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Video conferencing standards and protocols are necessary to define common means for video encapsulation and session management. Encapsulation standards define how video and audio are captured, converted to digital format, transmitted between endpoints and decoded.
Signaling standards control session establishment, teardown and management. Session Initiation Protocol (SIP) is widely supported for video session management, though many older systems rely on H.323. Gateways and multipoint control unit (MCUs) can make SIP and H.323 work together.
Encapsulation protocols vary in terms of vendor support and performance. Popular encapsulation standards include the International Telecommunication Union's (ITU) H.264, as well as VP8 for video, ITU G.711/G.722/G.729 for voice, and ITU H.239/T.120 for data, such as screen sharing or web conferencing. H.264 is widely supported by video conferencing vendors, while VP8 is widely used in WebRTC-capable browsers, like Google Chrome and Mozilla Firefox.
Some of these video conferencing standards and codecs often form the lowest common denominator for interoperability. Vendors such as Microsoft, Polycom and Vidyo have their own enhanced and proprietary versions of H.264 that incorporate scalable video coding (SVC) to improve video performance over lossy networks, like public Wi-Fi or cellular-based services. Microsoft Skype for Business also provides support for Microsoft's own Real-Time Video codec. Microsoft also relies on a variant of WebRTC known as ORTC, or Object Real-Time Communications, to support video conferencing natively within its Edge browser.
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Newer video encapsulation standards include H.265 and VP9. These codecs use less bandwidth for high-definition video and offer better video quality and better support for video over lossy networks by natively incorporating SVC.
Licensing and competitive considerations drive variances in video codec support. H.264 and H.265 require royalty payments for use. VP8 and VP9 are royalty-free, but competitors are reluctant to embrace these codecs, since they're controlled by Google, not natively supported in most video conferencing room systems and do not support hardware optimization in Apple mobile devices.
More recently, a new organization called the Alliance for Open Media was formed by leading video conferencing vendors -- including AMD, Cisco, Intel, Microsoft, NVIDIA and Vidyo -- to develop a royalty-free alternative to H.265 and VP9.
Varying encapsulation approaches are an obstacle for buyers wishing to integrate different products from different vendors or take advantage of WebRTC to enable video conferencing within browsers and browser-based apps. Vendors continue to perceive competitive advantage toward offering a "better-than-standard" service while supporting baseline interoperability for well-defined video conferencing standards.
Integrating systems that use different video codecs requires deploying an on-premises MCU or a bridging software platform like Acano or Pexip, a cloud-bridging service like StarLeaf, or a cloud video conferencing service like Blue Jeans, Cisco, Fuze, Videxio, Vidyo or Zoom. Any of these services will typically provide transcoding between codecs, but with additional cost and complexity.
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