MXF and AAF

Many broadcasters know about MXF, and they have heard of things such as MXF for Finished Programs (AS-03) and MXF for Commercials (AS-12). But, this month, I want to focus on MXF’s bigger brother, AAF.

In the middle 1990s, a joint task force was created by the SMPTE and EBU. The purpose was to address the impending flood of digital video proposals. There were a number of different, competing proposals on the table regarding compression, handling of metadata and the exchange of program material as files. Many in the industry were concerned that without a concerted effort, the market would fracture, leaving end users to sort it out. Fortunately, the task force produced a number of recommendations that later led to standards that have helped drive industry consensus about what constitutes interoperable
digital video.

The remit of the task force went beyond coming up with recommendations for interoperable digital video formats, however. The final report included in its name “Harmonized Standards for the Exchange of Program Material as Bitstreams.”  The group spent a significant amount of time working on something called wrappers. After spirited debate, it was decided that two classes of wrappers should be developed — one for broadcast and one for editing. The group felt that a single wrapper could not accommodate the differing needs of these two application areas. Ultimately, the wrapper for broadcast became MXF, and the wrapper for editing became AAF.

Before we delve fully into AAF, let’s talk about wrappers, what they do and why they are important.