Network Options IP Based ISDN Based Both Multimedia System 030728ppt 50

Network options ip based isdn based both multimedia

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Network Options IP Based ISDN Based Both Multimedia System 030728.ppt 50 Videoconferencing using an MCU Multipoint control unit (MCU) ISDN/broadband network/ dedicated-circuit network Two-way simultaneous integrated speech-and-video information streams to/from all parties Multimedia System 030728.ppt 51 Multiparty Video Conferencing In principle, a separate window appears on the screen of each participant’s PC/workstation is used to display the video image of all the participants. This would require multiple integrated speech-and-video communication channels, one for each participant, being sent to each of the other participants. Normally, this would require more bandwidth than is available. The integrated speech-and-video information stream from each participant is sent to the MCU which then selects just a single information stream to send to each participant. Sometimes it is known as always presence. Other feature:- Chair control / Admission Control Multimedia System 030728.ppt 52 Videoconferencing on IP Network The Internet does not support multicasting but multicasting is supported on LAN. Multicasting means that all transmissions from any of the PCs/workstations belonging to a predefined multicast group are received by all the other members of the group. Thus with networks that support multicasting, it is possible to hold a conferencing session without an MCU. Only a limited number of participants are involved owing to the high load it places on the network. Neither continuous presence nor admission control is available Video Conferencing
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Multimedia System 030728.ppt 53 Common Video Conferencing Standards Network PSTN N-ISDN LAN ITU-T Rec. H.324 H.320 H.323 Video Codec H.261*, H.263* H.261*, H.263 H.261*, H.263 Data Conference T.120 T.120 T.120 System Control H.245 H.230 H.242 H.245 Multiplex H.223 H.221 H.225 Security H.233, H.234 H.235 MCU H.231, H.243 H.323 Interface V.34 I.400 TCP/IP Setup Signaling SS7 Q.931 Q.931, H.225 ISDN BRI 2B + 1D Channel PRI – 23B Channel B channel Bandwidth 64kbps D channel Bandwidth 16kbps Multimedia System 030728.ppt 54 H.323 Video Conference Terminal Multimedia System 030728.ppt 55 Examples of Video Coding Standards Network-friendly packet-based video < 64 Kb/s H.26L ITU-T PSTN video phone < 64 Kb/s H.263 Version 2 ITU-T Interactive audio/video 24-1024 Kb/s CD 1496-2 MPEG-4 Video ISO PSTN video phone 64 Kb/s or below H.263 ITU-T SDTV, HDTV 4-80 Mb/s IS 13818-2 MPEG-2 Video ISO CD-ROM 1.2 Mb/s IS 11172-2 MPEG-1 Video ISO ISDN video phone p x 64 Kb/s, p=1, 2, , 30 H.261 ITU-T Typical applications Typical range of bit rates Video-coding standard Standards organization Multimedia System 030728.ppt 56 High resolution graphics display Resolution as dot matrix resolution is given as the size of the dot matrix in pixels per inch Resolution as sharpness means the sharpness of an image as measured by the number of dots in a given space normally given as dpi (dots per inch) let's consider two cathode ray tube (CRT) monitors both having a resolution of 1,024 by 768, but one of which is listed as 17 " (15.5 ") and the other 19" on the diagonal; the 17" monitor may be displaying 85 dpi
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