Researcher:
Gürler, Cihat Göktuğ

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Cihat Göktuğ

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Gürler

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Gürler, Cihat Göktuğ

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2007 - 200932010 - 201315

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Researcher Of Publications: search.filters.isAuthorOfPublication.4ed25f89-8ba4-44a8-a50f-857f1e2f8641

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Now showing 1 - 10 of 18
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    Evaluation of asymmetric stereo video coding and rate scaling for adaptive 3D video streaming
    (IEEE-Inst Electrical Electronics Engineers Inc, 2011) N/A; N/A; Department of Electrical and Electronics Engineering; Saygılı, Görkem; Gürler, Cihat Göktuğ; Tekalp, Ahmet Murat; Master Student; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 26207
    It is well known that the human visual system can perceive high frequencies in 3D stereo video, even if that information is present in only one of the views. Therefore, the best perceived 3D stereo video quality may be achieved by asymmetric coding where the reference and auxiliary (right and left) views are coded at unequal PSNR. However, the questions of what is the best level of asymmetry in order to maximize the perceived quality and whether asymmetry should be achieved by spatial resolution reduction or PSNR (quality) reduction have been open issues. We conducted extensive subjective tests, which indicate that if the reference view is encoded at sufficiently high quality and the auxiliary view is encoded at a lower quality but above a certain PSNR threshold, then the degradation in 3D video quality is unnoticeable. Since asymmetric coding by PSNR reduction gives finer control over achievable PSNR values over spatial resolution reduction, asymmetry by PSNR reduction allows us to encode at a point more close to this just-noticeable asymmetry PSNR threshold; hence will be preferred over the spatial resolution reduction method. Subjective tests also indicate that below this just-noticeable asymmetry threshold, where subtle artifacts start to appear, symmetric coding performs better than asymmetric coding in terms of perceived 3D video quality. Therefore, we show that the choice between asymmetric vs. symmetric coding depends on PSNR; hence, the available total bitrate. This paper also proposes a novel asymmetric scalable stereo video coding framework to enable adaptive stereoscopic video streaming taking full advantage of these observations and subjective test results.
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    Multi-threaded architectures and benchmark tests for real-time multi-view video decoding
    (IEEE, 2009) Aksay, Anıl; Akar, Gözde Bozdağı; Department of Electrical and Electronics Engineering; N/A; Tekalp, Ahmet Murat; Gürler, Cihat Göktuğ; Faculty Member; PhD Student; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; 26207; N/A
    3D video based on multi-view representations is becoming widely popular. Real-time encoding/decoding of such video is an important concern as the number and resolution of views increase. We present systematic methods for design and optimization of real-time multi-view video encoding/decoding algorithms using multi-core processors and provide benchmark results. The proposed multi-core decoding architectures are fully compliant with the current JVT-MVC international standard, and enable multi-threaded processing with negligible loss of encoding efficiency. Benchmark results show that multi-core processors and multi-threading decoding is necessary for real-time multiview video decoding and display.
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    Peer-to-peer system design for adaptive 3D video streaming
    (Institute of Electrical and Electronics Engineers (IEEE), 2013) N/A; Department of Electrical and Electronics Engineering; Gürler, Cihat Göktuğ; Tekalp, Ahmet Murat; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 26207
    3D video is destined to be available in homes and mobile devices. Stereoscopic TV broadcasts have already begun in frame-compatible format for stereoscopic 3D. The natural next step is to deliver 3D content in the form of multiview video (MVV) that enables a natural glasses-free 3D experience. Unfortunately, the number of views needed to drive multiview displays varies depending on the price vs. quality trade-off. Therefore, the bitrate requirement of MVV content changes according to users-display technology, making transmission over fixed bit rate channels inefficient. IP provides a flexible transport mechanism for 3D content; however, wellknown problems such as fluctuations in available link capacity and varying transmission delays pose challenges to 3D video services over the Internet. In this study, we discuss quality-ofexperience-aware rate adaptation methods specific to 3D video and efficient encoding schemes. Then, we introduce a framework to design P2P overlays to deliver 3D video. P2P overlays offer a promising approach to alleviate the high bandwidth requirement of MVV. Furthermore, two use case scenarios are provided to show the discussed methods can help to make 3D video delivery practical over the Internet.
