Quality assessment of in-the-wild videos is a challenging problem because of the absence of reference videos and shooting distortions. Knowledge of the human visual system can help establish methods for objective quality assessment of in-the-wild videos. In this work, we show two eminent effects of the human visual system, namely, content-dependency and temporal-memory effects, could be used for this purpose. We propose an objective no-reference video quality assessment method by integrating both effects into a deep neural network. For content-dependency, we extract features from a pre-trained image classification neural network for its inherent content-aware property. For temporal-memory effects, long-term dependencies, especially the temporal hysteresis, are integrated into the network with a gated recurrent unit and a subjectively-inspired temporal pooling layer. To validate the performance of our method, experiments are conducted on three publicly available in-the-wild video quality assessment databases: KoNViD-1k, CVD2014, and LIVE-Qualcomm, respectively. Experimental results demonstrate that our proposed method outperforms five state-of-the-art methods by a large margin, specifically, 12.39%, 15.71%, 15.45%, and 18.09% overall performance improvements over the second-best method VBLIINDS, in terms of SROCC, KROCC, PLCC and RMSE, respectively. Moreover, the ablation study verifies the crucial role of both the content-aware features and the modeling of temporal-memory effects. The PyTorch implementation of our method is released at https://github.com/lidq92/VSFA.

Quality Assessment of In-the-Wild Videos

从个人PC到企业级应用 Windows在PC市场的牢固地位在为微软赢得丰厚回报的同时，也似乎使微软被Windows“套牢”在PC市场。微软显然不甘于这种定位，于是越来越积极主动地拓展着市场广阔的企业级市场。事实上，从WindowsNT4.0开始拓展企业级应用市场，微软对企业级市场的脚步就从来没有放缓过。以下事实可证：

Microsoft：微软“变脸”

It is generally recognized that severe video distortions that are transient in space and/or time have a large effect on overall perceived video quality. In order to understand this phenomena, we study the distribution of spatio-temporally local quality scores obtained from several video quality assessment (VQA) algorithms on videos suffering from compression and lossy transmission over communication channels. We propose a content adaptive spatial and temporal pooling strategy based on the observed distribution. Our method adaptively emphasizes “worst” scores along both the spatial and temporal dimensions of a video sequence and also considers the perceptual effect of large-area cohesive motion flow such as egomotion. We demonstrate the efficacy of the method by testing it using three different VQA algorithms on the LIVE Video Quality database and the EPFL-PoliMI video quality database.

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Video Quality Pooling Adaptive to Perceptual Distortion Severity

The ITU-T draft H.264 video coding standard has been designed enabling a new generation of digital video applications.While the basic coding framework of the standard is similar to that of currently popular video standard, H.264 includes many coding features not present in earlier standard. We firstly introduces the important features and key techniques in H.264. Then, we presents the performance of it. Study on the new generation ITU-T draft H.264 is of great importance in application field.

Overview of the H.264 / AVC Video Coding Standard

Based on the study of Fast Block Matching Algorithms (FBMA) for motion estimation, this paper attempts to make an overview of fast block matching algorithms First, it describes the theory of motion estimation Then it reveals the key technique for improving the algorithm efficiency, analyses the correlative algorithms and compares their properties At the end, the future trend of motion estimation research is discussed

Block Matching Algorithms for Motion Estimation

Objective video quality evaluation incorporates spatial and temporal degradation effects to calculate quality grade for each video frame alone, as well as the overall quality grade for the whole sequence. Distortion visibility depends not only on the level of degradation but also on video content and viewer's preferences. Temporal pooling is a method that collapses series of frame quality scores to one quality score for whole video sequence and it should be aware of an influence of the video quality variation to the human overall judgments of quality. In this paper six pooling methods applied to five objective video quality metrics are compared. The best prediction capability has been obtained by those pooling methods that reflect two phenomena: a recency effect and the worst quality section influence. Moreover, the statistics of individual frames scores tends to be of high importance and strongly influences pooling method capabilities.

Influence of temporal pooling method on the objective video quality evaluation

Virtualization enables installation and running of multiple virtual machines on the same computer system. Operating system that communicates directly with hardware is known as the host operating system whereas virtual operating systems have all the features of a real operating system, but they run inside the host operating system. A virtual machine is separated from the computer hardware resources and it runs on the emulated hardware. Performance of the virtual operating system running on the same computer system hardware depends on the performance of the host operating system. In this paper we study how different host operating systems influence virtual machine performance. Windows XP®, Windows Vista™ and Windows 7™ are used as host operating systems using Windows Vista as a virtual operating system. Performance measurement of the virtual operating system is done in the same controlled conditions for all three host operating systems using benchmark applications. Performance measurement results show that the virtual operating system has the best performance when Windows 7 is used as the host operating system.

Impact of the host operating systems on virtual machine performance

Worldwide Interoperability for Microwave Access (WiMAX) is a new wireless broadband technology based on IEEE 802.16 standard. Its radio interface enables high data transmission rates in the frequency range of 2-11 GHz and 10-66 GHz. The existing empirical models, most often used for path loss prediction, are mostly developed for frequencies below 2 GHz. This paper analyses empirical models suitability for the receiving power prediction in complex urban environments for a WiMAX system working at 3.5 GHz. Predicted values have been compared with values measured in urban and suburban areas as well as in rural surrounding of city Osijek in Croatia. Received power prediction is obtained by four empirical propagation models: SUI C, COST 231-Hata, Macro model and Ericsson model. Analysis is made separately for locations with urban, suburban and rural propagation conditions.

Receiving Power Level Prediction for WiMAX Systems on 3.5 GHz

In modern communication systems with video transmission as their important part, objective video quality evaluation is necessary in the QoS (quality of service) assessment. This article analyzes spatial masking effects on the visibility of compression artifacts, and consequently its importance in the digital video quality evaluation process. Luminance masking and texture masking are mechanisms referred to as having a great influence on the objective quality metrics fidelity. Eleven maskers (6 for luminance and 5 for texture) are constructed, and their effectiveness is analyzed first for each masker alone, and then for combinations of luminance and texture maskers. By nonlinear addition of luminance and texture maskers used in a simple pixel-based quality metric a high correlation with subjective mean opinion scores (MOS) is obtained (Pearson correlation coefficient higher than 0.95).

Spatial Masking and Perceived Video Quality in Multimedia Applications

This paper proposes a novel video quality metric — Foveation-based content Adaptive Structural SIMilarity index — FA-SSIM, which combines the Structural SIMilarity index (SSIM) and the foveation-based sensitivity function S f . Function S f is based on the Human Visual System (HVS) behavior that spatial resolution is the highest around the point of fixation and decreases rapidly with increasing eccentricity. Furthermore, S f captures effect of further spatial acuity reduction due to motion in a video sequence. Accuracy of proposed metric is tested on the LIVE video quality database. The results of quality evaluation show that FA-SSIM outperforms SSIM as well as VQM and MS-SSIM metric and that is even competitive with state of the art MOVIE metric.

Snjezana Rimac-Drlje

Papers

Influence of temporal pooling method on the objective video quality evaluation

Impact of the host operating systems on virtual machine performance

Receiving Power Level Prediction for WiMAX Systems on 3.5 GHz

Spatial Masking and Perceived Video Quality in Multimedia Applications

Foveation-based content Adaptive Structural Similarity index