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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07 Aug 2002TL;DR: Simulation results show the implemented QoS control schemes that use the feedbacks from the agent and control transmission rate and robustness provide better video quality than a simple rate control mechanism.
Abstract: We propose a of control architecture for mobile multimedia streaming in which RTP monitoring agents report QoS information to media servers. The RTP monitoring agents lie midway between wired networks and radio links, monitor RTP packets sent from media servers to mobile terminals, and report quality information to media servers so that the servers can realize network-adaptive QoS control. By analyzing the information sent from the agents, the servers can distinguish quality degradation caused by network congestion from that caused by radio link errors, and can improve service quality by controlling the transmission rate and robustness against packet loss. Simulation results show our implemented QoS control schemes that use the feedbacks from the agent and control transmission rate and robustness provide better video quality than a simple rate control mechanism.
98 citations
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TL;DR: Experimental results demonstrate the proposed Rate-GOP based rate control has much better R-D performance than the two state-of-the-art rate control schemes for HEVC.
Abstract: In this paper, a Rate-GOP based frame level rate control scheme is proposed for High Efficiency Video Coding (HEVC). The proposed scheme is developed with the consideration of the new coding tools adopted into HEVC, including the quad-tree coding structure and the new reference frame selection mechanism, called reference picture set (RPS). The contributions of this paper mainly include the following three aspects. Firstly, a RPS based hierarchical rate control structure is designed to maintain the high video quality of the key frames. Secondly, the inter-frame dependency based distortion model and bit rate model are proposed, considering the dependency between a coding frame and its reference frame. Thus the distortion and bit rate of the coding frame can be represented by the distortion and bit rate of its reference frame. Accordingly, the Rate-GOP based distortion model and rate model can be achieved via the inter-frame dependency based distortion model and bit rate model. Thirdly, based on these models and a mixed Laplacian distribution of residual information, a new ρ-domain Rate-GOP based rate control is proposed. Experimental results demonstrate the proposed Rate-GOP based rate control has much better R-D performance. Compared with the two state-of-the-art rate control schemes for HEVC, the coding gain with BD-PSNR can be up to 0.87 dB and 0.13 dB on average respectively for all testing configurations. Especially for random access low complexity testing configuration, the BD-PSNR gain can be up to 1.30 dB and 0.23 dB respectively.
98 citations
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06 Dec 2007TL;DR: In this paper, the authors proposed video-aware opportunistic network coding schemes that take into account both aspects, namely (i) the decodability of network codes by several receivers and (ii) the distortion values and playout deadlines of video packets.
Abstract: In this paper, we study video streaming over wireless networks with network coding capabilities. We build upon recent work, which demonstrated that network coding can increase throughput over a broadcast medium, by mixing packets from different flows into a single packet, thus increasing the information content per transmission. Our key insight is that, when the transmitted flows are video streams, network codes should be selected so as to maximize not only the network throughput but also the video quality. We propose video-aware opportunistic network coding schemes that take into account both aspects, namely (i) the decodability of network codes by several receivers and (ii) the distortion values and playout deadlines of video packets. Simulation results show that our schemes significantly improve both video quality and throughput.
98 citations
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01 Aug 2003
TL;DR: A simple and fast method for face detection is proposed to define ROIs dynamically in real time applications using the color information Cr and RGB variance to determine the skin-color pixels.
Abstract: The ability to give higher priority to regions-of-interest (ROI) is the emerging functionality for present day video coding. A simple and fast method for face detection is proposed to define ROIs dynamically in real time applications. We use the color information Cr and RGB variance to determine the skin-color pixels. Because the two color spaces are commonly used in most hardware and video codec standards, there is no extra computation overhead required for conversion. Low-pass filtering is applied to the background to reduce used bits. For the video coding system, a region-based video codec based on H.263+ with the option mode of modified quantization is set up. We adjust the distortion weight parameter and variance at the macroblock layer to control the qualities at different regions. Experimental results show that the proposed methods can significantly improve quality at the ROI. Our methods are suitable for real time videoconferencing.
97 citations
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TL;DR: A Hammerstein-Wiener model is presented for predicting the time-varying subjective quality (TVSQ) of rate-adaptive videos and it is shown that the model is able to reliably predict the TVSQ of rate adaptive videos.
Abstract: Newly developed hypertext transfer protocol (HTTP)-based video streaming technologies enable flexible rate-adaptation under varying channel conditions. Accurately predicting the users' quality of experience (QoE) for rate-adaptive HTTP video streams is thus critical to achieve efficiency. An important aspect of understanding and modeling QoE is predicting the up-to-the-moment subjective quality of a video as it is played, which is difficult due to hysteresis effects and nonlinearities in human behavioral responses. This paper presents a Hammerstein-Wiener model for predicting the time-varying subjective quality (TVSQ) of rate-adaptive videos. To collect data for model parameterization and validation, a database of longer duration videos with time-varying distortions was built and the TVSQs of the videos were measured in a large-scale subjective study. The proposed method is able to reliably predict the TVSQ of rate adaptive videos. Since the Hammerstein-Wiener model has a very simple structure, the proposed method is suitable for online TVSQ prediction in HTTP-based streaming.
97 citations