SHVC

SHVC, or Scalable High Efficiency Video Coding, is a scalable extension to the HEVC (High Efficiency Video Coding) standard. It adds the ability to encode a single video stream with multiple layers, enabling a base layer that can be decoded on its own and one or more enhancement layers that improve resolution, frame rate, or visual quality. This structure allows devices or networks with limited bandwidth to access a degraded but playable version, while higher-capacity channels can reveal the full-quality stream by decoding additional layers.

Technically, SHVC provides spatial scalability (different resolutions), temporal scalability (different frame rates), and quality scalability (improved detail or signal-to-noise ratio) within one bitstream. The dependency and signaling among layers are managed so that a decoder can selectively discard enhancement layers and still present a coherent video at the base layer. The approach supports flexible adaptation to varying network conditions and device capabilities without switching between entirely separate streams.

Standardization and status: SHVC was developed through collaboration between ITU-T VCEG and MPEG and is documented as an extension to HEVC, sometimes referred to as Annex G in the HEVC family. While it offers theoretical efficiency advantages by combining multiple representations into a single stream, adoption has been limited in practice due to added encoder/decoder complexity and licensing considerations. In many deployments, adaptive streaming relies on multiple conventional HEVC representations (separate bitstreams) rather than true SHVC layered bitstreams.

Relationship to related concepts: SHVC is distinct from the earlier Scalable Video Coding framework used with H.264/AVC, though both pursue scalable coding goals. SHVC is intended to provide scalable bitstreams within the HEVC framework for applications such as broadcasting, streaming, and multi-device delivery.