An edit decision list or EDL is used in the post-production process of film editing and video editing. The list contains an ordered list of reel and timecode data representing where each video clip can be obtained in order to conform the final cut - wikipedia 
# Coding with video timecode
Ffmpeg and the MLT Multimedia Framework are command-line tools for editing and manipulating video based on video timecode (or edit decision lists.
# EDL Formats
This section describes components of an EDL using the CMX 3600 EDL format. Other formats may vary slightly.
In an EDL, each clip in your sequence is represented by a line of text called an event, which has a unique event number.
A clip in an EDL is defined by a source reel name and two pairs of timecode In and Out points. The first pair of timecode numbers describes the source tape (or clip) In and Out points. The second pair describes the timecode location where that clip should be placed onto a master tape (or Timeline).
# Elements of an EDL
The elements of an EDL are described in the following sections.
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171 001 V C 01:38:41:00 01:39:15:24 01:38:41:00 01:39:15:24
001004VC04:31:13:04 04:31:22:23 01:00:00:00 01:00:10:00 001014VD030 14:27:03:03 14:27:25:22 01:00:10:10 01:00:30:00
# Title and Sequence Timecode Format The first line of an EDL contains the title of the sequence. In NTSC sequences, the second line displays whether the sequence timecode is drop frame or non-drop frame.
Row 1: TITLE (the title of the EDL) Row 2: FCM: – Frame Code Mode
Column 1: 001 – number of edit event Column 2: TAPE1 – name of Source tape Column 3: V – this tells that edit is Video only Column 4: C, D or W (Cut, Dissolve or Wipe) Column 5: timecode for Source In point Column 6: timecode for Source Out point Column 7: timecode for Master / Recorder In point Column 8: timecode for Master / Recorder Out point
# Column 1: Event Number An event number uniquely identifies each event in the EDL. An EDL event requires two lines if more than one source is used. For example, a dissolve requires one line for the outgoing shot and a second line for the incoming shot.
# Column 2: Reel Name A reel name describes which source tape (or reel) the clip comes from. Final Cut Pro assumes that clips without reel names come from non-tape sources, such as color bars, black, or other generators. Final Cut Pro automatically designates these auxiliary sources with the reel name AX. Important: Make sure all clips with timecode sources have reel names before exporting an EDL, or you won’t be able to easily re-create your sequence when you open the EDL on another editing system.
# Column 3: Track Type Each edit uses one or more tracks in the sequence. In the case of tape-to-tape editing, this field determines which tracks are turned on on the record deck during this event.
- V: Video - A: Audio (Some EDL formats label this 1 or 2.) - A2: Audio 2 - AA: Both channels of audio
Video track V1 is the only video track exported. Clips on video track V2 appear as key effect (K) over the V1. Video tracks V3 and above are ignored during EDL export.
# Column 4: Edit (or Transition) Type An EDL can represent several kinds of video edits, or transitions. A cut requires a single source, while all other types of edits require two sources, and thus two lines in an EDL.
- C: Cut. This is the simplest kind of edit. - D: Dissolve. This transition begins with one source and dissolves to a second source. - W: A wipe. This is followed by a wipe code that indicates the type of standard wipe. - K: A key edit. Clips on Video track 2 can be used as the foreground (fill) layer in a standard video key.
A dissolve from a Final Cut Pro sequence is shown below in EDL format.
Figure. Timeline window showing a cross dissolve transition. 001002VC02:10:42:13 02:11:16:18 01:00:00:00 01:00:34:05 001002VD024 02:18:32:07 02:18:56:19 01:00:34:05 01:00:58:17
# Column 5: Transition Duration (sometimes) The duration of a transition (in frames) follows the transition type. For example, D 024 indicates a 24-frame dissolve.
# Column 5 & 6: Source In and Out In each line of an EDL, the first pair of timecode numbers are the source In and Out points.
# Column 7 & 8: Record In and Out The second pair are the record In and Out points, which correspond to the clip’s location in the Timeline.
# Edits and Transitions
Edits that use transitions such as dissolves or wipes require two lines. The first line represents the source before the transition, and the second line is the source after the transition.
On tape-to-tape editing systems, the tapes containing the two shots are loaded in two video decks—VTR A and VTR B. To perform a dissolve or wipe, the edit controller plays both decks simultaneously and uses a hardware video switcher to create the transition effect as it’s recording on the final master tape. However, when both shots in a dissolve, wipe, or key are on the same reel, it is impossible to perform the effect in a tape-based editing suite. This is because the tape cannot be in both places at the same time. For a workaround to this problem, see Settings and Options in the EDL Import Dialog.
Split edits, where the video and audio have separate In and Out points, require three lines. Figure. Timeline window showing a split edit. SPLIT: VIDEO DELAY= 00:00:02:00 004002AAC02:18:30:07 02:18:56:19 01:00:32:05 01:00:58:17 004002VC02:18:32:07 02:18:56:19 01:00:34:05 01:00:58:17
The first line indicates which track is delayed and by how much, the second line indicates the track (audio or video) that plays through the entire edit duration, and the third line contains the delayed track.
# See also - Edit decision list - B-Roll