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Li Jian Bie Hongxia 《电子科学学刊(英文版)》2006,23(6):831-836
Video transmission over wireless networks has received much attention recently for its restricted bandwidth and high bit-error rate, Based on H.263+, by reversing part stream sequences of each Group Of Block (GOB), an error resilient scheme is presented to improve video robustness without additional bandwidth burden. Error patterns are employed to simulate Widcband Code Division Multiple Acccss,(WCDMA) channels to check out error resilience performances. Simulation results show that both subjective and objective qualities of the reconstructed images are improved remarkably. The mean Peak Signal to Noise Ratio (PSNR) is increased by 0.5dB, and the highest increment is 2dB. 相似文献
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Chen Jie Wang Baocang Hu Yupu 《电子科学学刊(英文版)》2006,23(3):423-427
This paper presents a new method for resynchronization attack, which is the combination of the differential cryptanalysis and algebraic attack. By using the new method one gets a system of linear equations or low-degree equations about initial keys, and the solution of the system of equations results in the recovery of the initial keys. This method has a lower computational complexity and better performance of attack in contrast to the known methods. Accordingly, the design of the resynchronization stream generators should be reconsidered to make them strong enough to avoid our attacks. When implemented to the Toyocrypt, our method gains the computational complexity of O(2^17), and that of 0(2^67) for LILI-128. 相似文献
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数字音频认证研究综述 总被引:2,自引:0,他引:2
现代音频信号处理技术使得对音频内容的篡改、替换,对时间序列的调换顺序等恶意操作可以以极低的代价进行,对音频完整性和真实性进行认证变得日益重要。对人类听觉系统来讲,音频认证技术需要保护的是音频内容而不是比特流本身,因此它应该能够容忍一些保持音频听觉质量或者语义的正常信号处理操作而不触发检测器。介绍了音频内容认证技术的产生背景、典型应用场合、需满足的必要性质、硬认证与软认证的特点、保持内容操作和恶意操作的划分,综述了典型的音频内容认证算法,最后总结并讨论了该研究领域的技术特点并提出了可能的解决方案。 相似文献
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This paper presents a new resynchronization marker (RM) positioning technique to effectively block the error propagation caused by channel errors. The optimal technique can be defined as the one minimizing the information loss under an error condition. For realization of the optimal technique, the amount of the information lost by errors needs to be measured. Thus, we introduce a novel measure that is successful in reflecting the actual importance of the lost data, which is measured by using error concealment techniques. That is, the amount of information lost by an error at a certain location is numerically specified by the difference between the image recovered by the error concealment and the image normally decoded without any error. Since such a measurement method is appropriate for reflecting the actual damage by errors, it is very useful for determining the RM positions. With the new measure, the optimal RM positioning technique is proposed and verified by experiments. 相似文献
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多媒体数据库系统中的同步表示管理 总被引:2,自引:2,他引:0
支持多媒体应用的扩展数据库系统必须具有新的机制以确保多种媒体数据流的同步表示。为了使用户同时具有多媒体数据流表示的灵活性和高效率,必须将媒体数据流分割成媒体对象,并且定义和保持其间的时间限制。为此要在现有数据库系统上采用能高效管理多媒体数据时间传性的新管理工具。文中讨论了多媒体数据库系统中同步表示管理。当考虑延迟的影响时,提出了多种媒体数据流同步表示的原则。基于这些原则,可以设计出各种同步机制。 相似文献
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