Michiaki Katsumoto

Performance Evaluation of 3D Sound Field Reproduction System Using a Few Loudspeakers and Wave Field Synthesis

A conventional 3D sound field reproduction system using wave field synthesis places a lot of loudspeakers around the listener. However, since such a system is very expensive and loudspeakers come into the listeners field of vision, it is very difficult to construct an audio-visual system with it. We developed and evaluated a 3D sound field reproduction system using eight loudspeakers placed at the vertex of cube and wave field synthesis. We compared the sound localization of a loudspeaker array with that of seventeen loudspeakers placed around the listener and found that their localization capabilities of twelve directions were good.

P2MVOD: peer-to-peer mobile video on-demand

We propose a new form of distributed multimedia communication, peer-to-peer mobile video on-demand (P2MVOD), that enables users to share an unlimited amount of video content without spatial and time constraints. P2MVOD allows a moving client to receive streaming data on demand from other moving clients in a peer-to-peer (P2P) architecture. Our scheme uses multicast VOD technology. To overcome mobile routing overhead and the service vulnerability of P2P, it divides video content into the same sized segments and broadcasts them from multiple clients. Broadcasting obviously consumes much bandwidth, but the segment aggregation allows content to be received by as many clients as possible, thus counteracting the resulting increase in traffic. Numerical analysis revealed the characteristics of the broadcast traffic on a network, the effectiveness of the segment aggregation, and the range of applications

A new multicast technique supporting source mobility for future vision delivery service

In this paper, we propose an innovative information delivery service on intelligent transport systems (ITS), which enables users to see their future vision delivered from users at further points along the route. This service requires special multicast and mobile routing schemes. We have developed a source mobility support multicast (SMM) technique that guarantees consecutive communication in high-speed mobile environments and minimizes the overhead in reconstructing multicast trees, which is caused by a source movement. SMM is based on a new concept where multicast tree is constructed over cellular IP network according to A. G. Valko (1999), in which a source point tree and a rendezvous point tree are combined into one multicast tree. SMM provides wide operability by partitioning the network and confining protocol uniqueness and topological constraints within the local access networks. This paper shows our design of SMM architecture and its detail protocols.

Directional sound radiation system using a large planar diaphragm incorporating multiple vibrators

This paper aims to construct a system that produces directional sound radiation. Directional sound is intrinsically radiated from a vibrating resonant body of such instrument as a violin. The directivity is said to give the sound a realistic and spatial effect. To reproduce a sound with such directivity, we propose a method that uses multiple vibrators to artificially induce bending vibrations on a large planar diaphragm. As the first step of this study, we constructed a prototype system and demonstrated that (i) the bending vibration of the diaphragm is controllable by adjusting accelerated vibrations and (ii) the radiated sound obtains directivity as a specified condition by a user using the algorithm we proposed. This directivity of the radiated sound was obvious enough for humans to perceive.

Theoretical Study of Near 3D Sound Field Reproduction Based on Wave Field Synthesis

It is very important to develop near 3D sound field reproduction techniques in order to realize the ultra‐realistic communication such as 3D TV and 3D tele‐conference. In this report, the principle of the near 3D sound field reproduction technique using wave field synthesis is defined from Kirchhoff‐Helmholtz integral equation and two methods (dipole control method and directional point control method) are proposed. The performance of two proposed methods is studied by computer simulation and it is shown that the dipole control method has good performance and that the directional point control method has good performance if the directivity of loudspeakers is unidirectional or shotgun.

Asynchronous media casting network: an optimal network scheme for on-demand video distribution

This paper describes a new network scheme that minimizes the consumption of network resources for on-demand streaming-video distribution through multicasting. In general, on-demand video distribution has been realized through unicasting. Asynchronous multicast techniques that reduce the load on the on-demand video server have been studied, but there has been little consideration of ways to reduce the network load. We have developed a statistical traffic-control theory based on asynchronous multicasting that can be used to adjust traffic on the trunk and branch links along the distribution tree to meet the network bandwidth design requirements to ensure QOS. In addition, we propose a dynamic bandwidth-allocation and traffic-adaptation algorithm that allows finite resources to be shared among different video deliveries by assigning the available bandwidth for each according to request rates. To show the implementability of these ideas, we consider their operation with protocols that autonomously construct a multicast tree and guarantee the QOS. We also discuss the effects of using this scheme based on a numerical analysis and simulation results regarding real traffic traces and the service-blocking rate.

A novel 3D audio display system using radiated loudspeaker for future 3D multimodal communications

It is very important to develop 3D audio display systems compatible with future 3D visual displays in order to realize future 3D multimodal communications systems such as 3D television. In this paper, two 3D audio display systems using the radiated loudspeaker, that were developed by the authors, are described. In one system, the spherical radiated loudspeaker, which consists of 26 loudspeaker units and displays the solo player, was used. In this study, the spherical radiated loudspeaker displays two types of solo players. In the other system, the rectangular radiated loudspeaker, which consists of 157 loudspeaker units and displays the ensemble, was used. In this study, the rectangular radiated loudspeaker displays the string quartet.

Performance Evaluation of 3D Sound Field Reproduction System with a Few Loudspeakers and Wave Field Synthesis

A conventional 3D sound field reproduction system using wave field synthesis places a lot of loudspeakers around the listener. However, since such a system is very expensive and loudspeakers come into the listeners field of vision, it is very difficult to construct an audio‐visual system with it. We developed and evaluated a 3D sound field reproduction system using eight loudspeakers placed at the vertex of cube and wave field synthesis. We compared the sound localization of a loudspeaker array with that of seventeen loudspeakers placed around the listener and found that their localization capabilities were equivalent except the normal direction of cubes planes.

Localization Model of Synthesized Sound Image Using Precedence Effect in Sound Field Reproduction Based on Wave Field Synthesis

Although it is very important to conduct listening tests when constructing a practical sound field reproduction system based on wave field synthesis, listening tests are very expensive. A localization model of synthesized sound images that predicts the results of listening tests is proposed. This model reduces the costs of constructing a reproduction system because it makes it possible to omit the listening tests. The proposed model uses the precedence effect and predicts the direction of synthesized sound images based on the inter-aural time difference. A comparison of the results predicted by the proposed model and the localized results of listening tests shows that the model accurately predicts the localized results.

A quality decision method for multi-object content based on user requirements

Several technologies to deal with multi-object content (SMIL, MPEG-4 and so on) have been developed. A technology to control the quality of each object in multi-object content is still needed so that we can provide content that adapts to various situations. In addition, as broadband networks become increasingly sophisticated, it is more important to control content quality based on user requirements rather than just the available network bandwidth. In this paper, we propose a quality decision method based on user requirements for multi-object content delivery applications. We assume that content creators and receivers use the application and they give priorities to the objects. The proposed method evaluates the objects using evaluate functions which take the given priorities as parameters and decides the quality for each object using dynamic programming or a greedy algorithm. To show the usefulness of our method, we applied our method to MPEG-4-based application. As a result, we could control the quality within a reasonable time. We also found that we obtained different quality assignments when we used different evaluation functions, and that our method reflected the user requirements.