Online digital audio is a rapidly growing resource, which can be accessed in rich new ways not previously possible. For example, it is possible to listen to just those portions of a long discussion which involve a given subset of people, or to instantly skip ahead to the next speaker. Providing this capability to users, however, requires generation of necessary indices, as well as an interface which utilizes these indices to aid navigation. We describe algorithms which generate indices from automatic acoustic segmentation. These algorithms use hidden Markov models to segment audio into segments corresponding to different speakers or acoustics classes (e.g. music). Unsupervised model initialization using agglomerative clustering is described, and shown to work as well in most cases as supervised initialization. We also describe a user interface which displays the segmentation in the form of a timeline, which tracks for the different acoustic classes. The interface can be used for direct navigation through the audio.

Trends such as the massive increase in information available via electronic networks, the use of on-line product data by distributed concurrent engineering teams, and dynamic supply chain integration for electronic commerce are placing severe burdens on traditional methods of information sharing and retrieval. Sources of information are far too numerous and dynamic to be found via traditional information retrieval methods, and potential consumers are seeing increased need for automatic notification services. Matchmaking is an approach based on emerging information integration technologies whereby potential producers and consumers of information send messages describing their information capabilities and needs. These descriptions, represented in rich, machine-interpretable description languages, are unified by the matchmaker to identify potential matches. Based on the matches, a variety of information brokering services are performed. We introduce matchmaking, and argue that it permits large numbers of dynamic consumers and providers, operating on rapidly-changing data, to share information more effectively than via traditional methods. Two matchmakers are described, the SHADE matchmaker, which operates over logical and structured text languages, and the COINS matchmaker, which operates over free text. These matchmakers have been used for a variety of applications, most significantly, in the domains of engineering and electronic commerce. We describe our experiences with the SHADE and COINS matchmaker, and we outline the major observed benefits and problems of matchmaking.

As agents see more use in dynamic, distributed information networks, information sharing facilitators, such as the SHADE matchmaker, and underlying knowledge-based agent communication protocols, such as the Knowledge Query and Manipulation Language, will see increased use. We have created several communities of agents collaborating via KQML and matchmaking within the domains of collaborative engineering and satellite image retrieval. Based on these experiences, matchmaking has proven to be very beneficial for multi-agent systems, but we have also identified a number of issues and extensions that are not only vital to KQML-based matchmaking, but to inter-agent protocols in general. These include representational approaches to advertising complex databases, approaches to error recovery and response timing, maintaining consistency among information providers, scalability, security, persistent requests in information brokering, and the dilemma between explicit vs. implicit brokering.

Structuring temporal relationships among multimedia information elements is one of the most important facilities for editing and creating multimedia documents. We have developed a multimedia system named MediaPreview which provides facilities for structuring and creating multimedia documents. In this paper, we present a document model which is adopted in MediaPreview. This model has been designed to realize spatial and temporal structuring for the documents. The main feature of this model is the concept of a "Multimedia Paragraph" (MMP) which is introduced to reduce the complexity of the temporal structuring, such as the asynchronous interactive operation among documents. The concept of "MMP" provides an explicit and basic unit which is used to create a document in a "top-down" manner. This paper also presents the system architecture and implementation of MediaPreview in a distributed environment including database system facilities. This system realizes "static" and "dynamic" integration schemes for multimedia information elements. Our system includes a parallel database engine which manipulates multimedia information elements as streams. This database engine is effectively used for creating multimedia documents.