Timecode

Timecode is the numeric label given to every frame of video or film, providing the temporal coordinate system that synchronizes picture, audio, metadata and all downstream operations across post-production. SMPTE timecode encodes hours, minutes, seconds and frames in the format HH:MM:SS:FF — for example 01:23:45:18 means 1 hour 23 minutes 45 seconds and frame 18. Frame counts vary by frame rate: at 24fps the FF field counts 0-23, at 25fps it counts 0-24, at 30fps it counts 0-29. Two formats coexist: non-drop-frame timecode (the count is exact, used at all integer frame rates 24, 25, 30 and at film-camera 23.976, with a discrepancy with wall-clock time at 29.97 and 23.976) and drop-frame timecode (a clever convention that drops two frames every minute, except every 10th minute, to keep the timecode synced to real wall-clock time at 29.97fps, used in broadcast). Timecode is typically recorded on set via jam-syncing all cameras and audio recorders to a master clock — Ambient Lockit or Tentacle Sync are common devices. In post, timecode is the master synchronization key: edit decision lists are timecode references, color grading reels reference timecode boundaries, audio mix sessions sync to picture timecode. SMPTE ST 12 is the governing standard.