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The electricity supply will become more volatile in energy systems with increasing shares of Renewable Energy Sources (RES). Since electricity demand varies as does the supply by RES, the remaining residual load must be covered by flexible technologies that are required to balance the different types of fluctuations. In this study, these flexibility options are divided into three categories: increasing...
Several studies have shown that the relationship between perceived video quality and frame rate is dependent on the video content. In this paper, we have analyzed the content characteristics and compared them against the subjective results derived from preference decisions between different spatial and temporal quality levels. We also propose simple yet powerful metrics for characterizing spatial...
In this paper, two questions related to long duration audiovisual content are addressed: firstly, we investigate whether users' quality expectations/requirements develop differently over extended periods of time for different types of content. We have found indicators suggesting that high spatial and temporal activity indices decrease quality requirements over time. Secondly, we show that for long...
We present a study that combines and compares explicit (questionnaire-generated) and implicit (EEG-based) feedback from test subjects on perceptual dimensions of different types of audiovisual content. We found significant differences in importance and evaluation of perceptual-, viewer-and clip-related dimensions across a limited set of contents. The results suggest that additional bio-feedback data...
About ten years ago, Quality of Experience (QoE) has been introduced as a concept that challenges the well-known Quality of Service (QoS) approach. Whereas QoS looks at the technical parameters of a network, service, device, or application to measure its performance, QoE looks beyond these parameters and includes the human user into the equation. It comes from the insight that ourperception of quality...
In this paper a new methodology for the evaluation of perceived quality for long duration audiovisual content is presented. This method allows the investigation of unexplored dependencies between perceived quality and impairment variations over extended periods of time. Instead of providing quality scores on predefined rating scales, assessors are asked to adjust the quality level of the displayed...
In video streaming applications, it is necessary to choose the rate of the encoded stream to match the available transmission channel capacity. To provide flexible means for rate adaptation, different scalable video coding schemes have been proposed. For example, if necessary the bitrate can be reduced either by downscaling the frame rate (temporal scalability) or the image quality (quality scalability)...
In this paper, we investigate whether the presence of audio with different quality levels can influence the outcome of subjective visual quality assessment in a Digital Cinema setting. We asked the participants to judge the visual quality when watching an audiovisual content in a Digital Cinema environment and investigated whether the participants can neglect the presence and the quality of audio...
In multimodal presentations the perceived audiovisual quality assessment is significantly influenced by the content of both the audio and visual tracks. Based on our earlier subjective quality test for finding the optimal trade-off between audio and video quality, this paper proposes a novel method for relative multimodal complexity analysis to derive the fusion parameter in objective audiovisual...
The categorization of audiovisual media content is still in its infancy. This paper explores content description using a 4×4 matrix approach, consisting of 4 perceptual dimensions and 4 attributes, as originally suggested by Woszczyk et al., but in a slightly different context. It compares and evaluates factors that real human viewers think are important for their overall experience when viewing audiovisual...
It is known that peak signal-to-noise ratio (PSNR) can be used for assessing the relative qualities of distorted video sequences meaningfully only if the compared sequences contain similar types of distortions. In this paper, we propose a model for rough assessment of the bias in PSNR results, when video sequences with both channel and source distortion are compared against video sequences with source...
In streaming applications, unequal protection of audio and video tracks may be necessary to maintain the optimal perceived overall quality. For this purpose, the application should be aware of the relative importance of audio and video in an audiovisual sequence. In this paper, we propose a subjective test arrangement for finding the optimal trade-off between subjective audio and video qualities in...
Experienced multimodal quality is often assessed using quantitative experiments disregarding participants' experienced quality factors. The goal of this paper is to explore multimodal quality by using both quantitative methods as well as qualitative methods. Monoscopic and stereoscopic visual presentation modes and related room acoustic simulations for small and large spaces were varied. The experiments...
Two video coding schemes with variable bit rates-JPEG 2000 and H.264/AVC-were compared in terms of perceived quality performance in a Digital Cinema environment. In this paper we describe in detail the procedure for a subjective quality assessment. The stimuli used were 10 seconds long color sequences at HD resolution (1920×1080 progressive), 30 fps, and YCbCr 4:2:0. We do not consider DCI-specified...
Objective metrics are widely used to estimate the perceived quality of audio and video content in consumer electronics applications. Although a number of such metrics exist, they have all been developed for the unimodal case-cross-modal interaction, i.e. the influence of video on audio and vice versa, is not considered by these metrics. We give an overview on these, and summarize human audiovisual...
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