Definitions for Videoconferencing Multipoint Control Units (MCUs)

The Videoconferencing MCU module provides in depth coverage of the multipoint bridging systems (or MCUs) that are generally required to facilitate multipoint videoconferencing meetings. Enterprise customers can purchase this equipment and then utilize it along with their video endpoints to handle their own videoconferencing services internally, running over their own network facilities (or over a network offered by a service provider). The availability of these systems gives enterprise users the option of handling their own multipoint video meetings rather than utilizing a videoconferencing service provider (and paying various usage fees) for these capabilities.

Videoconferencing MCU systems are designed to support varying numbers of point-to-point and multipoint videoconferencing sessions connecting individuals (using Desktop/Personal or Executive video systems) and Room/Group video locations. Most of the systems covered in the database are open platform systems supporting traditional videoconferencing endpoints from a variety of vendors (so long as they are standards-based systems), but some are also proprietary in nature (supporting only a particular vendor’s video endpoints, unless additional equipment is connected. Some of the MCUs support only standard definition videoconferencing, while others support both standard and high definition videoconferencing. Some of the systems also support the connection of high-end video telepresence systems.

T3i Group’s comparative database module provides detailed information on each vendor’s individual product offerings so all products can be viewed and compared on an equal footing. Each module includes approximately 35 fields of information, each of which is defined as follows:

Company Name: Provides the name of the videoconferencing MCU product vendor

Headquarters Location: Lists the city and state where the vendor’s headquarters are located

Main Telephone Number: The primary telephone number at the vendor’s headquarters location

Internet Address: The vendor’s web site address

Product Name: The model name for each of the vendors’ products being covered

Product Introduction Date: The date that the vendor first introduced or first started shipping the product

Type of Equipment: Describes the particular type of equipment being offered (usually Video MCU) and also states if it is a proprietary type system

Date Information Verified: The actual date when the product information was last checked and verified to be correct and current

Number of Video Ports: states the total number of video ports supported on the system

Number of Audio Ports: states the total number of audio ports supported on the system

Number of Concurrent Meetings: states the maximum number of concurrent (or simultaneous) videoconferencing meetings that can be supported on the system

Number of Participants per Meeting: states the maximum number of video endpoints that can participate in one meeting

Bandwidths Supported: May state the bandwidth (or bandwidth range) supported per video channel by the product for either or both IP/ISDN connectivity

Reservationless/On Demand Meetings: If this capability is supported then users can set up ad hoc meetings without prior reservations or schedules; the meeting organizer (or host) just needs to inform the other attendees to dial in to a particular location

Reserved/Scheduled Meetings: If this capability is supported then users can schedule (or reserve) meeting facilities in advance (and typically be allowed to set up schedule for recurring meetings), advising meeting attendees to dial in to a particular location at some point in the future

Dial-in Service: this capability allows users to dial in to a central location to participate in a videoconference

Dial-out Service: indicates whether or not the user (typically the meeting host) or an operator can dial-out to add a meeting participant to the conference session

Audio Standards Supported: Lists the audio standards (as defined by the International Telecommunications Union (ITU)) supported by each product, along with the audio range.

G.711-a 56/64Kbps bit stream for 3.4KHz audio

G.722-a 48/56/64Kbps bit stream for 7KHz audio

G.722.1-a 24/32Kbps bit stream for 7KHz audio

G.722.1 Annex C-the ITU’s adoption of Polycom’s Siren 14-14KHz audio

G.723.1-a 5.3/6.4Kbps bit stream for 3.4KHz audio

G.728-a 16Kbps bit stream for 3.4KHz audio

G.729-an 8Kbps bit stream for 3.4KHz audio

AAC-LD-MPEG2 Advanced Audio Coding-Low Delay format for 7KHz or 14Khz audio; also MPRG4 AAC-LD for 20KHz audio (CD quality)

Audio range is stated as 3.4KHz, 7KHz, 14KHz, 16KHz, 20KHz, etc.

The user should keep in mind that typical human hearing range is from 20Hz to 20KHz; therefore a videoconferencing system supporting audio capability below 20Khz will provide something less than the full available range that the human ear can detect. Also keep in mind that typical telephone quality audio is at 3.4KHz, while CD quality audio is at 20Khz.

