Toolkits

Videoconferencing Endpoints - Technology Overview

Many people consider telemedicine to be synonymous with video teleconferencing, or VTC.  Indeed, VTC has been used in an incredibly diverse range of clinical settings for decades.  Many states and insurance providers will only reimburse for telemedicine if consultations take place over a videoconference, further reinforcing the videoconferencing position as a fundamental part of the telemedicine landscape.

Videoconferencing can potentially involve many complex, interconnected parts.  Many people who use VTC products are not fully aware of what happens behind the scenes, instead looking at videoconferencing as a camera and monitor.  This portion of the toolkit aims to look at the CODECs, monitors, and cameras that make up the user-facing endpoints of VTC systems.  Additional information on bridges and software systems can be found elsewhere, in the Videoconferencing Bridges and Desktop Video Applications toolkits.

What is an Endpoint?

Many of the people who use videoconferencing systems – physicians, nurses, patients, and administrators – may not be aware all of the components used in a typical session, but have quite possibly heard the term “endpoint” used in discussions.  Technically, the endpoint is a uniquely-addressable point on a network that can engage in a call with another videoconferencing endpoint.  More broadly speaking, an endpoint is the CODEC, camera, and monitor used for videoconferencing. 

The CODEC is the hardware that is used to code and decode audiovisual data sent in a videoconferencing session.  It essentially serves as the brains of a videoconferencing endpoint, taking video data from the camera, transmitting a video signal to the monitor, taking in audio and video information from peripheral devices, and communicating with either core infrastructure or other endpoints.  The CODEC may come in a variety of shapes and sizes, ranging from large PC-like boxes to small, all-in-one units.

The cameras used in videoconferencing connect to the CODECs, providing the video image that is sent to other systems and to the local monitor (also referred to as “near”).  Camera designs and functionality vary, though they can broadly be placed in two categories – fixed and pan-tilt-zoom (PTZ).  A fixed camera cannot be moved without physically changing the position of the device by hand, and are often built into monitors or all-in-one desktop units.  These cameras tend to have a fairly wide angle lens, with some devices providing various levels of zoom and magnification.  PTZ cameras can be moved through use of an electronic controller, and many of them allow a user at the remote site, or “far” end, to change where the camera is pointed.

Monitors vary widely in size, resolution, and design.  Videoconferencing equipment manufacturers may include their own monitors in some product lines, while others will support the use of external, third-party monitors.  The choice of monitor will often be driven by manufacturer recommendations, room and/or cart size, and budget.

The Types

Endpoints come in a variety of sizes and shapes, with each fitting a different intended audience and use.  Manufacturers may use slightly different terms to describe their endpoints, or may use the same terms with different meanings and definitions.  Below are a broad set of descriptions of the types of endpoints.

Mobile and Software

Mobile products, such as tablets and cell phones, utilize a software system that communicates with other videoconferencing infrastructure to manage calls with standard hardware-based conferencing platforms.  This software may be a variation of other software-based packages from the vendors, which operate on a similar basis.  For more information on the software systems, please refer to the Desktop Video Applications toolkit.

Video Phone

A variety of products can fit into a broad “video phone” category.  As opposed to smartphones and mobile PCs that use a software application, these video phones are small, purpose-built products that support phone calls and video conferences.  They are characterized by relatively small screens and cameras.  The cameras are not capable of pan or tilt functionality, though they may support a basic or digital zoom feature.  Additionally, these products typically lack additional inputs for other video or serial data devices.

Stand-Alone Desktop

The desktop units (not to be confused with desktop software) are all-in-one products that provide a monitor, camera, and built-in CODEC for use as a videoconferencing.  Screen size varies with these products, though they are generally comparable to video phone screens.  The monitors often have the capacity to serve as a secondary monitor, allowing a desktop VTC unit to serve as both a computer monitor and as a videoconferencing platform.  The cameras are not capable of pan or tilt functionality, though they may support a basic or digital zoom feature.  Depending on the model and manufacturer, there may be options to connect either additional video products or serial data devices.

Room Unit – Cart or Mounted

The platform that often jumps to peoples’ minds when thinking about videoconferencing is the room-based platform.  The CODEC and camera may be sold separately from the monitor, or may be sold as an all-in-one unit with a built-in pan-tilt-zoom camera.  These models will typically have some variety of additional input offered, though the exact inputs vary by manufacturer.

