Video quality

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

Error-resilient transcoding for video over wireless channels

Abstract: We describe a method to maintain quality for video transported over wireless channels. The method is built on three fundamental blocks. First, we use a transcoder that injects spatial and temporal resilience into an encoded bitstream. The amount of resilience is tailored to the content of the video and the prevailing error conditions, as characterized by bit error rate. Second, we derive analytical models that characterize how corruption propagates in a video that is compressed using motion-compensated encoding and subjected to bit errors. Third, we use rate distortion theory to compute the optimal allocation of bit rate among spatial resilience, temporal resilience, and source rate. Furthermore, we use the analytical models to generate the resilience rate distortion functions that are used to compute the optimal resilience. The transcoder then injects this optimal resilience into the bitstream. Simulation results show that using a transcoder to optimally adjust the resilience improves video quality in the presence of errors while maintaining the same input bit rate.

The Influence of Video Quality on Perceived Audio Quality and Vice Versa

Abstract: Three questions are being studied Question one: To what extent is the perceived audio quality of an audiovisual stream influenced by the video quality? Question two is the reverse: To what extent is the perceived video quality of an audiovisual stream influenced by the audio quality? Finally: How do audio and video quality contribute to the overall perceived audiovisual quality? The quality ranges from broadcast audio and video quality to standard videophone (telephone) quality The main conclusion is that when subjects are asked to judge the audio quality of an audiovisual stimulus, the video quality will contribute significantly to the subjectively perceived audio quality The effect is about 12 points on a nine-point quality scale The reversed effect is much smaller, about 02 point Furthermore a simple mapping from the audio and video quality to the overall audiovisual quality is given, and it is shown that the video quality dominates the overall perceived audiovisual quality in nonconversational experiments

Subjective assessment of H.264/AVC video sequences transmitted over a noisy channel

Abstract: In this paper we describe a database containing subjective assessment scores relative to 78 video streams encoded with H.264/AVC and corrupted by simulating the transmission over error-prone network. The data has been collected from 40 subjects at the premises of two academic institutions. Our goal is to provide a balanced and comprehensive database to enable reproducible research results in the field of video quality assessment. In order to support research works on Full-Reference, Reduced-Reference and No-Reference video quality assessment algorithms, both the uncompressed files and the H.264/AVC bitstreams of each video sequence have been made publicly available for the research community, together with the subjective results of the performed evaluations.

Parametric Packet-Layer Model for Monitoring Video Quality of IPTV Services

Abstract: IPTV services will become key services in the next- generation network (NGN). To provide a high-quality service for users, designing and managing the quality of experience (QoE) appropriately is extremely important. To do this, developing an objective quality-assessment method that estimates subjective quality based on physical characteristics of the IPTV system is desirable. We propose a parametric packet-layer model for monitoring video quality of IPTV services. Our proposed model is useful as a network monitoring tool for assessing several video parameters that affect the quality of IPTV services. For constructing the parametric packet-layer model, we derived a relationship between video quality and quality parameters from a subjective quality assessment. The results indicated that cross- correlation was larger than 0.9, and the evaluation error was smaller than the statistical uncertainty of the value of subjective quality. Therefore, our proposed model could be applied to effective design, implementation, and management of IPTV services.

Quality metric for spherical panoramic video

Abstract: Virtual reality (VR)/ augmented reality (AR) applications allow users to view artificial content of a surrounding space simulating presence effect with a help of special applications or devices. Synthetic contents production is well known process form computer graphics domain and pipeline has been already fixed in the industry. However emerging multimedia formats for immersive entertainment applications such as free-viewpoint television (FTV) or spherical panoramic video require different approaches in content management and quality assessment. The international standardization on FTV has been promoted by MPEG. This paper is dedicated to discussion of immersive media distribution format and quality estimation process. Accuracy and reliability of the proposed objective quality estimation method had been verified with spherical panoramic images demonstrating good correlation results with subjective quality estimation held by a group of experts.