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1.
Multimedia streaming applications are computation and network intensive that put a high demand on battery usage of mobile devices. Battery usage forms an important metric in user satisfaction, as increased battery consumption results in faster battery depletion and eventually leads to battery outage. In this paper, we propose an adaptation technique, referred as Battery-Aware Rate Adaptation (BARA) scheme, which adapts to the appropriate bit rate to prolong the battery lifetime. BARA considers both the wireless channel conditions, as well as the device’s battery level, to determine the best transmission rate for optimizing the mobile battery consumption. Actual experiment and simulation results corroborate that compared to the conventional techniques, BARA can save more than 40% of battery power, while extending the video playback time by 20%. 相似文献
2.
Multimedia Tools and Applications - This paper presents a categorization-based video streaming approach (CVS) to mitigate the Internet traffic in content delivery services. The CVS uses the... 相似文献
3.
Peer-to-Peer (P2P) live video streaming systems are known to suffer from intermediate attacks due to its inherent vulnerabilities. The content pollution is one of the common attacks that have received little attention in P2P live streaming systems. In this paper, we propose a modeling framework of content pollution in P2P live streaming systems. This model considers both unstructured and structured overlays, and captures the key factors including churns, user interactions, multiple attackers and defensive techniques. The models are verified with simulations and implemented in a real working system, Anysee. We analyze content pollution and its effect in live streaming system. We show that: (1) the impact from content pollution can exponentially increase, similar to the random scanning worms, leading to playback interruption and unnecessary bandwidth consumption; (2) content pollution is influenced by peer cooperation, peer degree and bandwidth in unstructured overlays, and topology breadth in structured ones; (3) the structured overlay is more resilient to content pollution; (4) a hybrid overlay result in better reliability and pollution resistance; (5) hash-based chunk signature scheme is most promising against content pollution. 相似文献
4.
针对C#语言中常用播放控制方法在视频动画的逆序及自定义播放时存在的较大问题,提出一种利用C#语言定义新视频文件、播放控制文件的方法.该方法创建继承于PictureBox的播放控件,从而轻松控制正序、逆序、自定义顺序播放及播放速度,可以使用简单的视频动画源(帧总数少)实现较为复杂的视频效果.实验结果表明,所设计的播放控制... 相似文献
5.
Multimedia Tools and Applications - Future Internet technology supports content adaptation to improve the QoS / QoE in a heterogeneous environment. The adaptation process removes partial data to... 相似文献
6.
传统的发送速率控制和播放速率控制由于各自的局限性,很难克服网络时延扰动对流媒体连续播放的影响.为了改善播放系统的性能,将双重控制策略应用到流媒体播放中,在发送端发送速率控制采用了内模控制器以克服传输延迟的影响,在接收端播放速率控制采用了简单的PID控制器,两种控制共同调节缓冲区长度.实验表明该方法能够处理传输时延和网络扰动引起的失步对播放的影响,缓冲区长度能够稳定在合理的区间,有效地防止缓冲区下溢造成的播放停顿以及缓冲区上溢造成的播放跳跃.发送速率变化率较小,有利于避免网络拥塞的发生.尤其是在网络出现大的扰动时,与其他方法相比,控制效果更加理想,播放更加流畅. 相似文献
8.
Multimedia Tools and Applications - Multimedia content has become widespread in network traffic. The high volume of data and flexibility must be addressed to guarantee the quality of experience... 相似文献
9.
This paper deals with monitoring user perception of multimedia presentations in a Universal Multimedia Access (UMA) enabled
system using objective no-reference (NR) metrics. These NR metrics are designed for an UMA-enabled system, in a novel architecture,
for a multimedia viewer. The first metric measures block-edge impairments in a video frame at the receiver end, based on the
observation that they occur in regions with low spatial activity. The second metric evaluates the quality of the reconstructed
video frame in the event of packet loss. Here, the structure of the artifact is itself exploited for the evaluation. Both
the metrics involve low computational complexity and are feasible for real-time monitoring of streaming video in a multimedia
communication scenario. Further, in rate-adaptive streaming of video, these metrics could serve as feedback parameters to
dynamically adapt the bit rates based on network congestion.
