Definitions for Video Phones
The Video Phones module provides in depth coverage of the video phone equipment market, and expands coverage of traditional Desktop/Personal videoconferencing systems.
Desktop/Personal systems are designed to provide videoconferencing capabilities to individuals and are generally referred to as Desktop, Personal, or Executive systems. Several options exist for provisioning this type of service, including personal or desktop systems, integrated IP-PBX endpoints, software and web conferencing based products with video capabilities (software client type offerings for enterprise deployment for example), and videophones. The coverage in the T3i Group database includes traditional Desktop or Personal videoconferencing systems (hardware and software based) that can typically deployed to individual users throughout an organization, and now video phones as well, and will also exclude telepresence systems as these will be covered in a separate module.
T3i Group’s comparative database modules provide detailed information on each vendor’s individual product offerings so all products can be viewed and compared on an equal footing. Each module includes over 40 fields of information, each of which is defined as follows:
Company Name: Provides the name of the video phone product vendor
U.S. Headquarters Location: Lists the city and state where the vendor’s U.S. headquarters are located
Main Telephone Number: The primary telephone number at the vendor’s U.S. headquarters location
Internet Address: The vendor’s web site address
Product: 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 (such as Analog PSTN, IP, or ISDN compatible)
Date Information Verified: The actual date when the product information was last checked and verified to be correct and current
Geographic Coverage: States the coverage areas where the products are being sold (either directly by the vendor or through distribution channels), which could include North America, Central and Latin America, Europe, Africa and Mid East, and Asia-Pacific, or Global (which could encompass multiple or all regions)
Bandwidth Requirements: May state the bandwidth (or bandwidth range) supported (or required) by the product, or could state the minimal or optimal bandwidth requirements for that product
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.
Full Duplex Audio: Full duplex audio means that the video phone allows conference participants at multiple locations to speak at the same time and be heard at all locations. In systems that do not support full duplex audio, a person speaking at one location may override and cut off those speaking at other locations (as the audio can only flow in one direction at a time).
Video Standards: 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.239 – Endpoints that support H.239 can receive and transmit multiple, separate media streams, usually for voice, video and data collaboration
H.241 – Defines extended video procedures and control signals for multimedia terminals
H.242 – Under H.320, defines protocols for call 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:
In addition to the H.239 standard (previously included under Video Standards), which allows for separate data streams to support data collaboration, there are a couple of significant data standards that are covered under this heading, which are: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 followsH.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 Resolution: 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: 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 and 30fps.
Inputs/Outputs: Provides information on the audio, video and ancillary inputs/outputs supported by the videoconferencing system. Typical inputs would be provided for headsets, microphones, a PC or other device. Typical outputs would be provided for monitors/displays, audio speakers, or other device. Note that most video phones are sold as complete, fully integrated units consisting of the codec, camera, display, microphone and speakers and so may not have any additional inputs/outputs other than the network connection itself.
Network Interfaces: This section identifies the basic type of network connections or interface options supported by the video phones, generally listed as IP (which can be IP, LAN, DSL or cable modem), ISDN, and PSTN (for the analog telephone network)
Display/Monitor Information: Lists the size and type of monitor/display unit supported by the video phone; these products typically come as an integrated unit with a built-in display; however some units require (or offer the option of) connecting to an external display (generally a standard TV monitor)
Camera Information: Lists the type of camera provided with the product. Most video phones come as integrated or packaged units with the camera included, which may be a manual focus, auto focus, or fixed focus unit.
Camera Controls: Typical camera controls would be manual focus, auto focus, manual tilt, and optical/digital zoom
High Definition: Identifies whether or not a video phone product can be operated in true high definition (HD) mode, running at 720p or 1080p resolution
Data/File Sharing: Indicates whether or not the video phone supports the sharing of data files or presentations (such as spreadsheets or other documents) on screen during the video call; this application would generally require a PC or other device to be integrated into or connected to the video phone
Additional Data Window: For phones that do support Data/File Sharing, states whether or not the video phone’s main display is able open up a data/file sharing window for that purpose
Multipoint: Video phones primarily operate in point-to-point mode (with two sites directly connected to each other); however, some devices also support three-way conferencing (typically for audio calls).
SIP: States whether or not the video phone product supports the Session Initiation Protocol (SIP), which is used to provide presence indication, among other things
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, and it is accomplished by transmitting multiple simultaneous images. This is not a feature that is generally supported on video phone products at the present time.
Picture in Picture (PIP): States whether or not the video phone product supports the Picture-in-Picture feature that allows two (or more) images to be shown on a single display at the same time, one (or more) of which is usually shown as a small (inset) window
Split Screen: This capability is typically used on single monitor video phones so that the far end participant and a data presentation (for example) could both be seen at the same time
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); this is not to be confused with multilingual services that would provide language translation among multiple participants or other such services
Record and Playback: States whether or not the video phone product supports a video recording capability which would allow users to record the videoconference session, store (or archive) it, and then access it at a later time for playback
Audio Mute: States whether or not the video phone supports an audio mute capability so a user can temporarily mute the audio portion of a call
Video Mute/Privacy: States whether or not the video phone supports a video mute or video privacy capability, allowing the user to turn off or block the camera during a call
Speed Dial: states the video phones ability and capacity to support stored Speed Dial numbers, for quick access calling of frequently dialed numbers
Do Not Disturb: states whether or not the video phone offers a Do Not Disturb feature to block incoming calls (and possibly route them to a voice mail or video mail greeting)
Speakerphone: states whether or not the video phone is equipped with full handsfree speakerphone capabilities
User Interface: Provides information on the type of user interface offered on the system for call setup and control; typical user interface offerings include integrated keypads, onscreen menus, and touchscreens
Dimensions: Lists the physical dimensions of the video phone product
Additional Capabilities: This field is used to list any additional capabilities or optional accessories that may be offered on the particular video phone product (that have not been addressed in any of the previous data fields)
Pricing: States the basic list price (in US$) for the video phone product; where available, typical discounts and/or street prices are also shown
Strengths: List the strengths of the video phone product and/or the vendor as compared to other like products available in the market
Weaknesses: List the weaknesses of the video phone product and/or the vendor as compared to other like products available in the market