In this chapter, we continue our examination of communications and consider television and radio broadcasting applications where data compression is used to reduce the bandwidth needed for delivering digitized data. Various combinations of lossless and lossy compression are used, with most algorithms being specially adapted for the transmission channels and the data being transmitted on those channels.
KeywordsData Compression Video Transmission Video Service Broadcast Channel Cable System
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- 1.A significant detail is that the Japanese HDTV system was transmitted via satellite because it required several times more bandwidth that standard television.Google Scholar
- 2.The plan for phasing in HDTV in the United States allows each of the more than 1400 terrestrial broadcasters who choose to air HDTV programming to apply for a second (UHF) channel [Hopk 94]. Conventional analog NTSC programming will air on the channel they now have been granted, simulcast along with digital HDTV programming on the second channel. At some point in time, analog broadcasts will be phased out.Google Scholar
- 3.Digital Satellite System is a joint effort of DirecTV-GM Hughes Electronics, RCA-Thompson Consumer Electronics, and United States Satellite Broadcasting-Hubbard Broadcasting. DSS began broadcasting in 1994 with 175 channels of video and music.Google Scholar
- 4.The complexity of MPEG-2 encoding delayed the arrival of encoder chips that could compress live broadcasts in real time. Non-real-time encoders, whether in hardware or in software running on powerful computers, which suffice for compressing programs stored on film or tape, could not handle sports events and other live DSS broadcasts.Google Scholar
- 5.Although DSS uses MPEG-2 compression, its bit-stream packet protocol is different than that found in the MPEG-2 specification.Google Scholar
- 6.Cable systems operate within various bandwidths. Modern urban hybrid coaxial/fiber cable systems provide a forward (headend-to-user) bandwidth range of 54-750 MHz, allowing up to 110 (6 MHz analog) broadcast channels to be carried. All-fiber networks provide 1 GHz bandwidth, allowing 150 channels.Google Scholar
- 7.Each 6-MHz cable channel can carry 40 Mbps of digitized video. With MPEG-2 compression, 10 high-quality SDTV video data streams can be carried by each channel.Google Scholar
- 8.DA VIC (the Digital Audio-Video Council) has set a cost target of $300 for the first standardized digital set-top box [Leop 95C].Google Scholar
- 9.Channel surfing is the fine art of using the remote control to quickly scan through channels to determine what to watch.Google Scholar
- 10.LEC is the name given to the Regional Bell Operating Companies (RBOC) and independent telephone companies that provide subscribers with local-loop connections to the telephone network.Google Scholar
- 11.Standard telephone line protocols are designed to allow low-cost, reliable communications over great distances and over lines of widely variable quality. ADSL takes advantage of advances in digital filtering, advances in VLSI that make more powerful coding techniques economical, and the fact that many LECs are using fiber optics to reduce the length of the copper portion of the local loop [Chen 94].Google Scholar