Advanced Authoring Format

The Advanced Authoring Format (AAF) is a professional file interchange format designed for the video post-production and authoring environment. It was created by the Advanced Media Workflow Association. The AMWA develops specifications and technologies to facilitate the deployment and operation of efficient media workflows, working closely with standards bodies like the SMPTE.

Technical work of the AMWA is through projects that strive for compatibility between AAF (Advanced Authoring Format), BXF, MXF (Material Exchange Format) and XML. The current projects fall into three categories: data models, interface specifications, and application specifications.

AAF was created to help address the problem of multi-vendor, cross-platform interoperability for computer-based digital video production. There are two kinds of data that can be interchanged using AAF:

• Audio, video, still image, graphics, text, animation, music, and other forms of multimedia data. In AAF these kinds of data are called essence data, because they are the essential data within a multimedia program that can be perceived directly by the audience

• Data that provides information on how to combine or modify individual sections of essence data or that provides supplementary information about essence data. In AAF these kinds of data are called metadata, which is defined as data about other data. The metadata in an AAF file can provide the information needed to combine and modify the sections of essence data in the AAF file to produce a complete multimedia program.

There are two major parts to AAF: the AAF Object Specification and the AAF Software Development Kit (SDK) Reference Implementation.

The AAF Object Specification defines a structured container for storing essence data and metadata using an object-oriented model. It defines the logical contents of the objects and the rules for how the objects relate to each other. The AAF Low-Level Container Specification describes how each object is stored on disk. It uses Structured Storage, a file storage system developed by Microsoft, to store the objects on disk.

AAF does a number of things:

By preserving source referencing, and abstracting the creative decisions that are made, AAF tries to improve workflow and simplify project management.

AAF is designed to be a data representation of works in progress, as compared to MXF (Material Exchange Format), which is for exchanging finished media products. While MXF uses a KLV (Key Length Value) format for storage, AAF uses the Microsoft Structured Storage system. MXF was developed to be essentially a subset of the AAF data model, under the Zero Divergence Directive (ZDD) policy. This allows for workflows that involve the mixing of AAF and MXF.

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