Multiple Description (MD) coding of predictively coded sources is of practical interest in several multimedia applications such as redundant storage of video/audio data, and real-time video/audio telephony. A key prob...
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ISBN:
(纸本)0780375106
Multiple Description (MD) coding of predictively coded sources is of practical interest in several multimedia applications such as redundant storage of video/audio data, and real-time video/audio telephony. A key problem associated with predictive MD coding is the occurrence of predictive mismatch. In the present paper, we pose the problem of predictive MD coding as a variant of the Wyner-Ziv decoder side-in formation problem. We propose an approach based on the use of coset codes for predictive MD coding, which avoids predictive mismatch without requiring restrictive channel assumptions or high latency. We specifically consider two-channel predictive MD coding of a first-order Gauss-Markov process. Results indicate that the proposed approach significantly out-performs alternative approaches in terms of rate-distortion performance.
We suggest a feature based facial image reconstruction technique. The encoding technique utilizes the affine structure of the face to capture the global facial motion. The structure information is transmitted only onc...
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We suggest a feature based facial image reconstruction technique. The encoding technique utilizes the affine structure of the face to capture the global facial motion. The structure information is transmitted only once at the bootstrapping stage. After that only the motion information for each frame is used to reconstruct the image at the decoder. An attempt is made to perform local reconstruction without any colour patching. For local reconstruction lips are tracked across frames using the snake model. An online database of facial features is created from distinct feature templates. The lip feature in each frame is locally reconstructed from existing templates using local warping. The eye templates for each frame are also recognized and pasted from the online database.
We propose a divide and conquer algorithm for the single resolution encoding of triangle mesh connectivity. Starting from a boundary edge we grow a zig-zag strip which divides the mesh into two submeshes which are enc...
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We propose a divide and conquer algorithm for the single resolution encoding of triangle mesh connectivity. Starting from a boundary edge we grow a zig-zag strip which divides the mesh into two submeshes which are encoded separately in a recursive process. We introduce a novel data structure for triangle mesh connectivity encoding, a binary tree with positive integer weights assigned to its nodes. The length of the initial strip is stored in the root of the binary tree, while the encoding of the left and right submesh are stored in the left and right subtree, respectively. We find a simple criterion determining which objects of this data structure correspond to triangle meshes. As the algorithm implicitly traverses the triangles of the mesh, it can be classified into the family of Edgebreaker like encoding schemes. Hence, the compression ratios, both in the form of theoretical upper bounds and practical results are similar to the Edgebreaker's, while the simplicity and flexibility of the algorithm makes it particularly suitable for applications where the connectivity encoding is only a small part of the problem at hand.
Multiagent opportunism refers to the ability of agents operating in a multiagent system (MAS) to recognize and respond to potential opportunities for mutual assistance in achieving individual goals. Two major potentia...
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Multiagent opportunism refers to the ability of agents operating in a multiagent system (MAS) to recognize and respond to potential opportunities for mutual assistance in achieving individual goals. Two major potential obstacles in operationalizing multiagent opportunistic assistance in real-world systems are (i) low amounts of knowledge shared between the agents, and (ii) limited ability of the agents to re-plan dynamically. We have previously shown that even under these limiting conditions, systems of agents can benefit from multiagent opportunism. In this work we discuss how multi-agent systems can exploit shared knowledge for opportunistic predictive encoding using an approach based on an abstract plan representation called partial order plan graphs (POPGs). Further, we present several approaches for increasing system-level performance by improving the efficiency of the plans containing predictively encoded opportunities, as well as the results of an empirical analysis of their impact on the system performance.
This paper discusses orthogonality in layered multicast schemes, and presents a general framework for the implementation of layered multicast. This framework can be applied to standard IP multicast or to any other mul...
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ISBN:
(纸本)0780374002
This paper discusses orthogonality in layered multicast schemes, and presents a general framework for the implementation of layered multicast. This framework can be applied to standard IP multicast or to any other multicast technology capable of transmitting a data stream to a group of subscriber nodes. The multirate transmission is accomplished by a multicast group management facility which maps the frames of the multimedia stream into a number of multicast groups according to different data resolutions. The subscriber nodes can then directly control the data rate of the stream that they receive by joining different multicast groups, thus eliminating the need for constant data rate negotiation with the sender node.
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