In video, a non-linear editing system (NLE) is a video editing (NLVE) or audio editing (NLAE) digital audio workstation (DAW) system which can perform random access non-destructive editing on the source material. It is named in contrast to 20th century methods of linear video editing and film editing.
Non-linear editing is a video editing method which enables direct access to any video frame in a digital video clip, without needing to play or scrub/shuttle through adjacent footage to reach it, as was necessary with historical video tape linear editing systems. It is the most natural approach when all assets are available as files on hard disks rather than recordings on reels or tapes, while linear editing is related to the need to sequentially view a film or read a tape to edit it. On the other hand, the NLE method is similar in concept to the "cut and paste" technique used in film editing. However, with the appropriation of non-linear editing systems, the destructive act of cutting of film negatives is eliminated. Non-linear, non-destructive editing methods began to appear with the introduction of digital video technology. It can also be viewed as the audio/video equivalent of word processing, which is why it is called desktop video editing in the consumer space.[1]
Contents |
Video and audio data are first captured to hard disks, video server, or other digital storage devices. The data are either direct to disk recording or are imported from another source. Once imported, the source material can be edited on a computer using application software, any of a wide range of video editing 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). Generation loss is also controlled, 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) and Blender3D, can be downloaded as free software; and some, like Microsoft's Windows Movie Maker or Apple Inc.'s iMovie, come included with the appropriate operating system.
A multimedia 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.
Various editing tasks can then be performed on the imported video before it is exported to another medium, or MPEG encoded for transfer to a DVD.
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 about half an hour of 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 LA-based post house Laser Edit (which later merged with Pacific Video as Laser-Pacific) also had an in-house system using recordable random-access laserdiscs. Another non-linear system was Ediflex, which used a bank of multiple Sony Betamax VCRs for offline editing. All were slow, cumbersome, and had problems with the limited computer horsepower of the time, but the mid-to-late-1980s saw a trend towards non-linear editing, moving away from film editing on Movieolas and the linear videotape method (usually employing 3/4" VCRs).
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 such as timeline editing and clip bins — both of these 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. The first long form documentary to be so edited was the HBO program Earth and the American Dream which went on to win a National Primetime Emmy Award for Editing in 1993. The Avid had quickly become the dominant NLE platform.
The NewTek Video Toaster Flyer included non-linear editing capabilities 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 Flyer portion of the Video Toaster/Flyer combination was a complete computer of its own, having its own Microprocessor and Embedded software. 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 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 led 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.[2]
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 they could take their confidential video tapes with them. 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. 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 discontinued the Optima system.
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.
Around the same period of time there were two other competitors, providing non-linear systems that required special hardware often cards that had to be added to the computer system. Fast Video Machine was a PC based system that first came out as an offline system and later became more online editing capable. Immix Video Cube was also a contender for Media Production companies. The Immix Video Cube had a control surface with faders to allow mixing and shuttle controls without the purchase of third party controllers. Data Translation's Media 100 came with 3 different JPEG codecs for different types of graphics of video and many resolutions. The Media 100 system kept increasing its maximum video resolution via software upgrades rather than hardware. This was because the Media 100 cards had enough processing power to be expanded to resolutions as high as Avid systems at the upper end of the Avid product line. Cards at the time had embedded, dedicated CPUs (for example a Motorola 68000 processor), which were as powerful as the processors inside the Macintosh systems that hosted the application. These other companies caused tremendous downward market pressure on Avid. Avid was forced to continually offer lower priced systems to compete with the Media 100 and other systems.
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 led 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 became 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. Final Cut Pro received a Technology & Engineering Emmy Award in 2002 and continues to develop a following.
Avid has held on to its market-leading position in the advent of cheaper software packages, notably Adobe Premiere in 1992 and 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.[3] With advances in raw computer processing power, new products have appeared including NewTek's software application SpeedEdit.
Since 2000, many personal computers include basic non-linear video editing software free of charge. This is the case of Apple iMovie for the Macintosh platform, PiTiVi for the Linux platform (it is installed by default on Ubuntu, the dominant desktop Linux distribution), and Windows Movie Maker for the Windows platform. This phenomenon has brought low-cost non-linear editing to consumers.
At one time, a primary concern with non-linear editing had been picture and sound quality. Storage limitations at the time required that all material undergo lossy compression techniques to reduce the amount of memory occupied.
Improvements in compression techniques and disk storage capacity have mitigated these concerns, and the migration to High Definition video and audio has virtually removed this concern completely. Most professional NLEs are also able to edit uncompressed video with the appropriate hardware.