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991.
帧内宏块更新是视频传输中一种重要的错误恢复方法。针对无线视频传输中的错误恢复问题进行分析,并对几种不同的帧内宏块更新方法进行对比,提出一种改进的帧内宏块更新方法。通过分析视频中主要的运动方向,选用不同的帧内宏块更新策略,在保证错误恢复能力的同时,尽量减小帧内宏块在码流中所占的比例。分别采用MPEG4的AIR方法、随机更新方法、按列更新方法和所提方法对不同的测试序列进行了错误恢复能力的实验。结果表明,所提方法既能保持良好的错误恢复能力,又能降低码率的波动以满足编码与传输实时性的要求,具有良好的主客观效果,同时与现有的各种视频编码标准兼容。 相似文献
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993.
介绍纠错编码原理,着重介绍几种纠错编码例如线性分组码、卷积码、级联码,同时介绍无线网络传输的特点,无线传输中误码产生的主要原因。结合这两点,介绍在无线局域网中采用的纠错编码方式,编码纠正错误对于帧错误概率和吞吐都有改善作用,在特定的误码率条件下吞吐量有显著的提高。 相似文献
994.
Kang-Sun Choi 《Digital Signal Processing》2013,23(4):1171-1180
A hybrid method of block truncation coding (BTC) and differential pulse code modulation (DPCM) offers better visual quality than the standard BTC for small block sizes due to its inherent multitone representation. Recently, a two-level quantizer design method has been proposed to increase the coding performance of the DPCM-BTC framework. However, the design method is near optimal in the sense that its coding performance depends on the initial bit plane patterns. In this paper, we propose a bit plane modification (BPM) algorithm to achieve further performance improvement. The BPM algorithm, inspired by error diffusion, effectively distributes large quantization error at a certain pixel to its neighboring pixels having small quantization errors by changing partial bit patterns. Experimental results show that the proposed algorithm successfully achieves much higher coding performance than various conventional BTC methods. The average PSNR performance of the proposed method is 2.31 dB, 5.15 dB, and 5.15 dB higher than that of BTC, DPCM-BTC, and a recently developed BTC scheme using error diffusion and bilateral filtering, respectively. 相似文献
995.
Ágnes Bogárdi-MészölyAuthor Vitae Tihamér Levendovszky Author Vitae 《Performance Evaluation》2011,68(1):45-57
Performance metrics can be predicted with appropriate performance models and evaluation algorithms. The goal of our work is to adapt the Mean-Value Analysis evaluation algorithm to model the behavior of the thread pool. The computation time and the computational complexity of the proposed algorithm have been provided. The limit of the response time and the throughput sequences computed by the novel algorithm has been determined. It has been shown that the proposed algorithm can be applied to performance prediction of web-based software systems in ASP.NET environment. The proposed algorithm has been validated and the correctness of performance prediction with the novel algorithm has been verified with performance measurements. Error analysis has been performed to verify the correctness of performance prediction. 相似文献
996.
In this paper we consider possible extensions of the classical multilayer artificial neural network model to the situation when the signals processed by the network are by definition compound and possibly structured. We discuss existing approaches to this problem in various contexts and provide our own model-the Normalizing Neural Network-for networks that process vectors as signals. We discuss possible uses of the proposed approach in a series of case studies. 相似文献
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998.
Guoqi Li Author VitaeChangyun WenAuthor Vitae Guang-Bin HuangAuthor VitaeYan Chen Author Vitae 《Neurocomputing》2011,74(5):771-782
Most existing online algorithms in support vector machines (SVM) can only grow support vectors. This paper proposes an online error tolerance based support vector machine (ET-SVM) which not only grows but also prunes support vectors. Similar to least square support vector machines (LS-SVM), ET-SVM converts the original quadratic program (QP) in standard SVM into a group of easily solved linear equations. Different from LS-SVM, ET-SVM remains support vectors sparse and realizes a compact structure. Thus, ET-SVM can significantly reduce computational time while ensuring satisfactory learning accuracy. Simulation results verify the effectiveness of the newly proposed algorithm. 相似文献
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1000.