128 research outputs found

    Coding and replication co-design for interactive multiview video streaming

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    DĂŒnaamiline kiiruse jaotamine interaktiivses mitmevaatelises video vaatevahetuse ennustamineses

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    In Interactive Multi-View Video (IMVV), the video has been captured by numbers of cameras positioned in array and transmitted those camera views to users. The user can interact with the transmitted video content by choosing viewpoints (views from different cameras in the array) with the expectation of minimum transmission delay while changing among various views. View switching delay is one of the primary concern that is dealt in this thesis work, where the contribution is to minimize the transmission delay of new view switch frame through a novel process of selection of the predicted view and compression considering the transmission efficiency. Mainly considered a realtime IMVV streaming, and the view switch is mapped as discrete Markov chain, where the transition probability is derived using Zipf distribution, which provides information regarding view switch prediction. To eliminate Round-Trip Time (RTT) transmission delay, Quantization Parameters (QP) are adaptively allocated to the remaining redundant transmitted frames to maintain view switching time minimum, trading off with the quality of the video till RTT time-span. The experimental results of the proposed method show superior performance on PSNR and view switching delay for better viewing quality over the existing methods

    Coding Structure and Replication Optimization for Interactive Multiview Video Streaming

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    Near-optimal content replication for interactive multiview video streaming

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    Anchor View Allocation for Collaborative Free Viewpoint Video Streaming

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    In free viewpoint video, a viewer can choose at will any camera angle or the so-called "virtual view" to observe a dynamic 3-D scene, enhancing his/her depth perception. The virtual view is synthesized using texture and depth videos of two anchor camera views via depth-image-based rendering (DIBR). We consider, for the first time, collaborative live streaming of a free viewpoint video, where a group of users may interactively pull and cooperatively share streams of different anchor views. There is a cost to access the anchor views from the live source, a cost to "reconfigure" the peer network due to a change in selected anchors during view switching, and a distortion cost due to the distance of the virtual views to the received anchor views at users. We optimize the anchor views allocated to users so as to minimize the overall streaming cost given by the access cost, reconfiguration cost, and view distortion cost. We first show that, if the reconfiguration cost due to view switching is negligible, the view allocation problem can be optimally and efficiently solved in polynomial time using dynamic programming. For the case of non-negligible reconfiguration cost, the problem becomes NP-hard. We thus present a locally optimal and centralized algorithm inspired by Lloyd's algorithm used in non-uniform scalar quantization. We further propose a distributed algorithm with convergence guarantee, where each peer group independently makes merge-and-split decisions with a well-defined fairness criteria. Simulation results show that our algorithms achieve low streaming cost due to its excellent anchor view allocation

    In-Network View Re-Sampling for Interactive Free Viewpoint Video Streaming

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    Interactive free viewpoint video offers the possibility for each user to independently choose the views of a 3D scene to be displayed at de- coder. The visual content is commonly represented by N texture and depth map pairs that capture different viewpoints. A server selects an appropriate subset of M ≀ N views for transmission, so that the user can freely navigate in the corresponding window of viewpoints without being affected by network delay. During navigation, a user can synthesize any intermediate virtual view image in the navigation window via depth-image-based rendering (DIBR) using two nearby camera views as references. When the available bandwidth is too small for the transmission of all camera views needed to synthesize views in the navigation window, we propose to synthesize intermedi- ate virtual views as new references for transmission—a re-sampling of viewpoints for the 3D scene—so that the synthesized view dis- tortion within the navigation window is minimised. We formulate a combinatorial optimization to find the best set of M virtual views to synthesize as new references, and show that the problem is NP- hard. We approximate the original problem with a new reference view equivalence model and derive in this case an optimal dynamic programming algorithm to determine to best set of M views to be transmitted to each user. Experimental results show that synthesiz- ing virtual views as new references for client-side view synthesis can outperform simple selection from camera views by up to 0.73dB in synthesized view quality
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