Video Standards Supported: To begin, there are three high level, umbrella standards issued by the ITU for videoconferencing. These are the H.320, H.323 and H.324 standards, and they are broadly defined as follows:

H.320 – the public switched telephone network (PSTN) standard for video over ISDN (BRI or PRI), and also applies to dedicated network connections such as T1 and satellite based services

H.323 – the standard for video over a LAN or IP network

H.324 – the standard for transmission over Plain Old Telephone Services (POTS), or audio telephony networks

Under these umbrella standards are several individual standards, each of which addresses various issues related to communications and video transmission, and includes the following:

H.221 – Under the H.320 umbrella, defines the transmission frame structure for teleservices from 56/64Kbps to 2 Mbps

H.223 – Multiplexing protocol for low bit rate multimedia connections, such as transfer of a combination of digital voice/audio, digital video/image, and data information over a single communications link

H.224 – Real time control protocol for simplex (one-way) use of a data channel using H.221 (for applications like far end camera control)

H.225 – Multiplexing transmission formats for media stream packetization and synchronization on a non-guaranteed QoS LAN

H.230 – Under H.320, for controlling synchronization of video frames

H.231 – Multipoint Control Unit (MCU) to bridge 3 or more conferencing systems at rates to 2Mbps

H.241 – Defines extended video procedures and control signals for multimedia terminals

H.242 – Under H.320, defines protocols for dall set up disconnect at rates up to 2Mbps

H.243 – Under H.320, defines control procedures and protocols for MCU call set up at rates up to 2Mbps

H.244 – Deals with H.221 bonding, or the aggregation of multiple 56/64Kbps channels

H.245 – Under H.323, relates to control of multimedia communications

H.261 – Video codec for audiovisual services at px64Kbps (supporting QCIF/CIF resolutions); defines how the picture information is compressed and coded for transmission over low bandwidth networks

H.261 Annex D – Protocol for transferring high quality still images at 4CIF resolution

H.263 – Video coding for low bit rate communications, designed for lower transmission rates (at 64Kbps to 128Kbps)

H.263+/++ - Represent two higher levels of the H.263 standard that include improved encoding efficiency and improvements against data loss during transmission

H.264 – A video codec standard that greatly improved image quality at significantly reduced bandwidths; this standard effectively made it possible to transmit the same quality video at half the bandwidth (as compared to systems that did not support the H.264 standard)

H.281 – Far end camera control protocol for videoconferences using H.224

H.331 – For broadcast mode videoconferencing

H.350 – Relates to storing and retrieving information from enterprise directories (also referred to as LDAP-Lightweight Directory Access Protocol); on systems supporting this protocol it is possible to link to existing corporate contact directories to set up videoconference calls, making it easier for the users

It should be noted that the comparative database modules list all of the standards that appear in the available literature for each vendor’s product (or for which the vendor has notified T3i Group of their support for that standard). There may, however, be some products listed that support more standards than are actually shown in the database (since some vendors do not see the point of listing each and every standard supported on their product, but instead mention only those standards that are of major significance).

Data Standards Supported: The data standards that are covered under this heading include:

H.239 – Endpoints that support H.239 can receive and transmit multiple, separate media streams, usually for voice, video and data collaboration

T.120 – A family of standards that define the protocols for data collaboration (such as file transfer, still image transfer, shared whiteboarding, etc.)

T.140 – Protocol for multimedia application text conversion (online chat) over an IP network, used by both H.323 and SIP systems

Additionally there are various encryption standards that are covered in the next attribute field of the database.

Encryption: There are a few key standards that relate to data encryption designed to help secure the multimedia conference sessions, using Advanced Encryption Standard (AES) based offerings, as adopted by the ITU, as follows

H.233 – The ITU’s data encryption standard for real time multimedia (applicable to H.320, H.323, and H.324)

H.234 – Encryption key management and authentication system for audiovisual services used by H.320 devices

H.235 – Security and encryption for H.323 and other H.245 based multimedia terminals

Video Resolutions Supported: Video resolution is a measure of image quality and clarity. The higher the resolution, the better the quality and clarity. Video resolution is measured as the number of pixels across times the number of pixels high (where pixels are individual colored dots that are used to form the images presented on screen). While higher numbers (and therefore higher resolutions) mean better pictures, they also mean more memory/bandwidth to store and transmit the information. In some cases there may also be tradeoffs in maximum frame rate (the speed at which the video images are refreshed expressed as frames per second or fps) and the maximum resolution. As an example, standard definition (SD) analog TV offers 480i resolution (at 720x480 pixels) running at 30fps; extended definition (ED) TV offers480p resolution (at 720x480 pixels) also running at 30fps; high definition TV offers 720p resolution (at 1280x720 pixels) and ultrahigh definition (HD) TV offers 1080p resolution (at 1280x1080, 1440x1080, or 1920x1080 pixels). The list of video resolutions offered and supported on the different systems consists of the following (which includes resolution levels applicable to still image/graphic files):

