DVB is a consortium of over 300 companies in the fields of broadcasting and manufacturing that work cooperatively to establish common international standards for digital broadcasting. DVB-generated standards have become the leading
international standards, commonly referred to as “DVB,” and the accepted choice for technologies that enable an efficient, cost-effective, high-quality, and interoperable digital broadcasting. The DVB standards for digital television have been adopted in the United Kingdom, across mainland Europe, in the Middle East, South America, and in Australasia. DBV standards are used for DTH satellite transmission 22 (and also for terrestrial and cable transmission).
The DVB standards are published by a Joint Technical Committee (JTC) of European Telecommunications Standards Institute (ETSI), European Committee for Electrotechnical Standardization (Comit´e Europ´een de Normalisation Electrotechnique—CENELEC), and European Broadcasting Union (EBU). DVB produces specifications that are subsequently standardized in one of the European statutory standardization bodies. They cover the following DTV-related areas:
- conditional access,
- content protection copy management,
- source coding,
Standards have emerged in the past 10 years for defining the physical layer and data link layer of a distribution system, as follows:
- satellite video distribution (DVB-S and DVB-S2),
- cable video distribution (DVB-C),
- terrestrial television video distribution (DVB-T),
- terrestrial television for handheld mobile devices (DVB-H).
Distribution systems differ mainly in the modulation schemes used (because of specific technical constraints):
- DVB-S (SHF) employs QPSK (Quadrature Phase-Shift Keying).
- DVB-S2 employs QPSK, 8PSK (Phase-Shift Keying), 16APSK (Asymmetric Phase-Shift Keying) or 32APSK; 8PSK is the most common at this time (it supports a 30-megasymbols pre-satellite transponder and provides a usable rate in the 75 Mbps range, or about 25 SD-equivalent MPEG-4 video channels).
- DVB-C (VHF/UHF) employs QAM (Quadrature Amplitude Moderation): 64-QAM or 256-QAM.
- DVB-T (VHF/UHF) employs 16-QAM or 64-QAM (or QPSK) along with COFDM (Coded Orthogonal Frequency Division Multiplexing).
- DVB-H: refer to the next section.
Because these systems have been widely deployed, especially in Europe, they may well play a role in the near-term 3DTV services. IPTV also makes use of a number of these standards, particularly when making use of satellite links (an architecture that has emerged is to use satellite links to provide signals to various geographically distributed headends, which then distribute these signals terrestrially to a small region using the telco IP network—these headends act as rendezvous point in the IP Multicast infrastructure). Hence, in the reasonable assumption that IPTV will play a role in 3DTV, these specifications will also be considered for 3DTV in that context.
As implied above, transmission is a key area of activity for DVB. See Table 4.2 for some of the key transmission specifications.
In particular, EN 300 421 V1.1.2 (1997–2008) describes the modulation and channel coding system for satellite digital multiprogram television (TV)/HDTV services to be used for primary and secondary distribution in Fixed Satellite Service (FSS) and Broadcast Satellite Service (BSS) bands. This specification is also known as DVB-S. The system is intended to provide DTH services for consumer IRD, as well as cable television headend stations with a likelihood
of remodulation. The system is defined as the functional block of equipment performing the adaptation of the baseband TV signals, from the output of the MPEG-2 transport multiplexer (ISO/IEC DIS 13818-1) to the satellite channel characteristics. The following processes are applied to the data stream:
- transport multiplex adaptation and randomization for energy dispersal;
- outer coding (i.e., Reed–Solomon);
- convolutional interleaving;
- inner coding (i.e., punctured convolutional code);
- baseband shaping for modulation;
DVB-S/DVB-S2 as well as the other transmission systems could be used to deliver 3DTV. As seen in Fig. 4.9, MPEG information is packed into PESs (Packetized Elementary Streams), which are then mapped to TSs that are then handled by the DVB adaptation. The system is directly compatible with MPEG- 2 coded TV signals. The modem transmission frame is synchronous with the MPEG-2 multiplex transport packets. Appropriate adaptation to the signal formats (e.g., MVC ISO/IEC 14496-10:2008 Amendment 1 and ITU-T Recommendation H.264, the extension of AVC) will have to be made, but this kind of adaptation has recently been defined in the context of IPTV to carry MPEG-4 streams over an MPEG-2 infrastructure (Fig. 4.10).
For Digital Rights Management (DRM), the DVB Project–developed Digital Video Broadcast Conditional Access (DVB-CA) defines a Digital Video Broadcast Common Scrambling Algorithm (DVB-CSA) and a Digital Video Broadcast Common Interface (DVB-CI) for accessing scrambled content:
- DVB system providers develop their proprietary conditional access systems within these specifications;
- DVB transports include metadata called service information (DVB-SI i.e., Digital Video Broadcast Service Information) that links the various Elementary Streams (ESs) into coherent programs and provides human-readable descriptions for electronic program guides.