Scalable Video Coding

The H.264 Scalable Video Coding standard was developed jointly by the ITU and ISO standards organizations. These two groups created the Joint Video Team (JVT) to develop the H.264 standard and then continued in development of the H.264 Scalable Video Coding standard which was ratified in 2007.

H.264 Scalable Video Coding (hereinafter “SVC”) enables the encoding of a high quality video bit stream that contains within it an H.264 compatible base layer and one or more enhancement layers. This layered approach to coding provides the ability for multiple representations of the video to be derived from the stream. The following modalities are possible:

• Temporal scalability: the ability to present the video at different frame rates
• Spatial scalability: the ability to present the video at different spatial resolutions
• SNR Quality scalability: the ability to present the video at different quality levels (i.e. bit rates)
• Combined scalability – combinations of three modalities described above

An example of spatial scalability is presented in figure 1. In order to deliver video at multiple resolutions using traditional methods, a separate copy of the video must be produced, stored and delivered at each resolution. With the layered approach of SVC a single stream can be produced from which derivative streams can be extracted at each of the required resolutions with minimal overhead.

This type of layering facilitates what is called Heterogeneous Device Support, meaning the ability to support multiple devices with different capabilities from a single stream. An example of this is shown below.