Technical papers about videoconferencing systems

Below are several technical papers that look at Videoconferencing in greater detail. They try to explain the technicalities of each subject and wherever possible, discuss the pros and cons of various systems as well as providing guidance in their selection.

How to choose a Videoconferencing system?

Well, you could just buy the same as the person you want to have a conference with. However, this might not be the best solution for you. There are essentially two types of systems, proprietary and standards based. If the person you want to have a conference with uses a proprietary system, then you must buy the same as them, or persuade them to buy something different. This paper concentrates on choosing a H.323 or H.320 standards based Video Conferencing systems.

Videoconferencing Standards and Terminology.

There is an ever increasing number of standards, terminologies and buzz-words used within the videoconferencing industry that can make understanding what is both available and compatible a minefield. We have the H.300's, the G.700's, the T.120's and now the H.460's, not to mention ISDN; LAN, WAN, ADSL, VPN, POTS and Cloud all mixed with NTSC, PAL, HD, 1080p, 720p, CIF, H.264, G.722.1C, AVC and SVC. This document explains how they relate to the various communications infrastructures of videoconferencing and how they relate to each other.

H.323 Gatekeepers and Endpoints.

The purpose of this paper is to explain in detail the function of one of the main H.323 network components, namely the H.323 Gatekeeper, when used in conjunction with H.323 standards based Videoconferencing systems. It is intended to provide an overview of these products and broaden their understanding by giving brief examples of their usage.

H.323 (E.164) Numbers and Dial Plan used by Gatekeepers etc.

The purpose of this paper is to explain in greater detail the use of H.323 Dial Plans and Service Codes used by Gatekeepers, Gateways, MCUs and Endpoints in initiating services used in Video Conferences. It discusses the H.323 User Number (E.164 number) and explains how it is used by the Gatekeeper to identify the end-user (Endpoint) being called. The concept of Service Codes for Gateways and MCUs is then introduced and how these are used in conjunction with the Gatekeeper and H.323 User Number to initiate more complex conferences. Finally, we introduce the concept of IP Video Telephony functions and how the whole H.323 infrastructure can be managed by ClearOne's Central (formerly VCON's Media Xchange Manger™, MXM).

IP Ports and Protocols used by H.323/SIP Devices.

The purpose of this paper is to explain in greater detail the IP Ports and Protocols used by H.323 and SIP devices during Video Conferences. This is essential information if there are endpoints that are protected by a Firewall. It lists the IP Port and the Protocol used for various H.323 and SIP functions along with the H.323 and SIP devices that may use the specific IP Port.

H.460 NAT/Firewall Traversal and SIP Registrars.

The purpose of this paper is to explain H.460 NAT/Firewall Traversal and SIP Registrars in greater detail. It discusses general Firewall, IP Port and Protocol issues, covers how NAT enhances basic security and then shows examples of H.460 NAT/Firewall Traversal solutions and SIP Registrars.

H.239 BFCP, RDP and VbSS Data Sharing within Video Conferencing.

The purpose of this paper is to explain H.239 Data Sharing in greater detail and how it differs from the older T.120 standard developed and put forward by Microsoft and previously used via NetMeeting. For Data Sharing (desktop application), the ITU initially approved the T.120 standard, which allowed data sharing and true collaboration to the extent that another endpoint could actually take control of the shared application. However, for H.323 standards compliant videoconferencing systems, T.120 has gone (NetMeeting last supported in Windows XP) and been replaced by the H.239 standard - sometimes referred to as Dual Video standard. H.239 defines how additional media channels are used and managed by H.323 systems.

However, Skype for Business (Lync) clients use the Microsoft proprietary Remote Desktop Protocol (RDP) for application sharing. This allows true collaboration so another Skype for Business (Lync) client can be granted and take control of the shared application. Unfortunately, H.323 (and SIP) systems don't understand or use RDP, so cannot directly data or application share with Skype for Business clients. This paper explains how it can be done.

Cloud or On-Premise Videoconferencing systems?

This papers discusses the Pros and Cons of using Cloud or On-Premise Videoconferencing systems. Not that long ago, virtually all videoconferencing systems and their associated infrastructure - including that required to host a multipoint conference - where located in-house (On-Premise). They would typically be bought outright as a capital expenditure and supported internally by company staff. This effectively limited the deployment and uptake of videoconferencing to larger organisations. But these restrictions have now been removed with the advent of Cloud based solutions which are charged as a fully supported service on an annual subscription. Cloud solutions are available to any size of organisation and you can use any common device (BYOD).

H.221 Framing used in ISDN Conferences.

The purpose of this paper is to explain in greater detail the H.221 framing structure used in ISDN based H.320 Video Conferences. It explains the framing structures used in 2B calls at 128kbps; the differences between 6B and BONDED calls at 384kbps and how 56kbps Channels communicate with 64kbps Restricted Channels.