The Digital Fact Book - Quantel

SEDSurface-conduction Electron-emitter Display technology is a mix of old and new, couplingCathode Ray Tube (CRT) and LCD technologies. SED screens comprise thousands, evenmillions, of minute electron emitters – hence the CRT connection. The screens are thinnerLCD displays and observers think SED technology is superior to current LCD and plasmamonitors. Deliveries are slated to start in 2008 but may be delayed, and will concentrateon the bigger-screen end of the market – around 55-inches, initially.Seek time (a.k.a. Positioning time)The time taken for the read/write heads of a disk drive to be positioned over a required track.Average seek time is the time to reach any track from the center track. Maximum seek/positioning time is the time to reach any track from any track. A high performance modernhard disk offers around 4 ms average seek time and typically twice that for the maximum.Minimum seek time to adjacent tracks is as low as 0.2 ms for read, 0.4 ms for write. Thesetimes are critical to disk performance, especially when operating with the very high datarates associated with video and digital film.See: Disk drives, FrameMagicSerial Digital Interface (SDI)Serial Digital Interface carries uncompressed digital video, multiple tracks of embeddedaudio and ancillary data over the ubiquitous 75-ohm coax cable, terminated in a BNCconnector. As the demands of television have grown so has SDI. Today there are three types.SDI SMPTE 259M – for SD 4:2:2 digital television, is based on a 270 Mb/s transfer rate.This is a 10-bit, scrambled, polarity-independent interface, with common scrambling forboth component ITU-R BT.601 and composite digital video and four groups each of fourchannels of embedded digital audio. Most broadcast digital equipment includes SDI whichgreatly simplifies its installation and signal distribution. It can transmit the signal over 200meters (depending on cable type).SHD-SDI Standardized in SMPTE 292M, this for 4:2:2 HD television. The serial bit-streamruns at 1.485 Gb/s to carry up to 10-bit Y,Cr,Cb component video as well as embeddedaudio and ancillary data. The interface is also specified for fiber for distances up to 2 km.3G SDI (SMPTE 424M) operates at 2.97 Gb/s, twice the clock rate HD-SDI and is designedto carry high bandwidth HD television such as 1080/50P, 1080/60P, HD RGB, as well as2K DI images.See also: Dual link, HSDL, Embedded audioServer editingVideo and audio editing that takes place within a server rather than in a workstation.See also: In-server editing153