In the area of Digital Cinema no more film reels will be sent to movie theaters. The DCP (Digital Cinema Package) is the replacement for film reels and contains digital film and audio data as well as subtitles for different languages. In order to ensure that every DCP can be shown in any movie theater worldwide, SMPTE and ISO standards were brought to its way under cooperation of the Fraunhofer IIS. All manufacturers, whose devices are compliant to these accepted specifications, will playback standard-compliant DCPs.
Most film producers and distributors rely on digital cinema encoding facilities to produce and quality control check a digital cinema package before release. Facilities follow strict guidelines set out in the DCI recommendations to ensure compatibility with all digital cinema equipment. For bigger studio release films, the facility will usually create a DCDM (Digital Cinema Distribution Master), a DCDM is the post-production step prior to a DCP, and a DCP can be encoded directly from a DCDM.
The DCP format is also used to store stereoscopic (3D) contents. In this case, 48 frames exist for every second - 24 frames for the left eye, 24 frames for the right. Depending on the projection system used, the left eye and right eye pictures are either shown alternatively (double or triple flash systems) at 48 fps or, on 4k systems, both left and right eye pictures are shown simultaneously, one above the other, at 24 fps. In triple flash systems, active shutter glasses are required whereas optical filtering such as circular polarization is used in conjunction with passive glasses on polarized systems.
The AES encryption is applied to all files. The encryption keys are generated and transmitted via a KDM (Key Delivery Message) to the projection site. KDMs are XML files containing encryption keys that can be used only by the destination device. A KDM is associated to each playlist and defines the start and stop times of validity for the projection of that particular feature.
What color gamut is
A color gamut (also known as a color space) is a range of colors found in the visual spectrum. Particular colors, one variation each of red, green, and blue, are established as the boundaries of a given range, and any colors that are found within those limits are considered part of that space.
Color gamuts are created by telecommunications standards organizations and help in establishing concrete specifications for what the TV must be capable of doing. To meet a given color gamut’s specifications, a TV must be able to display all of the colors included in that space.
At present, there are three main color gamuts that are important to TVs: Rec.709, DCI-P3 and Rec.2020.
Rec.709 is the current standard space required for every kind of widescreen home media available today, from DVDs to HD cable, Blu-rays to streaming video. Most HDTV and UHD TVs are not meant to display colors beyond those contained within this space.
Rec.709 is quite limited in terms of the amount of color it represents, only capturing just over a third of the visual spectrum. Of course, video still looks good, but upcoming media that take advantage of the larger color spaces will offer more variety to the color you see, offering greater detail and truer-to-life video.
Rec 709 Color Space
ITU-R Recommendation BT.709, first approved in 1990 and often referred to as Rec. 709 or BT.709, standardizes the format of High Definition Television (HDTV). This color space is identical to the sRGB color space and covers 35.6% of the CIE 1931 color space. All HD displays should be able to cover 100% of the Rec. 709 color space.
DCI/P3 Color Space
DCI-P3 is a popular high dynamic range (HDR) RGB color space that was introduced in 2007 by SMPTE and features a color gamut much wider than Rec. 709, covering 45.5% of all colors perceptible to humans as per the CIE 1931 color space. All Digital Cinema Projectors are capable of displaying the entire DCI P3 color space. DCI/P3 has assumed importance in recent times since this is the reference color gamut for current ‘Ultra HD Premium TV’s, which are expected to support at least 90% of the DCI/P3 color space with a minimum brightness of 0.05nits and maximum brightness of 1000nits
The Rec. 2020 color space
ITU-R Recommendation BT.2020, more commonly known by the abbreviations Rec. 2020 or BT.2020 is the de facto standard for HDR10 which defines various aspects of UHDTV such as resolution, frame rates, bit depth, chroma subsampling and color space. The associated color space is also commonly referred to as Rec. 2020. It covers 75.8% of all colors perceptible to humans as per the CIE 1931 xy color space. In August 2015, the Consumer Electronics Association (CEA) standardized the HDR10 Media Profile format for all HDR compatible display devices. Support for REC.2020 color primaries and ST2084 EOTF transfer characteristics are essential to this format.