of MPEG-2 are coded in this way and use DCT. In the MPEG-2 sequence only I-frames can be edited as they are only independent frames. See also: DCT, I-frame only, JPEG, MPEG-2
I-only
See: I-frame only IP
A B C D E F G H I J
K L
M N O P Q R S T U V
W X Y Z
Internet Protocol is the de facto standard for networking and is the widest used of the network protocols that carry the data and lie on top of physical networks and connections. Besides its internet use it is also the main open network protocol that is supported by all major computer operating systems. IP, or specifically IPv4, describes the packet format for sending data using a 32-bit address to identify each device on the network with four eight-bit numbers separated by dots e.g. 192.96.64.1. Each IP data packet contains a source and destination address. There is now a move toward IPv6 which brings, among many other enhancements, 128-bit addressing – enough for over 6,000 billion devices and relieving IPv4’s address shortage. Above IP are two transport layers. TCP (Transmission Control Protocol) provides reliable data delivery, efficient flow control, full duplex operation and multiplexing (simultaneous operation with many sources and destinations). It establishes a connection and detects corrupt or lost packets at the receiver and re-sends them. Thus TCP/IP, the most common form of IP, is used for general data transport but is slow and not ideal for video. UDP (User Datagram Protocol) uses a series of ‘ports’ to connect data to an application. Unlike the TCP, it adds no reliability, flow-control or error-recovery functions but it can detect and discard corrupt packets by using checksums. This simplicity means its headers contain fewer bytes and consume less network overhead than TCP, making it useful for streaming video and audio where continuous flow is more important than replacing corrupt packets. There are other IP applications that live above these protocols such as File Transfer Protocol (FTP), Telnet for terminal sessions, Network File System (NFS), Simple Mail Transfer Protocol (SMTP) and many more. Website:
www.ipv6forum.com
IP Datacast Forum (IPDC)
The IPDC Forum was launched in 2002 to promote and explore the capabilities of IP-based services over digital broadcast platforms (DVB and DAB). See also: IP over DVB Website:
www.ipdc-forum.org
IP over DVB The delivery of IP data and services over DVB broadcast networks. Also referred to as datacasting, this takes advantage of the very wideband data delivery systems designed for the broadcast of digital television, to deliver IP-based data services – such as file transfers, multimedia, Internet and carousels, which may complement, or be instead of, TV. See also: IP Datacast Forum, Data carousel
IPTV Internet Protocol Television is the use of the IP packetized data transport mechanism for delivery of streamed realtime television signals across a network.
IRD
Integrated Receiver Decoder. A device that has both a demodulator and a decoder (e.g. for MPEG-2) built in. This could be a digital television set or a digital set-top box. See also: IDTV
ISDB
Integrated Services Digital Broadcasting – standard for digital broadcasting used in Japan. ISDB has many similarities to DVB including OFDM modulation for transmission and the flexibility to trade signal robustness against delivered data rate. See also: COFDM, DiBEG, DVB Website:
www.dibeg.org
ISO International Standards Organization.An international organization that specifies international standards, including those for networking protocols, compression systems, disks, etc. See: Directory Website:
www.iso.ch
Isochronous A form of data transfer that carries timing information with the data. Data is specified to arrive over a time window, but not at any specific rate within that time. ATM, IEEE 1394 and Fibre Channel can provide isochronous operation where links can be booked to provide specified transfer performance. For example, 60 TV fields can be specified for every second but their arrival may not be evenly spread through the period. As this is a guaranteed transfer it can be used for ‘live’ video but is relatively expensive on resources. See: ATM, Asynchronous, Fibre Channel, IEEE 1394, Synchronous
ITU International Telecommunications Union. The United Nations regulatory body covering all forms of communication.The ITU sets mandatory standards and regulates the radio frequency spectrum. ITU-R (previously CCIR) deals with radio spectrum management issues and regulation while ITU-T (previously CCITT) deals with telecommunications standardization. Suffix BT. denotes Broadcasting Television. See: Directory Website:
www.itu.ch
ITU-R BT.601
This standard defines the digital encoding parameters of SD television for studios. It is the international standard for digitizing component television video in both 525 and 625 line systems and is derived from SMPTE RP125. ITU-R BT.601 deals with both color difference (Y, R-Y, B-Y) and RGB component video and defines sampling systems, RGB/Y, R-Y, B-Y matrix values and filter characteristics. It does not actually define the electro-mechanical interface – see ITU-R BT. 656. See also: 13.5 MHz, 4:2:2
ITU-R BT.656 The international standard for interconnecting digital television equipment operating to the 4:2:2 standard defined in ITU-R BT.601. It defines blanking, embedded sync words, the video multiplexing formats used by both the parallel (now rare) and serial interfaces, the electrical characteristics of the interface and the mechanical details of the connectors.
ITU-R BT.709 In 2000, ITU-R BT.709-4 recommended the 1080 active line standard for 50 and 60 Hz interlace scanning with sampling at 4:2:2 and 4:4:4. Actual sampling rates are 74.25 MHz for luminance Y, or R, G, B and 37.125 MHz for color difference Cb and Cr, all at 8 bits or 10 bits, and these should be used for all new productions. It also defines these 1080-line square-pixel standards as a common image formats (CIF) for international exchange. The original ITU-R BT.709 recommendation was
74
GLOSSARY OF TERMS
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99