Page 301 - DCAP101_BASIC_COMPUTER_SKILLS

Basic Computer Skills

Notes 3. howling created by feedback. Echo cancellation is a processor-intensive task that
usually works over a narrow range of sound delays.

14.5.5 Problems
Some observers argue that three outstanding issues have prevented videoconferencing from
becoming a standard form of communication, despite the ubiquity of videoconferencing-
capable systems. These issues are:
1. Eye Contact: Eye contact plays a large role in conversational turn-taking, perceived
attention and intent, and other aspects of group communication. While traditional
telephone conversations give no eye contact cues, many videoconferencing systems are
arguably worse in that they provide an incorrect impression that the remote interlocutor
is avoiding eye contact. Some telepresence systems have cameras located in the screens
that reduce the amount of parallax observed by the users. This issue is also being
addressed through research that generates a synthetic image with eye contact using
stereo reconstruction.
Telcordia Technologies, formerly Bell Communications Research, owns a patent for
eye-to-eye videoconferencing using rear projection screens with the video camera
behind it, evolved from a 1960s U.S. military system that provided videoconferencing
services between the White House and various other government and military facilities.
This technique eliminates the need for special cameras or image processing.

2. Appearance Consciousness: A second psychological problem with videoconferencing
is being on camera, with the video stream possibly even being recorded. The burden
of presenting an acceptable on-screen appearance is not present in audio-only
communication. Early studies by Alphonse Chapanis found that the addition of video
actually impaired communication, possibly because of the consciousness of being on
camera.
3. Signal latency: The information transport of digital signals in many steps need time.
In a telecommunicated conversation, an increased latency larger than about 150-300 ms
becomes noticeable and is soon observed as unnatural and distracting. Therefore, next
to a stable large bandwidth, a small total round-trip time is another major technical
requirement for the communication channel for interactive videoconferencing.
The issue of eye-contact may be solved with advancing technology, and presumably the issue
of appearance consciousness will fade as people become accustomed to videoconferencing.

Success Story of Web Servers

n 1989 Tim Berners-Lee proposed to his employer CERN (European Organization for
Nuclear Research) a new project, which had the goal of easing the exchange of
Iinformation between scientists by using a hypertext system. As a result of the
implementation of this project, in 1990 Berners-Lee wrote two programs:
• a browser called World Wide Web;
• the world’s first web server, later known as CERN httpd, which ran on NeXTSTEP.

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