April 8, 2013

Delivering Video Interoperability

Multiple video standards and proprietary solutions are available, ranging from standard definition desktop solutions to immersive HD high definition room systems, and most are not interoperable. The growth and value of video conferencing has now been accepted; however, the interoperability issues still need to be addressed.

The Video Interoperability Problem

The issues for interoperability go far beyond codec differences. Video conferencing is a video call like a two party VoIP call. Multipoint calls/conferences are proportionally more common than a two party video calls. Video interoperability also must address these and other issues:

  • Call control and signaling (H.323 or SIP or ISDN H.320)
  • Bandwidth management
  • Call queuing
  • Hold and forwarding functions
  • Contact center operations
  • Wireless device compatibility
  • Legacy endpoint support

Standardizing Video Interoperability

Standards bodies are moving to deliver video interoperability. The Open Visual Communications Consortium (OVCC), is a group of vendors and service providers who endorse interoperability among multivendor video conferencing and collaboration systems. The OVCC members are developing technical and commercial interoperability specifications. They are basing their specifications on industry standards, best practices, and business approaches. These specifications define interconnection, addressing, signaling, interoperability, and service coordination among multivendor video systems. The specifications range from room-based systems using high definition and standard definition telepresence, to desktop clients, and mobile devices.


A big challenge to interoperability is that many video conference solutions on the market today contain some form of proprietary solution. Many video systems also require licenses to use the technology, so even if video endpoints can technically work together, licenses are required to interoperate legally.

A second challenge is that the endpoints (PC, tablet, cell phone, and dedicated video systems) are different, as is resolution quality (ranging from basic conferencing to HD telepresence), and these differences create inherent incompatibility.

A third challenge in deploying video conferencing is to deliver smooth and uninterruptible flow of audio-visual information, anytime and anywhere. Multimedia content, originally authored and compressed with a certain format, may need bandwidth adjustment and format conversion in order to allow access by receiving devices that are not uniform in their implementations. Video conferences can also involve data sharing (e.g. text and graphics) that the other endpoint cannot support.

Transcoding is required to make the content adaptive to the capabilities of different networks and endpoints.  Transcoding is the direct digital-to-digital data conversion. Video transcoding can happen in the cloud, in a premise-based network element, or within an endpoint device. Devices such as video gateways, session border controllers, or software applications can provide transcoding. 

A video transcoder can perform several additional functions. For example, the bandwidth required for a video connection can fluctuate due to traffic congestion, and a transcoder can provide adjustments in the bandwidth consumed without imposing additional functional requirements in the decoder. A video transcoder can also change the coding parameters of the compressed video, adjust spatial and temporal resolution, and modify the video content.  One drawback is that transcoding can reduce the video picture quality.

Endpoint Solutions

Endpoints, especially those that support applications, could contain multiple applications each supporting a different video conferencing technology. There are even free applications like Skype that support limited video conferencing. As the number of participants grows, the free application cannot support more than a few participants. The endpoint could also support proprietary solutions that are interoperable with dedicated video endpoints from the same vendor. 

Some endpoint solutions can support video calls and personal HD, but not telepresence room HD. The endpoint may also have limited picture quality. It is uncommon for endpoints to support multiple versions of video communications simultaneously on the same device.

Gateway Solutions

Video gateways (also referred to as conceptually as a black box) can translate one video stream into a different stream. This solution has mainly been implemented by service providers. Gateways can interconnect different types of media streams to create a transparent end-to-end path for voice, video, and data. These gateways are also available to enterprises to support their video conferencing needs. 

The earlier gateways connected an ISDN H.320 endpoint to an H.323 endpoint, but gateway products have matured to support H.323 to SIP endpoints. While this interoperability solution may be too complex for the average IT department to install and implement, a gateway would be most attractive to organizations that have or will have significant video conferencing traffic.

Cloud Solutions

A growing cloud based service for video conferencing is a solution with low capital cost. It is paid for on a usage basis. As a service, the IT department does not need the same level of expertise as would be required with a premise-based gateway solution. A cloud based service offers:

  • A system agnostic solution

  • Simple and easy to schedule connections 

  • Scalable in conference size 
  • Secure cloud controlled operation

The attractiveness of the cloud is that even small organizations can afford it. The cloud can also be used to federate with other external organizations for B2B voice and video communications.

WebRTC and Video Interoperability

While Web Real Time Communications (WebRTC) is still in its infancy it, initial WebRTC supports peer-to-peer video chat. Today, WebRTC video chat requires an HTML5 compliant browser (on the endpoints) and a compliant signaling server for call control. 

Draft standards call for WebRTC to support browser based multimedia sessions in the future so that any browser can establish multimedia calls directly without a separate app or plug-in. The voice codecs have been selected for this feature, but video codec standards are yet been defined. A non-proprietary, license free video codec will likely be selected to ensure interoperability. 


Connectivity between different video systems is not automatic, and many enterprises will be unable to easily support interoperability. Because solutions are limited, the enterprise may have to eliminate older video conferencing systems because of technology or license constraints.

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1 Comment

Also important is the UCI Forum, which is focused on addressing the challenges of interoperability between Unified Communications Solutions, both between device manufactures and UC vendors (e.g. webcams) and between different UC vendors. To date UCI Forum handled the issue of webcam interoperability as well as video coding interoperability (H.264 SVC). The next focus areas are video transport and signaling.

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