Multimedia Synchronization Research Articles

Multimedia teleorchestra with independent sources: Part 1 ? temporal modeling of collaborative multimedia scenarios

Multimedia synchronization involving independent sources is a challenging issue imposed by the distributed multimedia applications. In our work, this issue is studied by investigating the teleorchestra application (remote multimedia presentation). In teleorchestration, among the data objects to be presented, relative and uncertain temporal requirements may be involved. "Fuzzy" presentation scenarios are thus generated. In this paper, we describe a temporal model that can handle these "fuzzy" scenarios that contain imprecise synchronization constraints, such as unknown object presentation durations and relative event occurring times. The model supports a distributed synchronization algorithm that can schedule the independent sources for the multimedia teleorchestration.

Toward a formal specification of multimedia synchronization scenarios

This paper introduces time stream Petri nets (Ts treamPn), a model for the formal specification of multimedia synchronization scenarios. This new model extends time Petri nets to formally describe the timed behaviour of multimedia objects and streams in asynchronous distributed systems. The proposed approach uses time intervals to label the arcs exiting from the places of the net, and typed transitions to define different firing rules. This model allows a complete and accurate specification of synchronization constraints between multimedia streams and can be used at different levels of granularity.

Multimedia synchronization and medical applications (draft)

Multimedia synchronization and medical applications (draft)

Techniques for multimedia synchronization in network file systems

One of the unique features that distinguishes digital multimedia from traditional computer data is the presence of multiple media streams, whose display must proceed in a mutually synchronized manner. The design of techniques for synchronization of multimedia data at the time of storage, and retrieval from network file servers is the subject matter of this paper. We present algorithms by which a file server can create a relative time system and synchronize media units transmitted by different sources on a network to construct a multimedia object. These algorithms stay robust in the absence of global clocks, presence of transmission jitter and generation rate mismatches. We develop a feedback technique using which the file server can detect asynchronies in display devices during retrieval of multimedia objects, and even restore synchrony by deleting or duplicating media units destined for asynchronous destinations. We then present strategies by which the file server can actually predict the time in future when the asynchrony of a device is expected to exceed the permitted bound, and take gradual preventive action to nullify the asynchrony in advance. These algorithms can be generalized to heterogeneous multimedia networks in which there may be variations in sizes of media units generated, differences in network locations of sources and destinations, etc. We are currently implementing these techniques in a digital multimedia on-demand storage server being developed at the UCSD Multimedia Laboratory.

Standardizing hypermedia information objects

The level of complexity that should be addressed by a standard for the interchange of multimedia and hypermedia information, leading to a layered structure which separates a generic object layer from upper layers dealing with specific applications and from lower layers dealing with operating systems and file formats is discussed. The presentation and encoding of such multimedia and hypermedia information objects for the special needs of real-time, interactive, and communicating applications is the purpose of an International Organization for Standardization/Interexchange Carrier (SIO/IEC) group, known as Multimedia and Hypermedia Information Coding Expert Group (MHEG), the work of which is presented. The scope of the MHEG standard is explained, and an overview of the hierarchy of objects classes is provided, followed by a description of the methodology and coding principles developed in MHEG. The authors describe several categories of multimedia synchronization, making use of spatial and temporal relations between component objects, and relying on a scriptlike structure for more demanding situations.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Computational model for distributed multimedia applications based on a synchronous programming language

Distributed multimedia applications pose new, interesting challenges in distributed operating system support. This paper focuses on a computational model, i.e. a set of programming system interface abstractions, well-suited for distributed multimedia applications. The paper advocates a mixed approach, based on the use of synchronous languages for programming multimedia synchronization. In particular, we discuss the use of ESTEREL, an imperative synchronous language, as a basic constituent of our mixed computational model, the usefulness and practicality of its semantic features, and its embedding in an asynchronous distributed system.

Multimedia synchronization protocols for broadband integrated services

Protocols to provide synchronization of data elements with arbitrary temporal relationships of both stream and non-stream broadband traffic types are proposed. It is specified that the provision of a synchronization function be performed within a packet switched network, and, accordingly, a two-level communication architecture is presented. The lower level, called the network synchronization protocol (NSP), provides the ability to establish and maintain individual connections with specified synchronization characteristics. The upper level, the application synchronization protocol (ASP), supports an integrated synchronization service for multimedia applications. The ASP identifies the temporal relationships among an application's data objects and manages the synchronization of arriving data for playout. The proposed NSP and ASP are mapped to the session and application layers of the open-systems-interconnection (OSI) reference model, respectively. >