Multimedia Terminology

The term "multimedia" refers to media that uses multiple forms of content types. As opposed to traditional forms of media which commonly only use one content type, multimedia can include various forms of content in a single piece of media such as audio, video, text, animations and stil imagery.

 

When working with multimedia, you may run across terms and/or acronyms that are foreign to you. The list below may help.

 

  • ASF - An audio or video file encoded for use with Windows Media Player.
  • ASX - A metafile that points to a Windows Media audio/video presentation. Artifacts - Distortion that occurs when audio or video is compressed to a low bit rate, also called noise.
  • AVI (audio/video interleave) - A Microsoft file format for files containing multiple streams of different types of data, such as audio, video, or MIDI. Video and sound elements are stored in alternate interleaved chunks in the file.
  • Bandwidth - In digital terms, the capacity of a connection to transmit data, expressed as data speed in bits per second (bps) or thousands of bits per second (Kbps). Bit - Describes the smallest unit of storage in a computer. It has a value of 0 or 1. Eight bits make up 1 byte which can store one letter, number or symbol.
  • Bit Rate - The speed at which binary content is streamed on a network, measured in kilobits per second (kbps). It takes 8 bits to make up 1 byte which is the size of one letter, number or symbol.
  • Byte - Describes a unit of storage which can contain one letter, number or symbol. Consists of 8 bits.
  • Broadband - Describes a high-speed network connection (T-1, DSL, cable modem) as opposed to a dial-up connection.
  • Buffering - Buffering is similar to the concept of "pre-filling". The stream of data begins before the media file actually plays. This data goes to local storage so that the incoming data always stays ahead of the actual data being viewed. Occasionally, if there is significant network congestion, a media file may stop playing momentarily so that the buffer can be refilled.
  • Cache - A place to store something temporarily so that it can be accessed quickly.¬†Web pages that are viewed are generally stored temporarily on the user's hard drive, for quick access on return visits. Caching can also refer to distributing Internet content to multiple servers that are periodically refreshed.
  • Capture - The process of changing or transferring digital or analog audio or video files to binary files which can then be edited and encoded.
  • DSL - Digital subscriber line. DSL utilizes unused portions of a phone line's bandwidth for transmitting data at high speed.
  • Digitize - See capture
  • CODEC - Stands for Compress/Decompress. A media file is encoded or compressed using an algorithm or formula and then decoded and decompressed as the user views or listens to the file.
  • Compression - It is desirable to compress media files to reduce file size and speed up the transmission time. This can be done using hardware, software or a combination of both. Compressed media files are then decompressed on the user's end.
  • Frames Per Second (FPS) - The number of video frames displayed each second. The higher the number, the smoother and sharper the images appear.
  • Lossy Compression - Data compression by eliminating perceptually insignificant information. However, since lossy compression introduces inaccuracies, it should only be used with graphics, audio, and video. Data files and executable programs can only be compressed with a lossless algorithm (i.e., a zip file).
  • Metadata - Additional, related information that can be stored as part of the compressed file or kept in a separate database. Examples include CD cover art, movie one-sheet images, or text-based information, such as author, title, etc.
  • NTSC - Input signal formats used in North America and Japan. Has 525 lines total with 480 lines visible per frame.
  • PAL - Input signal format used in Europe, Brazil, Argentina, Paraguay and Uruguay. Has 625 lines total, 576 lines visible.
  • Secam - Input signal format used in France and a few other countries. Has 625 lines total, 576 lines visible.
  • Packet Loss -Data is transmitted in small units known as packets. Occasionally, packets are lost or delayed due to network congestion, resulting in dropped frames.
  • Pixel - One unit of screen information. A video image is composed of individual colored dots, referred to as pixels. Depending on how a monitor is set, a pixel can take up 8 bits/1 byte (256 colors), 16 bits/2 bytes (high color), or 24 bits/3 bytes (true color).
  • Streaming Media - Streaming media allows the user to watch or listen to a media file without downloading it. The file is simultaneously "streamed" to the user as he or she is watching or listening to it. The user needs a player to view or listen to the files - files must be decompressed by a media player that is compatible with the format of the file.
  • Transcoding - The conversion of one digital file format to another digital file format (i.e., MP3 to Windows Media). The ideal method for encoding to multiple streaming media formats is to use the original, uncompressed source material and encode it into the new formats, avoiding transcoding completely.
  • Webcasting (also known as Internet Broadcasting) - Capturing, encoding, and hosting a live event, such as a concert, award show, meeting, or conference, usually from a remote location, for Internet broadcast on a one-time or limited basis. Live events usually require establishing an internet connection and/or satellite uplinks for streaming over the Internet.¬†Live events can also be archived for viewing on demand.
  • VOD (Video on Demand) - Video that can be accessed at any time by the user.