Digital cinema is a promising application that utilizes high-speed optical networks to transfer super high definition (SHD) images. The networks are primarily used for distributing digital cinema contents in packet data form, and are also used to support new services such as the live streaming of musicals and sport games to movie theaters. While current transfer services offer high-definition (HD) quality video, live-streaming applications will soon shift to providing cinema quality 8K content to both business and movie theaters users. The extra- high-quality 8K format enables a realistic telepresence, and will be combined with special tools such as video editing systems to realize effective remote collaboration for business workspaces. This paper introduces successive research on SHD image transmission and its application, especially in digital cinema and associated application fields.
The deployment of digital cinema stimulates many advanced applications that will use superhigh- definition (SHD) imaging systems and high-speed optical fiber networks. Theater sys- tems for digital cinema, projectors, and playback video servers have been commercialized based on the standards issued by the Digital Cinema Initiative (DCI). 8K is the SHD video format defined in DCI specification. It has a resolution of 4096 2160 pixels, so its image qual- ity is equivalent to that of 35-mm film. The total bit rate of raw 8K videos with the frame rate of 24 frames/s is about 7 Gb/s. This necessitates the use of the JPEG2000 algorithm to compress the bit rate to 250 Mb/s. To deliver the movie data to movie theaters, hard disk drives and courier services appeared to be the easiest approach, but a business trial demonstrated that network-based delivery was more cost effective and secure against content piracy.
Furthermore, network transfer also supports a wider variety of contents, namely public viewing of live-streaming content. Four years before the digital cinema industry standardized the DCI specification, in 2001, the worlds first video JPEG decoder system was developed that could display SHD images (38402048 pixel spatial resolution) with 24-frames/s time resolution. This decoder was designed to realize IP transmission of extra-high-quality videos, while fully utilizing the full bandwidth of emerging commercial communication networks based on 1-Gb Ethernet. In 2002, the second prototype SHD image decoder was developed that exploits a highly parallel processing unit of JPEG2000 de-compressors. The decoder receives the IP streams of 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 using a dedicated digital video interface for the decoder. This architecture allows the decoded videos to be transferred and shown in completely digital form. This system triggered detailed discussions on the digital cinema video format for DCI. The question was whether a higher image quality than HDTV was required to replace movie films. In order to solve the question, an experiment was conducted by the Entertainment Technology Center (ETC) of the University of Southern California (USC) involving 100 digital cinema engineers; it compared the image quality of conventional films, highdefinition television (HDTV), and SHD images with 8-million-pixel resolution. The results of this experiment yielded the consensus that the horizontal resolution of around 4000 pixels was required 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 movie format of 40962160 pixels, and simply called it 8K.
DCI finalized version 1.0 in 2005 and version 1.2 in 2008. Currently, further standardization activities are in progress at the Society of Motion Picture and Television Engineer (SMPTE). To explore the application range of 8K video beyond digital cinema, we developed a JPEG2000-based 8K real time streaming codec system. This codec can compress/ decom- press 8K videos: the total bit rate exceeds 12 Gb/s (4 : 2 : 2, 60 frames/s), and the resulting 5001000-Mb/s compressed streams are transferred as IP packets. While digital cinema em- ploys the 24-frames/s movie format to replicate the cinema style, it is believed that at least 60 frames/s is needed for realistic video communication services such as teleconferencing. The following sections describe the features of the 8K imaging systems used in digital cinema and live streaming.
8K is a new resolution standard designed for digital cinema and computer graphics. It has following advantages:
1. Higher image definition quality.
2. More detailed picture.
3. Better fast-action.
4. Larger projection surface visibility.