Non-linear editing for film and television postproduction is a modern editing method which involves being able to access any frame in a video clip with the same ease as any other. This method is similar in concept to the "cut and paste" technique used in film editing from the beginning. It can also be viewed as the audio/video equivalent of word-processing. However, when working with film, it is a destructive process, as the actual film negative must be cut. Non-linear, non-destructive methods began to appear with the introduction of digital video technology.
Video and audio data are first captured to hard disks or other digital storage devices. The data is either recorded directly to the storage device or is imported from another source. Once imported they can be edited on a computer using any of a wide range of software. For a comprehensive list of available software, see List of video editing software, whereas Comparison of video editing software gives more detail of features and functionality.
In non-linear editing, the original source files are not lost or modified during editing. Professional editing software records the decisions of the editor in an edit decision list (EDL) which can be interchanged with other editing tools. Many generations and variations of the original source files can exist without needing to store many different copies, allowing for very flexible editing. It also makes it easy to change cuts and undo previous decisions simply by editing the edit decision list (without having to have the actual film data duplicated). Loss of quality is also avoided due to not having to repeatedly re-encode the data when different effects are applied.
Compared to the linear method of tape-to-tape editing, non-linear editing offers the flexibility of film editing, with random access and easy project organization. With the edit decision lists, the editor can work on low-resolution copies of the video. This makes it possible to edit both standard-definition broadcast quality and high definition broadcast quality very quickly on normal PCs which do not have the power to do the full processing of the huge full-quality high-resolution data in real-time.
The costs of editing systems have dropped such that non-linear editing tools are now within the reach of home users. Some editing software can now be accessed free as web applications, some, like Cinelerra (focused on the professional market), can be downloaded free of charge, and some, like Microsoft's Windows Movie Maker or Apple Computer's iMovie, come included with the appropriate operating system.
A computer for non-linear editing of video will usually have a video capture card to capture analog video and/or a FireWire connection to capture digital video from a DV camera, with its video editing software. Modern web based editing systems can take video directly from a camera phone over a GPRS or 3G mobile connection, and editing can take place through a web browser interface, so strictly speaking a computer for video editing does not require any installed hardware or software beyond a web browser and an internet connection.
The first truly non-linear editor, the CMX 600, was introduced in 1971 by CMX Systems, a joint venture between CBS and Memorex. It recorded & played back black-and-white analog video recorded in "skip-field" mode on modified disk pack drives the size of washing machines. These were commonly used to store data digitally on mainframe computers of the time. The 600 had a console with 2 monitors built in. The right monitor, which played the preview video, was used by the editor to make cuts and edit decisions using a light pen. The editor selected from options which were superimposed as text over the preview video. The left monitor was used to display the edited video. A Digital PDP-11 computer served as a controller for the whole system. Because the video edited on the 600 was in black and white and in low-resolution "skip-field" mode, the 600 was suitable only for offline editing.
Various approximations of non-linear editing systems were built in the '80s using computers coordinating multiple laser discs, or banks of VCRs. One example of these tape & disc-based systems was Lucasfilm's EditDroid, which used several laserdiscs of the same raw footage to simulate random-access editing (a compatible system was developed for sound post production by Lucasfilm called SoundDroid--one of the earliest digital audio workstations).
The term "nonlinear editing" or "non-linear editing" was formalized in 1991 with the publication of Michael Rubin's Nonlinear: A Guide to Digital Film and Video Editing (Triad, 1991) -- which popularized this terminology over other language common at the time, including "real time" editing, "random-access" or "RA" editing, "virtual" editing, "electronic film" editing, and so on. The handbook has remained in print since 1991, currently in its 4th edition (Triad, 2000).
Computer processing advanced sufficiently by the end of the '80s to enable true digital imagery, and has progressed today to provide this capability in personal desktop computers.
An example of computing power progressing to make non-linear editing possible was demonstrated in the first all-digital non-linear editing system to be released, the "Harry" effects compositing system manufactured by Quantel in 1985. Although it was more of a video effects system, it had some non-linear editing capabilities. Most importantly, it could record (and apply effects to) 80 seconds (due to hard disk space limitations) of broadcast-quality uncompressed digital video encoded in 8-bit CCIR 601 format on its built-in hard disk array.
