• 인터넷정보학회논문지
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• 제21권4호
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• pp.51-57
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• 2020

Currently, High-efficient video coding (HEVC) has become the most promising video coding technology. However, the implementation of HEVC in video streaming systems is restricted by factors such as cost, design complexity, and compatibility with existing systems. While HEVC is considering deploying to various systems with different reached methods, H264/AVC can be one of the best choices for current video streaming systems. This paper presents an adaptive method for manipulating video streams using video coding on an integrated circuit (IC) designed with a private network processor. The proposed system allows to transfer multimedia data from cameras or other video sources to client. For this work, a series of video or audio packages from the video source are forwarded to the designed IC via HDMI cable, called Tx transmitter. The Tx processes input data into a real-time stream using its own protocol according to the Real-Time Transmission Protocol for both video and audio, then Tx transmits output packages to the video client though internet. The client includes hardware or software video/audio decoders to decode the received packages. Tx uses H264/AVC or HEVC video coding to encode video data, and its audio coding is PCM format. By handling the message exchanges between Tx and the client, the transmitted session can be set up quickly. Output results show that transmission's throughput can be achieved about 50 Mbps with approximately 80 msec latency.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 신호처리소사이어티 추계학술대회 논문집
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• pp.287-290
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• 2003

In recent years, one of the main trends of GIS is to construct and provide realistic and human-perceptible information of spatial object using video data. The rapid progress of wireless mobile technology makes the multimedia source using video data possible on mobile environment. Instead of traditional map-based service, video-based location services, that provide video data as location context, would be of interest in connection with various mobile applications requiring location service, such as telematics, LBS, etc. In this paper, we present the location service system using geo-referenced video on wireless mobile environment.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.607-610
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• 2002

Even though digital video coding techniques have been developed very rapidly, rate controlling is still an unsolved problem. This paper presents a new scene adaptive video encoding scheme for MPEG-1 and MPEG-2 video encoders. Degradation of picture quality at scene changes due to poor prediction of global complexity measure is addressed. The proposed scheme determines the picture types adaptively based on scene contents of each video frame. The effective placement of reference and inter-reference frames is studied at sudden scene changes and gradual scene changes respectively. Results show that the proposed scheme demonstrates a significant improvement in performance compared to TM5〔1〕.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권10호
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• pp.3520-3537
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• 2014

Video copy detection methods have emerged in recent years for a variety of applications. However, the lack of efficiency in the usual retrieval systems restricts their use. In this paper, we propose a parallel implementation strategy for content based video copy detection (CBCD) by using a multi-core processor. This strategy can support video copy detection effectively, and the processing time tends to decrease linearly as the number of processors increases. Experiments have shown that our approach is successful in speeding up computation and as well as in keeping the performance.

• 한국멀티미디어학회논문지
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• 제21권7호
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• pp.795-801
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• 2018

In these days, various technologies to provide a service of high quality of 360 VR media contents is being studied and developed. However, rendering high-quality of media images is very difficult with the limited resources of HMD (Head Mount Display). In this paper, we designed and implemented a 360 VR Player for high quality 360 tiled video image render to HMD. Furthermore, we developed multi-resolution-based Foveated Rendering technology. By conducting several experiments, We have confirmed that it improved the performance of video rendering far more than existing tiled video rendering technology.

• Educational Technology International
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• 제14권1호
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• pp.1-26
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• 2013

This study is to identify whether three types of online instruction (text-based, video-based, and video-based instruction without text) and age category have a different influence on students' comprehension and motivation. Online students were randomly assigned to one of six groups, and they attended two-week online lectures via Course Management System. The comprehension test and the short form of IMMS were implemented when 114 participants accomplished two-week online lectures. The results revealed that using instructional video in online instruction is more effective instructional medium than text only in order to promote learner's motivation. Besides, older adults aged 41-60 are significantly different from younger adults (21-40 years old) in terms of students' comprehension. Furthermore, three types of online instructions are likely to be influenced by age category.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권4호
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• pp.1768-1789
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• 2016

In contemporary video streaming systems based on HTTP protocol, video players at the client side are responsible for adjusting video quality to network conditions and user expectations. However, when multiple video clips are streamed simultaneously, an intricate application logic implemented in the video players overlays the TCP mechanism which is responsible for a balanced access to a shared network link. As a result, some video players may not obtain a fair share of network throughput and may be vulnerable to an unstable video bit-rate. Therefore, we propose to simplify the algorithms implemented in the video players, which are responsible for the adjustment of video quality and constrain their functionality only to sending feedback to a server about a state of the player buffer. The main logic of the system is shifted to the server, which is now responsible for bit-rate selection and prioritisation of the video streams transmitted to multiple clients. To verify our proposition, we performed several experiments in a laboratory environment which show that when the server cooperates with the clients, the video players experience fewer quality switches and the system achieves better fairness when allocating network throughput among the video players. However, this comes at the cost of worse utilisation of network bandwidth.

