms defined in ISO/IEC 14478- 1 (Fundamentals of PREMO).
PREMO Part 2 definitions
32 .
This part of ISO/IEC 14478 makes use of all terms defined in ISO/IEC 14478-2 (Foundation component).
33 l PREMO Part 3 definitions
This part of .ISO/IEC 14478 makes use of all terms defined in ISOAEC 14478-3 (Multimedia Systems Services component).
Additional Definitions
34 .
For the purposes of this part of ISO/IEC 14478, the following definitions apply.
3.2.1 modeller: a virtual device that produces primitives on at least one output Port.
3.2.2 renderer: a device that accepts primitives on at least one of its input ports.
3.2.3 media engine: a virtual device that accepts primitives from at least one of its input ports, and produces primitives on
at least one of its output ports.
3.2.4 presentation: a collection of primitives that tan be perceived by the Operator.
3.2.5 coordinate: a primitive used to define a location in an nD space.
3.2.6 primitive: a structure describing information to be rendered, or information received through interaction.
3.2.6.1 form primitive: a primitive whose presentation has to be constructed by a renderer from an explicit description
in terms of aspects or properties that characterize a class of perceivable representations.
3.2.6.1.1 geometric primitive: a form primitive used to define a shape or extent within nD space.
3.2.6.2 captured primitive: a primitive for which some or all of the perceivable aspects of the primitive have been en-
coded in some format defined externally to the PREMO Standard.
structured primitive: a primitive that contains a collection of other primitives.
3.2.6.3
3.2.6.4 modifier primitive: a primitive that describes a Change to the presentation of another primitive.
3.2.6.4.1 acoustic modifier:
a modifier that changes properties of the Sound generated by other primitives.
3.2.6.4.2 structural modifier: a modifier that affects the spatial and/or temporal aspects of another primitive.
a modifier that affects the (non structural) visual appearance of a primitive.
3.2.6.4.3 visual modifier:

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ISO/IEC 14478-4: 1998(E)
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wrapper primitive: a primitive that carries a value drawn from some PREMO non-Object data type.
3.2.6.5
tracer primitive: a primitive that carries an event for use in monitoring and coordinating the transfer of media
3.2.6.6
data across a network.
3.2.7 input device: a device used to obtain data from the Operator.
3.2.8 graphics: the construction, manipulation, analysis and presentation of pictorial representations.
3.2.9 Scene: a device for storing and controlling access to a collection of primitive structures.
3.2.10 primitive structure: a collection of primitives organized into a structure that represents some or all of the data that
describes a multimedia presentation.
3.2.11 coordinator: a MRI device that tan manipulate the streams connecting its components.
3.2.12 router: a device for controlling the flow of data between streams connected to its ports.
temporal extent: the duration in time allocated or used for the presentation of some primitive.
3.2.13
3.2.14 operator-: the external Object that sends or receives information through a virtual device interface.
3.2.15 application: the external Object or client that uses a PREMO System by creating objects, invoking operations on ob--
jects, and using types defined by PREMO. Applications are not modelled in the PREMO System, but their interactions with
.a PREMO System are modelled.
The following alphabetical list gives the sub-clause of each definition.
3.2.6.4.1
acoustic modifiel
3.2.15
application
captured primitive 3.2.6.2
3.2.5
coordinate
3.2.11
coordinator
3.2.6.1
form primitive
oeometric primitive 3.2.6.1.1
c
graphics 3.2.8
input device 3.2.7
media engine 3.2.3
3.2.1
modeller
3.2.6.4
modifier primitive
3.2.14
Operator
3.2.4
presen tation
primitive 3.2.6
primitive structure 3.2.10
renderei 3.2.2
3.2.12
router
3.2.9
Scene
structural modifier 3.2.6.4.2
structured primitive 3.2.6.3
temporal extent 3.2.13
3.2.6.6
tracer primitive
3.2.6.4.3
visual modifier
3.2.6.5
wrapper primitive

