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在保证可分级视频流延时要求的情况下,为了有效提高其在无线网络中传输的带宽利用率,提出了一种新的调度方案。该方案利用可分级视频流的分解特性以及不同的流采用不同的调度周期来提高带宽利用率。数值结果表明该方案非常有效,特别是当物理层传输速率较大的时候,其有效性更加明显。 相似文献
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In multi-user video (MUV) delivery scenarios,the available resources of receiver devices,such as processing capability,link packet error rate (PER),and bandwidth,are usually different.We propose a relay-assisted hierarchical adaptation (RHA) scheme to maximize the total perceptual quality of all users when transmitting video streams coded via scalable video coding (SVC).First,MUV bitstreams are adaptively extracted under the constraints of network bandwidth and individual decoding capacity.Next,the relay links are introduced as substitutes of possible bad direct links for packets retransmissions.Approximately equal opportunity of transmission is allocated to each stream while the packets inside a stream are scheduled according to their priorities.The priorities are determined by the links states and packets loss distortions.Simulation results show that our RHA scheme has significant performance improvements compared with other schemes. 相似文献
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Recent years have seen intensive investigations of Periodic Broadcast, an attractive paradigm for broadcasting popular videos. In this paradigm, the server simply broadcasts segments of a popular
video periodically on a number of communication channels. A large number of clients can be served simultaneously by tuning
into these channels to receive segments of the requested video. A playback can begin as soon as a client can access the first
segment. Periodic Broadcast guarantees a small maximum service delay regardless of the number of concurrent clients. Existing
periodic broadcast techniques are typically evaluated through analytical assessment. While these results are good performance
indicators, they cannot demonstrate subtle implementation difficulty that can prohibit these techniques from practical deployment.
In this paper, we present the design and implementation of a video broadcasting system based on our periodic broadcast scheme
called Striping Broadcast. Our experience with the system confirms that the system offers a low service delay close to its analytical guaranteed delay
while requiring small storage space and low download bandwidth at a client. 相似文献
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An important research issue in video streaming is how to efficiently utilize the network resources to provide clients instant
access to multiple video objects. Caching strategy and transmission scheme are the two essential points inside the video streaming
framework. Recent research efforts on them are not sufficient due to their inflexible support for scalable encoded video streams
and heterogeneous requests from clients. In this paper, we propose an optimized caching strategy (OCS) and a scalable transmission
scheme (STS) for scalable coded video streaming. By exploring the characteristics of video streaming workload and system design
objectives, OCS and STS work efficiently to minimize both network bandwidth cost and user access latency. Firstly, we analyze
the caching problem for the proxy-assisted video streaming system and derive a maneuverable caching scenario. Secondly, we
develop an efficient transmission scheme for scalable coded videos. Thirdly, we formulate a multi-objective optimization model
with closed-form expressions to obtain the optimized caching strategy. Finally, with designed algorithms, an excellent compromise
between two competing objectives (minimizing the bandwidth cost and the access latency) is achieved. We start our evaluation
by studying the optimized caching strategy for a single video object. Then we apply the strategy to multiple video objects
and illustrate the tradeoff between the optimization objectives. Our evaluation results show that compared with other caching
strategies, the proposed optimized scalable caching strategy can achieve a significant reduction in bandwidth cost with even
a small proxy cache size. Meanwhile, the best performance (in terms of bandwidth cost) is obtained together with the proposed
scalable batch-patching transmission scheme.
