DCI Specs - Digital Cinema Initiatives

implementation, the Central Storage is required to also provide the capability to sustainthe peak bit rate of all screens being fed simultaneously, along with ingest.7.5.3.4. Local StorageLocal storage implies a single storage system for each screen. Local storage is requiredto be able to sustain the bit rate required for the playback of all content for that screen.7.5.3.5. Combined Central and Local Storage.A combination of central and local storage for a multiplex can be the best solution. Thecentral storage can be used for ingest of material and redundancy of content, while thelocal storage is encouraged to hold just the content required for the immediatepresentation(s).7.5.3.6. BandwidthThe storage system is required to provide enough output to support a continuous streamof 307 Mbits/sec for compressed image, uncompressed audio (16 channels, 24 bitsample, 96 kHz) and subtitle data to allow for non interrupted Digital Cinema playback.7.5.3.7. CapacityExcluding storage necessary for redundancy, the storage system is required to providefor, at a minimum, the storage of three features (including pre-show content) per screen(one feature currently showing and a second or upcoming feature). Shown in Table 9below, are some example storage requirements. The numbers are based on:• One three-hour feature• 20 minutes of pre-show material at the same resolution• 16 channels of uncompressed audio at 48 kHz at 24 (AES3) bits• 3,000 sub pictures in PNG file format• 3,000 Timed Text linesAverage Bit 3 Hour 3 Hour 20 min. Sub Timed 3 HourRate Image Audio pre-show Picture Text Total(Mbits/sec) (GBytes) (GBytes) (Gbytes) (GBytes) (GBytes) (GBytes)250 337.500 2.074 37.500 0.300 0.001 377.374200 270.000 2.074 30.000 0.300 0.001 302.374125 168.750 2.074 18.750 0.400 0.001 189.974100 135.000 2.074 15.000 0.600 0.001 152.67480 108.000 2.074 12.000 0.800 0.001 122.874Table 9: Example of Storage Capacity for one 3-Hour Feature (12 bits @ 24 FPS)Image size: Calculated by: {Average or max bit rate (Mbits/sec) * hours * 60min/hour * 60 sec/min} / {8 bits/byte *1000} the results is inGBytesAudio size: Calculated by: {32 (AES bits) * 48,000 samples/sec *16(channels) * hours * 60 min/hour * 60 sec/min / 8 (bits/byte) =sizeorCalculated by: {32 (AES bits) * 96,000 samples/sec *16DCI Digital Cinema System Specification v.1.2 Page 69