TERM
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Definition
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| Application Instance
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An occurrence of code loaded and executing on the computer when an application has been started. Most applications can be launched repeatedly, each launch resulting in a different application instance. For example, multiple instances of RealProducer are launched on the ViewCast Power Encoding Station.
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| Bandwidth
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The ability of a communications link to cope with
the volume of data transported in a fixed time, usually measured in
bits/second. Common bandwidths for desktop communications are
28.8 kbps (telephone), 56 kpbs (ISDN) and 'other' ( which means 'high speed' such as 10baseT LAN, T1, xDSL, Cable modem, etc.)
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| CIF
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An ITU-T standard video picture format where information is stored as
luminance (brightness) plus two color difference components. Luminance is held at 352 pixels per line and 288 lines per picture, color differences are 176 pixels per line and 144 lines/picture.
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| Codec
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A coder/decoder, typically used to convert analog signal (typically video or audio) into digital signal and vice versa. May also be used to compress or decompress the digital data (as the Osprey 1000)
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| Conference
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A real-time collaborative interaction, typically between two or more parties at different locations, in which a set of policies or rules of behavior are enforced. Examples of conferences include formal conferences, informal conferences and multiparty conferences.
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| Frame
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In the context of video, this generally defines a single screen image. In the context of data transmission, this defines a unit information for transmission at the physical layer. On this website, the term is used only in the context of video display.
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| Frames Per Second (fps)
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The number of video frames displayed each second. Most people see continuous motion
about 17 fps. Standard NTSC (US) television displays at 60 fields
per second (30 frames interlaced); standard PAL (non-US) television displays at 25 interlaced frames per second.
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| H.320
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An ITU-T international recommendation for audio and video conferencing,
targeted particularly at ISDN networks.
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| H.323
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An ITU-T international recommendation for audio and video conferencing,
targeted particularly at local area networks (LAN).
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| H.324
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An ITU-T international recommendation for audio and video conferencing,
targeted particularly at low-speed telephone lines.
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| Instance
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An occurrence of code loaded and executing on the computer when an application has been started. Most applications can be launched repeatedly, each launch resulting in a different application instance. For example, multiple instances of RealProducer are launched on the ViewCast Power Encoding Station.
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| LAN / Local Area Network
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LAN, a communications network typically interconnecting devices and workstations in a relatively small geographical area. Characterized by high speed. LANs may be bridged together to form wide area networks.
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| Multimedia
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A vague term which is generally interpreted to mean the full range of data types including numeric, text, image, graphic, audio and video data.
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| NTSC
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A standard for broadcast television established by the National Television Standards
Committee. Used in North America, Japan and some other countries. At 12.27 Mhz, with square pixel display, NTSC image total resolution is 780 x 525 pixels, but the active resolution area is 640 x 480. NTSC imaging is generally less attractive than PAL, but is compatible with the early black-and-white television standards.
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| PAL
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A standard for broadcast television widely used
outside of the United States. At 14.75 Mhz, square pixel display, PAL total resolution is 944 x 625 pixels, but the active resolution area is 768 x 576. PAL is generally
characterized by stronger color and more attractive image than NTSC, however it is not compatible with early black-and-white television standards.
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| POTS
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Plain Old Telephone Service. Basic, low-speed telephone communications lines are referred to as 'POTS'.
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| QCIF
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An ITU-T standard video where information is stored as luminance (brightness) and two color difference components. The luminance is held at 176 pixels per line and 144 lines per picture; the color differences are held at 88 pixels per line and 72 lines per picture. QCIF is literally 'quarter CIF'.
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| Streaming |
Audio and video files contain a great deal of data. The larger they
are, the longer they take to transfer from the server to the
client. Streaming is the process whereby the client computer that is
receiving the audio and video information
starts playing the information to the viewer before the
entire file has been received. The practical impact is that you do not have to wait
as long before you can see information. |
| TCP/IP
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Transmission Control
Protocol/Internet Protocol; a suite of protocols designed to provide interconnection between a variety of host systems. The Internet network is based on TCP/IP, although provision is made for two other protocols: UDP (User
Datagram Protocol) and IPMC (Internet Protocol, MultiCast).
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| WAN / Wide Area Network
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A communications network formed by interconnecting LANS over wide geographic areas through bridges and routers.
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