Digital cinema
Digital cinema is the digital technology used within the film industry to distribute or project motion pictures as opposed to the historical use of reels of motion picture film, such as 35 mm film. Whereas film reels have to be shipped to movie theaters, a digital movie can be distributed to cinemas in a number of ways: over the Internet or dedicated satellite links, or by sending hard drives or optical discs such as Blu-ray discs, then projected using a digital video projector instead of a film projector.
Typically, digital movies are shot using digital movie cameras or in animation transferred from a file and are edited using a non-linear editing system. The NLE is often a video editing application installed in one or more computers that may be networked to access the original footage from a remote server, share or gain access to computing resources for rendering the final video, and allow several editors to work on the same timeline or project.
Alternatively a digital movie could be a film reel that has been digitized using a motion picture film scanner and then restored, or, a digital movie could be recorded using a film recorder onto film stock for projection using a traditional film projector.
Digital cinema is distinct from high-definition television and does not necessarily use traditional television or other traditional high-definition video standards, aspect ratios, or frame rates. In digital cinema, resolutions are represented by the horizontal pixel count, usually 2K or 4K. The 2K and 4K resolutions used in digital cinema projection are often referred to as DCI 2K and DCI 4K. DCI stands for Digital Cinema Initiatives.
As digital cinema technology improved in the early 2010s, most theaters across the world converted to digital video projection. Digital cinema technology has continued to develop over the years with RealD 3D, IMAX, RPX, 4DX, Dolby Cinema, and ScreenX, allowing moviegoers more immersive experiences.
History
The transition from film to digital video was preceded by cinema's transition from analog to digital audio, with the release of the Dolby Digital audio coding standard in 1991. Its main basis is the modified discrete cosine transform, a lossy audio compression algorithm. It is a modification of the discrete cosine transform algorithm, which was first proposed by Nasir Ahmed in 1972 and was originally intended for image compression. The DCT was adapted into the MDCT by J.P. Princen, A.W. Johnson and Alan B. Bradley at the University of Surrey in 1987, and then Dolby Laboratories adapted the MDCT algorithm along with perceptual coding principles to develop the AC-3 audio format for cinema needs. Cinema in the 1990s typically combined analog photochemical images with digital audio.Digital media playback of high-resolution 2K files has at least a 20-year history. Early video data storage units fed custom frame buffer systems with large memories. In early digital video units, the content was usually restricted to several minutes of material. Transfer of content between remote locations was slow and had limited capacity. It was not until the late 1990s that feature-length films could be sent over the "wire". On October 23, 1998, Digital light processing projector technology was publicly demonstrated with the release of The Last Broadcast, the first feature-length movie, shot, edited and distributed digitally. In conjunction with Texas Instruments, the movie was publicly demonstrated in five theaters across the United States.
Foundations
In the United States, on June 18, 1999, Texas Instruments' DLP Cinema projector technology was publicly demonstrated on two screens in Los Angeles and New York for the release of Lucasfilm's Star Wars Episode I: The Phantom Menace. In Europe, on February 2, 2000, Texas Instruments' DLP Cinema projector technology was publicly demonstrated, by Philippe Binant, on one screen in Paris for the release of Toy Story 2.From 1997 to 2000, the JPEG 2000 image compression standard was developed by a Joint Photographic Experts Group committee chaired by Touradj Ebrahimi. In contrast to the original 1992 JPEG standard, which is a DCT-based lossy compression format for static digital images, JPEG 2000 is a discrete wavelet transform based compression standard that could be adapted for motion imaging video compression with the Motion JPEG 2000 extension. JPEG 2000 technology was later selected as the video coding standard for digital cinema in 2004.
In 1992, Hughes-JVC was founded by JVC and Hughes Electronics to develop ILA digital video projectors for commercial movie theaters using liquid crystal on silicon technology. In 1997, JVC introduced D-ILA technology with a 2K resolution digital video projector. In 2000, JVC introduced a 4K resolution video projector using D-ILA technology.
Initiatives
On January 19, 2000, the Society of Motion Picture and Television Engineers, in the United States, initiated the first standards group dedicated to developing digital cinema. By December 2000, there were 15 digital cinema screens in the United States and Canada, 11 in Western Europe, 4 in Asia, and 1 in South America. Digital Cinema Initiatives was formed in March 2002 as a joint project of many motion picture studios to develop a system specification for digital cinema. The same month it was reported that the number of cinemas equipped with digital projectors had increased to about 50 in the US and 30 more in the rest of the world.In April 2004, in collaboration with the American Society of Cinematographers, DCI created standard evaluation material for testing of 2K and 4K playback and compression technologies. DCI selected JPEG 2000 as the basis for the compression in the system the same year. Initial tests with JPEG 2000 produced bit rates of around 75125 Mbit/s for 2K resolution and 100200 Mbit/s for 4K resolution.
