banner art


To find a term in the glossary, click the letter of the alphabet that is the first letter in the term you want to look up.

You can also read glossary terms within the text of Help by clicking the underlined glossary term links. After you click a glossary link, the glossary term and definition appear in a pop-up window. To close the window, click anywhere on the screen.



access control list (ACL)

A list of security protections that applies to either an entire object, a set of the object's properties, or an individual property of an object.

See also: system access control list (SACL)


See definition for: access control list (ACL)


A Windows Media metafile that gives a player the information needed to receive content. Announcement files contain Extensible Markup Language (XML) scripts.


A name-value data pair.


The process of verifying that an entity or object is who or what it claims to be. For example, a username and password may be used to authenticate a user.

See also: authorization


The process of granting access to protected resources.

See also: authentication

Back to Top



The data transfer capacity of a transmission medium.

bit rate

The number of bits transferred per unit of time, typically expressed in bits per second.


A method by which a client receives a stream. During a broadcast connection, clients cannot control the stream. This is the opposite of an on-demand presentation.

broadcast publishing point

A type of publishing point that streams content to multiple users at once, similar to a television broadcast. Content streamed from a broadcast publishing point can be delivered as a multicast or unicast stream.


An area of computer memory reserved for temporarily holding data before that data is used on the receiving computer. Buffering protects against the interruption of data flow.

bumper advertisements

Advertising content that is played before and after the primary content.

See also: interstitial advertisement, wrapper playlist

Back to Top



A temporary data storage location, or the process of storing data temporarily. A cache is typically used for quick data access.

cache/proxy server

A server running Windows Media Services for which a cache/proxy plug-in has been enabled, allowing the server to provide cache and proxy support to another Windows Media server.


Text that accompanies images or videos, either as a supplemental description or a transcript of spoken words.


Any computer or program connecting to, or requesting the services of, another computer or program. Client can also refer to the software that enables the computer or program to establish the connection.


An abbreviation for compressor/decompressor. Software or hardware used to compress and decompress digital media.


A process for removing redundant data from a digital media file or stream to reduce its size or the bandwidth used.


Audio, video, images, text, or any other information that is contained in a digital media file or stream.

Coordinated Universal Time (UTC)

The standard time common to every place in the world, coordinated by the International Bureau of Weights and Measures. UTC is used for the synchronization of computers on the Internet. Also known as Greenwich Mean Time.

Back to Top



See definition for: discretionary access control list (DACL)

discretionary access control list (DACL)

An access control list that is controlled by the owner of an object and that specifies the access particular users or groups can have to the object.

distribution server

A server running Windows Media Services that publishes content received from another streaming source, such as an encoder or another Windows Media server.

Back to Top



A fundamental syntactic unit in markup languages, such as HTML or XML. Elements are delimited by start tags and end tags. Empty elements are defined using an empty-element tag.


To convert audio and video content to a specified digital format.


A technology that converts live or prerecorded audio and video content to a specified digital format. Typically, content is compressed during encoding. Windows Media Encoder is an example of an encoder.


An action or occurrence to which a program might respond. Examples include state changes, data transfers, key presses, and mouse movements.

exclusive element

In a playlist, an element used to contain media elements that have an indeterminate start time.

See also: element, media element

Extensible Markup Language (XML)

A markup language that provides a format for describing structured data. XML is a World Wide Web Consortium (W3C) specification, and is a subset of Standard Generalized Markup Language (SGML).

Back to Top


Fast Streaming

A method of delivering content that combines downloading and streaming to use the available network bandwidth in the most effective manner.


A combination of hardware and software that enforces a boundary between two or more networks and prevents unauthorized access to a private network.


One of many sequential images that make up video.

frame rate

The number of video frames displayed per second. Higher frame rates generally produce smoother movement in the picture.

Back to Top



A part of the file structure that contains information required by an application to decompress and render the content. The header in a protected file also contains information required to get a license.


See definition for: Hypertext Transfer Protocol (HTTP)

Hypertext Transfer Protocol (HTTP)

The Internet protocol used to deliver information over the World Wide Web.

Back to Top



See definition for: Internet Group Management Protocol (IGMP)

intelligent streaming

A type of streaming that detects network conditions and adjusts the properties of a video or audio stream to maximize quality.

Internet Group Management Protocol (IGMP)

A protocol used by IP hosts to report their multicast group memberships to neighboring multicast routers.

Internet Protocol version 6 (IPv6)

A revised version of the Internet Protocol (IP) designed to address growth on the Internet. Improvements include a 128 bit IP address size, expanded routing capabilities, and support for authentication and privacy.

interstitial advertisement

An advertisement that appears between pieces of content. When one piece of content finishes playing, the ad appears before the next piece of content plays.

See also: wrapper playlist


See definition for: Internet Protocol version 6 (IPv6)

Back to Top



The delay that occurs while data is processed or delivered.

load balancing

A technique used for scaling the performance of a server-based program by distributing client requests across multiple servers.


To record actions that take place on a computer, or the record of those actions.


To repeat a stream continuously.

Back to Top



See definition for: multiple bit rate (MBR)

media element

A content item that is streamed from a playlist. This can be a file, a stream from an encoder, a remote stream, another playlist file, or a Windows Media file on a Web server.


Data about data. Title, subject, author, and size are examples of a file's metadata.

Microsoft Media Server (MMS) protocol

A proprietary protocol using UDP or TCP to deliver content as a unicast stream.