QSIF – 180x120

SIF – 352x240

4SIF – 704x480

QCIF – 176x144

CIF (or FCIF) – 352x288 (about the same as VHS quality video)

4CIF – 704x576 (close to broadcast or DVD quality video)

QVGA – 320x240

Half VGA – 640x240

W288p – 512x288

400p – 528x400

W448p – 576x448

VGA – 640x480

W576p – 1024x576

SXGA – 1280x1024

XGA – 1024x768 (typical PC/laptop display)

480i/p – 720x480

720p – 1280x720 (high definition)

1080p – 1920x1080, 1280x1080, or 1440x1080 (ultra high definition)

Video Frame Rates Supported: Defines the speed at which the video image is displayed, so 30frames per second (30fps) means that 30 separate frames are changed every second. As a basis to understand this term, standard definition TV typically runs at 30fps while high definition TV typically runs at 50/60 fields per second. The higher the frame rate the smoother the video image. Lower frame rates could result in less fluent video movement and very low frame rates could result in a rather choppy appearing video. Typical frame rate offerings include 15fps, 30fps, and 50/60 fields per second.

Network Interfaces: This section identifies the basic type of network connections or interface options supported by the video MCU systems, generally listed as IP (which can be IP, LAN, DSL or cable modem), SIP (session initiation protocol), ISDN (which could be BRI or PRI, or both), T1/E1, and V.35 (for a private line network)

Transcoding/Speed Matching: in many cases (either on a point to point or a multipoint video call) different endpoints will be accessing the network at different bandwidths; these systems can all be accommodated on videoconferencing MCUs that support speed matching or transcoding, which allows different users to access the conference at different connection speeds, with the conference experience being maximized for each

Continuous Presence: Support of continuous presence allows a user in a multisite videoconference call to be able to see the other participants in the meeting at the same time – on multiple monitors or using multiple display windows on a single monitor, and it is accomplished by transmitting multiple simultaneous images

Data Sharing/Collaboration: Indicates whether or not the videoconferencing system supports the sharing of data files or presentations (such as spreadsheets or other documents) on screen during the video conference

Latency: latency represents a delay in the transmission of data between endpoints; a misalignment of audio and video of less than 20 milliseconds (ms) is generallyconsidered imperceptible; however, as the time approaches 50 ms, some viewers will begin to notice that the audio/video signals are not completely synchronized; therefore, systems with the lowest latency offer the highest quality experience

Microsoft Outlook Integration: allows users to access, schedule and set up videoconference meetings using Microsoft Outlook, as well as get meeting reminder notifications

Lotus Notes Integration: allows users to access, schedule and set up videoconference meetings using Lotus Notes

High Definition: Identifies whether or not a videoconferencing MCU system can be operated in true high definition (HD) mode, supporting video endpoints running at 720p or 1080p resolution

Multilingual: Defines whether or not the system supports multilingual services, such as for the user interface and call setup screens (which could be on the users monitor or accessed via an online web portal

Record and Playback: States whether or not the videoconferencing MCU system supports a video recording capability which would allow users to record videoconference sessions, store (or archive) them, and then access them at a later time for playback

Telepresence: states whether or not the system supports the connection of high-end video telepresence systems

Management/Adminstrative Interface: Provides information on the type of interface offered on the system for call setup and control, scheduling, and other management/administrative functions; typical interface offerings include web-based tools

Additional Capabilities: This field is used to list any additional capabilities or optional accessories that may be offered on the particular videoconferencing MCU system (that have not been addressed in any of the previous data fields)

Pricing: States the basic list price (in US$) for the videoconferencing MCU system and its primary components and options; where available, typical discounts and/or street prices are also shown

Strengths: List the strengths of the videoconferencing MCU system and/or the vendor as compared to other like products available in the market

Weaknesses: List the weaknesses of the videoconferencing MCU system and/or the vendor as compared to other like products available in the market