What Is an AAF File?
An AAF file is how a picture edit hands off to a sound mixer without anyone re-cutting the timeline by hand. It carries the sequence structure, not just a video file, which is exactly what a re-recording mixer needs and exactly what an EDL or a plain video export can't provide.
Definition
What an AAF actually is
AAF stands for Advanced Authoring Format, a container file that carries a video sequence's structure: tracks, clips, in and out points, basic effects, and often embedded or referenced audio, so it can be opened in a different application and still look like the same timeline. It's the standard handoff for a picture edit going to a mixing stage, most commonly into Pro Tools for the sound mix.
Origin
Where the format came from
The Advanced Authoring Format was published in April 1998 by a consortium that included Microsoft, Avid, Digidesign, Pinnacle Systems, Adobe, and several other production toolmakers, under what was then called the Advanced Authoring Format Association, now part of the Advanced Media Workflow Association (AMWA). It was built specifically to solve a problem the earlier AVI and WAV formats couldn't: moving a structured, multi-track project between different production tools without flattening it into a single video file first.
AAF Vs OMF
How AAF replaced Avid's older OMF format
Before AAF, Avid used OMF (Open Media Framework Interchange) for the same handoff job, and OMF's design directly informed AAF's technical foundation. OMF has a 2GB file size ceiling and limited metadata support, which becomes a real problem on a feature film with dozens of audio tracks. AAF removed that size limit and added richer structural data, which is why most modern post houses default to AAF and only fall back to OMF for older systems that don't support the newer format.
In Practice
A worked example: picture lock to sound mix
A 22-minute documentary segment locks picture in DaVinci Resolve with eight audio tracks: two interview mics, ambient sound, three music cues, and two sound effect layers. The editor exports an AAF from Resolve, which carries every track, every clip's in and out point, and references to the original audio files. The mixer opens that AAF in Pro Tools and sees the identical track layout the editor built, ready to clean up dialogue and balance levels, instead of receiving a single stereo video file and rebuilding the track separation from scratch.
Here is that exact export, from a locked timeline to an AAF a mixer can open in Pro Tools:
Format Comparison
AAF, EDL, and XML: which one to use when
| Format | Carries | Best for |
|---|---|---|
| AAF | Full sequence structure, multiple tracks, audio references | Picture-to-sound-mix handoff, Avid import |
| EDL | Flat, single-track cut list with timecodes | Simple assemble cuts, older systems |
| XML / FCPXML | Sequence structure for Premiere Pro or Final Cut Pro | Cross-NLE picture handoff |
Common Mistakes
Where AAF exports go wrong
Exporting before picture lock and then re-exporting after the mixer has already started work overwrites their session with a new structure, which is why AAF handoff should happen only after picture is genuinely locked. Embedding versus referencing audio is the second trap: an AAF that references external audio files breaks completely if those files move, while embedding audio avoids that but produces a much larger file. The third is sending an AAF with mixed frame rates between the picture edit and the audio session, which causes sync drift that's obvious on dialogue but easy to miss on music beds.
How This Connects To The Pre-Edit
AAF is the end of a chain that starts with a transcript
The AAF handoff to a mixer is the last export in a chain that, for interview-heavy work, usually starts with a transcript. ScriptCut's role sits at the front of that chain: selections marked on a word-level transcript export as XML, EDL, or AAF into the NLE, where the editor builds and locks picture, before that locked sequence gets its own AAF export to the mix stage. Same format, two different jobs, one for story selection into the edit, one for the finished picture into sound.
Related: Export a Paper Edit to Final Cut Pro and Avid, What Is a Paper Edit?, What Is Offline Editing?, and What Is Timecode?
Sources
frequently asked questions
It hands off a locked picture edit to a sound mixer, most often into Pro Tools, carrying the full track structure, clip in/out points, and audio references so the mixer sees the same timeline the editor built.
OMF is Avid's older interchange format with a 2GB file size ceiling and limited metadata. AAF, built on OMF's foundation, removed the size limit and added richer structural data, which is why most post houses default to it now.
After. Exporting before lock and then re-exporting once the mixer has started work overwrites their session with a new structure and discards their progress.
Not usually. AAF primarily carries the sequence's audio structure and references. Picture typically travels separately as a reference movie or the locked video export.
Use AAF when the sequence has multiple audio tracks or layered structure that needs to survive the handoff, like a picture-to-mix export. EDL only holds up for a flat, single-track cut list, and XML/FCPXML is for picture handoff between NLEs, not audio mixing.
A 1998 consortium including Microsoft, Avid, Digidesign, Pinnacle Systems, and Adobe published the Advanced Authoring Format specification, now maintained by the Advanced Media Workflow Association.
They can if audio is embedded rather than referenced, since embedding avoids broken file links but produces a much larger file than referencing external audio.
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