Depending on the model and organizational preferences, these units can often be mounted in many different ways, with common options being to mount the devices to a wall, a stationary platform or pedestal, or a mobile cart.  The carts can come in a variety of formats, with additional features such as built-in Uninterruptible Power Supplies, movable writing surfaces, articulating screen mounts, and attachment points for other peripherals.

Robotic and Remote-Controlled Platforms

Much interest has been generated by motorized, robotic platforms for videoconferencing.  These systems provide the ability to remotely control a mobile videoconferencing platform, allowing a distant operator to navigate through hallways and rooms while maintaining a live video connection.
Interfaces for “driving” these platforms vary from web-based controllers to PC-based software applications with dedicated hardware controllers.  Web-based controllers provide freedom from a dedicated controlling station, while PC-based systems with hardware controllers allow for a more tactile controlling experience.

It is important to note that these systems, which use either a software or web-based interface for controlling the robotic platform, do not work with standards-based systems.  There is not yet a standardized method of sending control information from a room-based videoconferencing endpoint to a mobile, robotic platform.  This means that robotic platforms will not work with existing infrastructure, nor will they work with other organizations’ infrastructures unless they are also using the same robotic platform or controlling systems.

Telepresence

Manufacturers, vendors, and media outlets use telepresence in different ways.  Some manufacturers have used the term telepresence to describe a high-definition CODEC attached to a large monitor, while others have used it to describe platforms with wheels.  An article on a technology blog referred to a modified Roomba with a video camera as providing “telepresence” as it allowed a videoconferencing platform to be “present” as the user moved around. 

For the sake of clarity here, telepresence is being defined as the use of very high-definition systems that are often configured to be viewed in such a way that the person is felt to be “present” in the room, often with the subject largely filling the frame.  These telepresence systems often include multiple monitors and cameras in a single videoconferencing installation to provide a realistic virtual meeting space.  These installations are often centered around purpose-built rooms, and can connect with other VTC platforms to create impressive, bandwidth-intensive conference centers.  These systems allow the sharing of content and provide various video inputs.

All videoconferencing could, technically, be defined as providing telepresence.  However, the industry is moving in a direction that increasingly emphasizes larger, more elaborate installation.  As the terminology is still being defined, this will likely be an area of some confusion in the short-term.

Infrastructure

While this toolkit focuses largely on the endpoints used in videoconferencing, it is important to make note of the other hardware that is often associated with videoconferencing.  This additional hardware is often mandatory for any serious videoconferencing deployment.  If managing this infrastructure within an organization is not feasible, options do exist for third-party hosting and support.

Gatekeeper

The functions performed by a gatekeeper will vary by model, but can generally be broken down into a handful of categories – address translation, admission control, bandwidth control, user authentication, and zone management.  Address translations allow an endpoint to be given a more user-friendly alias, with internal addressing and routing handled by the gatekeeper whenever another endpoint tries to dial the alias.  Admission control and bandwidth control limit how many simultaneous calls can take place, and manage bandwidth allocation.  Zones are associated with a single gatekeeper; zone management can help control devices registered in a single zone, as well as how the endpoints communicate with other zones.

Multipoint Conferencing Unit (MCU)

The MCU supports connecting multiple endpoints in a single call.  Also referred to as “bridges”, these devices are typically required to allow more than two endpoints to join in a conference call.  Note that some manufacturers do provide limited bridging capabilities in their endpoints, which can allow for a handful of simultaneous connections if one of the endpoints supports this functionality.

Gateway

Despite the fact that standardization has been widely adopted by videoconferencing manufacturers, getting devices from different manufacturers to communicate with one another can be a challenge.  Standards have changed, new standards have been introduced, and optional features of some standards have been implemented in different ways between manufacturers.  Gateways help manage these communication difficulties, connecting and translating (transcoding) between endpoints, MCUs, and other network devices.  

Proxies

Videoconferencing often takes place across the boundaries of at least one network, with connections needing to occur between different organizations or between internet-based endpoints and a single organization.  There are certain challenges inherent in connecting these various networks.  Proxies are designed to help mitigate these problems, sitting on the “edge” of a network and managing communication with endpoints, gateways, and gatekeepers.

Connecting the Pieces

There are many different components that can come together in a videoconferencing system, including internal infrastructure, medical equipment, legacy systems, products from diverse manufacturers, and other videoconferencing networks.  

