In the world of meaningless acronyms SVC is at the forefront; well, at least in the video communications space it is. SVC is being touted as the savior of video conferencing. What’s behind those three letters will supposedly fix all that is broken with video conferencing from poor video quality to high latency and possibly in its spare time cure a disease or two. The fact is very few people have any idea what SVC is, but what they do know is they want it.
The purpose of this series of blog articles is to provide an unbiased, non-technical explanation of SVC and identify what problems it solves for anyone who works with or uses video conferencing technology in their work environments, from sales and marketing departments to support teams to engineers and executives.
So let’s get started. What is SVC? SVC stands for Scalable Video Coding. It is a new annex to the H.264/MPEG-4 AVC video compression standard (going forward I’ll refer to it as just simply AVC), meaning it is an enhancement on top of H.264. The truth is it’s not new; the concept has been part of nearly every major video compression standard from H.263 to MPEG-4. Basically, SVC provides the ability to encapsulate multiple compressed video streams at various frame rates and resolutions into a single stream. The video compression algorithm at the core of SVC’s technology is still very much AVC, so SVC really just explains how to put multiple video sequences at various frame rates and resolutions into one container, then takes it a step further and allows these same video sequences to share information with each other in order to improve the quality of video (more on that in later blog posts).
SVC is made up of two components: 1) temporal scalability and 2) spatial scalability. (A third mode called quality scalability exists, but for our purposes it’s just a special case of spatial scalability). Temporal scalability provides the ability to have multiple frame rates for a given resolution. Spatial scalability provides the ability to have multiple resolutions of a given video sequence. Each unique frame rate or resolution within the video sequence is referred to as a layer. In the next few blog posts, I’ll further define temporal and spatial scalability, and how they differ. Stay tuned!
Stefan Slivinski is the Manager of the Video Team at LifeSize, a division of Logitech. His team designs and develops all of the video algorithms that go into LifeSize’s current and next generation video communications equipment. His responsibilities over his ten-year career have spanned design and development of embedded video compression algorithms. Prior to joining LifeSize in 2005, he was at UB Video, developing video compression codecs for many of the major video conferencing OEM providers.