DVB related

excerpted from http://en.wikipedia.org/wiki/Digital_Video_Broadcasting etc.

DVB
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 they are published by a Joint Technical Committee (JTC) of 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.[1] Many aspects of DVB are patented, including elements of the MPEG video coding and audio coding.

DVB systems distribute data using a variety of approaches, including by satellite (DVB-S, DVB-S2 and DVB-SH; also DVB-SMATV for distribution via SMATV); cable (DVB-C, DVB-C2); terrestrial television (DVB-T, DVB-T2) and digital terrestrial television for handhelds (DVB-H, DVB-SH); and via 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.

The conditional access system (DVB-CA) defines a Common Scrambling Algorithm (DVB-CSA) and a physical Common Interface (DVB-CI) for accessing scrambled content. DVB-CA providers develop their wholly proprietary conditional access systems with reference to these specifications. Multiple simultaneous CA systems can be assigned to a scrambled DVB program stream providing operational and commercial flexibility for the service provider.

ASI
ASI is streaming data format which often carries an MPEG Transport Stream (MPEG-TS).
DVB-ASI interface has become popular for use with infrastructure equipment. DVB-ASI is a fixed-frequency serial interface with a clock rate of 270 Mbps that transmits MPEG-2 data in PA fashion. The physical layer is based upon a subset of fiber channel levels (FC-0 and FC-1), and makes use of the 8B/10B channel coding of that standard.
An ASI signal can carry one or multiple SD, HD or audio programs that are already compressed, not like an uncompressed SDI.
An ASI signal can be at varying transmission speeds and is completely dependent on the user's setup requirements. Generally, the ASI signal is the final product of video compression, either MPEG2 or MPEG4.
DVB-ASI interfaces must support 188-byte MPEG packets and optionally may support 204-byte packets with either 16 Reed-Solomon (RS) error correction bytes or 16 dummy bytes.

SDI
Serial digital interface (SDI) is a serial link standardized by ITU-R BT.656 and the Society of Motion Picture and Television Engineers (SMPTE). SDI transmits uncompressed digital video over 75-ohm coaxial cable within studios, and is seen on most professional video infrastructure equipment.

Data is encoded in NRZI format, and a linear feedback shift register(LFSR) is used to scramble the data to reduce the likelihood that long strings of zeroes or ones will be present on the interface. The interface is self-synchronizing and self-clocking. Framing is done by detection of a special synchronization pattern, which appears on the (unscrambled) serial digital signal to be a sequence of ten ones followed by twenty zeroes (twenty ones followed by forty zeroes in HD); this bit pattern is not legal anywhere else within the data payload.

The first revision of the standard, SMPTE 259M, was defined to carry digital representation of analog video such as NTSC and PAL over a serial interface and is more popularly known as standard-definition (SD) SDI. The data rate required to transmit SD SDI is 270 Mbps.

With the advent of high-definition (HD) video standards such as 1080i and 720p, the interface was scaled to handle higher data rates of 1.485 Gbps. The 1.485-Gbps serial interface is commonly called the HD SDI interface and is defined by SMPTE 292M, using the same 75-ohm coaxial cable.

Studios and other video production facilities have invested heavily on the hardware infrastructure for coaxial cable and have a vested interest in extending the life of their infrastructure. Fortunately, SMPTE recently ratified a new standard called SMPTE 424M that doubles the SDI data rates to 2.97 Gbps using the same 75-ohm coaxial cable. This new standard, also called 3-Gbps (3G)-SDI, enables higher resolution of picture quality required for 1080p and digital cinema. This interface supports 4:4:4 at 2K resolution on ONE BNC.