Medical Devices and Peripherals

Telemedicine services often use medical devices in conjunction with videoconferencing in order to provide relevant data to the consulting site.  Connectivity options for these devices vary widely, ranging from standard- and high-definition video, 3.5 mm audio, serial, USB, and Bluetooth.  Not all of these inputs are supported on videoconferencing endpoints.

Video

Most videoconferencing systems will support the use of an external standard-definition video source, typically through either an S-Video or Composite Video connector.  These inputs can then be set as the primary source while conferencing, allowing the video stream to be sent to the far site.  Common imaging devices include patient exam cameras, camcorders, digital cameras with video outputs, and otoscopes.

High-definition video is typically sent through an HDMI, HDMI-mini, or DVI connector. While there is a rise in the number of videoconferencing endpoints that support high-definition video, not all manufacturers support high-definition inputs.  This should become a more common feature as both peripheral and endpoint manufacturers continue to switch to high definition.  Note that older videoconferencing systems and legacy endpoints may not support this feature.

Audio

Audio connectivity is currently fairly limited when linking medical devices to videoconferencing endpoints.  VTC endpoints may support XLR, RCA, Bluetooth, or 3.5 mm inputs, but the medical devices typically will support only 3.5 mm cables.  Note that some stethoscopes use a 1.5-to-3.5mm cable for connecting to other devices.  Connecting to videoconferencing endpoints requires either a 3.5 mm cable, if available, or a 3.5mm-to-RCA adapter.

Videoconferencing endpoints may support other audio devices through their additional inputs.  There are a wide assortment of microphone options for videoconferencing.  These microphones can have different performance characteristics, with each one suited for different environments and settings.

Sounds sent through an endpoint’s various audio inputs will be subject to the same encoding and decoding that the rest of the audio goes through (namely, the G.7xx standards).  As such, these sounds are prone to some of the same issues of latency, jitter, and compression.  Using other methods of transmission, such as serial data for some stethoscopes, may produce a more satisfactory result.

Serial Data – RS232

At this time there is only one category of devices commonly used in telemedicine that rely on serial data transfer over VTC – electronic stethoscopes.  Even within the category of electronic stethoscopes there are only two manufacturers producing devices that perform this function (though some of these have been rebranded and sold through other outlets).

These particular electronic stethoscopes work by digitizing the audio and converting it to a serialized stream of data, which is then sent to the videoconferencing endpoint.  The data is not compressed within the endpoint.  Upon transmission to the receiving site, the data is streamed to another electronic stethoscope device that decodes the serialized information and plays it back through the headphones.  This bypasses the compression that occurs through audio channels in the VTC endpoint.

Unfortunately, as mentioned in the standards section of this document, manufacturers have taken different approaches to transmitting serialized data.  This means that it is not possible to send a serialized stream from one manufacturer’s endpoint to the endpoint of a different manufacturer.  Further, serial inputs are not implemented by all manufacturers.

Other VTC Products

One of the advantages of using standards in the development of videoconferencing systems is that products from different manufacturers will work together, at least in theory.  Because of differences in how some standards are interpreted or implemented, some features may not work as well when connecting products from different manufacturers, if at all.

It is not uncommon to connect endpoints from one manufacturer to an MCU of another manufacturer.  Some products require that other manufacturers first connect to an intermediary gateway before connecting to their bridge.  Many manufacturers also support direct point-to-point calls between endpoints from other manufacturers without going through a bridge, assuming that network connectivity is available. 

Robots and Mobile Platforms

Much interest has been generated by various mobile or robotic platforms for videoconferencing.  These systems provide the ability to remotely control a mobile videoconferencing platform, allowing a distant operator to navigate through hallways and rooms while maintaining a live video connection.

It is important to note that these systems, which use either a software- or web-based interface for controlling the robotic platform, do not work with other standards-based systems.  There is not yet a standardized method of sending control information from a room-based videoconferencing endpoint to a mobile, robotic platform.  This means that robotic platforms will not work with existing infrastructure, nor will they work with other organizations’ infrastructures unless they are also using the same robotic platform or controlling systems.

Conclusion

Videoconferencing technology encompasses an enormous range of devices, standards, and possible challenges.  While standardization has done a lot to improve the ease with which networks and systems can be connected and managed, there still exists a sizeable difference between exactly how the pieces all fit together. 

Videoconferencing endpoints often need to work within these larger networks and systems.  While it may seem daunting to consider implementing a enterprise-wide videoconferencing system, these additional elements can help improve user experience, ease management issues, and ensure the ongoing success of a videoconferencing deployment.