TITRE Adaptive Packet Video Streaming Over IP Networks - LaBRI

Appendix A
A Appendix A: Overview of the MPEG-4
Framework
A.1 Introduction
MPEG-4 standard [22][23][24] is an emerging digital multimedia standard with associated
protocols for representing, manipulating and transporting natural and synthetic multimedia content
(i.e. audio, video and data) over a broad range of communication infrastructures.
The MPEG-4 standard introduces a new technique of coding multimedia scenes called
“object-based compression”. This technique allows the encoding of different audio-visual objects in
the scene independently.
The original characteristic of MPEG-4 is to provide an integrated object-oriented
representation of multimedia content for the support of new ways of communication, access, and
interaction with digital audiovisual data, and offering a common technical solution to various
telecommunications, broadcast, and interactive services. MPEG-4 addressed a broad range of
existing and emerging multimedia applications such as video on the Internet, multimedia
broadcasting, content-based audiovisual database access, games, audiovisual home editing,
advanced audiovisual communications and video over mobile networks.
An MPEG-4 scene consists of one or more Audio Visual Objects (AVO), each of them is
characterized by temporal and spatial information. The hierarchical composition of an MPEG-4
scene is depicted in Figure A-1. Each Video Object (VO) may be encoded in a scalable (multi-layer)
or non scalable (single layer) form. A layer is composed of a sequence of a Group of Video-Object-
Plane (GOV). A Video Object Plane (VOP) is similar to the MPEG-2 frame. VOP supports intra
coded (I-VOP) temporally predicted (P-VOP) and bi directionally predicted (B-VOP).
To reach the defined objective of MPEG-4 standard, a set of tools was defined in several
recommendations of the standard. First, the media compression schemes are defined in the Visual
[22] and the Audio [23] parts of the MPEG-4 framework. Every multimedia element to be
compressed is presented as individual AVO. The combination of these elements is assured by the
scene description language called Binary Format for Scenes (BIFS) defined in MPEG-4 Systems
document [22]. The delivery of the media is defined in the Delivery Multimedia Integrated Framework
(DMIF) [144], which is the part 6 of MPEG-4 specification. DMIF is actually the control plane of
MPEG-4 Delivery layer. It allows applications to transparently access, retrieve, and view multimedia
streams whether the source of the stream is located on a remote or local end-system.
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