Format guide

AVB files: the Avid bin format.

An AVB file is an Avid Media Composer bin. The .avb extension marks a proprietary binary container that stores the clips, subclips, sequences, groups, effects, bin views and column metadata belonging to one bin inside an Avid project folder. AVB is not an interchange format and is not media: it holds references to media files rather than the picture and sound themselves, and Avid publishes no public specification for it. Media Composer opens AVB files natively; outside Media Composer they can be read with the open-source pyavb library, which is what the Avid Media Composer MCP server uses for offline bin analysis.

What is inside an AVB file?

An Avid bin is an object graph, not a flat table. Media Composer serialises the bin's objects — the same mobs, tracks and components model that AAF later standardised — into a single binary file. Reading one means walking that graph rather than parsing lines.

A typical bin contains the following object families.

Master mobs: the clips shown in the bin, each pointing at source material by identifier rather than by path.
Source mobs: the tape, file or import sources those clips were logged from, carrying reel names, timecode and file descriptors.
Composition mobs: sequences and subclips, with video and audio tracks made of source clips, filler, transitions and effects.
Bin presentation state: column layouts, sift and sort settings, custom columns, frame or script view state and clip colours.
User metadata: comments, markers, and any column values entered by the assistant or editor.

AVB vs AAF vs MXF: which file does what

These extensions appear side by side in an Avid workflow and are routinely confused. They occupy different layers.

Extension	Layer	Portable?	Contains media?
`.avb`	Avid bin, project-internal	No — Avid only	No, references only
`.aaf`	Interchange composition or embedded essence	Yes — open AMWA standard	Optionally, when embedded
`.mxf`	Media essence container	Yes — SMPTE standard	Yes, the picture or sound itself
`.ale`	Tab-delimited metadata log	Yes — plain text	No
`.edl`	CMX-style cut list	Yes — plain text	No

How to open an AVB file

There is no general-purpose AVB converter, because there is no published specification to convert from. Three approaches are practical.

Media Composer: open the containing project and the bin, then export the parts you need as AAF, ALE or EDL. This is the only path that is fully faithful.
pyavb: an open-source Python reader for Avid bins. It exposes the object graph directly and is the basis for most non-Avid AVB tooling.
An MCP server: avid_analyze_bin in the Avid Media Composer MCP wraps pyavb and returns mobs, tracks, clips, sequences, views and metadata as structured JSON that an AI client can reason over, without opening Media Composer and without modifying the bin.

Reading a bin safely

Bins are live project state. An assistant editor's working bin can be open in Media Composer, locked by another user on shared storage, or mid-save. Any offline reader has to respect that.

The MCP server treats a bin as read-only and never writes to .avb files. It also reports the neighbouring .lck bin locks it finds, so an automated audit can distinguish a bin that is genuinely in use from one holding an orphaned lock left by a crash. When pyavb cannot decode a structure, the result is labelled as opaque evidence rather than guessed at.

MCP tools for this

The open-source Avid Media Composer MCP server exposes these tools to any MCP-compatible AI client. Every one of them is read-only.

Install the server All tools

Frequently asked questions

What is an AVB file?

An AVB file is an Avid Media Composer bin — a proprietary binary container storing clips, subclips, sequences, effects and bin metadata for one bin in an Avid project. It references media rather than containing it.

How do I open an AVB file without Media Composer?

Use the open-source pyavb Python library, or a tool built on it such as the avid_analyze_bin tool in the Avid Media Composer MCP server, which returns the bin's mobs, tracks, clips and metadata as structured JSON.

Is there an AVB to AAF converter?

There is no reliable standalone converter. The supported route is to open the bin in Media Composer and export the sequence or clips as AAF. pyavb can read a bin's structure programmatically, but faithfully rewriting it as AAF is a separate translation problem.

What is the difference between an AVB file and an MXF file?

An AVB file is an Avid bin holding editorial metadata and references. An MXF file is a media container holding the actual picture or sound essence. Deleting a bin loses editorial work; deleting MXF media loses the footage.

Related guides

This page documents an independent open-source project. It is not affiliated with or endorsed by Avid Technology, Inc. Behaviour described for the MCP server reflects the published package; confirm format and application details against Avid's own documentation before relying on them in production.