相似文献
Kenneth OngEmail: |
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Scalable video quality enhancement refers to the process of enhancing low quality frames using high quality ones in scalable video bitstreams with time-varying qualities. A key problem in the enhancement is how to search for correspondence between high quality and low quality frames. Previous algorithms usually use block-based motion estimation to search for correspondences. Such an approach can hardly estimate scale and rotation transforms and always introduces outliers to the motion estimation results. In this paper, we propose a pixel-based outlier-free motion estimation algorithm to solve this problem. In our algorithm, the motion vector for each pixel is calculated with respect to estimate translation, scale, and rotation transforms. The motion relationships between neighboring pixels are considered via the Markov random field model to improve the motion estimation accuracy. Outliers are detected and avoided by taking both blocking effects and matching percentage in scaleinvariant feature transform field into consideration. Experiments are conducted in two scenarios that exhibit spatial scalability and quality scalability, respectively. Experimental results demonstrate that, in comparison with previous algorithms, the proposed algorithm achieves better correspondence and avoids the simultaneous introduction of outliers, especially for videos with scale and rotation transforms. 相似文献
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A video streaming proxy server needs to handle hundreds of simultaneous connections between media servers and clients. Inside,
every video arrived at the server and delivered from it follows a specific arrival and delivery schedule. While arrival schedules
compete for incoming network bandwidth, delivery schedules compete for outgoing network bandwidth. As a result, a proxy server
has to provide sufficient buffer and disk cache for storage, together with memory space, disk space and disk bandwidth. In
order to optimize the throughput, a proxy server has to govern the usage of these resources. In this paper, we first analyze
the property of a traditional smoothing algorithm and a video staging algorithm. Then we develop, based on the smoothing algorithm,
a video staging algorithm for video streaming proxy servers. This algorithm allows us to devise an arrival schedule based
on the delivery schedule. Under this arrival and delivery schedule pair, we can achieve a better resource utilization rate
gracefully between different parameter sets. It is also interesting to note that the usage of the resources such as network
bandwidth, disk bandwidth and memory space becomes interchangeable. It provides the basis for inter-resource scheduling to
further improve the throughput of a video streaming proxy server system.
相似文献
Daniel P. K. LunEmail: |
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WANG Guijin ZHANG Qian ZHU Wenwu & LIN Xinggang . Department of Electronic Engineering Tsinghua University Beijing China . Microsoft Research Asia Beijing China Correspondence should be addressed to Wang Guijin 《中国科学F辑(英文版)》2004,47(2):246-259
With the growth of the Internet and abundant network resources, video streaming is becoming one of the increasingly important Internet applications. However, the current IP-based network provides only a single class best effort service. Video packet can be regarded as a packet loss by the video decoder either due to network congestion or due to exceeding the maximum delay threshold. It remains an open challenging task as to how to cope with the packet loss in the video streaming over the Int… 相似文献
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针对现有多视点立体视频FGS(Fine-Granular-Scalability)可分级方案编码效率低的问题进行改进,充分利用相邻视点之间的相似性,适应解码端质量优先或视点优先的不同需求,提出一种折衷方案,其中分I、P、B帧三种情况,以中间视点作为基本层进行编码,其他视点均预测自相邻视点部分恢复的FGS增强层,以此为基础产生当前视点的FGS增强层。实验证明,该方案具有更为灵活、广泛的可分级性能,更能适应用户对视点图像质量和立体观感的需求。 相似文献
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Pradeep K. Atrey Wei-Qi Yan Mohan S. Kankanhalli 《Multimedia Tools and Applications》2007,34(1):107-135
This paper addresses the problem of ensuring the integrity of a digital video and presents a scalable signature scheme for
video authentication based on cryptographic secret sharing. The proposed method detects spatial cropping and temporal jittering
in a video, yet is robust against frame dropping in the streaming video scenario. In our scheme, the authentication signature
is compact and independent of the size of the video. Given a video, we identify the key frames based on differential energy
between the frames. Considering video frames as shares, we compute the corresponding secret at three hierarchical levels.
The master secret is used as digital signature to authenticate the video. The proposed signature scheme is scalable to three
hierarchical levels of signature computation based on the needs of different scenarios. We provide extensive experimental
results to show the utility of our technique in three different scenarios—streaming video, video identification and face tampering.
