Bandwidth: The total data throughput capacity of a network or Internet connection. For example, the bandwidth of a “56k” dial-up connection is up to 56kbps. Bandwidth is also a measure of the network capacity used for a webcast. Webcasting to larger audiences and/or at increasing video quality uses more bandwidth. Bandwidth costs money, so the larger the audience for a webcast, and the higher the quality of the streaming video, the more bandwidth is used and the more it costs.

Bitrate: The amount of bandwidth (usually expressed in kilobits-per-second, as in “300kbps”) required to play a digital media file. Generally, the higher the bitrate, the better the quality. Streaming media is usually encoded at different bitrates to accommodate audiences with faster and slower internet connections.

Buffering: To deal with network congestion, streaming media players store a few seconds’ worth of video in memory before playing it. Buffering contributes to a time-delay (usually 15-30 seconds) when watching a live webcast.

Cable: High-speed Internet connection over cable TV lines, such as Time Warner’s Roadrunner service. Popular for residential use, the bandwidth of cable connections vary, but is usually 10-50 times faster than dial-up. Viewers with cable modems can receive high-quality video.

Codec: COmpression-DECompression. Software for compressing (and later decompressing for playback) audio and video to reduce its size while preserving as much quality as possible. Each digital media format (Windows Media, QuickTime, RealSystem, etc.) utilizes its own codecs, which are continually improved as new versions of the players are released.

Dial-up: Still the most common type of Internet connection, it uses regular telephone lines. Bandwidth is limited to 56kbps, which can carry only low-quality video.

DSL: Digital Subscriber Line. High-speed Internet connection over digital telephone lines. Popular for residential and business use, the bandwidth of DSL connections vary, but is usually 10-50 times faster than dial-up. Viewers with DSL connections can receive high-quality video.

DV: Digital Video. Popular broadcast-quality format ideal for recording video.

DVD: “Digital Versatile Disc” (also “Digital Video Disc”). A popular disc format for delivering high-quality video to be played on televisions or computers with DVD drives.

Editing: Time-consuming process of taking raw audio or video footage and producing a final program with cuts, transitions, graphics, music, voiceovers, etc.

Encoding: Process of converting audio and video into a streaming media format, such as Windows Media or QuickTime, so it can be webcast.

Flash: Popular format for highly-interactive web content that supports graphics, animation, sound and video.

Firewall: Security mechanism used by most companies to prevent unauthorized access to their networks. Sometimes firewalls interfere with webcast reception. It’s a good idea to give viewers a way to test their ability to view streaming media before a live webcast.

ISP: Internet Service Provider (such as AOL, MSN, and Earthlink).

MP3: Short for “MPEG-1 Audio Layer III” (not MPEG-3, a common misconception). A high-quality audio codec popular for encoding music for playback on computers and portable audio players.

MPEG: A family of codecs for video and audio. Most common is MPEG-2, which is used for all DVD-Video discs as well as digital cable and direct satellite TV broadcasts. MPEG-4 is a newer one gaining popularity for streaming media.

Multicast: A way of webcasting to large audiences on a company network without using too much bandwidth. Each viewer receives a copy of the same stream (similar to a traditional TV broadcast), rather than each viewer having their own connection to a streaming server. Unfortunately, the Internet does not support multicast.

PowerPoint: Popular presentation software included with Microsoft Office. PowerPoint slides can be included in a live webcast. Also, video and PowerPoint can be mixed to create interactive training applications for delivery over the Internet or on CD-ROM.

Real: One of three popular streaming media formats. Made by Real Networks.

Streaming: The delivery of digital media in real-time (as it plays) to a computer over a network from a streaming server.

QuickTime: One of three popular streaming media formats. Made by Apple Computer.

Switched: If more than one camera is used for a live webcast, a director operates a switcher to change between camera angles.

T1: Common type of high-speed digital telecommunication link for businesses. The bandwidth of a T1 line is 1.5mbps (megabits per second), or 1576kbps, which is about 30 times faster than dial-up.

T3: An even faster telecommunication link, with bandwidth of 45mbps (30 times faster than a T1).

Unicast: The opposite of multicast. Each viewer has his own connection to the server, and uses up an amount of bandwidth equal to the stream’s bitrate. As the audience grows, so does the load on the network and streaming servers. All webcasts over the Internet are unicast.

URL: Uniform Resource Locator, as in http://www.aep.com, that links to a specific web page, graphic, video, etc.

Video On Demand (VOD): The delivery of pre-recorded video for viewing over a network at any time (not on a schedule). Most live webcasts are stored for later on-demand viewing.

Windows Media: One of three popular streaming media formats. Made by Microsoft.