Chapter 19:
Managing Video and Audio Conferencing Equipment

Overview

Videoconferencing will become a necessity in the near future.  This chapter discusses the primary factors to consider when selecting video and audio conference equipment.  It also covers the main features and offers suggestions on additional factors such as equipment room design and ease of operation in affecting how equipment is accepted. 

Video Standards

·        Videoconferencing can be conducted over analog or digital facilities
·        Analog conferencing is of the highest quality because video cameras and monitors are inherently analog devices
·        A majority of conference calls are held over long distances which precludes the use of analog facilities; therefore the analog video signal must be digitized and compressed
·        Video compression/decompression devices can compress a signal down to use only one or two digital voice channels, but the picture quality is then compromised

Videoconferencing Equipment

·        Videoconferencing equipment consists of the codec, monitor, camera, audio, and control systems
·        For multipoint conferences a multipoint control unit (MCU) may be used
·        Dual monitors are desirable in a videoconference because they can show both the far and near ends simultaneously
·        A desktop videoconferencing unit can be used and it runs on a PC that has a camera mounted on the unit

Codecs

·        Codecs are the heart of the system and contain most of its operational intelligence
·        When purchasing and comparing codecs, look at the ability to handle motion at various bandwidths
·        Try to participate in an actual videoconference as opposed to a canned demonstration

Camera Systems

·        Camera systems are equipped for full remote control of pan, tilt, and zoom
·        Most system have multiple presets so that the conference coordinator can switch to different targets without panning
·        Consider other video sources as well as the cameras
·        Most conference rooms are equipped with a VCR for recording conferences and playing prerecorded tapes

Monitors

·        The quality and size of monitors needed depends on the size of the conference room and the number of participants
·        Twenty-one inch monitors are acceptable for three to five people
·        Twenty-seven inch monitors are good for six to eight people
·        For a larger group of people, a 35-inch monitor or projection unit is best

Control System

·        All videoconferencing systems have a control unit for switching video sources, remotely controlling the camera, controlling the monitor, and setting up calls
·        Sometimes videoconference users are intimidated by the control unit
·        PC-based systems have an advantage because they have icons and mouse movement which are familiar to most people

Audio System

·        The general belief is that audio quality is the most important part of the conference
·        Microphones should be strategically placed so that all conferees can be heard
·        Speakers must also cover the conference room
·        Greater bandwidth improves audio at the expense of picture quality, but the degradation is unimportant when six or more digital channels are used for the conference

Multipoint Conferences

·        Two-point conferences are easy to set up and use, but multipoint conferences require the addition of a multipoint control unit (MCU)
·        Generally conferences use common carrier facilities.  The carrier provides a telephone number that each person can dial to join the conference
·        The MCU is assigned to a site by one of three methods:
·        Control by the conference chair
·        Rotation among sites
·        Voice activation, which is the most common

Meeting Rooms

·        When selecting a videoconference room location consider the following:
·        The location should be quiet and not subject to interruption
·        Lighting should be soft and subdued
·        The colors should be muted, but blue tones are good
·        The room should be acoustically treated with tile and drapes to eliminate echoes

Network Requirements For Videoconferencing

State-of-the-art videoconferencing requires at least two 56/64Kb/s digital channels, the more bandwidth the better the conference quality.  This section discusses the alternatives for obtaining bandwidth and the pros and cons of each.

Switched 56

·        Switched 56 service is the digital equivalent of an ordinary dial-up voice channel
·        A switched 56 line from the LEC can connect to any IXC that has switched 56 access to the LEC
·        This is the preferable connection if you are conferencing with other companies who may be using a different IXC, or if the other end uses ISDN

ISDN

·        ISDN is the ideal medium for dial-up videoconferencing
·        ISDN makes video set-up extremely easy
·        ISDN provides two 64-Kb/s bearer channels plus a 16-Kb/s signaling channel for setting up and controlling the call outside the voice band
·        Most videoconferences require at least six ISDN B channels or 384 Kb/s of bandwidth for satisfactory quality

Inverse Multiplexing

·        An inverse multiplexer is a device that combines multiple 56 or 64-Kb/s circuits into a single bit stream of higher bandwidth
·        It is used to improve video quality
·        Because circuits take different paths as they are dialed up, an inverse multiplexer must synchronize the individual channels by holding frames, and not sending them to the codec until all channels have arrived

Connecting Through a PBX

·        PBXs provide two methods of connecting a videoconference
·        Large PBXs support line-side basic rate ISDN (BRI) ports
·        Connection of a data module to a digital port on the PBX
·        Connection through the PBX offers several advantages
·        The PBX eliminates the need for BRI or switched 56 connections
·        The PBX allocates bandwidth from the PRI to videoconferencing as necessary

Dedicated Channel

·        For frequent videoconferencing between two companies connected by a T-1, a portion of the T-1 can be dedicated to video service by means of add-drop muliplexers
·        This method links conference rooms directly with a channel that is always available
·        A disadvantage of the add-drop multiplexer is that bandwidth isn’t available for other purposes when video is idle
·        Also, it must be reconfigured to change the amount of bandwidth allocated to video if the previous bandwidth isn’t required for each conference

Videoconferencing Administration

·        Videoconference administration does not take a great deal of time, however someone must be responsible for the system
·        Establish ground rules that top management supports
·        Users should understand when it is appropriate to use videoconferencing in stead of travel
·        Give users instructions that deal with common issues, like scheduling the conference room, and how to use the equipment properly, etc.

Audio Conferencing

Until videoconferencing equipment becomes widespread, many companies will continue to rely on audio conference equipment.

Conference Bridges

·        When conference calling volume increases a conference bridge in the PBX can be used to maintain an acceptable transmission level
·        Conference bridges are usually connected to the PBX through T-1 connections
·        Companies that make a lot of audio conference calls may need several bridges, which are monitored by a group of conference operators

Conferencing System Selection Considerations

There are many decisions to make when acquiring conferencing equipment.  Many companies begin with the objective of reducing travel costs but find that network costs have risen significantly.  Below are some things to consider when selecting videoconferencing equipment.

Videoconferencing Selection Criteria

·        Videoconferencing equipment can be separated into three categories
·        Desktop video – is not effective for group conferencing
·        Rollabout units – are normally intended for small conferences, and have only one monitor
·        Fixed videoconferencing equipment – is the most desirable
·        Here are some general questions to ask yourself and vendors in selecting videoconferencing equipment
·        What facilities will you use
·        Will a PBX be used
·        How do codecs connect
·        Is the system easy to configure and use
·        Does the system interface BRI lines directly or is an inverse multiplexer required
·        What is the process for adding users and dropping them from the conference
·        Can the equipment support audio-only conferees

Selecting Audio Conferencing Equipment

When audio conferencing requires more than six parties an external bridge is required.  The frequency that it is used determines whether a conferencing service is more economical than owning and operating your own bridge.  Below are some suggested questions to investigate in purchasing a bridge.

·        Can the requirement be satisfied with dial-out service or is meet-me conference required
·        How are conference time and channel slots divided and reserved
·        How are participants identified as they enter and leave the conference
·        Is the bridge a stand-alone device or does it connect through the PBX
·        How much manual attention is needed to reserve conference slots
·        What is the process for extending a conference that is overrunning its allocated time
·        What kind of usage statistics does the system provide