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ISO/IEC 14478-4: 1998(E) 0 ISO/IEC
4 Symbols and abbreviations
CGRM: Computer Graphits Reference Model.
CSG: Constructive Solid Geometry
GKS: Graphical Kerne1 System.
IEC: International Electrotechnical Commission.
ISO: International Organization for Standardization.
MPEG: Moving Picture Experts Group.
MRI: Modelling, Rendering and Interaction
Multimedia Systems Services
MSS:
PHIGS: Programmers Hierarchical Interactive Graphits System.
PREMO: Presentation Environment for Multimedia Objects.
VRML: Virtual Reality Modeling Language.
nD: Multi-dimensional.
2D: Two-dimensional.
3D: Three-dimensional.
Conformance
5
A conforming implementation of the PREMO Modellin g, Rendering and Interaction Component shall comply with the general
conformance rules defined in clause 5 of ISO/IEC 14478 1 and the component specification in clause 16.
6 Overview of the Modelling, Rendering and Interaction Component.
Introduction
61 .
This clause presents an overview of the modellin g, rendering, and interaction component (Part 4) of PREMO. It summarises the
concepts defined in the document, and explains how these concepts contribute to the goals set out in the Introduction. More de-
tailed descriptions of the concepts used in the overview are given in subsequent clauses. This part of ISO/IEC 14478 also makes
extensive use of facilities provided by PREMO Parts 1-3, in particular the device and stream concepts introduced in ISO/IEC
144783. A summary of these dependencies is included in this clause.
62 . Overview
The model underlying this part of ISO/IEC 14478 is that a multimedia System consists of modeilers, renderers, and other devices
(some media specific) linked together via streams that carry data of a particular format. These concepts of stream and device arc
those defined in ISO/IEC 14478-3. A device consists of a processing facility, together with a number of ports through which it
tan accept input and produce output, using a format defined by the Port. Figure 1 Shows a high-level view of a (simplified) ex-
ample System in which a graphical user interface is used to control Parameters of an audio-visual presentation System. Rectangles
on the sides of devices represent ports, and the thick lines between such ports represent media flow via streams. Thin lines rep-
resent other forms of interaction, for example Operation invocation. See also Annex B for a table defining the Symbols used in
the figure. The System in Figure 1 consists of:

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ISOREC 14478-4: 1998(E)
43 lSO/IEC
from
application
Figure 1 - An audiohisual System
- two modellers, one for audio data and one for graphical data, that might be used to construct and edit primitives via an
interface to the application specific to the needs of each modeller;
- a Video engine, accepting a stream of Video data from the application and constructing a stream of information in .some
Video formst;
- a Scene, which encapsulates primitives produced by the two modellers and which mediates access to the collection of
primitives by both the modellers and the associated renderers;
- an audio engine, that takes primitives from the Scene and converts into a data format that tan be used to drive an audio-
specific device;
- a graphics engine (acting as a mixer or composition tool) uses the Video output from the Video renderer and primitives
from t he scen e to construct a further stream of pri miti ves, integrating the two sets of Source data within some appropriate
visual represe ntation. The p rimitives produced by t he e ngine may be some subset suita .ble for input to a specific renderer;
- two renderers, one for audio and one for graphics, that convert a stream of primitives into a form that tan be processed in
the context beyond the MRI network (in this case, presented to the end user of the application).
The t ‘igure Shows just one way in which such a System might be implemented. A different implementation may collapse the three
engines into a Single device, if it has access to a media engine that tan take both graphical and audio primitives as input and that
tan generate the correspondin g output streams. Another implementation may decompose the graphics engine into, for example,
a number of components that manage specific functionalities such as viewing or clipping. Finally, a high-performance implemen-
tation might collapse all components into a Single device.
Key components of this part are derived from the Object types defined in ISO/IEC 14478-3, in particular the property inquiry and
constraint facilities. These types and facilities may be used by the factory mechanism described in ISO/IEC 14478-2 to produce
ob-jects tha
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