Non-linear editing with computers as we know it today was first introduced by Editing Machines Corp. in 1989 with the EMC2 editor; a hard disk based non-linear off-line editing system, using half-screen resolution video at 15 frames per second. A couple of weeks later that same year, Avid introduced the Avid/1, the first in the line of their Media Composer systems. It was based on the Apple Macintosh computer platform (Macintosh II systems were used) with special hardware and software developed and installed by Avid. The Avid/1 was not the first system to introduce modern concepts in non-linear editing, however, such as timeline editing and clip bins -- both of which were pioneered in Lucasfilm's EditDroid in the early 1980s.
The video quality of the Avid/1 (and later Media Composer systems from the late 80s) was somewhat low (about VHS quality), due to the use of a very early version of a Motion JPEG (M-JPEG) codec. But it was enough to be a very versatile system for offline editing, to revolutionize video and film editing, and quickly become the dominant NLE platform.
In October 1990 NewTek introduced Video Toaster, a hardware and software solution for the Commodore Amiga 2000 computer system, taking advantage of the video-friendly aspects of that system's hardware to deliver the product at an unusually low cost ($1499). The hardware component was a full-sized card which went into the Amiga's unique single video expansion slot rather than the standard bus slots, and therefore could not be used with the A500 and A1000 models. The card had several BNC connectors in the rear, which accepted four video input sources and provided two outputs (preview and program). This initial generation system was essentially a real-time four-channel video switcher.
For the second generation NewTek introduced the Video Toaster Flyer. The Flyer was a far more capable Non-linear editing system. In addition to processing live video signals, the Flyer made use of hard drives to store video clips and audio, and allowed complex scripted playback. The Flyer was capable of simultaneous dual-channel playback, which allowed the Toaster's Video switcher to perform transitions and other effects on Video clips without the need for rendering.
The hardware component was again a card designed for the Amiga's Zorro 2 expansion slot, and was primarily designed by Charles Steinkuehler. The Flyer portion of the Video Toaster/Flyer combination was a complete computer of its own, having its own Microprocessor and Embedded software, which was written by Marty Flickinger. Its hardware included three embedded SCSI controllers. Two of these SCSI buses were used to store video data, and the third to store audio. The hard drives were thus connected to the Flyer directly and used a proprietary filesystem layout, rather than being connected to the Amiga's buses and were available as regular devices using the included DOS driver. The Flyer used a proprietary Wavelet compression algorithm known as VTASC, which was well regarded at the time for offering better visual quality than comparable Motion JPEG based non-linear editing systems.
Until 1993, the Avid Media Composer could only be used for editing commercials or other small content projects, because the Apple Macintosh computers could access only 50 gigabytes of storage at one time. In 1992, this limitation was overcome by a group of industry experts lead by Rick Eye a Digital Video R&D team at the Disney Channel. By February 1993, this team had integrated a long form system which gave the Avid Media Composer Apple Macintosh access to over 7 terabytes of digital video data. With instant access to the shot footage of an entire movie, long form non-linear editing (Motion Picture Editing) was now possible. The system made its debut at the NAB conference in 1993, in the booths of the three primary sub-system manufacturers, Avid, Silicon Graphics and Sony. Within a year, thousands of these systems replaced a century of 35mm film editing equipment in major motion picture studios and TV stations world wide, making Avid the undisputed leader in non-linear editing systems for over a decade.
Although M-JPEG became the standard codec for NLE during the early 1990s, it had drawbacks. Its high computational requirements ruled out software implementations, leading to the extra cost and complexity of hardware compression/playback cards. More importantly, the traditional tape workflow had involved editing from tape, often in a rented facility. When the editor left the edit suite he could take his confidential video tapes with him. But the M-JPEG data rate was too high for systems like Avid on the Mac and Lightworks on PC to store the video on removable storage, so these used fixed hard disks instead. The tape paradigm of keeping your (confidential) content with you was not possible with these fixed disks. Editing machines were often rented from facilities houses on a per-hour basis, and some productions chose to delete their material after each edit session, and then recapture it the next day, in order to guarantee the security of their content. In addition, each NLE system had storage limited by its hard disk capacity.
