DCI Specs - Digital Cinema Initiatives

(channels) * hours * 60 min/hour * 60 sec/min / 8 (bits/byte) =sizeSub Picture size: Calculated by: 100,000 (bytes/png file @ level 1) * 3,000(subtitles/feature) = sizeTimed Text size:7.5.3.8. Storage SecurityCalculated by estimate of 1 MBytes per featureIt is required that image and audio essence on storage devices retains the original AESencryption, if present during ingest. It is required that decrypted plaintext (image oraudio) essence is never stored on the storage system.7.5.4. Media Block7.5.4.1. IntroductionAnother key component in the playback chain is the Media Block. One or more MediaBlocks are responsible for converting the packaged, compressed and encrypted datainto raw image, sound and subtitles.Depending upon implementation, both security and non-security functions take placewithin Media Blocks. Security functions of Media Blocks (those functions which processplain text essence or Security Data such as decryption keys) may take place only withinphysically secure perimeters called Secure Processing Blocks (SPB). The more generalfunctions of the Media Block and variations on implementation are described here. Notall such functions are required to be within an SPB. Detailed security requirements ofMedia Blocks are discussed in Section 9.4 Theater Systems Security.The Media Block can be implemented in a server configuration, as shown in Figure 11.This is where the storage and the Media Block are closely coupled. In this configuration,the content data is then pushed to the final playback device. In this configuration, LinkEncryption is required to protect the uncompressed content.Figure 11: Media Block Server Configuration 8The Media Block can also be implemented as a component within the projection system.This provides the option of not requiring Link Encryption. In this configuration, the Media8 The double-lined boxes of Figure 11 and Figure 12 show those processing functions required to take place withinphysically secure SPB type 1 perimetersDCI Digital Cinema System Specification v.1.2 Page 70