MPEG-4 –Introduction –MPEG4 Video –MPEG4 Tools –MPEG4 Video Object –MPEG4 Video Profile –MPEG4 Simple Profile –MPEG4 Advanced Simple Prolile
Introduction ITU/ISO 1994 年制定， 1998 年成为标准，对应的标准 号为 目的是要在异构网络环境下能够高度可靠地工作，并 且具有很强的交互功能。 制定了一个称为传输多媒体集成框架 (Delivery Multimedia Integration Framework ， DMIF) 的会话协议， 它用来管理多媒体数据流 ， DMIF 覆盖了三种主要技术： – 广播技术 – 交互网络技术 – 光盘技术 相对其他编码标准，引入了对象的概念，以对象为编 码单位，有自然数据扩展到合成数据，对象可以是自 然的，也可以计算机合成的，可以是图像，也可以是 声音，可以是一段文字，总之对象是一个抽象的概念， 对向的操作引入了组合，合成和编排等概念
MPEG － 4 标准的 16 个部分 Part 1, Systems: Scene description, multiplexing of audio, video and related information,synchronisation, buffer management, intellectual property management. Part 2, Visual: Coding of ‘ natural ’ and ‘ synthetic ’ visual objects (see Chapter 5). Part 3, Audio: Coding of natural and synthetic audio objects. Part 4, Conformance Testing: Conformance conditions, test procedures, test bitstreams. Part 5, Reference Software: Publicly-available software that implements most tools in the standard. Part 6, Delivery Multimedia Integration Framework:Asession protocol for multimedia streaming. Part 7, Optimised Visual Reference Software: Optimised software implementation of selected Visual coding tools. This Part is a Technical Report (and not an International Standard).
MPEG － 4 标准的 16 个部分 Part 8, Carriage of MPEG-4 over IP: Specifies the mechanism for carrying MPEG-4 coded data over Internet Protocol (IP) networks. Part 9, Reference Hardware Description: VHDL descriptions of MPEG-4 coding tools (suitable for implementation in ICs). This Part is a Technical Report and is still under development. Part 10, Advanced Video Coding: Efficient coding of natural video (see Chapter 6). This Part is under development and due to become an International Standard in Part 11, Scene Description and Application Engine. Part 12, ISO Base Media File Format. Part 13, Intellectual Property Management and Protection Extensions. Part 14, MPEG-4 File Format Part 15, AVC File Format Part 16, Animation Framework Extension.
MPEG － 4 视频 和 MPEG-1/-2 Video 不同， MPEG4 视频形状 可以是矩形的也可以被分割成许多任意形状 的图像区，每个区都有可能覆盖描述场景中 感兴趣的物理对象或者内容，这种区被定义 为图像对象区 VOP 。 VO 的属性：形状，纹理，移动
MPEG4 中的 Tools A tool is a subset of coding functions to support a specific feature 一些编码技术，比如 DCT ，帧内编码， 前向预测，双向预测 ….
MPEG4 中的视频对象 A entity that a user is allowed to access (seek, browse) and manipulate (cut and paste) A video object (VO) is an area of the video scene that may occupy an arbitrarily-shaped region and may exist for an arbitrary length of time.
Rectangular Video Object
Arbitrary shape Video Object
Video Scene
Profiles A profile is a set of object types that a CODEC isexpected to be capable of handling. Profile 中明确了使用那些技术对那些对象进行编码
Profile of nature video
Profile of synthetic or hybrid video
Visual Profile and Visual Object Type
Levels
Simple Profile Define Subset Tools for Simple Video Objects –I-VOP (Intra-coded rectangular VOP, progressive video format); – P-VOP (Inter-coded rectangular VOP, progressive video format); –short header (mode for compatibility with H.263 CODECs); –compression efficiency tools (four motion vectors per macroblock, unrestricted motion vectors, Intra prediction); – transmission efficiency tools (video packets, Data Partitioning, Reversible Variable Length Codes).
Advanced Simple Profile An Advanced Simple ProfileCODECmust be capable of decoding Simple objects as well as Advanced Simple objects which may use the following tools in addition to the Simple Profile tools –B-VOP (bidirectionally predicted Inter-coded VOP); –quarter-pixel motion compensation; –global motion compensation; –alternate quantiser; –interlace (tools for coding interlaced video sequences).
Visual Object Types Visual ToolsAdvanced Simple simple I-VOPXX P-VOPXX B-VOPX DC PredictionXX AC PredictionXX 4-MV, Unrestricted MVXX Slice ResynchronizationXX Data PartitioningXX Reversible VLCXX Short HeaderXX Method 1/Method 2 QuantizationX InterlaceX Global Motion CompensationX Quarter-pel Motion CompensationX Tools of SP and ASP
图像的合成
Video Object
MPEG4 编码框图