(1) The number of beats/amount of time a sample starts before the playback marker.
(2) In SMPTE timecode synchronization for videotape post-production, a number of seconds and/or frames which are to be automatically subtracted from any record-in point (some brands of synchronizer subtract the pre-roll from the mark-in point, rather than the record-in point.) The synchronizer will then return master and slave machines to a point located ahead of the record-ins by the duration of the specified pre-roll. This assures that all machines will be up to speed, properly interlocked, and that the talent can find their place and be ready to perform by the actual record-in point. For example, if the record-in point is 20:10:00, and the pre-roll is 5:00, the deck will actually stop at 20:05:00, precisely five seconds before the specified record-in. See post-roll.