|
Digital Video Broadcasting (DVB) is a suite of internationally accepted open standards for digital television. DVB standards are maintained by the (DVB Project ), an international industry consortium with more than 270 members, and are published by a ''Joint Technical Committee'' (JTC) of the European Telecommunications Standards Institute (ETSI), European Committee for Electrotechnical Standardization (CENELEC) and European Broadcasting Union (EBU). The interaction of the DVB sub-standards is described in the ''DVB Cookbook''.〔(【引用サイトリンク】title=Digital Video Broadcasting (DVB); A Guideline for the Use of DVB Specifications and Standards )〕 Many aspects of DVB are patented, including elements of the MPEG video coding and audio coding. ==Transmission== DVB systems distribute data using a variety of approaches, including: * Satellite: DVB-S, DVB-S2 and DVB-SH * * DVB-SMATV for distribution via SMATV * Cable: DVB-C, DVB-C2 * Terrestrial television: DVB-T, DVB-T2 * * Digital terrestrial television for handhelds: DVB-H, DVB-SH * Microwave: using DTT (DVB-MT), the MMDS (DVB-MC), and/or MVDS standards (DVB-MS) These standards define the physical layer and data link layer of the distribution system. Devices interact with the physical layer via a synchronous parallel interface (SPI), synchronous serial interface (SSI), or asynchronous serial interface (ASI). All data is transmitted in MPEG transport streams with some additional constraints (DVB-MPEG). A standard for temporally-compressed distribution to mobile devices (DVB-H) was published in November 2004. These distribution systems differ mainly in the modulation schemes used and error correcting codes used, due to the different technical constraints. DVB-S (SHF) uses QPSK, 8-PSK or 16-QAM. DVB-S2 uses QPSK, 8-PSK, 16-APSK or 32-APSK, at the broadcasters decision. QPSK and 8-PSK are the only versions regularly used. DVB-C (VHF/UHF) uses QAM: 16-QAM, 32-QAM, 64-QAM, 128-QAM or 256-QAM. Lastly, DVB-T (VHF/UHF) uses 16-QAM or 64-QAM (or QPSK) in combination with (C)OFDM and can support hierarchical modulation. The DVB-T2 specification was approved by the DVB Steering Board in June 2008 and sent to ETSI for adoption as a formal standard. ETSI adopted the standard on 9 September 2009.〔(【引用サイトリンク】title=Work Programme: Details of 'DEN/JTC-DVB-228' Work Item Schedule )〕 The DVB-T2 standard gives more robust TV reception and increases the possible bit rate by over 30% for single transmitters (as in the UK) and should increase the max. bit rate by over 50% in large single-frequency networks (as in Germany, Sweden). DVB has established a 3D TV group (CM-3DTV) to identify "what kind of 3D-TV solution does the market want and need, and how can DVB play an active part in the creation of that solution?". The CM-3DTV group held a DVB 3D-TV Kick-off Workshop in Geneva on 25 January 2010, followed by the first CM-3DTV meeting the next day.〔http://www.dvb.org/news_events/news/dvb-3d-tv-workshop/index.xml〕 DVB now defines a new standard for 3D video broadcast: DVB 3D-TV. Modes and features of latest DVB-x2 system standards in comparison: 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Digital Video Broadcasting」の詳細全文を読む スポンサード リンク
|