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Desktop Videoconferencing. by Gerald Knezek & Rhonda Christensen. Terminology. Teleconferencing audio combined audio/video videoconferencing implies audio also (continued). (continued) Desktop Videoconferencing One form of Teleconferencing Phone-line based
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Desktop Videoconferencing by Gerald Knezek & Rhonda Christensen
Terminology Teleconferencing • audio • combined audio/video • videoconferencing implies audio also(continued)
(continued) • Desktop Videoconferencing • One form of Teleconferencing • Phone-line based • Lumaphone (black &white, $350) • Sony, ATT (color, $1K)(continued)
(continued) • Internet based • Audio system (Internet Phone, Mave, $0-100) • Video/keyboard typing system (Original CU SeeMe, free) • Combined Audio-Video (Commercial Systems, <$150)
Videoconferencing Distinctions Frame Refresh Rate • > 24 frames per second required to perceive full motion • full motion (TV) systems provide 30 FPS • partial motion systems provide about 15 FPS (continued)
(continued) • internet based systems provide 5-15 FPS (CU SeeMe) • Slow-Scan TV provides 1 frame every 4 seconds • Cost • Higher fidelity requires more bandwidth • Color costs more • Usually trade off audio for video quality
IP Addresses • Unique Identifier (like phone number) • 129.120.20.91 for Mac Quadra in 322G • 129.120.20.127 for Mac Mac IIsi in 322 (continued)
(continued) • 129.120.20.2 for CECS Reflector • alias pizza.cecs.unt.edu • Similar addresses exist for hundreds of public reflectors
Internet Conferencing Tools • CU SeeMe (v.68k0.80b2) • videoconferencing from Internet (T-1, SLIP, PPP) • point to point vs. reflector • max 2 participants with former • uninvited participants with latter (continued)
(continued) • Maven/Internet Phone (v.2.0a37) • audioconferencing • takes priority over video • Special considerations • >8 Mb RAM (w/system 7.5) to run both • Audio input for AV machines • Camera technology
Reflector Site vs. Point-to-Point • Reflector Sites • Public • Usually allow max. of 8 (continued)
(continued) • Point-to-Point • Private • Allows max of 2 for CU SeeMe (Mac) • Allows max of 8 with Maven • Private Reflectors • restricted access through code • combines privacy and multiple access rights