Seamless Playback of Video/Audio in Ambulant: Design and Implementation

The past decade has witnessed an almost explosive growth of multimedia presentations. A typical multimedia presentation today consists of a set of video/audio clips, which are relative to each other in terms of temporal and spatial relationships. These video/audio clips can come either from the same media source, or from various media sources, or even from different servers. To avoid service interruption and eliminate switch delay among these clips as if they are continuously rendered from one media source, proper cache and prefetch strategies must be employed.

SMIL is the W3C standard used for rich media presentations that integrates streaming audio and video with images, text or any other media type.

In this paper, we present the design and implementation of seamless playback for video/audio in Ambulant, which is an open-source media player with support for SMIL 3.0. To optimize the playback experience, various facilities, both automatic and author-controlled, are designed and implemented with the intention of reusing renderers and prefetching the media clips in advance. We carried out experiments in order to validate that our techniques can lower the initial start delay of media rendering, decrease streaming disruptions, increase cache utilization and improve service response time. In addition, we are planning to study the applicability of our techniques to other languages than SMIL.