客观视频质量评估方法研究

介绍了三类客观视频质量评估方法的基本概念和实现方法;在此基础上,提出了一种基于H.264视频压缩算法的无参考评估的特征提取方法,并进行了实验论证,证明该方法能够有效结合编码算法的特性进行无参考视频质量评估;最后对视频质量评估方法的研究进行了总结和展望。     

视频质量的主客观评估方法研究

介绍了目前存在的各种视频质量的主、客观评估方法，并分析了其各自的优缺点和应用环境，最后展望了视频质量评估的研究热点。     

视频质量评估方法及规范

在视频业务应用(如视频电话)越来越广泛的今天,研究其质量评估方法具有十分重要的意义.本文结合ITU-T规范介绍了视频质量评估的研究背景和现状、评估方法、规范进展等,其中包含了一些还在研究的规范,使得对视频质量评估的国际规范进程有了一定了解,对以后的研究工作和业务的更好开展都有着促进作用.     

杂谈网络视频质量评价

针对网络视频质量相差较大,不能沿用传统的视频评价体系的问题,本文介绍了如何从多个角度评判网络视频的质量,拓展了网络视频的评价维度,提出了可能存在的问题以及容易引起质疑之处。     

网络视频主持人发展现状及趋势

2006年是网络视频的发展元年,网络视频作为一种崭新的媒体正式登台亮相。历经近十年的发展,网络视频节目已经具备了一定的规模和影响力,网络视频节目主持人也理应受到人们的关注。本文着重就目前网络视频节目主持人发展现状如何,存在哪些问题,下一步的发展趋势等进行分析,并试图找到目前网络视频主持人暴露的问题和解决的方法。     

采用模糊控制的网络视频质量评估方法

随着宽带通信技术的快速发展，网络视频业务迅猛普及。尽管人们可以方便收看网络视频，但是由于网络视频在传输过程中，会受到各种因素干扰，降低用户感受。本文针对网络视频质量评估问题，提出一种采用模糊控制的评估方法。首先分析了影响视频质量的网络、应用、图像等主要指标；通过仿真实验提取了不同情况下的影响指标，构造了三层模糊控制的评估模型；为了进一步提高方法的准确性，对每个模糊层赋予了不同权值，同时给出了两种去模糊化方法。该方法综合考虑了不同影响因素，适用性广，且具有较好的实用性。实验结果表明，该算法能够有效地提高视频质量评估的主客观相似度。      

学校网络视频监控系统设计

学校的安全是学校的一项重要工作,学校的视频监控系统在学校的安全体系中是非常重要的一环,根据学校的现状和实际情况,就如何在学校内实施视频监控进行了论述,对建立完善的学校监控系统提供帮助,在监控的发展过程中引入网络监控系统也是目前的发展趋势。     

面向超高清视频质量评估方法的初探

随着超高清视频时代的到来,视频作为对物理世界的数字还原,持续向更高清的画质和更实时的交互的目标演进。本文从第一性原理出发,分析了影响超高清视频质量的底层关键因素,介绍了ITU（国际电信联盟）最新的超高清流媒体视频质量评估方法,并对该评估方法进行了初步探索。结合笔者的工作实践提出一个面向机顶盒的超高清视频质量评估方法。     

三网融合下视频业务质量评估体系的研究

随着三网络融合的推进,由电信运营的IPTV、手机影视等视频业务必将加速发展,对视频业务的质量评估和质量保障将日趋紧迫。本文探讨了基于用户主观体验的的视频质量评估模型和指标体系,并根据IPTV业务的特点,提出了适用的关键指标和指标阈值。视频质量评估模型和指标是构建IPTV等视频业务监测手段的关键,是提升视频质量监测评估不可或缺的重要前提。     

