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Mpeg-4 Overview. Gerhard Roth. Overview. Much more general than all previous mpegs standard finished in the last two years standardized ways to support: coding representing units of audio, visual, audiovisual content composition
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Mpeg-4 Overview Gerhard Roth
Overview • Much more general than all previous mpegs • standard finished in the last two years • standardized ways to support: • coding • representing units of audio, visual, audiovisual content • composition • describing how these objects are composed together to produce compound media objects • multiplex • multiplex and synchronize data associated with media objects • interaction • interacting with user
System overview • a number of decoders for each type of media • a composition process which puts the decoded parts together • composition ideas are similar to VRML • scene graph of objects • composition information is defined in the links • hierarchical structure, not necessarily static • composition stream has extra information for mp4 • spatial relationships • temporal relationships
Multiplex synchronization • timing and synchronization of media • three layers • specific information for timing and synchronization of the coded media (synchronization layer) • multiplex streams with different characteristics (flexible multiplex layer) • add the multiplex stream to a particular network (transport multiplex layer)
Intellectual property protection • ipmp = intellectual property management and protection • interface that permits mp4 to host one or more ipmp systems • ipmp framework has • normative interface that permits mpeg-4 terminal to host one or more IPMP systems • non normative component that provides intellectual property management
Video • Tools for efficient compression of • images, video, 2d textures • time varying geometry (animated meshes) • efficient random access • extended manipulation functionality • content based coding and scalability • error robustness and resilience • based on video object • entity in scene that user can manipulate and access • video object planes • instances of video objects at a given time
Media integration of text and graphics • 3d graphics • like VRML including script nodes • face animation • face definition parameters (FDPs) • face animation parameters (FAPs) • 2d mesh encoding • dynamic mesh, a temporal sequence of 2d triangular meshes • texture coding via wavelets
Face definition parameters • a number of feature points on a neutral face
Face animation parameters • a number of face • animation points
2d mesh decoding • mesh vertices points can move in 2d
2d mesh augmentation of fish • the letters are synthetically overlaid on the video object and move in synchronization with it
Conclusion • a superset of old VRML and Mpeg-1 and Mpeg-2 • very general, many concepts • can mix and match many different compression algorithms for different objects • handles everything (audio, video, 2d-3d, faces, mesh…) • is a first attempt at integrating 2d and 3d worlds • DivX is a software application that uses the MPEG-4 standard to compress digital video • DivX is done with the open source community • much better compression than ordinary DVDs