共查询到19条相似文献,搜索用时 171 毫秒
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由于无线网络带宽不足,不能满足高质量视频的传输要求,终端用户往往会遭受频繁的播放中断.为了解决上述问题,一种可能的办法是利用终端的多模特性并发地多路传输视频流.多路传输视频流的关键技术之一是分组调度算法,即将视频分组分配到适合的接口进行传输.本文研究了一种多路传输可伸缩编码视频流下基于质量驱动的分组调度算法.为了最大限度地提升接收端的视频质量,该分组调度算法考虑了接入网络的特性以及视频帧的特征.在本文中,视频数据包调度的问题建模为一个受限多重背包问题,而这个问题是已知为NP-hard的.然后,提出了一种分组调度算法,将视频分组调度到合适的接入网进行传输.在NS-2仿真软件中使用真实的视频trace文件去验证该算法利用多模终端传输可伸缩编码视频的性能.仿真结果表明,分组调度算法在PSNR上优于速率控制算法和传统的round-robin算法. 相似文献
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无线接入和视频应用的日益普及使无线视频传输成为新的研究热点。随着研究的深入,跨层优化和不平等保护的思想逐渐为大多数研究所采纳。基于IEEE 802.11e协议研究无线视频传输质量的改善方法,提出一种综合考虑视频帧优先级和相对排队延时、适用于优先级数目有限的任何编码算法的视频帧调度算法。仿真实验结果表明,提出的算法具有远高于标准EDCA及其已有改进方案的平均峰值信噪比。 相似文献
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在没有服务质量保证的无线传输环境中,按照传统视频编码标准压缩的码流很容易遭到破坏,这在Ⅰ帧中尤为突出.因此需要对传统视频压缩标准加以改进以提高在无线传输环境中的自身容错性能.针对这一问题提出了一种用于提高视频流Ⅰ帧容错能力的算法.该算法首先对视频流中不同部分对发生在自身的码位错误所引起误差传播的敏感度进行分析,然后以此分析结果和Ⅰ帧重建中码流信息的不同重要性作为决定Ⅰ帧码流中重要信息的原则,最终通过对这些Ⅰ帧中的重要信息加以保护、提取和集中,以减少发生帧内误差传播范围.通过H.263+baseline测试码流在加性高斯白噪声无线信道仿真实验的结果可以证明,该算法在增加少量冗余信息和计算复杂度的情况下,相比参考算法在主观和客观质量上都有较大幅度的提高. 相似文献
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在没有服务质量保证的无线传输环境中,按照传统视频编码标准压缩的码流很容易遭到破坏,这在I帧中尤为突出。因此需要对传统视频压缩标准加以改进以提高在无线传输环境中的自身容错性能。针对这一问题提出了一种用于提高视频流I帧容错能力的算法。该算法首先对视频流中不同部分对发生在自身的码位错误所引起误差传播的敏感度进行分析,然后以此分析结果和I帧重建中码流信息的不同重要性作为决定I帧码流中重要信息的原则,最终通过对这些I帧中的重要信息加以保护、提取和集中,以减少发生帧内误差传播范围。通过H.263+baseline测试码流在加性高斯白噪声无线信道仿真实验的结果可以证明,该算法在增加少量冗余信息和计算复杂度的情况下,相比参考算法在主观和客观质量上都有较大幅度的提高。 相似文献
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基于调度集合的多播单播数据联合调度算法 总被引:1,自引:0,他引:1
首先定义和分析了IEEE802.16e无线城域网中的一个新问题,即如何在保证移动终端服务质量的前提下,通过合理地调度终端的单播业务和多播业务来降低终端能耗.针对该问题,提出一种基于调度集合的联合调度算法(scheduling set based integrated scheduling,简称SSBIS).SSBIS算法将所有移动终端划分到多播调度集合或单播调度集合中,并利用多播数据的传输特点,在多播数据传输的相邻时隙内发送多播调度集合中所有终端的单播数据,而对于单播调度集合中的终端,则通过凸优化方法求得使终端休眠时间最长的单播业务调度方案,以达到降低终端能耗的目的.仿真实验显示,SSBIS算法在满足移动终端的最小数据速率要求的同时,可以明显地降低终端能耗. 相似文献
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针对瓶颈链路中视频带宽分配不均导致的用户QoE不公平以及带宽利用率低的问题,提出了一种基于联邦深度强化学习的分布式视频流公平调度策略。该策略能够根据客户端网络状态和视频QoE等级动态生成带宽分配权重因子,服务器端的拥塞控制算法则根据带宽分配权重因子为瓶颈链路中的每个视频流分配带宽,以保障瓶颈链路中视频流的公平传输。每个视频终端都运行一个带宽分配agent,且多个agent以联邦学习的方式周期性地训练,以便代理模型能够快速收敛。带宽分配agent通过共识机制同步联邦训练参数,实现了在异步播放请求条件下带宽分配agent模型参数的分布式聚合,并确保了agent模型参数的安全共享。实验结果表明,与最新方案相比,提出策略在QoE公平性和整体QoE效率方面分别提高了10%和7%,这表明提出策略在解决视频流带宽分配不均问题和提升用户体验方面具有潜力和有效性。 相似文献
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在ZigBee无线图像传输中创新地设计了链路建立、唤醒机制及数据帧跨层传输方式,以及相应的软件。测试结果表明,该设计能有效提高图像数据传输的可靠性和效率。该方案稳定、切实可行,在无线数据传输领域具有广阔的应用前景。 相似文献
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Minoo Kargar Bideh Behzad Akbari Abdollah Ghaffari Sheshjavani 《Peer-to-Peer Networking and Applications》2016,9(2):436-448
In mesh-based Peer-to-Peer (P2P) live video streaming systems packet scheduling is an important factor in overall video playback quality. In mesh based P2P video streaming systems, each video sequence is divided into chunks, which are then distributed by multiple suppliers to the receivers. The suppliers need to be coordinated by the receiver through specifying a transmission schedule for each of them. Many previous studies on scheduling of P2P streaming tend to mainly focus on networking issues which strongly depend on a particular P2P architecture such as tree or mesh. These algorithms suffer from some design issues: 1) they are too complex to deploy, 2) they do not take video characteristics into account and 3) they do not have sender-side transmission policy. To address all three of these problems, we propose a new chunk scheduling scheme which consists of two parts: i) receiver-side scheduler and ii) sender-side transmission order scheme. The proposed receiver-side scheduler considers the contribution level of each video frame as well as the frame’s urgency in order to define a priority for each video frame. It attempts to request frames with highest priority from peers which can deliver them in a shorter time. We also design a new chunk transmission order scheme that decides which requested chunk will be sent out first based on its importance to the requesting neighbor. Our simulation results show that the proposed scheduling scheme improves the overall quality of the perceived video in mesh-based P2P video streaming architectures substantially. 相似文献