Blind video quality assessment based on multilevel video perception

Blind video quality assessment (VQA) metrics predict the quality of videos without the presence of reference videos. This paper proposes a new blind VQA model based on multilevel video perception, abbreviated as MVP. The model fuses three levels of video features occurring in natural video scenes to predict video quality: natural video statistics (NVS) features, global motion features and motion temporal correlation features. They represent video scene characteristics, video motion types, and video temporal correlation variations. In the process of motion feature extraction, motion compensation filtering video enhancement is adopted to highlight the motion characteristics of videos so as to improve the perceptual correlations of the video features. The experimental results on the LIVE and CSIQ video databases show that the predicted video scores of the new model are highly correlated with human perception and have low root mean square errors. MVP obviously outperforms state-of-art blind VQA metrics, and particularly demonstrates competitive performance even compared against top-performing full reference VQA metrics.     

视频用户体验理论与实践

随着视频服务逐渐成为人们获取信息的主要途径之一,消费者对观看体验的要求不断提高,视频用户体验质量已经成为视频服务的主要竞争因素.首先对用户体验质量理论进行了系统的阐述,指出了用户体验质量与服务质量之间的差别和联系,同时给出了用户体验评价方法的主要步骤和视频质量评价的具体方法.进一步地,对我国现阶段视频用户体验评价研究及标准化的进展进行详细介绍,概括了目前我国视频服务的用户体验现状并给出了相关的改进方向意见.     

Binocular perception based reduced-reference stereo video quality assessment method

A new reduced-reference (RR) stereo video quality assessment method is proposed in this paper by considering temporal characteristics of video and binocular perception in human visual system (HVS). Firstly, motion intensity is utilized to extract RR frames for the purpose of temporal characteristics in stereo video. Secondly, according to internal generative mechanism of HVS, fusion and rivalry in the process of binocular perception is modeled, and the RR frames are divided into binocular fusion portion and binocular rivalry portion. Then, RR frame quality indicators are computed for these two portions. Finally, the RR frame quality indicators of the original and distorted frames are compared. A temporal pooling strategy is utilized on these quality indicators to obtain final stereo video quality score, where the motion intensity is used for toning the pooling parameters. Experimental results show that the proposed method has better performances when compared to other state-of-the-art quality assessment methods.     

基于运动和视差信息的立体视频质量客观评价

在研究人类 立体视觉特性及现有立体图像/视频质量评价算法的基础上,提出了一种基于运动信息和视 差信息的立 体视频质量的客观评价方法。方法包括视频质量评价(VQA)和视频立体感评价(VSSA)两个指 标,其中VQA的估计基于梯度的结构相似度(GSSIM) 算法,并充分考虑了帧内的亮度信息和结构信息、帧间运动信息以及人眼的感知特性对视频 质量的影响, 特别是根据人类的视觉特性,对左右视点的质量赋予了不同的权重;VSSA的估计 是通过计算参考 视频的绝对差值图和降质视频的绝对差值图之间的峰值信噪比(PSNR)而得到。实验结果表明,本文方法对基于H.264 编码的失真视频的评价结果与主观测试有较高的一致性,很好地体现人眼的视觉特性。     

基于半马尔科夫决策过程的视频传输拥塞控制算法

针对传输控制协议(TCP, transmission control protocol)的拥塞控制算法未能满足视频传输质量要求的问题,提出了一种基于半马尔科夫决策过程的视频传输拥塞控制算法。首先, 为克服目前基于峰值信噪比的视频质量评估方法实时性低的缺点,设计了一种可在线运行的无参考视频质量评估方法。其次,根据接收端视频质量的反馈,采用半马尔科夫决策过程对拥塞控制进行建模,并通过求解此模型得到拥塞控制参数的调整策略。仿真实验结果表明,与目前典型的拥塞控制算法相比,该算法不但具备更好的TCP友好性,而且有效地提高了解码后视频序列的主观和客观质量。     

Content-adaptive bitstream-layer model for coding distortion assessment of H.264/AVC networked video

