Data-independent sequencing with the timing object: a JavaScript sequencer for single-device and multi-device web media

Media players and frameworks all depend on the ability to produce correctly timed audiovisual effects. More formally, sequencing is the process of translating timed data into correctly timed presentation. Though sequencing logic is a central part of all multimedia applications, it tends to be tightly integrated with specific media formats, authoring models, timing/control primitives and/or predefined UI elements. In this paper, we present the Sequencer, a generic sequencing tool cleanly separated from data, timing/control and UI. Data-independent sequencing implies broad utility as well as simple integration of different data types and delivery methods in multimedia applications. UI-independent sequencing simplifies integration of new data types into visual and interactive components. Integration with an external timing object [7] ensures that media components based on the Sequencer may trivially be synchronized and remote controlled, both in single-page media presentations as well as global, multi-device media applications [5, 6, 7, 16]. A JavaScript implementation for the Sequencer is provided based on setTimeout, ensuring precise timing and reduced energy consumption. The implementation is open sourced as part of timingsrc [2, 3], a new programming model for precisely timed Web applications. The timing object and the Sequencer are proposed for standardization by the W3C Multi-device Timing Community Group [20].