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Real-time Audio and Video Conferencing

Real-time Audio and Video Conferencing. Allan Tuchman Computing and Communication Services Office University of Illinois. Presentation Goals. Show examples of internet telephony and video conferencing Explain some of the concepts Discuss how video conferencing is used.

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Real-time Audio and Video Conferencing

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  1. Real-time Audio and Video Conferencing Allan Tuchman Computing and Communication Services Office University of Illinois

  2. Presentation Goals • Show examples of internet telephony and video conferencing • Explain some of the concepts • Discuss how video conferencing is used

  3. Related Topics Overlap Somewhat • Internet Telephony • Video Conferencing • Audio and video on demand • Live audio and video • Multimedia • Web integration

  4. Hardware Requirements • Pentium 100 or better • Sound board and speakers • optional video camera; e.g. Connectix or Videum • any standard video controllers • - or - Macintosh • optional video camera; e.g., Connectix • Direct network connection or dialup slip or PPP at least 28.8 kb

  5. Let’s just try it! • Click an application NetMeeting Intel Video Phone

  6. Vocabulary and Concepts • Compression/Decompression (CODEC) • hardware or software • decompression must be real-time. Compression also, or nearly as fast. • Full/half duplex • Audio data has priority over video data

  7. Concepts, continuted : Packets and Buffering • Packet switched network -- internet technology • TCP and UDP

  8. Bandwidth • Audio is more important than video • Audio requires ~8 kpbs • Video ideal is 10-20 fps (~370 kbps) • These estimates are based on minimal data and simple compression • 33.6 kbps Dialup is likely to see 1-3 fps with good audio

  9. Telephony • Intel Internet Video Phone • VocalTec Internet Phone • Many other phones • Videoconferencing applications can do simple calls (e.g. NetMeeting)

  10. Point-to-Point Connection John john.isp.com Mary mary.artic.no

  11. Conferencing • CU-SeeMe (Cornell freeware) • Enhanced CU-SeeMe (White Pines) • Microsoft NetMeeting • Others coming • Collaborative components (e.g., moo)

  12. Cross-platform Interoperability • Few options • About 3-4 Unix application • A handful of Mac applications • Ten’s of Window’s applications • CU-SeeMe works for Mac’s and PC’s • Cooltalk is supposed to • It will get better with standards (H.323)

  13. Let’s try another CU-SeeMe

  14. A Multi-point Conference • Reflector serves audio/video streams to each person Alice Mary Arnie Reflector John CU-SeeMe example

  15. One more time • Conferencing, sharing, collaboration Microsoft NetMeeting

  16. Listing Services -- ILS/ULS • Four11 • Bigfoot • Internet Address finder (IAF) • Microsoft • … other LDAP servers

  17. LDAP Protocol • Lightweight Directory Access Protocol • Netscape • Microsoft • University of Michigan LDAP

  18. Web Integration • URL can identify a person and directory server • Works much as other multimedia URL’s, for example, RealAudio • Caller must have the application on their machine • Callee must have a compatible app, and be registered with the directory server (logged in)

  19. Web Integration, continued LDAP server www.xyz.com cgi script tuchman@uiuc.edu 3 1. lookup name 2. return mime type 2 4 Web page : http://www.xyz.com/dir.cgi/... : 1 Caller’s PC

  20. Environment • Privacy • Distraction • Headsets with microphone available

  21. Summary • Quality is acceptable to very good • Audio/Video conferencing programs are easy to install • Generally easy to use • Some programs still crash the machine • Some interactions between products • Interoperability increasing • Low startup costs

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