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Digital films can be made in a bewildering range of incompatible formats. Film producers, film distributors, cinemas and audiences all face choices between competing systems. Faced with potentially disruptive confusion, the seven major Hollywood studios2, along with some smaller producers, established a working group called the Digital Cinema Initiative (DCI). This expert group aimed to produce an open architecture specification for the distribution of digital films which would ensure that cinemas would be able to screen their (Hollywood) films. Additionally the DCI specification aimed to implement systems which would protect their films and prevent piracy.
In July 2005 the DCI published ‘Digital Cinema Specification v1.0’ which the major studios intend to become the standard for distribution and exhibition of major, commercial Hollywood films – films which account for the majority of cinema attendances in many countries including much of Europe.3 The DCI specification, which runs to over 160 pages, does not provide a technical standard for the entire digital cinema system nor does it have any legal status (although it may be referred to in film booking contracts). About half of the DCI specification is concerned with antipiracy measures. The German Fraunhofer Institute, a large applied research organisation, was commissioned by DCI to produce a framework of standards which could be used to test digital cinema equipment in order to verify whether the equipment satisfies the requirements detailed by DCI. In October 2007 DCI issued their Compliance Test Plan v1.0 (474 pages) which covers all aspects of the digital cinema environment and delivery system.
In parallel with the DCI’s work, the US Society of Motion Picture Technicians and Engineers (SMPTE) established a separate working group (DC28) in order to provide a complete set of standards for digital cinema distribution and exhibition.
Data Format :
Digital moving images require huge amounts of computer file storage. In order to distribute a digital film it is necessary to compress the images and reduce the file size. There are several ways of achieving this but the main approaches are systems known as MPEG2, MPEG4 and JPEG2000. The format chosen during the first ten years of digital cinema (approximately 1995-2005) was MPEG2 which was felt to offer the most economical solution. In some countries such as Brazil, the MPEG4 format has been used by digital pioneer Rain Networks. However the DCI specification requires the JPEG2000 format which is felt to offer the best quality and that is what all the mainstream cinema equipment manufacturers are now concentrating on. Digital films are stored on special servers such as the Doremi DCP-2000, Kodak CineServer MN2000, Dolby Show Player DSP100 for name a few or the DTS Filmstore which store and playback digital films. The digital servers are the equivalent of 35mm film platters or towers.
Digital image quality depends on factors including colour quality, contrast and resolution. However digital cinema systems have, like still image cameras, been popularly classified according to their resolution rather than any of the other factors. The DCI specification requires a ‘2K’ resolution (2048 x 1080 pixels per image) while aiming for ‘4K’ as the ultimate goal (4096 x 2160 pixels). The 2K systems are effectively an industry standard at present with over 6,000 systems installed from manufacturers such Christie, Barco, Kinoton, NEC, Strong, and Cinemeccanica. There are less than one hundred 4K systems operating worldwide, all utilising Sony’s CineAlta 4K projector although more manufacturers are expected to offer 4K systems in the relatively near future. Confusingly the broadcast television sector also refer to the new High Definition (HD) systems as ‘2K’ but in their sector this means 1920 x 1080 pixels – a small but important difference especially for cinemas which want to screen material which has been created primarily for television viewing, for example live broadcasts of opera, rock concerts, football or motor sport, or documentary films. The earlier digital cinema systems, and a popular range of lower cost digital projectors, operate with 1.3K or 1.4K resolutions. While most audiences would find it difficult to tell the difference between a film screened using 1.3K projectors and 2K projectors, the DCI specification excludes the lower resolution equipment, effectively denying the possibility of a lower cost implementation of digital cinema. Nevertheless a number of cinemas, arts centres and other entertainment venues in Europe and the USA are using 1.3K ‘non-DCI compliant’ projectors for non-mainstream films and the HD alternative content described above.