1080i
See HDTV

720p
See HDTV

codec
An abbreviation for encoder-decoder, a codec is any technology that converts analog video and audio signals into a digital format for transmission and also converts received digital signals back into analog format.

digital asset management system
The process, or a combination of software and equipments, for storing, retrieving and distributing digital assets (files), such as video files, photos and documents in a centralized and systematically organized system, allowing for the quick and efficient storage, retrieval and reuse of the digital files that are essential to all businesses.

DigitalWell™
A grid-enabled digital asset management system developed by ResearchChannel and the University of Washington that provides an easy way to acquire, collect, classify, store and deliver large collections of digital media over IP-based networks. For more about DigitalWell™, click here.

HDTV
HDTV, short for high-definition television, refers to several expanded-resolution digital systems for use with entertainment and information-delivery systems. 1080i is one of several high-definition video standards produced by the U.S. Advanced Television Standards Committee. It refers to 1,080 lines of interlaced video (540 lines per field) and  refers to 1920x1080 resolution in 16:9 aspect ratio. 720p is another high-definition video standard 720 lines of progressive video (720 lines per frame) at 1280x720 resolution. Both 1080i and 720p are higher definition than standard television or DVD video (480i or 480p).

HD over IP
Use of Internet Protocol network to carry a bitstream of high-definition video encapsulated in a stream of IP packets. Program material is usually compressed using a video codec so it can be streamed using an optimal bandwidth (i.e., one that balances video quality and amount of bandwidth required). Challenges include packet loss, network delay variation, lack of adequate bandwidth and timing reconstruction. The advantage over satellite transmission is being able to keep the stream running without ongoing charges, as opposed to having to pay hourly transponder and uplink charges.

iHDTV™
Short for Internet high-definition television, iHDTV™ is ResearchChannel and the University of Washington’s proprietary delivery system for high-definition video over IP-based networks. For more on iHDTV™, click here.

interlace
In video display systems, interlaceing is the process of updating the picture on the display device in two halves, or fields. The lines of the second half of the picture are placed between lines of the first half of the picture. NTSC (National Television System Committee) is a 2:1 interlaced system.

IP Multicast
A means of simultaneously transmitting data from a server to a group of selected users on a TCP/IP network, (internal, intranet or Internet). IP multicast is used for streaming audio and video over the network.

IP Network
The Internet Protocol (IP) is a data-oriented protocol used by source and destination hosts for communicating data across a packet-switched internetwork. Data in an IP internetwork are sent in blocks referred to as packets or datagrams (the terms are basically synonymous in IP).

linear
ResearchChannel, and other video programming producers and distributors, uses this term to refer to its programming distributed over cable and satellite systems to delineate that programming from its on-demand video library.

latency
Latency is a combination of time required to send information across a distance (usually close to the speed of light) and the processing time required at each end. High latency refers to a longer delay, while low latency refers to a shorter delay. When the latency is very low, the delay is not noticeable. This is especially significant in two-way communications such as teleconferencing.

MPEG
Short for Moving Picture Experts Group, MPEG is the name given to a family of International Standards used for encoding audio-visual information in a digitally compressed format. MPEG standards include MPEG1, MPEG2 and MPEG4.

MPEG1
The standard on which such products as Video CD and MP3 audio are based.

MPEG2
The standard on which products such as digital television set-top boxes and DVDs are based.

MPEG4
The standard for multimedia on the Web.

packet loss
The discarding of data packets in a network when a device (e.g., switch, router) is overloaded and cannot accept any incoming data at a given moment. High-level transport protocols such as TCP/IP ensure all the data sent in a transmission is received properly at the other end.

packetization
A process by which the network stack software decides how to break up data sent by programs into network frames.

podcasting
The distribution of audio or video files, such as radio programs or music videos, over the Internet using either RSS or Atom syndication for listening on mobile devices and personal computers.

SDTV
Short for standard definition television, this term refers to television systems that have a lower resolution than HDTV systems. The term is usually used in reference to digital television, in particular when broadcasting at the same (or similar) resolution as traditional analog systems. In ATSC, SDTV is broadcast at 640 pixels x 480 lines (4:3 ratio). The refresh rate can be any of 24, 30 or 60 pictures per second. Digital SDTV in 4:3 aspect ratio has the same appearance as the regular analog TV (NTSC, PAL, PAL2, SECAM), without ghosting, snowy images and static noises. Standards that can broadcast digital SDTV include DVB, ATSC and ISDB. The latter two were originally developed for HDTV, but they have more often been used for their ability to deliver multiple SD video and audio streams via multiplexing rather than using the entire bitstream for one HD channel.

SRB
Short for Storage Resource Broker, SRB is an open distributed data management  software facility developed at the University of California at San Diego. It is used with ResearchChannel’s DigitalWell digital asset management system to facilitate federated interoperation  with other leading digital library systems and data grids.

transcoding
The process of converting a media file such as audio or video from one format to another. Often used to convert video formats (e.g., Beta to VHS, VHS to QuickTime, QuickTime to MPEG). But it is also used to fit HTML files and graphics files to the unique constraints of mobile devices and other Web-enabled products. These devices usually have smaller screen sizes, lower memory, and slower bandwidth rates. In this scenario, transcoding is performed by a transcoding proxy server or device, which receives the requested document or file and uses a specified annotation to adapt it to the client.

VOD
Short for video on demand, VOD systems allow users to select and watch video content at any time they wish over video cable system or a network as part of an interactive television system. Selections are limited by server storage capacity. VOD systems are either streaming, in which viewing can start as the video streams over the Internet (or other network), or download, in which the program is brought in its entirety to a set-top box before viewing starts.

webcast
The term used to describe an audio or video broadcast conducted over the Internet.