Due to the explosive growth of the Internet and increasing demand for multimedia information on the Web, streaming video over the Internet has received tremendous attention from academia and industry. Transmission of real-time video typically has bandwidth, delay, and loss requirements. However, the current best-effort Internet does not offer any quality of service (QoS) guarantees to streaming video. Furthermore, for video multicast, it is difficult to achieve both efficiency and flexibility. Thus, Internet streaming video poses many challenges. In this article we cover six key areas of streaming video. Specifically, we cover video compression, application-layer QoS control, continuous media distribution services, streaming servers, media synchronization mechanisms, and protocols for streaming media. For each area, we address the particular issues and review major approaches and mechanisms. We also discuss the tradeoffs of the approaches and point out future research directions.

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Streaming video over the Internet: approaches and directions

A system is described for maintaining synchrony of operations among a plurality of devices having independent clocking arrangements. A task distribution device is to distribute tasks to a synchrony group comprising a plurality of devices to perform tasks distributed by the task distribution device in synchrony. The task distribution device distributes each task to synchrony group members over a network. Each task is associated with a time stamp that indicates a time, relative to a clock maintained by the task distribution device, at which synchrony group members are to execute the task. Each synchrony group member periodically obtains from the task distribution device an indication of current time indicated by its clock, determines a time differential between the task distribution device's clock and its respective clock and determines therefrom a time at which, according to its respective clock, the time stamp indicates that it is to execute the task.

System and method for synchronizing operations among a plurality of independently clocked digital data processing devices

A framework for collaborative computing and multi-sensor data fusion in body sensor networks

One or more streams from a number of real-time video streams available to be transmitted across a communications network, are selected for display on respective terminals of a first, and at least one other user. First, a policy of the first user for making the selection, is determined, the policy containing conditions to be evaluated, selectable by the first user. Then, which streams to select for the first user is determined dynacamically by evaluating the current conditions according to the first user's policy. Only the selected streams are passed for display on the terminal of the first user, independently of selections made for passing to the other users. Dynamic selection from multiple streams enables the user to concentrate on the content not the form of presentation. Individual control of what is displayed, independent of what other users see, enables tailoring to suit resources and user priorities. Both enable larger video conferences to be handled more easily.

Dynamic selection of media streams for display

In general, user interfaces for controlling a plurality of multimedia players in groups are disclosed. According to one aspect of the present invention, a user interface is provided to allow a user to group some of the players according to a theme or scene, where each of the players is located in a zone. When the scene is activated, the players in the scene react in a synchronized manner. For example, the players in the scene are all caused to play a multimedia source or music in a playlist, wherein the multimedia source may be located anywhere on a network. The user interface is further configured to illustrate graphically a size of a group, the larger the group appears relatively, the more plays there are in the group.

User Interfaces for Controlling and Manipulating Groupings in a Multi-Zone Media System

Researchers have addressed multimedia synchronization from various perspectives. The major issues include how to specify and how to implement synchronization. Especially in the specification area a variety of techniques have been published and implemented. This survey summarizes briefly synchronization requirements, presents a multimedia synchronization reference model, shows details of various specification approaches and applies the reference model to compare existing prominent approaches as case studies.

G. Blakowski

Papers

A media synchronization survey: reference model, specification, and case studies