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    Architectures for multi-threaded MVC-compliant multi-view video decoding and benchmark tests
    (Elsevier, 2010) Aksay, Anıl; Akar, Gözde Bozdağı; N/A; Department of Electrical and Electronics Engineering; Gürler, Cihat Göktuğ; Tekalp, Ahmet Murat; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 26207
    3D video based on stereo/multi-view representations is becoming widely popular. Real-time encoding/decoding of such video is an important concern as the number and spatial/temporal resolution of views increase. We present a systematic method for design and optimization of multi-threaded multi-view video encoding/decoding algorithms using multi-core processors and provide benchmark results for real-time decoding. The proposed multi-core decoding architectures are compliant with the current MVC extension of H.264/AVC international standard, and enable multi-threaded processing with negligible loss of encoding efficiency and minimum processing overhead. Benchmark results show that multi-core processors and multi-threading decoding are necessary for real-time high-definition multi-view video decoding and display. (C) 2010 Elsevier B.V. All rights reserved.
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    Evaluation of adaptation methods for multi-view video
    (IEEE, 2012) Department of Electrical and Electronics Engineering; N/A; N/A; Tekalp, Ahmet Murat; Gürler, Cihat Göktuğ; Savaş, Saadet Sedef; Faculty Member; PhD Student; PhD Student; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 26207; N/A; N/A
    Multi-view video (MVV) is the next step in the evaluation of 3DTV. Using IP networks as the transport medium seems to be the most promising solution because MVV has flexible bitrate requirements that can change based on the number of views requested from the receiver. With the advanced streaming technologies like scalable video coding, the capability of video services over IP has been greatly enhanced. However, a successful MVV delivery service cannot be achieved without properly addressing the perceived quality of experience (QoE) of MVV. QoE is an important issue especially in adaptive video streaming in which the quality of the content varies to match the available channel capacity. This study evaluates the effect of different scaling methods some of which are unique to MVV and propose a novel systematic adaptation strategy in order to deliver the best QoE under diverse network conditions. Extensive subjective tests are conducted to compare different scaling methods on MVV by using high definition contents.
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    Adaptive streaming of multi-view video over P2P networks
    (Elsevier, 2012) Ekmekçioğlu, Erhan; Worrall, Stewart; Kondoz, Ahmet; N/A; N/A; Department of Electrical and Electronics Engineering; Savaş, Saadet Sedef; Gürler, Cihat Göktuğ; Tekalp, Ahmet Murat; PhD Student; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 26207
    In this paper, we propose a novel solution for the adaptive streaming of 3D representations in the form of multi-view video by utilizing P2P overlay networks to assist the media delivery and minimize the bandwidth requirement at the server side. Adaptation to diverse network conditions is performed regarding the features of human perception to maximize the perceived 3D. We have performed subjective tests to characterize these features and determined the best adaptation method to achieve the highest possible perceived quality. Moreover, we provide a novel method for mapping from scalable video elementary stream to torrent-like data chunks for adaptive video streaming and provide an optimized windowing mechanism that ensures timely delivery of the content over yanlis gibi. The paper also describes techniques generating scalable video chunks and methods for determining system parameters such as chunk size and window length.
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    A standards-based, flexible, end-to-end multi-view video streaming architecture
    (IEEE, 2007) Aksay, Anıl; Akar, Gözde Bozdağı; Kurutepe, Engin; Bilen, Çaǧdaş; Sikora, Thomas; Department of Electrical and Electronics Engineering; N/A; Tekalp, Ahmet Murat; Gürler, Cihat Göktuğ; Faculty Member; PhD Student; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; 26207; N/A
    In this paper we propose a novel framework for the streaming of 3-D representations in the form of Multi-View Videos (MVV). The proposed streaming system is completely standards based, flexible and backwards compatible in order to support monoscopic streaming to legacy clients. We demonstrate compatibility of the proposed system with various possible encoding schemes and operating scenarios. In the current implementation, the MVV's in the server are compressed using a simplified form of MVC with negligible loss of compression efficiency and streamed using Real Time Streaming Protocol (RTSP), Session Description Protocol (SDP) and Real Time Protocol (RTP) to the clients. We describe our extensions to SDP and discuss a preliminary RTP payload format for MVC. The clients in this implementation perform basic error concealment to reduce the effects of packet losses and decode MVC in near-real-time. The modular clients can display decoded 3-D content on a multitude of 3-D display systems.
