The Digital Fact Book - Quantel

Sampling standardA standard for sampling analog waveforms to convert them into digital data. The officialsampling standard for 625/50 and 525/60 television is ITU-R BT.601. ITU-R BT.709 andSMPTE 274M specify sampling for HD formats. They are generally written as the numberof pixels per line x number of lines per frame/vertical refresh rate (in Hz) progressive orinterlaced (P or I). For example: 1920 x 1080/50I. Sometimes the pixel count of the linesis omitted (but understood), making the example 1080/50I.SANStorage Area Networks are a well-established method of providing shared video storageand can offer platform-independent storage that may be accessed from, say, both Windowsand Linux workstations. They allow applications direct access to shared storage by cuttingout the usual client-server ‘middle men’ to provide improved workflow and better worksharing on a common store.LANWorkstation Workstation WorkstationWorkstationWorkstationSAN Fabric: networklinks and switchesSAN Fabric: networklinks and switchesSShared storagedeviceRAIDTapeRAIDThe design recognizes that moving large amounts of data (video) is inconsistent withnormal-network general-data traffic. Therefore they form a separate network to connectdata-hungry workstations to a large, fast array of disks. Although any network technologycould be used, Fibre Channel predominates. Its original 800Mb/s thoughput (1 Gb/s linerate) data rate has now grown to 8Gb/s and direct connections to disks are ideal for makinglarge, fast storage networks. SANs are scalable but additions may be complex to implement.Currently, expansion is ultimately limited by architecture and management considerations.149