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Packet scheduling is a critical component in multi-session video streaming over mesh networks. Different video packets have different levels of contribution to the overall video presentation quality at the receiver side. In this work, we develop a fine-granularity transmission distortion model for the encoder to predict the quality degradation of decoded videos caused by lost video packets. Based on this packet-level transmission distortion model, we propose a content-and-deadline-aware scheduling (CDAS) scheme for multi-session video streaming over multi-hop mesh networks, where content priority, queuing delays, and dynamic network transmission conditions are jointly considered for each video packet. Our extensive experimental results demonstrate that the proposed transmission distortion model and the CDAS scheme significantly improve the performance of multi-session video streaming over mesh networks. 相似文献
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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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The encoded video bitstreams have to suffer from quality degradation when transmitted over unreliable channels. In this paper, a novel flexible macroblock ordering (FMO)-based error-resilient scheme is proposed to cope with this problem, which is aimed at the video surveillance scenarios. This scheme could not only meet the need of prioritized transmission environment, but also take advantage of FMO’s inherent error-resilient function. A motion region extraction algorithm is first advised and utilized, and each motion region’s error sensitivity is then estimated based on both pictures’ features and transmission condition. According to the error sensitivity value, the optimal FMO encoding mode for each motion region is selected, which enables the error-resilient intensity to be more adaptive. The intra refresh enhancement is introduced at the same time to further improve the error-resilient performance of the proposed FMO structure. To reduce the complexity, most information for calculations is derived from the encoding process. Experiments demonstrate that the proposed scheme performs better than the conventional schemes, and improves the video quality efficiently. 相似文献
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针对目前智能手机定位监控和实时视频指挥系统分散无法整合的问题,在Android平台上提出一种融合GPS定位数据基于无线网络的流媒体通信架构。采用H.264格式和基于RTP/RTCP协议进行流媒体的压缩、分包和管理,把GPS定位等复合信息存储在RTP扩展包内与音频数据组包传输,智能终端既能完成视频通话也能同步传输和展示GPS定位信息。实践证明融合GPS信息对音视频传输延迟影响小、集成度高,并可扩展融合图片和文字数据,应用广泛。 相似文献
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We propose a novel data embedding scheme for fractional-pixel based video coding algorithms such as H.263 and MPEG-2. By modifying the motion estimation procedure at fractional-pixel precision, two bits data can be embedded in a motion vector (MV) for an inter-mode coded macroblock (MB). For half-pixel precision motion estimation, the resulted bitstream is compatible with the current video coding standards. Performance of the proposed data embedding scheme in terms of compression efficiency is also studied. As an application example of the proposed data embedding scheme, an error-resilient video coding scheme is also presented where some redundant information, which is used to protect MVs and coding modes of MBs in one frame, is embedded into the MVs in the next frame. When errors occur in one group of blocks (GOB), the decoder can exactly recover the MVs of the corrupted GOB if the next frame can be received correctly. Simulations show that the proposed scheme has better performance than standard H.263 coding scheme for transmission over error-prone channels 相似文献
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结合运动搜索的混合域I帧错误隐藏 总被引:1,自引:0,他引:1
在数字广播电视,移动视频终端和视频电话中错误恢复是一个必须的部分。最新的视频压缩标准H.264/AVC为一系列视频消费电子应用提供更高的编码效率。但是H.264的视频流仍然容易发生传输错误。根据H.264的编码特性和网络特性众多的错误隐藏方法已经被提出。在H.264中I帧的错误隐藏尤为重要,因为I帧的错误会通过运动估计传播到后续的P帧或B帧中。结合时域和空域错误隐藏算法,本文提出一种用于I帧的低复杂度自适应空域/时域运动估计算法。实验结果显示,本文提出的算法的视觉效果和PSNR都优于原算法。 相似文献