Video conferencing relies on a series of standards and protocols for video encapsulation and session management. Encapsulation standards, for example, define how video and audio are captured, converted to digital format, transmitted between endpoints and decoded.
Video conferencing standards for signaling control session establishment, teardown and management. Session Initiation Protocol (SIP) is widely supported for video session management, although some older systems may rely on the H.323 protocol that predates the development of SIP. In addition, some vendors use proprietary approaches to build additional functionality into their video conferencing applications.
Encapsulation protocols digitize audio and video for transmission across data networks. For audio, the open source, royalty-free Opus codec has emerged as the most widely used encapsulation approach. Other popular audio codecs include SILK -- initially developed by Skype -- as well VoIP encapsulation standards, such as the International Telecommunication Union's (ITU) G.711/G.722/G.729 for voice, providing either uncompressed or compressed audio capture.
For video, popular codecs include ITU H.264, which has several variants, as well as the open source Advanced Video Coding codec. Additional video encapsulation options include Google's royalty-free open source VP9 and previous versions. H.264 is widely supported by video conferencing vendors, while VP9 is widely used in web browsers, like Google Chrome and Mozilla Firefox.
Vendors often use open source codecs to form the lowest common denominator for interoperability. They may then add further functionality, such as better support for lossy networks or integrated features, like chat and whiteboards, in their own way.
Web Real-Time Communications (WebRTC) is another widely supported technology to enable voice and video conferencing from within web browsers without the need for plugins.
It's worth noting that vendors often use open source codecs to form the lowest common denominator for interoperability. They may then add further functionality, such as better support for lossy networks or integrated features, like chat and whiteboards, in their own way.
What's new in video conferencing standards?
Newer video encapsulation standards include H.265 and AOMedia Video 1 (AV1) from the Alliance for Open Media. These codecs natively incorporate scalable video coding -- a technology capable of minimizing the visual impact of frames lost in transmission -- to use less bandwidth for high-definition video and offer better video quality and better support for video over lossy networks. Late in 2023, Cisco announced a new AI-based codec for Webex that supports high-definition audio and video in extremely lossy or low-bandwidth networks.
Licensing and competitive considerations drive variances in video codec support. H.264 and H.265 may require video conferencing vendors to pay royalty fees for use. VP8 and VP9 are royalty-free, but some competitors are reluctant to embrace these codecs because they're controlled by Google and do not support hardware optimization in Apple mobile devices. Vendors may not be willing to support other royalty-free codecs, such as AV1, due to lack of control and ability to differentiate.
At the same time, varying encapsulation approaches pose an obstacle for buyers wishing to integrate different products from different vendors or take advantage of WebRTC. Vendors continue to perceive competitive advantage toward offering a better-than-standard service, while they support baseline endpoint interoperability for well-defined video conferencing standards.
Integrating systems that use different video codecs requires deploying an on-premises multipoint control unit; bridging software platform, like Pexip; or gateway from a video conferencing software vendor that supports open standards-based endpoints. Any of these services typically provide transcoding between codecs but with additional cost and complexity.
Irwin Lazar is president and principal analyst at Metrigy, where he leads coverage on the digital workplace. His research focus includes unified communications, VoIP, video conferencing and team collaboration.
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