High definition H.264/AVC subjective video database for evaluating the influence of slice losses on quality perception

Prior to the construction or validation of objective video quality metrics, ground-truth data must be collected by means of a subjective video database. This database consists of (impaired) video sequences and corresponding subjective quality ratings. However, creating this subjective database is a timeconsuming and expensive task. There is an ongoing effort towards publishing such subjective video databases into the public domain. This facilitates the development of new objective quality metrics. In this paper, we present a new subjective video database consisting of impaired High Definition H. 264/AVC encoded video sequences and associated quality ratings gathered from a subjective experiment. This database can be used freely to determine impairment visibility or estimate overall quality of a video in the case of lost slices due to network impairments

Perceived quality of full HD video - subjective quality assessment

In recent years, an interest in multimedia services has become a global trend and this trend is still rising. The video quality is a very significant part from the bundle of multimedia services, which leads to a requirement for quality assessment in the video domain. Video quality of a streamed video across IP networks is generally influenced by two factors “transmission link imperfection and efficiency of compression standards. This paper deals with subjective video quality assessment and the impact of the compression standards H.264, H.265 and VP9 on perceived video quality of these compression standards. The evaluation is done for four full HD sequences, the difference of scenes is in the content“ distinction is based on Spatial (SI) and Temporal (TI) Index of test sequences. Finally, experimental results follow up to 30% bitrate reducing of H.265 and VP9 compared with the reference H.264

Recover Subjective Quality Scores from Noisy Measurements

Simple quality metrics such as PSNR are known to not correlate well with subjective quality when tested across a wide spectrum of video content or quality regime. Recently, efforts have been made in designing objective quality metrics trained on subjective data (e.g. VMAF), demonstrating better correlation with video quality perceived by human. Clearly, the accuracy of such a metric heavily depends on the quality of the subjective data that it is trained on. In this paper, we propose a new approach to recover subjective quality scores from noisy raw measurements, using maximum likelihood estimation, by jointly estimating the subjective quality of impaired videos, the bias and consistency of test subjects, and the ambiguity of video contents all together. We also derive closed-from expression for the confidence interval of each estimate. Compared to previous methods which partially exploit the subjective information, our approach is able to exploit the information in full, yielding tighter confidence interval and better handling of outliers without the need for z-scoring or subject rejection. It also handles missing data more gracefully. Finally, as side information, it provides interesting insights on the test subjects and video contents.Comment: 16 pages; abridged version appeared in Data Compression Conference (DCC) 201

Measuring Subjective Wellbeing in Developing Countries.

The paper explores the conceptual and methodological issues entailed in using subjective measures of well-being in developing countries. In the first part I define, situate and contrast subjective quality of life (QoL), subjective well-being (SWB), and well-being. I also look at the conceptual and methodological shortcomings of subjective measures of well-being and suggest ways of overcoming these by combining different approaches. I then explore how an expanded concept of subjective quality of life fits into the theoretical framework of the UK-based Well-being in Developing Countries study (or WeD), specifically how it plans to produce a new, “development-related” profile of quality of life, drawing on the methodology of the WHOQOL group (1995; 1998)

Standardized toolchain and model development for video quality assessment: the mission of the joint effort group in VQEG

International audienceSince 1997, the Video Quality Experts Group (VQEG) has been active in the field of subjective and objective video quality assessment. The group has validated competitive quality metrics throughout several projects. Each of these projects requires mandatory actions such as creating a testplan and obtaining databases consisting of degraded video sequences with corresponding subjective quality ratings. Recently, VQEG started a new open initiative, the Joint Effort Group (JEG), for encouraging joint collaboration on all mandatory actions needed to validate video quality metrics. Within the JEG, effort is made to advance the field of both subjective and objective video quality measurement by providing proper software tools and subjective databases to the community. One of the subprojects of the JEG is the joint development of a hybrid H.264/AVC objective quality metric. In this paper, we introduce the JEG and provide an overview of the different ongoing activities within this newly started group

Subjective and objective quality evaluation of compressed medical video sequences

Existing objective video quality metrics such as VQM from NTIA [1] and MOVIE [2] are known to perform well for assessing compression degradation in natural scene and broadcast television sequences but their suitability for the quality evaluation of compressed medical video has not been studied extensively. In this work we assess the quality of compressed medical video sequences using objective metrics and a subjective evaluation study conducted with non-expert subjects. Test sequences consist of High Definition medical video of laparascopic surgery. Four compression types (Motion JPG and three variants of H.264) at four bit-rates (5, 12, 20, and 45 Mbps) are studied and compared to original uncompressed sequences. One reduced reference metric (VQM) and one full-reference metric (MOVIE) are studied. Subjective video evaluation consists of overall quality scores as well as difference scores between compressed and uncompressed sequences for similarity and five types of artifacts or attributes: blurring, blocking, noise, color fidelity, and motion artifacts. The results of the subjective and objective evaluations exhibit similar trends across the compression types and bit-rates, and may indicate that these objective quality metrics may be valid reflections of subjective quality judgments made by non-expert observers on compressed medical video sequences. In future work we will expand the subjective quality evaluation to include expert laparoscopic surgeons as subjects

Measuring match quality using subjective data

We examine whether data routinely collected in household surveys and surveys of workers can be used to construct a measure of underlying match quality between worker and firm which helps test matching models and predict subsequent labour market outcomes of workers. We use subjective data from employees both on reported levels of job satisfaction with various aspects of the current job and on whether they would like a new job with a new employer to construct a measure of underlying match quality. We then use this to test several implications of matching models relating to wage-tenure profiles, wages, and separations.panel data, wages, job mobility, match effects, BHPS

Assessing quality of experience of IPTV and video on demand services in real-life environments

The ever growing bandwidth in access networks, in combination with IPTV and video on demand (VoD) offerings, opens up unlimited possibilities to the users. The operators can no longer compete solely on the number of channels or content and increasingly make high definition channels and quality of experience (QoE) a service differentiator. Currently, the most reliable way of assessing and measuring QoE is conducting subjective experiments, where human observers evaluate a series of short video sequences, using one of the international standardized subjective quality assessment methodologies. Unfortunately, since these subjective experiments need to be conducted in controlled environments and pose limitations on the sequences and overall experiment duration they cannot be used for real-life QoE assessment of IPTV and VoD services. In this article, we propose a novel subjective quality assessment methodology based on full-length movies. Our methodology enables audiovisual quality assessment in the same environments and under the same conditions users typically watch television. Using our new methodology we conducted subjective experiments and compared the outcome with the results from a subjective test conducted using a standardized method. Our findings indicate significant differences in terms of impairment visibility and tolerance and highlight the importance of real-life QoE assessment

Subjective quality of life in war-affected populations

PMCID: PMC3716711This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited