1166908
Distributed rate allocation for multi-stream video transmission over ad hoc networks
When multiple video streams are present in an ad hoc network, they share and compete for the common network resources. A rate allocation algorithm must balance the available resources among the video streams in a fair and efficient manner. In addition, it is desirable to have a distributed solution so that nodes do not need to collect global information of the network and that the computational burden can be shared. We propose a distributed rate allocation algorithm which minimizes the total distortion of all video streams. Based on the subgradient method, the proposed scheme only requires link price updates at each relay node based on local observations and rate adaptations at each source node derived from rate-distortion (RD) models of the video. Simulation results show that the proposed scheme can achieve the same optimal rate allocation as that obtained from exhaustive search.
1786671
Light field compression using disparity-compensated lifting and shape adaptation
We propose disparity-compensated lifting for wavelet compression of light fields. With this approach, we obtain the benefits of wavelet coding, such as scalability in all dimensions, as well as superior compression performance. Additionally, the proposed approach solves the irreversibility limitations of previous light field wavelet coding approaches, using the lifting structure. Our scheme incorporates disparity compensation into the lifting structure for the transform across the views in the light field data set. Another transform is performed to exploit the coherence among neighboring pixels, followed by a modified SPIHT coder and rate-distortion optimized bitstream assembly. A view-sequencing algorithm is developed to organize the views for encoding. For light fields of an object, we propose to use shape adaptation to improve the compression efficiency and visual quality of the images. The necessary shape information is efficiently coded based on prediction from the existing geometry model. Experimental results show that the proposed scheme exhibits superior compression performance over existing light field compression techniques.
1251013
Congestion-aware rate allocation for multipath video streaming over ad hoc wireless networks
For multipath video streaming over ad hoc wireless networks, received video quality is influenced by both the encoder performance and the delayed packet arrivals due to limited bandwidth. We propose a rate allocation scheme to optimize the expected received video quality based on simple models of encoder rate-distortion performance and network rate-congestion tradeoffs. Given the embedded bit-streams of a group of video frames and the cross traffic condition on a given set of paths, a gradient descent method is used to determine the amount of bits to be transmitted over the multiple paths for each frame. Two rate allocation strategies, layered representation and partial repetition are also investigated. Simulation results of video streaming over a 15-node wireless ad hoc network demonstrates the benefit of performing rate allocation optimization over a simple heuristic scheme. It is also shown that while layered representation is more efficient for mild delay constraints, partial repetition is more robust against packet losses.
45349056
Automatic Scene Detection in News Program by Integrating Visual Feature and Rules
Organizing video sequences from shot level to scene level is a challenging task, however, without the scene information, it will be very hard to extract the content of the video. In this paper, a visual and rule information integrated strategy is proposed to detect the scene information of the News programs. First, we extract out the video caption and anchor person (AP) shots in the video. Second, the rules among the scene, video caption, AP shots will be used to detect the scenes. Third, the visual features will also be used to analysis the scene information in the region which can not be covered by the rules. And experimental results based on this strategy are provided and analyzed on broadcast News videos.
2715724
Accessing Video Contents through Key Objects over IP
In order to support content-based video database access over the Internet Protocol (IP), achieving the following objectives are important: (i) video query by a representative object (key object) or some statistical characterization of the target contents, (ii) bandwidth-efficient browsing over IP, and (iii) scalable and user-centric video transmission over a heterogeneous and variable-bandwidth network. We present a video object extraction and scalable coding system designed to meet the above objectives. In our system, key objects of meaning to video database users are generated via a human-computer-interaction procedure, and are tracked across frames. Given a key object, an algorithm classifies a subset of its VOPs as key VOPs. This subset forms the basis of a highly bandwidth-efficient base layer for supporting activities such as browsing and refining queries. Over the base layer, a number of enhancement layers can be defined to progressively increase the spatial and temporal resolutions of retrieved video. It is expected that heterogeneous users can subscribe to different numbers of the enhancement layers according to their own conditions, such as access authorization, available connection bandwidth, and quality preference.
9568730
Exploring video content structure for hierarchical summarization
Abstract.In this paper, we propose a hierarchical video summarization strategy that explores video content structure to provide the users with a scalable, multilevel video summary. First, video-shot- segmentation and keyframe-extraction algorithms are applied to parse video sequences into physical shots and discrete keyframes. Next, an affinity (self-correlation) matrix is constructed to merge visually similar shots into clusters (supergroups). Since video shots with high similarities do not necessarily imply that they belong to the same story unit, temporal information is adopted by merging temporally adjacent shots (within a specified distance) from the supergroup into each video group. A video-scene-detection algorithm is thus proposed to merge temporally or spatially correlated video groups into scenario units. This is followed by a scene-clustering algorithm that eliminates visual redundancy among the units. A hierarchical video content structure with increasing granularity is constructed from the clustered scenes, video scenes, and video groups to keyframes. Finally, we introduce a hierarchical video summarization scheme by executing various approaches at different levels of the video content hierarchy to statically or dynamically construct the video summary. Extensive experiments based on real-world videos have been performed to validate the effectiveness of the proposed approach.
15233730
Circulant Distant Two Labeling and Circular Chromatic Number
Let G be a graph and d,d 0 be positive integers, d 0 d. An m-(d,d 0 )-circular distance two labeling is a function f : V (G) ! {0,1,2,···,m 1} such that |f(u) f(v)|m d if u and v are adjacent; and |f(u) f(v)|m d 0 if u and v are distance two apart, where |x|m := min{|x|,m| x|}. The minimum m such that there exists an m-(d,d 0 )-circular labeling for G is called the d,d0-number of G and denoted by d,d 0(G). The d,d 0-numbers for trees can be obtained by a first-fit algorithm. In this article, we completely determine the d,1-numbers for cycles. In addition, we show connections between generalized circular distance labeling and circular chromatic number.
8130739
Homomorphisms to oriented cycles
We discuss the existence of homomorphisms to oriented cycles and give, for a special class of cyclesC, a characterization of those digraphs that admit, a homomorphism toC. Our result can be used to prove the multiplicativity of a certain class of oriented cycles, (and thus complete the characterization of multiplicative oriented cycles), as well as to prove the membership of the corresponding decision problem in the classNPϒcoNP. We also mention a conjecture on the existence of homomorphisms to arbitrary oriented cycles.