Video quality

About: Video quality is a research topic. Over the lifetime, 13143 publications have been published within this topic receiving 178307 citations.

Deriving and Validating User Experience Model for DASH Video Streaming

Abstract: Ever since video compression and streaming techniques have been introduced, measurement of perceived video quality has been a non-trivial task. Dynamic adaptive streaming (DASH) over hypertext transfer protocol, is a new worldwide standard for adaptive streaming of video. DASH has introduced an additional level of complexity for measuring perceived video quality, as it varies the video bit rate and quality. In this paper, we study the perceived video quality using DASH. We investigate three factors which impact user perceived video quality: 1) initial delay; 2) stall (frame freezing); and 3) bit rate (frame quality) fluctuation. For each factor, we explore multiple dimensions that can have different effects on perceived quality. For example, in the case of the factor stall, while most previous research have studied how stall duration correlates with user experience, we also consider how the stalls are distributed together with the amount of motion in the video content, since we believe they may also impact user perceived quality. We conduct extensive subjective tests in which a group of subjects provide subjective evaluation while watching DASH videos with one or more artifacts occurring. Based on the subjective tests, we first derive impairment functions which can quantitatively measure the impairment of each factor, and then combine these impairment functions together to formulate an overall user experience model for any DASH video. We validate with high accuracy the user experience model, and demonstrate its applicability to long videos.

Impact of Network Dynamics on User's Video Quality: Analytical Framework and QoS Provision

Abstract: We develop an analytical framework to investigate the impacts of network dynamics on the user perceived video quality. Our investigation stands from the end user's perspective by analyzing the receiver playout buffer. In specific, we model the playback buffer at the receiver by a G/G/1/? and G/G/1/N queue, respectively, with arbitrary patterns of packet arrival and playback. We then examine the transient queue length of the buffer using the diffusion approximation. We obtain the closed-form expressions of the video quality in terms of the start-up delay, fluency of video playback and packet loss, and represent them by the network statistics, i.e., the average network throughput and delay jitter. Based on the analytical framework, we propose adaptive playout buffer management schemes to optimally manage the threshold of video playback towards the maximal user utility, according to different quality-of-service requirements of end users. The proposed framework is validated by extensive simulations.

NAMA3DS1-COSPAD1: Subjective video quality assessment database on coding conditions introducing freely available high quality 3D stereoscopic sequences

Abstract: Research in stereoscopic 3D coding, transmission and subjective assessment methodology depends largely on the availability of source content that can be used in cross-lab evaluations. While several studies have already been presented using proprietary content, comparisons between the studies are difficult since discrepant contents are used. Therefore in this paper, a freely available dataset of high quality Full-HD stereoscopic sequences shot with a semiprofessional 3D camera is introduced in detail. The content was designed to be suited for usage in a wide variety of applications, including high quality studies. A set of depth maps was calculated from the stereoscopic pair. As an application example, a subjective assessment has been performed using coding and spatial degradations. The Absolute Category Rating with Hidden Reference method was used. The observers were instructed to vote on video quality only. Results of this experiment are also freely available and will be presented in this paper as a first step towards objective video quality measurement for 3DTV.

Cross-Dimensional Perceptual Quality Assessment for Low Bit-Rate Videos

Abstract: Most studies in the literature for video quality assessment have been focused on the evaluation of quantized video sequences at fixed and high spatial and temporal resolutions. Only limited work has been reported for assessing video quality under different spatial and temporal resolutions. In this paper, we consider a wider scope of video quality assessment in the sense of considering multiple dimensions. In particular, we address the problem of evaluating perceptual visual quality of low bit-rate videos under different settings and requirements. Extensive subjective view tests for assessing the perceptual quality of low bit-rate videos have been conducted, which cover 150 test scenarios and include five distinctive dimensions: encoder type, video content, bit rate, frame size, and frame rate. Based on the obtained subjective testing results, we perform thorough statistical analysis to study the influence of different dimensions on the perceptual quality and some interesting observations are pointed out. We believe such a study brings new knowledge into the topic of cross-dimensional video quality assessment and it has immediate applications in perceptual video adaptation for scalable video over mobile networks.

Perceptual-based quality assessment for audio-visual services: A survey

Abstract: Accurate measurement of the perceived quality of audio-visual services at the end-user is becoming a crucial issue in digital applications due to the growing demand for compression and transmission of audio-visual services over communication networks. Content providers strive to offer the best quality of experience for customers linked to their different quality of service (QoS) solutions. Therefore, developing accurate, perceptual-based quality metrics is a key requirement in multimedia services. In this paper, we survey state-of-the-art signal-driven perceptual audio and video quality assessment methods independently, and investigate relevant issues in developing joint audio-visual quality metrics. Experiments with respect to subjective quality results have been conducted for analyzing and comparing the performance of the quality metrics. We consider emerging trends in audio-visual quality assessment, and propose feasible solutions for future work in perceptual-based audio-visual quality metrics.