See also: Transmission Control Protocol (TCP), User Datagram Protocol (UDP)

MMS protocol

See definition for: Microsoft Media Server (MMS) protocol


A content delivery method in which a single stream is transmitted from a media server to multiple clients. The clients have no connection with the server. Instead, the server sends a single copy of the stream across the network to multicast-enabled routers, which replicate the data. Clients can then receive the stream by monitoring a specific multicast IP address and port.

multicast-enabled network

A network that has routers that can interpret Class D IP addresses.

multiple bit rate (MBR)

A characteristic of a data stream in which the same content is encoded at several different bit rates in order to optimize content delivery.

Back to Top


on-demand publishing point

A type of publishing point that streams content to clients by request. Content streamed from an on-demand publishing point is always delivered as a unicast stream.

origin server

A Windows Media server from which content is published.

Back to Top



A unit of information transmitted as a whole from one device to another on a network.


To break input into smaller chunks so that a program can act upon the information.


A client program or control that receives digital media content streamed from a server or played from local files. Windows Media Player is an example of a player.


A list of digital media content.


An auxiliary software component that extends or enhances the features of other software.


A connection point in a computer through which a peripheral device or another computer can communicate.


A set of formats and procedures that enable computers to exchange information.

See also: Hypertext Transfer Protocol (HTTP), Microsoft Media Server (MMS) protocol, Real Time Streaming Protocol (RTSP), Transmission Control Protocol (TCP), User Datagram Protocol (UDP)

protocol rollover

A procedure that enables switching from one protocol to another when a Windows Media server fails to make a connection using a particular protocol.

proxy server

A server located on a network between client software, such as a Web browser, and another server. It intercepts all requests to the server to determine whether it can fulfill them itself. If not, it forwards the request to another server.

publishing point

An organized memory location that translates a client request for content into the physical path on the server hosting the content. A publishing point essentially acts as a redirector.

Back to Top


Real Time Streaming Protocol (RTSP)

An Internet protocol that deliver real-time, live, or stored audio and video streams over a network.


To display video, audio, or text content from a file or stream using a software program, such as Windows Media Player.


The process by which the server breaks down existing data packets and reassembles them into different-sized data packets for distribution to clients.


See definition for: Real Time Streaming Protocol (RTSP)

Back to Top



See definition for: system access control list (SACL)


In a multicast transmission, the reach of a stream. The scope of a multicast transmission can be set to reach either an immediate subnetwork only or the entire Internet.

script commands

Named data that is associated with a designated time in Windows Media-based content. The data can be used by players to perform a specific action such as displaying a Web page.

Simple Network Management Protocol (SNMP)

A network protocol used to manage TCP/IP networks. In Windows, the SNMP service is used to provide status information about a host on a TCP/IP network.


See definition for: Synchronized Multimedia Integration Language (SMIL)


See definition for: Simple Network Management Protocol (SNMP)


Digital media that is in the process of being delivered in a continuous flow across a network.

stream format

Information about the properties of a stream, such as the codecs used, frame rate, and frame size. A player uses stream format information to decode a stream.

stream format file

A file used by a player to decode a multicast stream.

See also: stream format

stream thinning

The process of lowering the frame rate of source video to reduce the bandwidth required for streaming to be lower than or equal to the available client bandwidth. If necessary, the video portion of the stream may stop streaming and only the audio portion streamed.

Synchronized Multimedia Integration Language (SMIL)

An XML-based language being developed by the World Wide Web Consortium (W3C) that would enable Web developers to divide content into separate streams (audio, video, text, and images), send them to a client computer, and then have them displayed as a single stream. This separation reduces the time required for transmission over the Internet.

system access control list (SACL)

A list that represents part of an object's security descriptor that specifies which events (such as logon attempts and file access) are to be audited per user or group.

See also: access control list (ACL)

Back to Top



See definition for: Transmission Control Protocol (TCP)

time-to-live (TTL)

The number of routers through which a multicast stream can pass before a router stops forwarding the stream.

Transmission Control Protocol (TCP)

The protocol within TCP/IP that governs the breakup of data messages into packets to be sent via IP, and the reassembly and verification of the complete messages from packets received by IP.


See definition for: time-to-live (TTL)

Back to Top



See definition for: User Datagram Protocol (UDP)

UDP resend

An error correction method that allows the client to request that the server retransmit lost data packets.


See definition for: Universal Naming Convention (UNC)


A method used by media servers for providing content to connected clients in which each client receives a discrete stream. No other client has access to that stream.

unicast rollover

Redirection of a client to a unicast stream in the event the client cannot access the multicast stream.

Universal Naming Convention (UNC)

The full name of a resource on a network. It conforms to the \\servername\sharename syntax, where servername is the name of the server and sharename is the name of the shared resource. UNC names of directories or files can also include the directory path under the share name, with the following syntax: \\servername\sharename\directory\filename.

User Datagram Protocol (UDP)

A connectionless transport protocol in the TCP/IP protocol stack that is used in cases where some packet loss is acceptable, for example, with digital media streams.


See definition for: Coordinated Universal Time (UTC)

Back to Top


Windows Media file

A file that contains audio, video, or script data. The content of the file is encoded with one of the Windows Media codecs.

Windows Media Format

The format of a digital media file or stream that was encoded with Windows Media codecs.

Windows Media metafile

In Windows Media technologies, a file that provides information about Windows Media files and their presentation. File name extensions for Windows Media metafiles include .asx, .wax, .wvx, .wmx, and .nsc.

wrapper playlist

A Windows Media metafile that places additional content at the beginning or end of a stream. Examples of this content include welcome messages, goodbye messages, advertisements, and station branding.

See also: interstitial advertisement

Back to Top



See definition for: Extensible Markup Language (XML)

Back to Top

© 2005 Microsoft Corporation. All rights reserved.