13511286
A novel rate control for H.264
An efficient rate control strategy for H.264 is proposed in this paper, which results an accurate bit stream required for each frame. A solution of the chicken and egg dilemma between rate control and R-D optimization (RDO) in H.264 is given, and hence different bits to different modes are allocated so that the bad situation for the quadratic R-D model is deviated. Simulation results show that the fluctuation of bits and PSNR of each frame in our algorithm is smaller that JVT-G012 while it super performs the method of JVT-G012 in the target bit rate matching. Unlike JVT-F086, RDO only performs once for each macroblock (MB). Therefore, the complexity is similar to JVT-G012.
12535990
Fast integer-pel and fractional-pel motion estimation for H.264/AVC
Abstract This paper gives out a fast motion estimation algorithm for H.264/AVC, which has almost the same quality performance as that of the Full Search scheme and also provides a strategy to balance the quality performance and the search speed. Integer-pel search is the most time consuming module for motion estimation. In this paper a hybrid Unsymmetrical-cross Multi-hexagon-grid Search (UMHexagonS) algorithm is introduced, which well solves the false motion vector estimation problem because of the local-minimum. As results, it saves more than 90% on search time whereas the averaging PSNR loss is less than 0.056 dB for all tested sequences with different motion extent compared with the Fast Full Search scheme. Fractional-pel fast search is not negligible when the integer motion estimation has been extensively speeded up. By utilizing the property of uni-modal error surface inside the fractional-pel search window, a novel Center Biased Fractional-pel Search (CBFPS) algorithm is proposed in this paper, which can save 30–50% computation compared with the Full Fractional-pel Search scheme. Early termination is another problem discussed in this paper, to construct a complete motion estimation method, giving a uniform method which can cover a wide range of applications, terminating the program at early and right stage is certainly required. A model based on the Normative SAD Difference (NSD) is given to assist the termination decision-making, and a tradeoff between the search speed and the reconstructed quality can be achieved by changing a modulation factor.
38590214
Motion Composition of 3D Video
3D video, which is composed of a sequence of mesh models and can provide the user with interactivity, is attracting increasing attention in many research groups. However, it is time-consuming and expensive to generate 3D video sequences. In this paper, a motion composition method is proposed to edit 3D video based on the user’s requirements so that 3D video can be re-used. By analyzing the feature vectors, the hierarchical motion structure is parsed and then a motion database is set up by selecting the representative motions. A motion graph is constructed to organize the motion database by finding the possible motion transitions. Then, the best path is searched based on a proposed cost function by a modified Dijkstra algorithm after the user selects the desired motions in the motion database, which are called key motions in this paper. Our experimental results show the edited 3D video sequence looks natural and realistic.
16343531
3D video segmentation using point distance histograms
Similar to 2D video segmentation, 3D video segmentation is to divide the 3D video in temporal domain into a set of meaningful and manageable segments (shots) that are used as basic elements for indexing. This paper proposes a temporal segmentation method for 3D video for the first time as far as we know. Point distance histograms are used considering the tradeoff between computational cost and effectiveness. In order to reflect the real motion of 3D object, three fixed points are selected, which can avoid what we call "the same sphere problem." And simulation results on total 285 frames, which are composed of four different sequences, show our method is very effective.
3231385
IP traceback-based intelligent packet filtering: a novel technique for defending against Internet DDoS attacks
Distributed denial of service (DDoS) is one of the most difficult security problems to address. While many existing techniques (e.g., IP traceback) focus on tracking the location of the attackers after-the-fact, little is done to mitigate the effect of an attack while it is raging on. We present a novel technique that can effectively filter out the majority of DDoS traffic, thus improving the overall throughput of the legitimate traffic. The proposed scheme leverages on and generalizes the IP traceback schemes to obtain the information concerning whether a network edge is on the attacking path of an attacker ("infected") or not ("clean"). We observe that while an attacker will have all the edges on its path marked as "infected", edges on the path of a legitimate client will mostly be "clean". By preferentially filtering out packets that are inscribed with the marks of "infected" edges, the proposed scheme removes most of the DDoS traffic while affecting legitimate traffic only slightly. Simulation results based on real-world network topologies (e.g., Skitter) all demonstrate that the proposed technique can improve the throughput of legitimate traffic by 3 to 7 times during DDoS attacks.
7874615
A generic framework for monitoring continuous spatial queries over moving objects
This paper proposes a generic framework for monitoring continuous spatial queries over moving objects. The framework distinguishes itself from existing work by being the first to address the location update issue and to provide a common interface for monitoring mixed types of queries. Based on the notion of safe region, the client location update strategy is developed based on the queries being monitored. Thus, it significantly reduces the wireless communication and query reevaluation costs required to maintain the up-to-date query results. We propose algorithms for query evaluation/reevaluation and for safe region computation in this framework. Enhancements are also proposed to take advantage of two practical mobility assumptions: maximum speed and steady movement. The experimental results show that our framework substantially outperforms the traditional periodic monitoring scheme in terms of monitoring accuracy and CPU time while achieving a close-to-optimal wireless communication cost. The framework also can scale up to a large monitoring system and is robust under various object mobility patterns.
12832200
A unified proof of minimum time complexity for reaching consensus and uniform consensus - an oracle-based approach
In this paper, we offer new proofs to two lower bound results in distributed computing: a minimum of f+1 and f+2 rounds for reaching consensus and uniform consensus respectively when at most f fail-stop faults can happen. Here the computation model is synchronous message passing. Both proofs are based on a novel oracle argument. These two induction proofs are unified in the following sense: the induction steps are the same and only the initial step (f=0) needs to be proved separately. The techniques used in the proof offer new insights into the lower bound results in distributed computing.
1351954
Cost-Sensitive Learning of SVM for Ranking
In this paper, we propose a new method for learning to rank. ‘Ranking SVM' is a method for performing the task. It formulizes the problem as that of binary classification on instance pairs and performs the classification by means of Support Vector Machines (SVM). In Ranking SVM, the losses for incorrect classifications of instance pairs between different rank pairs are defined as the same. We note that in many applications such as information retrieval the negative effects of making errors between higher ranks and lower ranks are larger than making errors among lower ranks. Therefore, it is natural to bring in the idea of cost-sensitive learning to learning to rank, or more precisely, to set up different losses for misclassification of instance pairs between different rank pairs. Given a cost-sensitive loss function we can construct a Ranking SVM model on the basis of the loss function. Simulation results show that our method works better than Ranking SVM in practical settings of ranking. Experimental results also indicate that our method can outperform existing methods including Ranking SVM on real information retrieval tasks such as document search and definition search.
872168
The super connectivity of shuffle-cubes
The shuffle-cube SQn, where n ≡ 2 (mod 4), a new variation of hypercubes proposed by Li et al. [T.-K. Li, J.J.M. Tan, L.-H. Hsu, T.-Y. Sung, The shuffle-cubes and their generalization, Inform. Process. Lett. 77 (2001) 35-41], is an n-regular n-connected graph. This paper determines that the super connectivity of SQn is 2n - 4 and the super edge-connectivity is 2n - 2 for n ≥ 6.