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Videoconferencing in General at DoIT

Intro to Videoconferencing tools at DoIT

Wikipedia articles about videoconferencing and telepresence.

Videoconferencing can be accomplished with special purpose appliances, like those made by Lifesize, Polycom, Sony, Tandberg or with software codecs running on on general purpose computers. Videoconference devices can be used in offices or meeting rooms, classrooms or auditoria.

Easy videoconferencing can be done with consumer-oriented technologies like iChat with video, AOL Instant Messenger (AIM), Yahoo Instant Messenger, Skype, Google Talk, and others.

Wikipedia has a great Comparison of VoIP Software (including video).

Definition of H.323 at Wikipedia.

The H.323 Global Dialing Scheme (GDS) explained at Wikipedia.

H.323 Gatekeeper explained at Wikipedia.

H.323 videoconference devices can connect to one other device. To connect more than two endpoints, a Multipoint Control Unit (MCU) is used.

There are software H.323 codecs available: PVX from Polycom (Windows only) and XMeeting, a free-open-source system (Mac only). These software codecs do not include echo cancellation technology. Echo occurs when the sound from the remote site is picked up by the microphone at the local site. Such echo can be so severe as to totally disrupt a conference. Echo is delayed by the transmission and buffer time, but if the volume level if high, each echo can get successively louder, blocking any verbal questions. If echo occurs on a conference, the first action to take is for everyone to immediately turn off or mute their microphones. Headsets with microphones stop echo from occurring, so users of software codecs should use headsets.

The H.323 protocol has some behaviors which are a challenge for firewalls and Network Address Translation (NAT). The protocol responds to call origination on different ports, and embeds IP addresses within packets. There are three ways to respond:

• Use a firewall that explicitly supports H.323 protocol, opening up the needed ports, and re-writing embedded IP addresses. The Cisco FWSM explicitly supports H.323 if the correct rule is used.
• Install a hardware device that manages H.323 devices inside a firewall.
• Put the H.323 device outside the firewall. (This is not a significant risk with hardware codecs, as these are special-purpose appliances, not general purpose computers. This is not a good alternative with software codecs.)

We sell licenses for Adobe Connect Pro at the DoIT Tech Store. Here are KB articles on Connect Pro: Adobe Connect - System Requirements.

Vidyo is a videoconferencing system with hardware central equipment and soft clients. The Internet2 Commons has demo Vidyo services.

VideoLAN VLC is free, general-purpose, open-source software for encoding and decoding video. VideoLAN can send out the desktop as a video stream. Using this method, slide shows like Powerpoint can be shared with others.

Cisco Telepresence is a high-end, high quality videoconference system. Cisco recently purchased Tandberg.

EVO is free videoconferencing software from Cal Tech.

Access Grid is free open-source videoconferencing software. The UW-Madison Computer Science Department operates an accessgrid node.

UW Extension Instructional Communications Systems (ICS), located at the Pyle Center, has an abundance of audio and video conferencing services. ICS has a great technical support page. ICS operates an H.323 Gatekeeper; to use you must register first. ICS operates Elluminate Live, a software-based videoconferencing technology.

ICS has a Test Polycom at . This can be used to test your H.323 videoconference equipment.

The Internet2 Commons is a group of services provided to participating members of Internet2. The University of Wisconsin-Madison is participating in the Commons. One of the Commons services is H.323 MCU services. To schedule an H.323 videoconference with two or more remote sites,contact ICS, our Commons Coordinator.

The Videoconferencing Cookbook from the now inactive ViDe group.

Microsoft Research created ConferenceXP, a software-based videoconferencing technology. ConferenceXP is open source software. Much ConferenceXP development is happening at the University of Washington Center for Collaborative Technologies.

The WIDE project in Japan has developed DVTS (Digital Video (DV) over IP). There are standard definition and high definition versions of DVTS. DVTS requires high bandwidth - 20 Mbps.

iHDTV is a software system for the transmission of uncompressed high definition television over IP. iHDTV requires very high bandwidth - 1.5 Gbps per channel for 3 channels.