Worldwide deployment
In China, in June 2005, an e-cinema system called "dMs" was established and was used in over 15,000 screens spread across China's 30 provinces. DMs estimated that the system would expand to 40,000 screens in 2009. In 2005, the UK Film Council Digital Screen Network launched in the UK by Arts Alliance Media creating a chain of 250 2K digital cinema systems. The roll-out was completed in 2006. This was the first mass roll-out in Europe. AccessIT/Christie Digital also started a roll-out in the United States and Canada. By mid-2006, about 400 theaters were equipped with 2K digital projectors with the number increasing every month. In August 2006, the Malayalam digital movie Moonnamathoral, produced by Benzy Martin, was distributed via satellite to cinemas, thus becoming the first Indian digital cinema. This was done by Emil and Eric Digital Films, a company based at Thrissur using the end-to-end digital cinema system developed by Singapore-based DG2L Technologies.In January 2007, Guru became the first Indian film mastered in the DCI-compliant JPEG 2000 Interop format and also the first Indian film to be previewed digitally, internationally, at the Elgin Winter Garden in Toronto. This film was digitally mastered at Real Image Media Technologies in India. In 2007, the UK became home to Europe's first DCI-compliant fully digital multiplex cinemas; Odeon Hatfield and Odeon Surrey Quays, with a total of 18 digital screens, were launched on 9 February 2007. By March 2007, with the release of Disney's Meet the Robinsons, about 600 screens had been equipped with digital projectors. In June 2007, Arts Alliance Media announced the first European commercial digital cinema Virtual Print Fee agreements. In March 2009, AMC Theatres announced that it closed a $315 million deal with Sony to replace all of its movie projectors with 4K HDR digital projectors starting in the second quarter of 2009; it was anticipated that this replacement would be finished by 2012.
As digital cinema technology improved in the early 2010s, most theaters across the world converted to digital video projection. In January 2011, the total number of digital screens worldwide was 36,242, up from 16,339 at end 2009 or a growth rate of 121.8 percent during the year. There were 10,083 d-screens in Europe as a whole, 16,522 in the United States and Canada and 7,703 in Asia. Worldwide progress was slower as in some territories, particularly Latin America and Africa. As of 31 March 2015, 38,719 screens in the United States have been converted to digital, 3,007 screens in Canada have been converted, and 93,147 screens internationally have been converted. By the end of 2017, virtually all of the world's cinema screens were digital. Digital cinema technology has continued to develop over the years with RealD 3D, IMAX, RPX, Dolby Cinema, 4DX, and ScreenX, allowing moviegoers with more immersive experiences.
Despite the fact that today, virtually all global movie theaters have converted their screens to digital cinemas, some major motion pictures even as of 2019 are shot on film. For example, Quentin Tarantino released his latest film Once Upon a Time in Hollywood in 70 mm and 35 mm in selected theaters across the United States and Canada.
Elements
In addition to the equipment already found in a film-based movie theatre, a DCI-compliant digital cinema requires a DCI-compliant digital projector and a powerful computer known as a server.Movies are supplied to the theater as a set of digital files called a Digital Cinema Package. For a typical feature film, these files will be anywhere between 90 GB and 300 GB of data and may arrive as a physical delivery on a conventional computer hard drive or via satellite or fibre-optic broadband Internet. As of 2013, physical deliveries of hard drives were most common in the industry. Promotional trailers arrive on a separate hard drive and range between 200 GB and 400 GB in size. Ingest of DCP files may be done at each cabin’s projector-server or may be stored in a central server called a Digital Cinema Library sharing its content over the cinema local area network and managed by the Theater Management System.
Regardless of how the DCP arrives, it first needs to be copied onto the internal hard drives of the server, either via an eSATA connection, or via a closed network, a process known as "ingesting." DCPs can be, and in the case of feature films almost always are, encrypted, to prevent illegal copying and piracy. The necessary decryption keys are supplied separately, usually as email attachments or via download, and then "ingested" via USB. Keys are time-limited and will expire after the end of the period for which the title has been booked. They are also locked to the hardware that is to screen the film, so if the theatre wishes to move the title to another screen or extend the run, a new key must be obtained from the distributor. Several versions of the same feature can be sent together. The original version is used as the basis of all the other playback options. Version files may have a different sound format or subtitles. 2D and 3D versions are often distributed on the same hard drive.
The playback of the content is controlled by the server using a "playlist". As the name implies, this is a list of all the content that is to be played as part of the performance. The playlist will be created by a member of the theatre's staff using proprietary software that runs on the server. In addition to listing the content to be played the playlist also includes automation cues that allow the playlist to control the projector, the sound system, auditorium lighting, tab curtains and screen masking, etc. The playlist can be started manually, by clicking the "play" button on the server's monitor screen, or automatically at pre-set times.
The Theater Manager System is a central system software for the whole cinema house, handling the central cinema content library and preparing the playback sessions with the correct KDM keys and the selected cinema content moved to each projector.