These issues were addressed by a small UK company, Eidos plc (which later became famous for its Tomb Raider video game series). Eidos chose the new ARM-based computers from the UK and implemented an editing system, launched in Europe in 1990 at the International Broadcasting Convention. Because it implemented its own compression software designed specifically for non-linear editing, the Eidos system had no requirement for JPEG hardware and was cheap to produce. The software could decode multiple video and audio streams at once for real-time effects at no extra cost. But most significantly, for the first time, it allowed effectively unlimited quantities of cheap removable storage. The Eidos Edit 1, Edit 2, and later Optima systems allowed the editor to use any Eidos system, rather than being tied down to a particular one, and still keep his data secure. The Optima software editing system was closely tied to Acorn hardware, so when Acorn stopped manufacturing the Risc PC in the late 1990s, Eidos stopped selling the Optima system; by this time Eidos had become predominantly a games company.
In the early 1990s a small American company called Data Translation took what it knew about coding and decoding pictures for the US military and large corporate clients and threw $12m into developing a desktop editor which would use its proprietary compression algorithms and off-the-shelf parts. Their aim was to 'democratize' the desktop — and take some of Avid's market. In August 1993 Media 100 entered the market and thousands of would-be editors had a low-cost, high-quality platform to use.
Inspired by the success of Media 100, members of the Premiere development team left Adobe to start a project called "Keygrip" for Macromedia. Difficulty raising support and money for development lead the team to take their non-linear editor to NAB. After various companies made offers, Keygrip was purchased by Apple as Steve Jobs wanted a product to compete with Adobe Premiere in the desktop video market. At around the same time, Avid — now with Windows versions of its editing software — was considering abandoning the Macintosh platform. Apple released Final Cut Pro in 1999, and despite not being taken seriously at first by professionals, it has evolved into a serious competitor to Avid.
Another leap came in the late 1990s with the launch of DV-based video formats for consumer and professional use. With DV came IEEE 1394 (FireWire/iLink), a simple and inexpensive way of getting video into and out of computers. The video no longer had to be converted from an analog signal to digital data — it was recorded as digital to start with — and FireWire offered a straightforward way of transferring that data without the need for additional hardware or compression. With this innovation, editing become a more realistic proposition for standard computers with software-only packages. It enabled real desktop editing producing high-quality results at a fraction of the cost of other systems.
More recently the introduction of highly compressed HD formats such as HDV has continued this trend, making it possible to edit HD material on a standard computer running a software-only editing application.
Avid is still considered the industry standard, with the majority of major feature films, television programs, and commercials created with its NLE systems. Avid products were used in the creation of every film nominated in the Best Picture, Directing, Film Editing, Sound Editing, Sound Mixing, Visual Effects, and Animated Feature categories of the 2005 Academy Awards. Avid systems were also the overwhelming NLE choice of the 2004-2005 Primetime Emmy Award nominees, being used on more than 50 shows in eleven major categories. Final Cut Pro continues to develop a strong following, and the software received an Technology & Engineering Emmy Award in 2002.
Avid has held on to its market-leading position, but faces growing competition from other, cheaper software packages, notably Adobe Premiere in 1992, and later Final Cut Pro in 1999. These three competing products by Avid, Adobe, and Apple are the foremost NLEs, often referred to as the A-Team.
One of the primary concerns with non-linear editing has always been picture and sound quality. The need to compress and decompress video leads to some loss in quality. While improvements in compression techniques and disc storage capacity have reduced these concerns, they still exist. Most professional NLEs are able to edit uncompressed video with the appropriate hardware.
With the more recent adoption of DV formats, quality has become an issue again: DV's compression means that manipulation of the image can introduce significant degradation. However this can be partially avoided by rendering DV footage to a non-compressed intermediary format, thereby avoiding quality loss through recompression of the modified video images. Ultimately it depends on what changes are made to the image; simple edits should show no degradation, however effects that alter the colour, size or position of parts of the image will have a more negative effect.
The range of user-friendly editing tools has given inexperienced people access to editing at high quality for the first time.