• Journal of KIISE
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• v.43 no.5
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• pp.606-612
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• 2016

The multi-view video service based on the DASH(Dynamic Adaptive Streaming over HTTP) switches the viewpoint or object which is selected by the user among the multiple video streams captured by multiple cameras. However, the problem is that the conventional DASH-based multi-view video service takes a long time to switch the viewpoint. The reason is that the conventional scheme switches to the new video stream after consuming all buffered segments of the previous video stream. In this paper, we propose a video streaming scheme for minimizing the viewpoint switching delay in the DASH-based multi-view video service. In order to minimize the viewpoint switching delay, the proposed scheme configures the video streams by controlling the GoP (Group of Pictures) size and controls the client buffer based on bandwidth estimation and playback buffer occupancy. Through the experimental results, we prove that the proposed scheme reduces the viewpoint switching delay.

• Proceedings of the Korea Multimedia Society Conference
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• 2012.05a
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• pp.166-167
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• 2012

High packet loss rate and impatience of messages passing through optical switches are essential characteristics in Optical Burst Switching system equipped with Optic Delay Lines buffer, which have not been solved efficiently yet by current existing models. In order to capture both effects, this paper introduces an analytical model from the viewpoint of classical queuing theory with impatient customers. We then apply it to evaluate and compare two wavelength-sharing cases, (1) all delay lines share a common wavelength resource and (2) each wavelength is associated with a number of delay lines. Our numerical results suggest to implement the first case because of lower packet loss rate for a fairly broad range of traffic load.

• Journal of the Korea Society of Computer and Information
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• v.6 no.2
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• pp.84-89
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• 2001

In this paper, an improved protocol of Multi-Link Switching Method is proposed by supplementing a concurrent processing function. This protocol is proposed to complement the shortcomings of the conventional Multi-Link Switching Method which is used for the medium access in LAN. We analyzed the improved protocol in channel utilization viewpoint and compared the result with that of the conventional protocol From this result, we showed that the channel utilization of the improved protocol is superior to that of the conventional protocol when the maximum normalized propagation delay is increased.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2021.06a
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• pp.242-245
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• 2021

시청자의 시점 위치를 선택하여 360VR 콘텐츠를 경험하는 다중시점 또는 자유시점 360VR 콘텐츠의 전송은 매우 높은 대역폭을 소비하게 된다. 특히 다중 사용자가 존재하는 셀룰러 환경에서는 특정 사용자에게 한정된 대역폭만을 할당할 수 있으므로 불가피하게 전송 품질 악화 또는 전송 지연을 겪게 된다. 다중시점(multi-viewpoint) 360VR 콘텐츠의 경우 시청자가 시점의 위치를 변경하면 해당 위치의 콘텐츠를 전송하므로, 한정된 대역폭이 주어지는 통신환경에서 시점을 이동할 때 마다 큰 전송 지연을 겪게되어 사용자 경험이 매우 떨어지는 것을 예상할 수 있다. 본 논문에서는 다시점 360 비디오에서 시점 변경을 시도할 때 전송지연을 줄이기 위하여 주변 위치의 영상을 적절히 Pre-Loading 하는 전송방식을 고려하고, 실질적인 5G 네트워크 환경에서 시점 변환에 따른 지연시간 성능을 분석하였다. 특정 수준 이하로 지연시간을 낮추기 위해서는 사용자 이동패턴에 대한 적절한 예측 기법이 요구되며, 정확도에 따른 지연시간 감소를 실험을 통하여 확인하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.3
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• pp.929-946
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• 2022

Free viewpoint video (FVV) service is an immersive media service that allows a user to watch it from a desired location or viewpoint. It is composed of various forms according to the direction of the viewpoint of the provided video, and includes zoom in/out in the service. As consumers' demand for active watching is increasing, the importance of FVV services is expected to grow gradually. However, additional considerations are needed to seamlessly stream FVV service. FVV includes a plurality of videos, video changes may occur frequently due to movement of the viewpoint. Frequent occurrence of video switching or re-request another video can cause service delay and it also can lower user's quality of service (QoS). In this case, we assumed that if a video showing an object that the user wants to watch is selected and provided, it is highly likely to meet the needs of the viewer. In particular, it is important to provide an object-oriented FVV service when zooming in. When video zooming in in the usual way, it cannot be guaranteed to zoom in around the object. Zoom function does not consider about video viewing. It only considers the viewing screen size and it crop the video view as fixed screen location. To solve this problem, we propose a zoom in/out method of object-centered dynamic adaptive streaming of FVV in this paper. Through the method proposed in this paper, users can enjoy the optimal video service because they are provided with the desired object-based video.