vCache: Supporting Cost-Efficient Adaptive Bitrate Streaming

In adaptive bitrate (ABR) streaming, each video must be transcoded into multiple representations. Transcoding and caching videos consume tremendous resources, and only a small percentage of video chunks are frequently requested. Thus a question arises: is it necessary to pre-transcode each video and cache all video chunks? To answer this, the authors designed a network function virtualization (NFV)-based virtual cache (vCache). In vCache, video chunks have two mutually exclusive caching states: physically cached and virtually cached. A physically cached video chunk can be directly read from storage, and it consumes storage resources. A virtually cached video chunk will be transcoded online when being requested, and it consumes computing resources. With NFV, vCache can dynamically manage video chunks cost-effectively and can intelligently provision resources to guarantee transcoding delays won't affect streaming services. Results from experiments show that vCache can greatly reduce operational costs for ABR. This article is part of a special issue on advancing multimedia distribution.