相似文献
Mohan S. KankanhalliEmail: |
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基于MPEG-4标准FGS可分级技术,提出一种将FGS可分级、视点可分级相结合的多视点立体视频可分级算法。该算法中,中间视点作为基本层进行编码,各视点均预测自中间视点,并产生各相应视点的FGS增强层。编码器结构中,分为I、P、B帧三种情况进行讨论,并针对这三种情况进行改进。所提方案具有灵活、广泛的可分级性能,能适应多种不同的传输需求。实验结果验证了该方案的多视点可分级性。 相似文献
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基于可伸缩视频编码的率失真优化编码算法* 总被引:1,自引:0,他引:1
可伸缩视频编码(SVC)可实现视频流空间、时间和信噪比的完全伸缩,但在差错信道上传输容易引起误差扩散,为此提出一种基于SVC的率失真优化编码算法。该算法在分析了差错信道下传输可伸缩视频流误差扩散失真的基础上,在率失真优化模型中引入时间和信噪比分级的误差分级参数,并根据信道状态自适应地确定宏块编码模式。该算法能够有效地抑制误码在各分层的扩散,提高了可伸缩视频流的鲁棒性。仿真结果表明,算法与以往的算法相比具有更好的抗误码性能,适合视频数据在差错信道上的传输。 相似文献
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可伸缩视频码流提取使视频流能够适应不同带宽的网络带宽和不同处理能力的终端。提出一种基于镜头描述的视频码流提取框架,通过离线预处理获得原始视频镜头的描述,建立参考帧二叉树,基于码流分析和镜头描述实现可伸缩码流提取。实验表明该方法可以实现快速码流提取,在不损失编码效率的前提下保证视觉质量。 相似文献
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Nicolas Moënne-Loccoz Bruno Janvier Stéphane Marchand-Maillet Eric Bruno 《Multimedia Tools and Applications》2006,31(3):309-325
Video document retrieval is now an active part of the domain of multimedia retrieval. However, unlike for other media, the management of a collection of video documents adds the problem of efficiently handling an overwhelming volume of temporal data. Challenges include balancing efficient content modeling and storage against fast access at various levels. In this paper, we detail the framework we have built to accommodate our developments in content-based multimedia retrieval. We show that not only our framework facilitates the development of processing and indexing algorithms but it also opens the way to several other possibilities such as rapid interface prototyping or retrieval algorithm benchmarking. Here, we discuss our developments in relation to wider contexts such as MPEG-7 and the TREC Video Track.This work is funded by EU-FP6 IST-NoE SIMILAR () and the Swiss NCCR IM2 (Interactive Multimodal Information Management). 相似文献
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Filippo Furfaro Giuseppe M. Mazzeo Domenico Saccà Cristina Sirangelo 《Knowledge and Information Systems》2008,15(3):335-380
Hierarchical binary partitions of multi-dimensional data are investigated as a basis for the construction of effective histograms.
Specifically, the impact of adopting lossless compression techniques for representing the histogram on both the accuracy and
the efficiency of query answering is investigated. Compression is obtained by exploiting the hierarchical partition scheme
underlying the histogram, and then introducing further restrictions on the partitioning which enable a more compact representation
of bucket boundaries. Basically, these restrictions consist of constraining the splits of the partition to be laid onto regular
grids defined on the buckets. Several heuristics guiding the histogram construction are also proposed, and a thorough experimental
analysis comparing the accuracy of histograms resulting from combining different heuristics with different representation
models (both the new compression-based and the traditional ones) is provided. The best accuracy turns out from combining our
grid-constrained partitioning scheme with one of the new heuristics. Histograms resulting from this combination are compared
with state-of-the-art summarization techniques, showing that the proposed approach yields lower error rates and is much less
sensitive to dimensionality, and that adopting our compression scheme results in improving the efficiency of query estimation. 相似文献
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Scalable video coding (SVC) is a newly emerging standard to be finalized as an extension of H.264/AVC. The most attractive
characters in SVC are the inter layer prediction techniques, such as Intra_BL mode. But in current SVC scheme, a uniform up-sampling
filter (UUSF) is employed to magnify all components of an image, which will be very inefficient and result in a lot of redundant
computational complexity. To overcome this, we propose an efficient component-adaptive up-sampling filter (CAUSF) for inter
layer interpolation. In CAUSF, one character of human vision system is considered, and different up-sampling filters are assigned
to different components. In particular, the six-tap FIR filter used in UUSF is kept and assigned for luminance component.
But for chrominance components, a new four-tap FIR filter is used. Experimental results show that CAUSF maintains the performances
of coded bit-rate and PSNR-Y without any noticeable loss, and provides significant reduction in computational complexity.
Supported by China Postdoctoral Science Foundation (Grant No. 20080430454), the Key Laboratory of Geo-informatics of State
Bureau of Surveying and Mapping (Grant No. 200834), the National High-Tech Research and Development Program of China (Grant
No. 2007AA12Z151), and the National Basic Research Program of China (Grant No. 2006CB701303) 相似文献