481878
Reducing Spatial Resolution for MPEG-2 to H.264/AVC Transcoding
Transcoding is an important technique for reducing the bit rate or spatial resolution to meet the constrained transmission bandwidths and terminal capabilities. In this paper, we propose a spatial downscaling transcoding method to convert an MPEG-2 bitstream into an H.264/AVC bitstream. A novel feature of the proposed method is to focus on the fast mode decision that fully exploits the advantages of variable block-size motion compensation feature in H.264/AVC. In the transcoder, types and motion vectors of pre-encoded macroblocks are considered together to decide the new encoding block type. While maintaining a reasonable image quality, the proposed method significantly reduces the computational complexity and facilitates the video servers to provide multimedia service in real time for heterogeneous clients. Experimental results show that our method is very effective.
8954904
Modification of the AdaBoost-based Detector for Partially Occluded Faces
While face detection seems a solved problem under general conditions, most state-of-the-art systems degrade rapidly when faces are partially occluded by other objects. This paper presents a solution to detect partially occluded faces by reasonably modifying the AdaBoost-based face detector. Our basic idea is that the weak classifiers in the AdaBoost-based face detector, each corresponding to a Haar-like feature, are inherently a patch-based model. Therefore, one can divide the whole face region into multiple patches, and map those weak classifiers to the patches. The weak classifiers belonging to each patch are re-formed to be a new classifier to determine if it is a valid face patch - without occlusion. Finally, we combine all of the valid face patches by assigning the patches with different weights to make the final decision whether the input subwindow is a face. The experimental results show that the proposed method is promising for the detection of occluded faces
18296363
A Real-Time Score Detection and Recognition Approach for Broadcast Basketball Video
For broadcast sports video, score information is an effective mid-level representation to facilitate high-level video content analysis. In this paper, we propose a real-time approach to detect score region and recognize scores in broadcast basketball video. First, score region is automatically detected using frame difference and texture information without any prior knowledge. Then, score digit is recognized using a coarse-to-fine scheme based on score spatial structure, temporal correlation and changing rules. Compared with traditional video text recognition method, our approach is computing-insensitive and independent of digit model training. Experimental results show that our approach achieves real-time performance and is robust for the variation of digit font, size, color and noise caused by low frame resolution in broadcast basketball video.
18884970
Performance Characterisation of Face Recognition Algorithms and Their Sensitivity to Severe Illumination Changes
This paper details the results of a face verification competition [2] held in conjunction with the Second International Conference on Biometric Authentication. The contest was held on the publically available XM2VTS database [4] according to a defined protocol [15]. The aim of the competition was to assess the advances made in face recognition since 2003 and to measure the sensitivity of the tested algorithms to severe changes in illumination conditions. In total, more than 10 algorithms submitted by three groups were compared. The results show that the relative performance of some algorithms is dependent on training conditions (data, protocol) as well as environmental changes.
15693719
Context-based Arithmetic Coding Reexamined for DCT Video Compression
This paper presents a new context modeling technique for arithmetic coding of DCT coefficients in video compression. A key feature of the new technique is the inclusion of all previously coded coefficient magnitudes in a DCT block in context modeling. This enables adaptive arithmetic coding to exploit the redundancy of the high-order Markov process in the DCT domain with a few conditioning states. In addition, a context weighting technique is used to further improve the coding efficiency. The complexity of the new arithmetic coding scheme is slightly lower than that of context-based adaptive binary arithmetic coding (CABAC) of H.264. Moreover, the scheme is made compatible to the AVS baseline profile. It achieves on average 13% improvement in compression ratio over context-based two dimension variable length coding (C2DVLC) designed for the DCT domain, and a similar coding efficiency as the CABAC technique in H.264.
37403020
Contour-motion feature (CMF): A space-time approach for robust pedestrian detection
This paper presents a contour-motion feature for robust pedestrian detection. The space-time contours are used as the low level representation of the pedestrian. Then we apply 3D distance transform to extend the 1-dimensional contour into 3-dimensional space. By this way, the relations between the local contours can be maintained implicitly. Further, by encapsulating the static and dynamic information by 3D Haar-like filters, we can generate the middle level pedestrian representation: contour-motion features. Then we use boosting method to select the most representative features. Our experiments demonstrate that the proposed approach can outperform Viola's well-known pedestrian detector in both detection accuracy and generalization ability. In addition, even though our approach is presented in pedestrian detection scenario, it has been extended to human activity recognition application and remarkable performance has been achieved.
