• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2018.06a
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• pp.92-95
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• 2018

가상 현실을 위한 360 영상 비디오 전송기술이 활발히 연구되고 있다. 그러나 현재 가상현실 기기의 컴퓨팅 연산능력과 대역폭은 고화질 360 영상을 재생하기에 한계가 있다. 이 한계를 극복하기 위해 본 논문은 High Efficiency Video Coding (HEVC)와 Scalability Extension of HEVC (SHVC)를 활용하여 타일 기반의 360 도 영상 전송 기법을 제안한다. 제안하는 HEVC 와 SHVC 인코더는 타일을 독립적으로 전송 할 수 있는 비트 스트림을 생성한다. 제안하는 추출기는 사용자 시점에 해당하는 타일의 비트 스트림을 추출한다. 제안하는 기법에 의해 추출된 SHVC 비트스트림의 기본계층은 전체화면을 나타내며, 강화계층은 사용자 시점에 해당하는 타일로 구성된다. 제안하는 HEVC 인코더를 사용할 때에는 저화질과 고화질을 따로 인코딩하여 고화질만 사용자 시점에 해당하는 타일을 추출한다. 전체화면을 고화질로 보내는 대신에 전체화면을 저화질로, 사용자화면을 고화질로 보내기 때문에 제안하는 기법은 디코더의 컴퓨팅 연산과 네트워크 bitrate 를 대폭 줄일 수 있다. 본 제안 기법의 실험 결과는 전체화면 전송 대비 47%이상의 bitrate 를 줄인다.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.10
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• pp.1207-1214
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• 2014

The first frame of a GOP is encoded in intra mode which generates a larger number of bits. In addition, the first frame is used for the inter mode encoding of the following frames. Thus the encoding results of the intra frame affects the first frame as well as the following frames. Traditionally, the quantization parameter for an intra frame is determined only depending on the bpp not considering the characteristics of the intra frame. For accurate intra frame encoding, we should consider not only bpp but also the complexity of the video sequence and the output bandwidth. In this paper, we propose a real-time quantization model which is used to calculate the quantization parameter for an intra frame encoding based on the investigation on the characteristics of a GOP. It is shown by experimental results that the proposed quantization model captures the characteristics of an intra frame effectively and the proposed method for model parameters accurately estimates the real values.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1834-1843
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• 2016

DVRs are the most common recording and displaying devices used for surveillance. Video compression plays a key role in DVRs for saving storage; the video compression standard, H.264/AVC, has recently become the dominant choice for DVRs. DVRs require various display modes, such as fast-forward, backward play, and pause; these are called trick modes. The implementation of precise trick mode play requires a very high decoding capability or a very intelligent scheme in order to handle the high computation complexity. The complexity is increased in many surveillance applications where more than one camera is used to monitor multiple spots or to monitor the same area using various angles. An implementation of a trick mode play and a frame buffer management scheme for the hardware-based H.264/AVC codec for multi-channel is presented in this paper. The experimental results show that exact trick mode play is possible using a standard H.264/AVC video codec with keyframe encoding feature at the expense of bitstream size increase.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.6
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• pp.1377-1383
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• 2012

The first frame of a GOP is encoded in intra mode which generates a larger number of bits. In addition, the first frame is used for the inter mode encoding of the following frames. Thus the intial QP for the first frame affects the first frame as well as the following frames. Traditionally, the initial QP is determined among four constant values only depending on the bpp. Although this initialization scheme is simple, yet it is not accurate enough. An accurate intial QP prediction scheme should not only depends on bpp but also on the complexity of the video sequence and the output bandwidth. In this paper, we propose a traffic model for finding the optimal initial QP which maximizes the PSNR of the GOP. We also propose a method to find model parameters for real-time video encoding. It is shown by experimental results that the proposed traffic model captures initial QP characteristics effectively and the proposed method for model parameters accurately estimates the real values.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12B
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• pp.758-766
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• 2007

IStreaming services with a client-server architecture have scalability problem because a server cannot accomodate clients more than its processing capability. This paper introduces a case study for implementing H.264 streaming system based on P2P architecture in order to provide scalable and stable broadcast streaming services over the internet. The prototype system called OmniCast264 consists of the H.264 encoding server, the streaming server, the proxy server, and peer nodes. The proxy server dynamically manages placement of the peer nodes on the P2P network. Omnicast264 has the concepts of distributed streaming loads, real-time playback, error-robustness and modularity. Thus, it can provide large-scale broadcast streaming services. Finally, we have built P2P streaming systems with 12 PCs connected serially or in parallel. The experiment shows that OmniCast264 can provide real-time playback.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.10
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• pp.990-994
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• 2010

Mobile WiMAX does not guarantee the media qualities because it does not consider the characteristics of video coding techniques. In this paper, PC-MCA(Priority-based Combining adaptive Modulation and Coding with ARQ), a priority based channel-adaptive streaming scheme, is proposed to guarantee media qualities. PC-MCA uses QoS scheduler by scheduling priority of the media and differentially controls modulation and coding schemes according to wireless channel condition and frame priorities. It also guarantees multimedia service quality through video decoding reliability.

