A newly minted standard, called scalable video coding (SVC), enables video streaming at multiple resolutions, quality levels and bit rates. The ability to scale video performance based on the end point is achieved through this relatively new technology called H.264/SVC (Scalable Video Coding) that not only compresses but also distributes the video stream.
The standard allows us to have layers of encoded video, and if we use intelligent devices, it can allow us do lots of other things as well. To understand the principle behind these intelligent devices, we need to look at how videoconferences usually work.
Today’s videoconferencing relies on fairly unintelligent devices at the edge, and intelligence in the core, which is also called a “mainframe” model. A multi-point conferencing unit receives streams of video from each participant, decodes them, combines them and re-encodes them.
The traditional approach of doing encoding and decoding in the core introduces delay. It also means that users all get the same data stream, rather than one suited to their bandwidth, window size and client. In short, transcoding in the cloud makes for lousy conversations.
The SVC architecture puts more intelligence at the edge and a specialized router in the core. In the new model, the router and each participant’s client work together. They tailor data transmission to each client’s demands. When a client shrinks the size of their video window, the router knows and as a result, sends fewer bits, less frames, or lower-quality video to that client without affecting everyone else. The router isn’t busy encoding, merging and decoding streams, but it knows about processing, window size and bandwidth, which it can adjust dynamically throughout the call.
The standard tells us how to decode. The method used to encode is a lot harder and is considered the secret sauce. The router is usually a 1RU, Linux-based quad-core computer that handles up to hundred-way conferences. It is usually sold as a subscription model for about $1,000 per HD port per year, which is cheaper than the traditionally capital-intensive spending around video conferencing. Video gateways that let “legacy” video conferencing hardware work with the new standard are also available in the market.
This technology allows us to get live, four-way web-based conferencing in which each participant may have different local settings from a high-definition video at 60 frames per second to a consumer-grade VGA connection to a notebook camera. And the best part is that a typical broadband connection will suffice for end users.