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A Flexible Finish
American Cinematographer Magazine
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The Advanced Authoring Format has its roots in OMF, the file-exchange format originally established by Avid Technology. But AAF Association executive director Brad Gilmer is quick to point out that AAF supercedes OMF with its capability of exchanging not simply files of picture and sound between devices, but information about those pictures and sounds. In other words, AAF contains metadata useful to the hybrid film-digital workflow.

"More of the production process is taking place in a computer environment," says Gilmer. "Being able to move information about what's happened so far on a project reliably between different vendors' equipment is becoming more and more critical. People are no longer content with just moving film from one point to another. They also want to move information about what's happened to the film. People can waste a lot of time in a facility trying to figure out what happened to the material - what aspect ratio it is, what sort of gamma curves were used when it was transferred. This can all be preserved as metadata in an AAF file and moved from one place to another."

The mission of the AAF Association is, in part, to develop "a multimedia file format that enables content creators to easily exchange digital media and metadata across platforms, and between systems and applications. The AAF simplifies project management, saves time, and preserves valuable metadata that was often lost when transferring media between applications in the past."

Association members comprise the typical panoply of manufacturers, including Adobe, and Apple, SGI, Thomson Grass Valley, Microsoft and Quantel. But there are also numerous members coming from the content-creation and distribution side, including the BBC, CNN, Sony, Turner Entertainment Networks, Warner Bros., E! Entertainment, the Dutch Broadcasting Services and The Post Group.

The "implementers" and "systems builders" include a wide range of equipment manufacturers that the cinematographer encounters on the path to completing a film. Typical systems include an Avid nonlinear editor, a da Vinci 2K color corrector, a Quantel iQ or simply an Apple or Microsoft computer.

"Dark metadata" allows manufacturers to transfer information that is not accessible to everyone and might be used, for example, to help an older, proprietary device "understand" the metadata that's being delivered from a newer AAF-compliant system. "Enlightened companies will use dark metadata for practical reasons that meet their users' needs," says Gilmer. But it's also possible for manufacturers to use dark metadata to make it impossible for their competitors to properly interpret the metadata being sent. The politics inherent in getting a group of competitors to agree to share information and create interoperability is unavoidable, and the members who make up the AAF Association are no exception.

"Total 'world peace' is impossible," says Quantel's Horton, who notes that Quantel was a "day one" adopter of AAF and that all of its shipping products have AAF in one form or another. "But the act of moving toward it is a good first step. AAF isn't aiming to do everything for everyone all the time. It's a first step toward doing more of what most people want to do most of the time."

As Gilmer puts it, the advent of networked digital productions has pushed the industry as a whole to endure the pain of creating a new metadata pipeline. What works well on paper is bound to reveal stumbling blocks and glitches as it's put into practice. Now is the perfect time - perhaps the only really useful time - to play a role in how that metadata pipeline will impact cinematographers and their work.

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© 2003 American Cinematographer.