• 방송공학회논문지
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• 제25권5호
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• pp.709-722
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• 2020

포인트 클라우드는 수많은 점의 집합으로 이루어진 데이터로 2차원 평면에서 벗어나 3차원 공간에서 3D 객체를 표현하는 것이 가능하다. 각 점은 기본적으로 3차원 공간의 좌표 정보가 필요하고 추가적으로 색 (Color), 반사율 (Reflectance) 같은 속성을 가질 수 있도록 구성되어 있다. 이처럼 3D 포인트 클라우드 표현에는 2D 영상보다 많은 데이터를 사용하고 있기에, 이를 사용자에게 효율적으로 제공하기 위해서는 고효율의 압축 기술 연구가 필요하며, 현재 국제 표준 기구인 MPEG에서는 포인트 클라우드 콘텐츠 압축 방법으로 2D 비디오 압축 기술을 사용한 Video-based Point Cloud Compression (V-PCC) 기술이 연구되고 있다. 이러한 고효율의 포인트 클라우드 압축방식에도 불구하고 단말의 성능이나 네트워크 환경 등의 문제로 인해 서비스가 제한되는 상황이 발생할 수 있다. 2D 영상의 경우 Scalable High efficiency Video Coding (SHVC) 혹은 Dynamic Adaptive Streaming over HTTP (DASH) 등의 다양한 기술을 사용하여 이러한 문제를 해결하고 있다. 이에 본 논문에서는 V-PCC 구조에 SHVC를 적용하여, 밀도 스케일러빌리티 기능을 가진 포인트 클라우드 압축 방안을 제안하는 것으로 이러한 문제를 해결하고자 한다.

• 한국통신학회논문지
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• 제40권7호
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• pp.1405-1412
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• 2015

최근 방송통신 및 비디오 코딩 기술의 급격한 발전으로 인해 3D 입체영상에 기반을 둔 실감 미디어 서비스의 요구는 지속적으로 증가하고 있다. 이러한 요구는 가정 내 고정된 3DTV 뿐만 아니라 개인 스마트기기, 자동차, 철도, 그리고 선박과 같이 자유롭게 이동하는 무선 채널 환경에서도 반드시 만족되어야 한다. 따라서 본 논문에서는 이러한 실감 미디어 서비스의 요구를 만족하기 위해 직접파가 반사파 보다 우세한 해양 라이시안 채널 환경을 고려하여 3D 입체영상을 전송한다. 또한 3D 입체영상은 일반적으로 V+D (Video plus Depth) 포맷을 통해 표현되기 때문에 이 포맷에 특성을 고려하여 계층 4/16-QAM을 적용한 비균등 오류보호 기법도 제안한다. 이는 아무리 수신 채널의 상태가 나쁜 선박이라도 중간에 끊어짐이 없이 방송서비스를 제공받을 수 있는 기술로 기대된다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권3호
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• pp.1434-1449
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• 2019

Video object segmentation is a significant task in computer vision, but its performance is not very satisfactory. A method of video object segmentation using weakly temporal information is presented in this paper. Motivated by the phenomenon in reality that the motion of the object is a continuous and smooth process and the appearance of the object does not change much between adjacent frames in the video sequences, we use a feed-forward architecture with motion estimation to predict the mask of the current frame. We extend an additional mask channel for the previous frame segmentation result. The mask of the previous frame is treated as the input of the expanded channel after processing, and then we extract the temporal feature of the object and fuse it with other feature maps to generate the final mask. In addition, we introduce multi-mask guidance to improve the stability of the model. Moreover, we enhance segmentation performance by further training with the masks already obtained. Experiments show that our method achieves competitive results on DAVIS-2016 on single object segmentation compared to some state-of-the-art algorithms.