Topic
Video quality
About: Video quality is a research topic. Over the lifetime, 13143 publications have been published within this topic receiving 178307 citations.
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Papers
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11 Jan 2012TL;DR: In this paper, a header extension is added to the video data packets by a transcoding system, which includes data associated with original and transcoded video data packet, and a network monitoring system monitors the header extension and evaluates the effect of video transcoding upon the overall QoE for users.
Abstract: Video data packets transmitted through a wireless network are captured by a network monitoring system. Video data sessions are detected from the video data packets. Key parameters are identified within the video data packets, such as video bit rate, resent or failed video packets, and video session duration. A Quality of Experience (QoE) is determined for some or all users associated with the video sessions based upon the key parameters. A header extension is added to the video data packets by a transcoding system. The header extension includes data associated with original and transcoded video data packets. The network monitoring system monitors the header extension and evaluates the effect of video transcoding upon the overall QoE for users. The monitoring system provides feedback to a transcoding policy engine based upon the effect of transcoding upon QoE.
82 citations
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TL;DR: The optimal trade-off between bits allocated to audio and to video under global bitrate constraints is investigated and models for the interactions between audio and video in terms of perceived audiovisual quality are explored.
Abstract: This paper studies the quality of multimedia content at very low bitrates. We carried out subjective experiments for assessing audiovisual, audio-only, and video-only quality. We selected content and encoding parameters that are typical of mobile applications. Our focus were the MPEG-4 AVC (a.k.a. H.264) and AAC coding standards. Based on these data, we first analyze the influence of video and audio coding parameters on quality. We investigate the optimal trade-off between bits allocated to audio and to video under global bitrate constraints. Finally, we explore models for the interactions between audio and video in terms of perceived audiovisual quality
82 citations
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16 Jun 2003TL;DR: The subjective ratings are used to validate the prediction performance of a real-time non-reference quality metric and compare codec performance as well as the effects of transmission errors on visual quality.
Abstract: This paper presents the results of our quality evaluations of video sequences encoded for and transmitted over a wireless channel. We selected content, codecs, bitrates and bit error patterns representative of mobile applications and we concentrated on the MPEG-4 and Motion JPEG2000 coding standards. We carried out subjective experiments using the Single Stimulus Continuous Quality Evaluation (SSCQE) method on this test material. We analyze the results of the subjective data and use them to compare codec performance and resilience to transmission errors. Finally, we use the subjective data to validate the prediction performance of a real-time non-reference quality metric.
82 citations
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TL;DR: The objective of this paper is to study the relationship between 3D quality and bitrate at different frame rates and show that increasing the frame rate of 3D videos beyond 60 fps may not be visually distinguishable.
Abstract: Increasing the frame rate of a 3D video generally results in improved Quality of Experience (QoE). However, higher frame rates involve a higher degree of complexity in capturing, transmission, storage, and display. The question that arises here is what frame rate guarantees high viewing quality of experience given the existing/required 3D devices and technologies (3D cameras, 3D TVs, compression, transmission bandwidth, and storage capacity). This question has already been addressed for the case of 2D video, but not for 3D. The objective of this paper is to study the relationship between 3D quality and bitrate at different frame rates. Our performance evaluations show that increasing the frame rate of 3D videos beyond 60 fps may not be visually distinguishable. In addition, our experiments show that when the available bandwidth is reduced, the highest possible 3D quality of experience can be achieved by adjusting (decreasing) the frame rate instead of increasing the compression ratio. The results of our study are of particular interest to network providers for rate adaptation in variable bitrate channels.
81 citations
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09 Jun 2013TL;DR: A proactive QoE-based approach for rewriting the client HTTP requests at a proxy in the mobile network that gives control of the video content adaptation to the network operator which has better information than the client on the load and radio conditions in the cell.
Abstract: This paper presents a Quality of Experience (QoE) driven approach for multi-user resource optimization in Dynamic Adaptive Streaming over HTTP (DASH) over next generation wireless networks. Our objective is to enhance the user experience in adaptive HTTP streaming by jointly considering the characteristics of the media content and the available wireless resources in the operator network. Specifically, we propose a proactive QoE-based approach for rewriting the client HTTP requests at a proxy in the mobile network. The advantage of the proposed approach is its applicability for over-the-top (OTT) streaming as it requires no adaptation of the media content. We compare our proposed scheme to both reactive QoE-optimized and to standard-DASH HTTP streaming. Our contributions are: 1) We first show that standard OTT DASH leads to unsatisfactory performance since the content agnostic resource allocation by the LTE scheduler is far from optimal, and we can achieve a clear QoE improvement when considering the content characteristics. 2) We additionally show that proactively rewriting the client requests gives control of the video content adaptation to the network operator which has better information than the client on the load and radio conditions in the cell. This results in additional gains in user perceived video quality. 3) A standard unmodified DASH client remains unaware of the proposed rewriting of the HTTP requests and can decode and play the redirected media segments.
81 citations