20072384
A Backward-Compatible Solution for Next Generation DVB-C System
In this paper, we propose hierarchical modulation as a backward compatible solution for next generation digital video broadcasting over cables (DVB-C2). Without modifying the architecture of legacy receivers, supplementary data can be transmitted via an added layer superimposed onto the legacy layer, and the resultant increase of transmission power is only a small fraction of that used by the legacy system. To obtain the upper bounds for the achievable throughputs, the modulation constrained capacities are derived for this layered transmission scheme. We formulate the hierarchical constellation design as a nonlinear optimization problem and then solve it through a simplified numerical method, which searches for the appropriate power allocation ratio in one-dimension space. Finally, to examine the inter-operability of channel encoder/decoder between DVB-S2 and DVB-C2, we investigate the error performance of the proposed scheme employing the LDPC codes given by DVB-S2 standard.
39625644
An AVS Based IPTV System Network Trial
This paper unveils the solution of an AVS1-P2 based IPTV (AVSIPTV) system network trial, which is architected with the common three levels such as national, provincial and urban level, and each system function of each level is described. In order to verify the solution, the AVS-IPTV testing and verification environment has been setup in the China Netcom Group labs, which promoted STB (Set-top box) to support AVS. An AVS-IPTV system network commercial trial has been successfully deployed to test and verify the performance of the AVS-IPTV system function, EPG (Electronic Program Guide), AVS streaming service, and the quality of experience. The trial makes AVS standard and AVS-IPTV system commercially applicable in the real world.
46501259
A proactive fault-detection mechanism in large-scale cluster systems
7527642
Spectrum Sensing for OFDM Systems Employing Pilot Tones and Application to DVB-T OFDM
Spectrum sensing is one of the core technologies of cognitive radio (CR) systems which provide a viable solution to the problem of sparsity of wireless spectrum. Nowadays, OFDM techniques are adopted by many existing or progressing wireless communication standards. Thus, a robust spectrum sensing algorithm for OFDM modulated signals is highly desired to implement CR when the primary signal uses OFDM modulation. Motivated by this demand, a time-domain symbol cross-correlation based spectrum sensing algorithm (TDSC method) is presented in this paper. The algorithm makes use of the property that the mean of the TDSC of two OFDM symbols is not zero if they have embedded the same frequency-domain pilot tones. The statistical behavior of the proposed spectrum sensor is explicitly analyzed and a theoretical lower bound on the misdetection probability is derived in this paper. An intuitive spectrum sensing method which utilizes the cyclic prefix nature of the OFDM modulated signals (CP method) is also described in this paper as a reference for comparison. Finally, we use the DVB-T Standard [8] as an application example to illustrate the proposed spectrum sensing algorithm. The simulated channel environments are the Ricean and Rayleigh channels defined in the DVB-T Standard and the additive white Gaussian noise (AWGN) channel. Four CP ratios defined in the DVB-T Standard are simulated for the probability of false alarm equaling 0.01 and the sensing time set equal to 50 ms. Simulation results show that the TDSC method can achieve a misdetection probability of 0.1 when the SNR equals -20.5 dB for all four CP ratios. The TDSC method outperforms the CP method in all cases. Furthermore, the proposed method has approximately the same detection performance for different CP ratios while the detection performance of the CP method degrades dramatically when the CP ratio becomes small. Results also reveal that the simulated performance is very close to the theoretical lower bound indicating that the lower bound can be used as a good prediction of performance.
5747221
Application Research of Design Patterns in Virtual Trade Platform
Shanxi Coal Transportation and Marketing Group Limited has abundant coal and infrastructure network resources, maturity the highway system of coal transportation. The construction of virtual trade platform can share resources, accelerate the circulation speed of resources, reduce business costs, and improve business efficiency. The paper applies design pattern to virtual trade platform. The system has the advantage of strong scalability and maintainability, easy to develop and support multiple types of user interface.