相似文献
10.
阐述以TMS320C64x为核心的DSP开发板IEKC64为开发工具,实现MPEG-4视频解码回放的方案。探讨了整个解码回放器的软件开发过程和步骤,论述了解码回放主程序的编程思路和说明了应用到的主要接口函数,以及解释解码回放程序的关键代码,对方案的进一步改进和完善提出了建议。 相似文献
11.
Internet视频传输是在Internet上以流媒体的形式传输视频信息。Internet视频传输技术是许多视频应用的基础,如视频点播、视频会议、远程教学等。由于Internet主要为突发性的数据传输设计,具有连续媒体流性质的视频在Internet中传输需要解决许多问题,例如视频数据的编码和压缩问题、传输的质量控制问题、同步控制问题等等。本文介绍了解决这些问题的一些关键技术。 相似文献
12.
网络视频应用增长迅猛,利用网络编码(NC)来提高网络吞吐量和传输可靠性进而改善视频流传输质量成为研究热点。针对如何优化网络编码进行视频流传输这一问题,必须要结合视频流自身特性作出改进并综合考虑所处的网络环境,才能充分发挥网络编码的优势。首先回顾了网络编码的基本概念和方法;然后对网络编码应用于视频流传输时需要考虑的视频业务特性,包括进行不等差错保护以优先保障重要等级视频数据包、降低数据包传输延迟以满足视频流实时性需求、增强网络差错恢复策略以提升传输可靠性等作了分析和归纳;接着阐述了基于网络编码的视频流传输策略在包括P2P、多源协作及内容中心网络等典型场景中的应用;最后对网络编码应用于视频流传输的研究趋势进行展望。 相似文献
13.
针对当前多平台多用户播放手机客户端直播、录像视频的需求,提出了一种手机移动客户端主动推送视频流到Darwin服务器直播、转播及录制供多平台多用户播放的解决方案。利用开源的流媒体服务器Darwin结合开源库mp4v2实现将手机客户端上传的视频流实时转发和录制;PC平台客户端由开源RTSP架构live555结合开源编解码库ffmpeg实现视频直播、点播播放。Web平台客户端由Html5技术实现视频点播,由插件实现直播。实验结果表明,该方案在现有的3G网络上具有较高的实时性和稳定性,视频具有较好的质量,能满足多平台多用户视频直播、点播播放的要求。 相似文献
14.
Object-oriented models are proposed for handling multimedia data: an object composition model and a playback model. The introduction of temporal glue, an extension of T EX's glue, and a mechanism for constructing composite multimedia data hierarchically, makes it quite easy to edit and reuse composite multimedia data. This paper explains the models and experimental results obtained for a set of C++ class libraries based on them. 相似文献
15.
This paper explores the performance of the emerging H.264/MVC standard for stereo video under various packetization schemes, encoding parameters and network conditions. An experimentation test-bed platform has been developed to support the multi session transmission approach for various video packetization options under various number of NAL units per frame. The paper presents measurements in terms of overhead as well as 3D video quality for sequences with different characteristics in terms of spatial resolution and motion. Extensive test-bed experiments indicate that the fragmentation of frames in more than one NAL units improves the perceived video quality measured objectively in terms of PSNR, VQM, SSIM for both base and non-base view as well as, subjectively in terms of 3D MOS. 相似文献
16.
This paper aims to reduce the amount of prebuffering required to ensure a maximum video continuity in streaming. Current approaches do this by slowing the playout frame rate of the decoder, this is known as adaptive media playout (AMP). However, doing this introduces playout distortion to the viewers as the video is played slower than its natural playout rate. We approach this by proposing a frame rate control scheme that jointly adjusts the encoder frame generation rate of the encoder and the playout frame rate of the decoder. In addition to using AMP to improve video continuity, we also allow the encoder to increase the encoder frame generation rate. This means the encoder will be sending more frames to the decoder to quickly increase the number of frames available at the playback buffer, thus lowering the chance of buffer underflow which causes discontinuity in video playback. At the same time, the increase in the number of frames at the playback buffer may mean that the decoder does not need to use AMP to delay the playback, thus lowering the playback distortion. However, the increase in encoder frame generation rate comes at a price because frame quality will need to decrease in order to meet the constraint on available network bandwidth. This implies that the scheme needs to find the optimal trade-off between frame quality, playout distortion and video continuity. To do that, we characterize the frame rate control problem using Lyapunov optimization. We then systematically derive the optimization policies. We also show that these policies can be decoupled into separate encoder and decoder optimization policies, thus allowing for a distributed implementation. Simulation results show significant reductions in the prebuffering requirements over a scheme that perform no frame rate control and lower playout distortions compared to the AMP schemes, while exhibiting a modest drop in frame quality. 相似文献
17.
