Edit decision list
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An Edit Decision List or EDL is a way of representing a film or video edit. It contains an ordered list of reel and timecode data representing where each video clip can be obtained in order to conform the final cut.
EDLs are created by offline editing systems, or can be paper documents constructed by hand. These days, linear editing systems have been superseded by non linear editing systems which can output EDLs electronically to allow autoconform on an online editing system - the recreation of an edited programme from the original sources (usually video tapes) and the editing decisions in the EDL.
They are also often used in the digital video editing world, so rather than referring to reels they can refer to sequences of images stored on disk.
Some formats, such as CMX3600, can represent simple editing decisions only. Both XML and the Advanced Authoring Format are relatively advanced file formats that can contain sophisticated EDLs.
[edit] B-Roll
Linear editing systems cannot dissolve between clips on the same tape. Hence, one of these clips will need to be dubbed onto a new tape. EDLs designate these occurrences by marking such dissolves' source reels as b-reels. For example, the EDL will change the 8th character of the reel name to the letter B.
However, sometimes editors will (confusingly) use the letter B to designate timecode breaks on a tape. If there is broken timecode on a tape, there will be two (or more) instances of a particular timecode on the tape. When re-capturing, it can be ambiguous as to which timecode is the right one. The letter B may indicate that the right timecode is from the second set of timecode on the tape.
[edit] EDL incompatibilities and potential problems
EDL formats such as CMX, GVG, Sony, Final Cut Pro, and Avid are similar but can differ in small (but important) ways. Particular attention should be paid to reel naming convention. On the Avid, reel names can be up to 15 characters, but only the first 8 are unique. On FCP, in CMX3600 format, only six characters are allowed. Particular attention should be paid towards b-reels. If the EDL handles dissolves to the same reel, reel names should be limited to 7 characters since the 8th character may be replaced.
EDLs can use either drop-frame or non-drop frame timecode, running at 25, 29.97 or 23.976fps.
Overall, EDLs are still commonly used as some systems do not support other more robust formats such as AAF and XML.
[edit] Further reading
[1] Guide to EDL management.
