Format guide
EDL files: the CMX cut list.
An EDL is an edit decision list: a plain-text file, almost always in the CMX 3600 dialect, that describes a cut as a numbered sequence of events. Each event names a source reel, a track type, a transition, and four timecodes — source in, source out, record in and record out. An EDL carries no media, no effects beyond simple transitions, and only one video track, which is why it survives as a conform and colour-grading handoff format rather than a general interchange format. Avid Media Composer exports EDLs through EDL Manager or the List Tool, and any text editor can open one.How to read an EDL event
A CMX 3600 event line is fixed-width and positional. A typical line reads:
003 TAPE01 V C 01:00:12:00 01:00:15:10 00:00:06:00 00:00:09:10
Read left to right, the fields are the event number, the source reel identifier, the track type, the transition code, and then source in, source out, record in and record out timecodes.
| Field | Example | Meaning |
|---|---|---|
| Event number | 003 | Sequential edit number, three digits |
| Reel | TAPE01 | Source identifier, historically eight characters |
| Track | V, A1, A2, AA | Video, audio channel, or both audio channels |
| Transition | C, D, W###, K | Cut, dissolve, wipe with pattern number, key |
| Duration | 025 | Transition length in frames, present only for non-cuts |
| Timecodes | four HH:MM:SS:FF values | Source in, source out, record in, record out |
Comment and note lines
Everything that CMX 3600 cannot express in an event line arrives as a comment. These lines are not decoration — a conform frequently depends on them.
* FROM CLIP NAME:and* TO CLIP NAME:carry the human-readable clip names either side of a transition.* SOURCE FILE:carries a file name for file-based sources, which matters when reel identifiers are not unique.M2motion effect lines carry a source speed for a retimed event, adjacent to the event they modify.FCM: NON-DROP FRAMEorFCM: DROP FRAMEsets the frame count mode for the timecodes that follow. Getting this wrong shifts every subsequent record timecode.TITLE:on the first line names the list.
Exporting an EDL from Avid Media Composer
Load the sequence in the Timeline, then open EDL Manager — on recent releases the List Tool serves the same role. Choose the CMX 3600 template, set the frame count mode to match the sequence, and select which tracks to output.
Because an EDL holds one video track, a multilayer sequence must be output as several lists or flattened first. Effects other than dissolves and simple wipes do not survive; the usual practice is to export the EDL for conform and hand the effects over separately as an AAF.
Validating an EDL before conform
avid_analyze_edl in the Avid Media Composer MCP server parses events, transitions, comment lines and motion effect lines with a native CMX-style parser and returns them as structured data with warnings for malformed events. It is a read-only inspection, so it can be pointed at a delivery folder to answer questions like which reels a list depends on, or whether the frame count mode is consistent across the file, before anyone loads it into a conform system.
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
What is an EDL file?
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An EDL is an edit decision list: a plain-text file, usually CMX 3600, describing a cut as numbered events. Each event names a source reel, track, transition and four timecodes — source in and out, record in and out.
How do I export an EDL from Avid Media Composer?
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Load the sequence, open EDL Manager or the List Tool, choose the CMX 3600 template, set the frame count mode to match the sequence, select the tracks, and save. Only one video track is output per list.
What does C or D mean in an EDL?
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They are transition codes. C is a cut, D is a dissolve, W followed by a pattern number is a wipe and K is a key. Non-cut transitions are followed by a duration in frames.
What is the difference between an EDL and an AAF?
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An EDL is plain text describing one video track of cuts and simple transitions. An AAF is a structured package carrying multiple tracks, effects, keyframes, descriptors and optionally the media itself. EDLs are used for conform and grading; AAFs for full picture and sound turnover.
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.