Scalable Video Coding (SVC)

A growing demand in video communications industries is the ability to deliver content to a set of devices with varying hardware capabilities. A video stream may be consumed by a handheld device and an HD TV at the same time. Such requirements are most commonly encountered in the broadcast and video conferencing markets.

As demand for HD content grows, and at the same time, mobile users on phones and PDAs are joining the networks, content providers find themselves in need of a new architecture to satisfy the widening range of requirements. A video conferencing system may likewise serve endpoints of different hardware and bandwidth capabilities.

The latest amendment to the H.264 standard, the Scalable Video Coding (SVC) extension, adds new AVC profiles that address exactly such a scenario. SVC allows a single coded stream to be used by receiver devices with different framerate or spatial resolution capabilities.

SVC improves the temporal (framerate) scalability already present in the original H.264 specification. Entire pictures can be omitted by the receiving party without disrupting motion compensation dependencies, achieving a lower framerate video than the original.

A bitstream encoded in one of the SVC profiles contains all the data needed to decode the video at the highest intended spatial resolution, but it also contains subset bitstreams for one or more lower resolutions. The higher-resolution streams use the subset streams as part of the encoding scheme, making the SVC implementation more bandwidth-efficient than broadcasting separate streams for each desired resolution.

Thus, either by dropping packets from the bitstream, or reading a subset of the coded stream, different devices can decode the same video to match their specific requirements.