Workflow guide
Avid bin locking, explained.
Avid bin locking is how Media Composer prevents two editors from writing to the same bin at once in a shared project. When a user opens a bin with write access, Media Composer creates a lock file next to it in the project folder — the same base name with a.lck extension — recording who holds the bin. Other users on the shared volume see the bin as locked and can open it read-only. The lock is advisory and file-based, not a database transaction: if Media Composer exits uncleanly the .lck file survives, and the bin appears locked by a session that no longer exists. That leftover file is an orphaned lock.What a .lck file is
A .lck file is small, plain and sits directly beside the bin it guards. Cut_v04.avb is locked by Cut_v04.lck in the same directory. It records the identity of the user or workstation holding the bin, which is what Media Composer displays when another editor tries to open it.
Because the mechanism is a file rather than a lock server, it works across any shared filesystem — Avid NEXIS, a SAN, or plain network storage — and it fails in the way file-based locks fail: the lock outlives the process that created it.
"Bin is locked at the file level"
This message is different from ordinary bin locking, and the distinction matters. It means the operating system or storage layer is refusing write access to the .avb itself, not that another Avid user holds it.
Common causes are read-only permissions on the project folder, a volume mounted read-only, a file marked read-only by a backup or sync tool, or an antivirus or cloud-sync client holding a handle on the file. Removing a .lck file does not fix this — the fix is at the filesystem or storage level.
Clearing an orphaned lock
Before deleting any lock file, confirm nobody actually has the bin open. A lock deleted while a live session holds the bin invites two editors writing to the same file, which is exactly the outcome locking exists to prevent.
- Confirm with the person or workstation named in the lock that Media Composer is closed.
- Check for a running Media Composer process on that workstation, not just a closed window.
- Delete only the specific
.lckfile, never the.avbbeside it. - Reopen the bin. If it is still read-only, the problem is file-level permissions, not an Avid lock.
Auditing locks across a project
On a large show, orphaned locks accumulate quietly and only surface when someone needs a bin. Auditing them is a read-only operation and is worth automating.
avid_inventory_project_files in the Avid Media Composer MCP server classifies every file in a project tree by kind, .lck bin locks included, and reports where each lock sits relative to its bin. avid_analyze_project rolls that up into a per-project lock count. Both tools are read-only: they report locks and never delete them, because deciding that a lock is orphaned requires knowing whether a human still has the bin open.
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.
Frequently asked questions
How does Avid bin locking work?
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When a user opens a bin with write access in a shared project, Media Composer writes a .lck file beside the bin recording who holds it. Other users see the bin as locked and open it read-only. The lock is a file, not a database transaction.
What is a .lck file in an Avid project?
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A bin lock file. It sits in the project folder next to the bin it guards, shares the bin's base name, and records the user or workstation currently holding write access to that bin.
Why does Avid say the bin is locked at the file level?
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Because the filesystem or storage layer is refusing write access to the .avb itself — read-only permissions, a read-only mount, a read-only file attribute, or a backup, antivirus or cloud-sync client holding the file. It is not an Avid bin lock, and deleting a .lck file will not clear it.
Is it safe to delete a .lck file?
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Only after confirming that nobody has the bin open and no Media Composer process is running on the workstation named in the lock. Deleting a live lock allows two editors to write to the same bin, which can corrupt it. Delete only the .lck file, never the .avb.
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.