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    Adaptive multi-view video streaming over P2P networks considering quality of experience
    (ACM, 2011) Department of Electrical and Electronics Engineering; N/A; N/A; Tekalp, Ahmet Murat; Gürler, Cihat Göktuğ; Savaş, Saadet Sedef; Faculty Member; PhD Student; PhD Student; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 26207; N/A; N/A
    Peer-to-peer (P2P) video streaming has recently drawn significant attention since P2P solutions offer scalability with increasing number of recipients. P2P streaming may be a feasible solution for multi-view video (MVV) delivery, which has significantly higher bandwidth requirements than the legacy 2D video. However, a practical P2P MVV service cannot be achieved without properly addressing the perceived quality of experience (QoE) of MVV. QoE is an important issue especially in adaptive video streaming in which the quality of the content varies to match the available channel capacity. In this study, we first evaluate the perceived quality of MVV, when various adaptation methods are adopted to scale MVV bitrate to a given rate, by using subjective tests. The results of these tests are used to identify the best rate adaptation method. Next, we propose a mesh-based P2P streaming architecture that employs rate adaptation according to the findings to deliver the best QoE under diverse network conditions. We implemented our protocols and ran experiments on PlanetLab testbed to evaluate the performance of our proposed solution. The experimental results validate that the proposed adaptation strategy ensures continuous play-out by prioritizing transmission of the base-layer and augments the video quality when additional bit rate is available.
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    Quality of experience aware adaptation strategies for multi-view video over P2P networks
    (IEEE, 2012) Department of Electrical and Electronics Engineering; N/A; N/A; Tekalp, Ahmet Murat; Gürler, Cihat Göktuğ; Savaş, Saadet Sedef; Faculty Member; PhD Student; PhD Student; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 26207; N/A; N/A
    This paper addresses quality of experience (QoE) aware adaptive streaming of multi-view video (MVV) over P2P networks. First, we investigate the effect of different adaptation methods over the QoE using subjective tests, and recommend an MVV adaptation decision chart according to peer buffer status. Second, we propose a simulcast MVV encoding scheme that uses a combination of both standard H.264/AVC and Scalable Video Coding (SVC) extension to achieve the best coding efficiency, while maintaining high adaptation capability. Third, we propose a chunk picking policy that is applicable to any P2P streaming architecture to enable QoE aware adaptive streaming. Finally, we perform P2P video streaming tests over a controlled LAN environment to demonstrate / validate the proposed solution.
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    Content aware delivery of visual attention based scalable multi-view video over P2P
    (IEEE, 2012) Ekmekcioglu, Erhan; Arachchi, Hemantha Kodikara; Kondoz, Ahmet; Gürler, Cihat Göktuğ; Savaş, Saadet Sedef; PhD Student; PhD Student; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; N/A; N/A
    3D media applications have become widespread thanks to the intense research being conducted on 3D enabling technologies, commercial products being released and service providers. There is also a huge potential for IP network to become a major means for delivering 3D video services, being highly flexible and allowing much custom and scalable applications to take up. Peer-to-Peer (P2P) video streaming, which offers high scalability in the presence of many media consuming peers, is suitable for multi-view video applications with significantly higher bandwidth requirements. To exploit flexible streaming and also serve a range of displays, P2P networking should be combined with scalable coded multi-view video that offers a useful bit-rate and maximum viewpoint adaptation range. However, since maintaining users' Quality of Experience (QoE) is a primary target, scalable coded video should ensure that perceptually sensible visual data is delivered with high accuracy at all times to users, even under severe network conditions. Hence, content-based visual attention models provide a suitable means for letting salient video data be delivered at all times to users. With the utilization of appropriate adaptation decision making process in users' equipment, the P2P protocol can adaptively stream the scalable 3D media. Work presented in this paper explains such a delivery framework over P2P networks. © 2012 IEEE.