• Science of Emotion and Sensibility
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• v.11 no.4
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• pp.629-636
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• 2008

In recent years, a large number of robots have been developed in several countries, and these robots have been built for the purpose to appeal to users by well designed human-robot interaction. In case of the robots developed so far, they show proper reactions only when there is a certain input. On the other hands, they cannot perform in a standby mode which means there is no input. In other words, if a robot does not make any motion in standby mode, users may feel that the robot is being turned-off or even out of work. Especially, the social service robots maintain the standby status after finishing a certain task. In this period of time, if the robots can make human-like behavioral patterns such like a person in help desk, then they are expected to make people feels that they are alive and is more likely to interact with them. It is said that even if there is no interaction with others or the environment, people normally reacts to internal or external stimuli which are created by themselves such as moving their eyes or bodies. In order to create robotic behavioral patterns for standby mode, we analyze the actual facial expression and behavior from people who are in neutral affective emotion based on ethnographic methodology and apply extracted characteristics to our robots. Moreover, by using the robots which can show those series of expression and action, our research needs to find that people can feel like they are alive.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12B
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• pp.1336-1348
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• 2009

In this paper, we propose an energy-aware multi-tree video multicast scheme for wireless ad hoc networks. Some network nodes may have energy enough to receive and forward the whole video content whereas some may not. Even though the video quality may vary depending on the remaining energy, our scheme enables the low-energy nodes to join the video multicast session. The video stream is split into a set of multiple and independent descriptions by MDC (Multiple description coding) scheme. Each description corresponds to a substream and number of substreams determine the video quality. The member nodes determine how many substreams it would receive depending on the remaining energy and expected amount of packets per substream. So does the intermediate tree nodes. That builds a tree per substream and multiple trees per session. The data source disseminates each substream through corresponding tree. The video quality of the member nodes varies according to number of participating trees. We evaluate the performance of our scheme by simulation. Our scheme showed better peak signal to noise ratio and extended the lifetime of the network nodes compared with MAODV, which builds a single tree, and MT-MAODV, which builds multiple trees but does not consider the available energy.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.4
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• pp.493-498
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• 2009

Bluetooth is a popular wireless data transmission method with low power consumption, but it has low data transmission rate. Thus, although many video stream players of a local or network file exist, there have been few players of video stream transmitted via Bluetooth. MPEG-4 AVC/H.264 codec is one of video codecs available with best compression rates for a certain quality, so a H.264 encoder seems to be adequate for video stream to be transmitted via Bluetooth. In this paper, we present a DirectShow filter based player of video stream encoded by H.264 codec, which is transmitted via Bluetooth. Details on the design and implementation of this program are described. Experimental results are shown to demonstrate the validity of the implemented program using various video samples.

• The KIPS Transactions:PartB
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• v.10B no.2
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• pp.143-150
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• 2003

Error concealment plays an important role in combating transmission errors. Methods of error concealment which produce better quality are generally of higher complexity, thus making some of the more sophisticated algorithms is not suitable for real-time applications. In this paper, we develop temporal and spatial error resilient video encoding and data hiding approach to facilitate the error concealment at the decoder. Block interleaving scheme is introduced to isolate erroneous blocks caused by packet losses for spatial area of error resilience. For temporal area of error resilience, data hiding is applied to the transmission of parity bits to protect motion vectors. To do error concealment quickly, a set of edge features extracted from a block is embedded imperceptibly using data hiding into the host media and transmitted to decoder. If some part of the media data is damaged during transmission, the embedded features are used for concealment of lost data at decoder. This method decreases a complexity of error concealment by reducing the estimation process of lost data from neighbor blocks. The proposed data hiding method of parity bits and block features is not influence much to the complexity of standard encoder. Experimental results show that proposed method conceals properly and effectively burst errors occurred on transmission channel like Internet.