Offline editing is the creative storytelling stage of film making and television production where the structure, mood, pacing and story of the final show are defined. Many versions and revisions are presented and considered at this stage until the edit gets to a stage known as picture lock. This is when the process then moves on to the next stages of post production known as online editing, colour grading and audio mixing.
Typically, during the Offline editing part of the post-production process, all the original camera footage (often tens or hundreds of hours) is digitized into a Non-Linear Editing System as a low resolution duplicate. The editor and director are then free to work with all the footage to create the final cut. Editing the copy allows multiple story and creative possibilities to be explored without affecting the camera original film stock or video tape. Once the project has been completely offline edited, the low resolution footage is replaced with the original high resolution media, or "brought online."
Modern offline video editing is conducted using specialized computer hardware and video editing software known as a non-linear editing (NLE) suite, such as Adobe Premiere, Final Cut Pro, Avid Media Composer, DaVinci Resolve, Sony Vegas, Lightworks and VideoPad. The availability of more powerful digital editing systems has made the offline editing workflow process much quicker than the previous method of time-consuming (video tape to tape) linear video editing.
The term offline originated in the computing and telecommunications industries, meaning "not under the direct control of another device" (automation).
History
From film to tape
Film editing used an offline approach almost from the beginning. Film editors worked with a workprint of the original film negative to protect the negative from handling damage. When two-inch quadraplex video tape recording was first introduced by Ampex in 1956, it could not be physically cut and spliced simply and cleanly as film negatives could be. One error-prone method option was to cut the tape with a razor blade. Since there was no visible frame line on the tape, a special ferrofluid developing solution was applied to the tape, allowing the editor to view the recorded control track pulse under a microscope, and thus determine where one frame ended and the next began. This process was not always exact, and if imperfectly performed would lead to picture breakup when the cut was played. Generally this process was used to assemble scenes together, not for creative editing.
The second option for video editing was to use two tape machines, one playing back the original tapes, and the other recording that playback. The original tapes were pre-rolled, manually cued to a few seconds prior to the start of a shot on the player, while the recorder was set to record. Each machine was rolled forward simultaneously, and a punch in recording, similar to punch in / out of early audio multitrack recordings was made at the appropriate moment. Beyond not being very precise, recorders of this era cost much more than a house, making this process an expensive use of the machines. This technique of re-recording from source to edit master came to be known as linear video editing.
This was the way things were for television shows shot on tape for the first 15 years. Even such fast-paced shows as Rowan & Martin's Laugh-In continued to use the razor blade technique.
New technological developments
Three developments of the late sixties and early seventies revolutionized video editing, and made it possible for television to have its own version of the film workprint/conform process.
Time code
The first was the invention of time code. Whereas film negative had numbers printed optically along the side of the film, so that every frame could be identified exactly, video tape had no such system. Only video, audio, and a control pulse were recorded. Early attempts to rectify this were primitive to say the least. An announcer reciting the seconds was recorded onto an audio channel on the tape. Time code introduced frame precision, by recording a machine readable signal on an audio channel. A time code reader device translated this signal into hours, minutes, seconds and frames, originally displayed on a Nixie tube display, and later with LED readouts. This innovation made it possible for the editor to note the exact frames at which to make a cut, and thus be much more precise. He could create a paper edit by writing down the numbers of the first and last frames of each shot, and then arrange them in order on paper prior to the actual edit session with the expensive VTRs.