详细分析了在视频监控系统中流媒体视频存储服务器的作用和功能,针对传统的流媒体定时长存储方式的不足提出了"固定空间存储"的新策略.该存储策略将总空间初始化为多个固定大小的数据文件,每个数据文件中存储的流媒体时长可能是不相同的.针对新存储策略下出现的"1秒尾巴","事件尾巴"等新问题,提出了解决方案."固定空间存储"策略虽然增加了索引的复杂度,但是有效避免了磁盘碎片的产生,对于改善流媒体视频存储服务器性能具有重要作用. 相似文献
18.
HTTP adaptive video streaming matches video quality to the capacity of a changing context. A variety of schemes that rely on buffer state dynamics for video rate selection have been proposed. However, these schemes are predominantly based on heuristics, and appropriate models describing the relationship between video rate and buffer levels have not received sufficient attention. In this paper, we present a QoE-aware video rate evolution model based on buffer state changes. The scheme is evaluated within a real-world Internet environment. The results of an extensive evaluation show an improvement in the stability, average video rate and system utilisation, while at the same time a reduction in the start-up delay and convergence time is achieved by the modified players. 相似文献
19.
Scalable streaming technology has been proposed to effectively support heterogeneous devices with dynamically varying bandwidth.
From the file system’s point of view, scalable streaming introduces another dimension of complexity in disk scheduling. Most
of the existing efforts on multimedia file systems are dedicated to I/O scheduling algorithm and data placement scheme that
efficiently guarantee I/O bandwidth. The important underlying assumption in these efforts is that most of the multimedia file
accesses are simple playback operations and therefore are sequential. However, this workload characteristic is not valid in
scalable streaming environment. In a scalable streaming environment, i.e., when only a subset of imagery is retrieved, the
playback does not necessarily coincide with the sequential access on the file. The current file structure and the file system
organization leaves much to be desired for supporting scalable streaming service. In this work, we propose a file system scheme,
Harmonic Placement to efficiently support scalable streaming. The basic idea of Harmonic placement is to cluster the frequently accessed layers
together to avoid unnecessary disk seeks. The data blocks are partitioned into two sets with respect to the layers: lower layers and upper layers. In Harmonic placement, the data blocks in the lower layers are placed with respect to their frame sequence and the
data blocks in the upper layers are clustered according to the layers they belong to. We develop elaborate performance models
for three different file system schemes: Progressive placement, Interleaved Placement and Harmonic Placement. We investigate the performance of the file server with different file system schemes. It was found that file system performance
is very sensitive to the file organization scheme. When most of the service requests are for low-quality video (e.g., 128
Kbits/s ISDN), Progressive placement scheme supports twice as many sessions as the Interleaved placement scheme. When most
of the service requests are for high-quality video (e.g., 1.5 Mbits/s MPEG-2 DVD quality), Interleaved placement can support
twice as many requests as Progressive placement. In both cases, Harmonic placement scheme yields the most promising performance.
Primitive version of this work has appeared on Proceedings of NOSSDAV ’06, Providence, Rhode Island, USA.
This work is in part funded by KOSEF throught National Research Lab (ROA-2007-000-200114-0) and by HY-SDR center at Hanyang
University. 相似文献
20.
Improving the effectiveness of learning when students observe video lectures becomes urgent with the rising advent of (web-based) video materials. Vital questions are how students differ in their learning preferences and what patterns in viewing video can be detected in log files. 相似文献
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