Bitstream-layer models are designed to use the information extracted from both packet headers and payload for real-time and non-intrusive quality monitoring of networked video. This paper proposes a content-adaptive bitstream-layer (CABL) model for coding distortion assessment of H.264/AVC networked video. Firstly, the fundamental relationship between perceived coding distortion and quantization parameter (QP) is established. Then, considering the fact that the perceived coding distortion of a networked video significantly relies on both the spatial and temporal characteristics of video content, spatial and temporal complexities are incorporated in the proposed model. Assuming that the residuals before Discrete Cosine Transform (DCT) keep to the Laplace distribution, the scale parameters of the Laplace distribution are estimated utilizing QP and quantized coefficients on the basis of the Parseval theorem firstly. Then the spatial complexity is evaluated using QP and the scale parameters. Meanwhile, the temporal complexity is obtained using the weighted motion vectors (MV) considering the variations in temporal masking extent for high motion regions and low motion regions, respectively. Both the two characteristics of video content are extracted from the compressed bitstream without resorting to a complete decoding. Using content related information, the proposed model is able to adapt to different video contents. Experimental results show that the overall performance of CABL model significantly outperforms that of the P.1202.1 model and other coding distortion assessment models in terms of widely used performance criteria, including the Pearson Correlation Coefficient (PCC), the Spearman Rank Order Correlation Coefficient (SROCC), the Root-Mean-Squared Error (RMSE) and the Outlier Ratio (OR).     

基于水印的视频质量评价研究

在数字媒体传输系统中会出现失真，所以在接收端对数据媒体进行质量评价是重要的。介绍基于水印的图像和视频传输质量评价方法。首先介绍了质量评价的特性、典型模型，然后详细讨论了水印应用、存在的问题等，最后讨论了发展的方向。     

MDVQM: A novel multidimensional no-reference video quality metric for video transcoding

In this paper, we study the impact of quantization, frame dropping and spatial down-sampling on the perceived quality of compressed video streams. Based on the analysis of quality ratings obtained from extensive subjective tests, we propose a no-reference metric (named MDVQM) for video quality estimation in the presence of both spatial and temporal quality impairments. The proposed metric is based on the per-pixel bitrate of the encoded stream and selected spatial and temporal activity measures extracted from the video content. All the values required to compute the proposed video quality metric can be obtained without using the original reference video which makes the metric for instance useful for making transcoding decisions in a wireless video transmission scenario. Different from comparable metrics in the literature, we have also considered the case when both frame rate and frame size are changed simultaneously. The validation results show that the proposed metric provides more accurate estimation of the video quality than the state of the art metrics.     

No-reference pixel based video quality assessment for HEVC decoded video

This paper proposes a No-Reference (NR) Video Quality Assessment (VQA) method for videos subject to the distortion given by the High Efficiency Video Coding (HEVC) scheme. The assessment is performed without access to the bitstream. The proposed analysis is based on the transform coefficients estimated from the decoded video pixels, which is used to estimate the level of quantization. The information from this analysis is exploited to assess the video quality. HEVC transform coefficients are modeled with a joint-Cauchy probability density function in the proposed method. To generate VQA features the quantization step used in the Intra coding is estimated. We map the obtained HEVC features using an Elastic Net to predict subjective video quality scores, Mean Opinion Scores (MOS). The performance is verified on a dataset consisting of HEVC coded 4 K UHD (resolution equal to 3840 × 2160) video sequences at different bitrates and spanning a wide range of content. The results show that the quality scores computed by the proposed method are highly correlated with the mean subjective assessments.     

A method of image quality assessment for compressive sampling video transmission

Based on compressive sampling transmission model, we demonstrate here a method of quality evaluation for the reconstruction images, which is promising for the transmission of unstructured signal with reduced dimension. By this method, the auxiliary information of the recovery image quality is obtained as a feedback to control number of measurements from compressive sampling video stream. Therefore, the number of measurements can be easily derived at the condition of the absence of information sparsity, and the recovery image quality is effectively improved. Theoretical and experimental results show that this algorithm can estimate the quality of images effectively and is in well consistency with the traditional objective evaluation algorithm.