- These are standards set by the ITU-T governing the transmission of audio.
G.711 An ITU-T Recommendation detailing a 32- to 64-Kbps 3.4-KHz
bandwidth audio coding algorithm. Part of the ITU-T codec and telephony
requirements. This algorithm produces telephone grade audio, especially
useful in videoconferencing at aggregate bit rates above 128 Kbps.
G.722 An ITU-T Recommendation detailing a 64-Kbps 7-KHz bandwidth
audio coding algorithm. Part of the ITU-T codec requirements. This
produces good quality audio but is generally not recommended at aggregate
bit rates below 256 Kbps.
G.723 An ITU-T Recommendation; Dual Rate Speech Coder for
Multimedia Communications Transmitting at 5.3 and 6.3 Kbps.
G.728 An ITU-T Recommendation detailing a 16-Kbps 3.4 KHz bandwidth
audio coding algorithm. Part of the ITU-T codec recommendations. Produces
good speech intelligibility and is a good choice for operation at 112 or
128 Kbps transmission.
- Green (G).
- The green video signal, part of an RGB
component video signal. G may also include synchronization information.
- The synchronization of a piece of video equipment by means of an external
video signal. In videoconferencing systems, all cameras should be genlocked
- A motion artifact in monitor
displays of compressed video images. As an image moves quickly across the
field of view (e.g., an arm waving) it leaves a trail of 'ghost' images that
resolve as the movement stops.
- This is the expansion card that will take the signal passed to it from an
external video source and convert it into digital video. If you use a
digital camera produced for DVC, you often will not need a video grabber
Graphical User Interface (GUI)
- An application, such as Microsoft Windows, that lies on top of other
applications and provides a user interface based on graphical icons.
- Allows user to accentuate or de-emphasize selected frequencies within an
audio sample. An example is the different 'tuning' for heart and lung sounds
in electronic stethoscopes.
- Document stand. Typically used for capturing and transmitting images of
documents. Can be used for skin lesions and the like. Typically uses a 1-CCD
(1-chip) camera. At a minimum, a graphic camera should have color and black
and white modes, manual iris, zoom, focus, and color adjustments, additional
overhead lights for uniform illumination, and a large (at least 8.5 x 11
inch) back-lighted base. The last feature is useful for capturing images of
transparencies and X-ray, CT, and MRI images.
- The levels (shades) of gray that a screen or pixel
within a screen can display. See bit depth.
- A videoconferencing system designed for a small group of people and
consists of a pan, zoom, tilt camera, large 20" SVGA monitor, echo
cancellation and automatic gain audio.
Group videoconferencing system
- A relatively large videoconferencing system that links groups of people
located at remote sites.