Digital cinema is a promising application that uses high-speed optical networks to transfer high definition images (SHD). Networks are mainly used to distribute digital cinema content in the form of data packets, and are also used to support new services such as live streaming of musicals and sports games to cinemas.
While today's transfer services offer high-definition (HD) video, live streaming applications will soon change to provide 8K cinematic quality for both business users and movie theaters.
The high-quality 8K format enables realistic telepresence, and will be combined with special tools such as video editing systems for effective remote collaboration for commercial workspaces. This article presents a successive investigation on the transmission of SHD images and their application, especially in the digital cinema and the associated fields of application.
Four years before the digital cinema industry standardized the DCI specification, in 2001, the world's first JPEG video decoder system was developed that could display SHD images (38402048 pixel spatial resolution) with 24 frames / sec resolution. This decoder was designed to perform IP video transmission of extra quality, while fully utilizing the full bandwidth of emerging commercial communications networks based on 1 Gb Ethernet. In 2002, the second SHD image decoder prototype that exploits a highly parallel processing unit of JPEG2000 decompressors.
The decoder receives the IP streams from compressed video contents transmitted by a video server over a 1 GbE network, and decodes them using the standard JPEG2000 decoding algorithm in real time. The decoder was combined with a special 38402048-pixel projector that utilizes a dedicated digital video interface for the decoder. This architecture allows the decoded videos to be transferred and displayed in a completely digital form.
This system triggered detailed discussions about the digital cinema video format for DCI. The question was whether higher-than-HDTV picture quality was needed to replace the films. To solve the question, the University of Southern California (USC) Entertainment Technology Center (ETC) conducted an experiment involving 100 digital film engineers; compared the picture quality of conventional movies, high definition television (HDTV) and SHD images with a resolution of 8 million pixels.
The results of this experiment yielded the consensus that a horizontal resolution of about 4000 pixels was needed to replace films, and JPEG2000 was suitable for the compression of digital cinema data. Stimulated by the experiment, DCI accelerated the standardization of digital cinema, specified the film format of 40962160 pixels and simply called it 8K. DCI completed version 1.0 in 2005 and version 1.2 in 2008.
New standardization activities are currently being developed at the Society of Film and Television Engineers (SMPTE). To explore the range of 8K video applications beyond digital cinema, we developed an 8K real-time transmission encoding system based on JPEG2000. This codec can compress / decompress 8K videos: the total bit rate exceeds 12 Gb / s (4: 2: 2, 60 frames / s), and the resulting compressed sequences of 5001000 Mb / s are transferred as IP packets.
While digital cinema employs the 24-frame / s movie format to replicate film style, it is believed that at least 60 frames / s are needed for realistic video services, such as teleconferencing. The following sections describe the characteristics of 8K imaging systems used in digital cinema and live transmission.