What Is an AAF File?
An AAF (Advanced Authoring Format) file is a professional interchange file that moves an edited timeline, its media, track layout, and metadata from one editing system to another, most commonly from a video editor into a digital audio workstation like Pro Tools for the final sound mix.
When the picture is locked and it is time to mix, the editor needs to hand the sound team everything: which clips play where, on which tracks, with what volume moves. An AAF is the package that carries all of it. Open it in Pro Tools and the editor's timeline rebuilds itself, ready to mix.
If you have ever wondered how a finished edit gets from the picture editor to the sound mixer without anyone rebuilding it by hand, the answer is usually AAF.
What an AAF is
AAF is an interchange format. Its job is to get video, audio, and metadata from one system to another without losing the structure that matters. It was designed for professional cross-platform post-production, so a project built in one tool can move to another and still make sense.
In day-to-day post, AAF is the standard handoff file for moving a project from a non-linear editor into a DAW, most commonly Pro Tools. The editor exports an AAF of the audio, the mixer imports it, and the session appears with the clips on the right tracks at the right times.
Where it came from
AAF was created by an industry group, the Advanced Media Workflow Association, and is being standardized through SMPTE. The original specification grew out of a consortium that included Avid and Microsoft, formed to solve a real headache: multi-vendor, cross-platform interoperability. Different facilities ran different tools, and projects needed to move between them without falling apart.
That origin explains its design. AAF is not tied to one company's software. It is a neutral container meant to preserve a project's structure as it crosses from one application to another.
AAF versus OMF
For years the audio handoff standard was OMF (Open Media Framework). AAF replaced it, and the reason is simple: AAF carries more.
OMF loses things in transit. When you move a project via OMF, you typically lose track names and volume automation. The mixer opens the session and sees generically numbered tracks with flat levels, then has to rebuild context by hand.
AAF keeps that information. It retains track names and volume automation, so the mix session arrives organized and intact. As one audio post resource sums it up, that is the single biggest reason post-production moved to AAF and why OMF is rarely used today.
There are other practical differences, like how media is embedded or linked, but the headline is preservation. AAF hands the sound team a session that already reflects the editor's intent.
A worked example
You finish cutting a documentary in your NLE and reach picture lock. Now the sound mixer needs to do the real audio work: clean the dialogue, balance levels, add effects, mix the music.
You export an AAF of your audio tracks. Inside it: every dialogue clip, every music cue, every sound effect, sitting on named tracks at exact timecode positions, with the rough volume moves you made during the edit. You send that one file to the mixer.
They import it into Pro Tools and your timeline reconstructs itself. Dialogue on the dialogue tracks, music where you placed it, levels roughly where you left them. Nothing rebuilt from scratch. The mixer starts from your edit instead of starting from zero, which saves hours and prevents the small errors that creep in when someone reassembles a timeline by ear.
AAF, EDL, XML: which is which
It helps to keep the interchange formats straight, because they do different jobs.
An EDL is the oldest and simplest, a plain text list of edits, mostly used for conform and color. FCPXML and XML carry richer timeline data, often used to move a full edit between video editors or into color. AAF is the one tuned for the audio handoff into a DAW, because it preserves the track and automation detail mixers need.
So you would not usually send an AAF to a colorist or an EDL to a mixer. You match the format to the destination.
Common mistakes
The first mistake is mishandling media. AAF can either embed the audio inside the file or link to external files. If you link and then move the media, the session opens with offline clips. Know which mode you exported and keep the media with the file.
The second is exporting before picture lock. An AAF reflects the edit at the moment you export it. If the cut changes afterward, the mix session is out of date and someone has to re-conform. Lock first, then hand off.
The third is assuming AAF carries the picture too. In the typical audio workflow it carries the sound. The mixer usually also gets a reference video export to mix against, exported separately.
How this connects to the pre-edit
AAF lives at the back end of post, the moment the locked edit hands off to the mix. The pre-edit lives at the front, where you decide what the story is in the first place. ScriptCut handles that front end: you transcribe, select the strongest moments, arrange the story, get client approval, and export a clean timeline as XML, EDL, or subtitles into your NLE. From there your normal finishing chain takes over, and when the picture is locked, your editor exports the AAF to the sound team. ScriptCut gets you to a solid cut faster, so the locked timeline that feeds the AAF is built on a story everyone already signed off on. For the export side, see what is an EDL and exporting a paper edit to Final Cut and Avid.
Sources
Frequently asked questions
What is an AAF file?
An AAF (Advanced Authoring Format) file is a professional interchange file that carries an edited timeline, its media, track layout, and metadata between editing systems. It is most often used to move audio from a video editor into a DAW like Pro Tools for the final mix.
What is the difference between AAF and OMF?
AAF carries more than OMF. OMF typically loses track names and volume automation in transit, while AAF preserves them. That preservation is the main reason modern post-production switched from OMF to AAF.
What is an AAF used for?
It is the standard handoff for moving a locked edit's audio from a non-linear editor into a digital audio workstation, so the sound mixer gets the clips on the right tracks at the right times with the editor's rough levels intact.
Should I export AAF before or after picture lock?
After picture lock. An AAF captures the edit as it exists at export time. If the cut changes afterward, the mix session is out of date and must be re-conformed, so lock the picture first, then hand off.