• Journal of the Semiconductor & Display Technology
• /
• v.13 no.1
• /
• pp.109-112
• /
• 2014

H.264/AVC is an international video coding standard that is established in cooperation with ITU-T VCEG and ISO/IEC MPEG, which shows improved code and efficiency than the previous video standards. Motion estimation using various macroblock from 44 to 1616 among the compression techniques of H.264/AVC contributes much to high compression efficiency. Generally, in the case of small motion vector or low complexity about P slice is decided $P16{\times}16$ mode encoding method. But according to circumstances, macroblock is decided $P16{\times}16$ mode despite large motion vector. If the motion vector variance is more than threshold and final select mode is $P16{\times}16$ mode, it is switched to $P8{\times}8$ mode, so this paper shows that the storage capacity is reduced. The results of experiment show that the proposed algorithm increases the compression efficiency of the H.264/AVC algorithm to 0.4%, even reducing the time and without increasing complexity.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• v.9 no.1
• /
• pp.800-803
• /
• 2005

모바일 단말 기반 동영상 서비스 기술에 관한 연구는 최근에 이르기까지 활발히 수행되고 있으며, 인터넷 기반에서 상용화가 가능한 기술 분야를 모바일에 응용하는 시도가 계속되고 있다. 모바일 단말 기반 영상서비스와 관련하여 최신형 모바일 단말에서는 관련기술을 하드웨어적으로 구현하거나 독자적 동영상 압축기술을 적용한 소프트웨어적 구현을 통하여 동영상 서비스를 제공하고 있다. 그러나 상당한 비율을 점하고 있는 기존 모바일 단말에서는 이들 하드웨어 칩이 없거나 추가적으로 애드온(add-on) 할 수 있는 표준적인 방법이 정해지지 않아 최신의 동영상 서비스 기술을 제공받을 수 없다. 따라서 시시각각으로 변화하는 모바일 동영상 서비스 환경에 적극적으로 대처하기 위해서는 소프트웨어적 해결방안이 필수적이라는 인식이 대두되고 있다. 본 연구에서는 모바일 단말에서 소프트웨어 디코더를 이용하여 기존 단말에서 뿐만 아니라 향후 최신단말에서도 적극적으로 대처하기 위하여 H.264/AVC 기반 소프트웨어 디코더를 모바일 단말에 적용하는 방안에 대하여 제안한다.

• Journal of Broadcast Engineering
• /
• v.13 no.1
• /
• pp.25-33
• /
• 2008

Video telephony is a representative service in 3G mobile network. And there have been efforts to improve quality of video telephony service in different fields. In Korea, the leading mobile service provider SKTelecom and KTF service the WCDMA network as 3G mobile network. Now, more than a million people is using the network. In this paper, we study about video telephony over WCDMA network. and propose error minimizing algorithm using cross-layer adaptation between physical layer and video codec. We simulated 3G-324M protocol with MPEG-4 video codec, and simulation results show suggested algorithm improve packet transmission rate for improving quality of video telephony service.

• MALSORI
• /
• no.61
• /
• pp.75-86
• /
• 2007

In this paper, we propose a scalable audio coder, which has a variable bandwidth from the narrowband speech bandwidth to the audio bandwidth and also has a bit-rate from 8 to 320 kbits/s, in order to cope with the quality of service(QoS) according to the network load. First of all, the proposed scalable coder splits bandwidth of the input audio into narrowband up to around 4 kHz and above. Next, the narrowband signals are compressed by a speech coding method compatible to an existing standard speech coder such as G.729, and the other signals whose bandwidth is above the narrowband are compressed on the basis of a psychoacoustic model. It is shown from the objective quality tests using the signal-to-noise ratio(SNR) and the perceptual evaluation of audio quality(PEAQ) that the proposed scalable audio coder provides a comparable quality to the MPEG-1 Layer III (MP3) audio coder.

• Proceedings of the Korean Information Science Society Conference
• /
• 2007.10b
• /
• pp.178-183
• /
• 2007

디지털 방송 기술의 비약적인 발전은 그 수요와 공급을 늘려가며 디지털 컨버전스 시대의 매력적인 산업으로 디지털 방송을 급부상시키고 있다. 이러한 발전 추세를 반영하듯 국내 아날로그 방송 서비스는 2012년을 기점으로 종료해야 하는 운명을 맞아 그 가속화는 더욱 빨라질 것으로 예상된다. 한편, 디지털 방송의 한 분야인 지상파 이동 멀티미디어 방송(Digital Multimedia Broadcasting, DMB) 역시 시류에 발맞추어 디지털 방송과 모바일 환경의 결합이라는 추가적인 이점을 안고, 몇 가지 서비스를 선보이고 있다. 하지만 이와 같은 이점에도 불구하고, DMB 서비스는 교육 혹은 광고 분야 등의 뚜렷한 수요의 증가를 가져오는 콘텐츠에 대한 제작과 배포가 쉽지 않고, 그 방법과 기준이 혼재하는 어려움으로 인하여 DMB가 지닌 무한한 가능성에 비해 크게 이슈화가 되지 못하고 있는 실정이다. 본 연구에서는 이러한 점에 착안하여, 지난 연구들에서 얻은 경험을 밑거름 삼아 기본적인 콘텐츠의 제작 및 배포는 물론 DMB 서비스에서 특화될 수 있는 콘텐츠를 더욱 쉴게 생성할 수 있으며, 기술적으로는 3차원 객체를 지원하는 부분을 보강하며, 편리한 인터페이스 등을 포함하는 저작 도구를 개발한다. 이를 위해 기존 연구들에서 다루어온 MPEG-4 Part 11 : BIFS(Binary Format for Scenes)를 기반으로 국내외에서 연구된 기존의 저작도구들을 비교하며, 새로운 아이디어들을 접목시켜 향후 DMB 서비스에서 효율적으로 쓰여 질 수 있는 저작도구를 개발한다.

• Journal of Information Processing Systems
• /
• v.15 no.4
• /
• pp.737-747
• /
• 2019

Shape description is an important and fundamental issue in content-based image retrieval (CBIR), and a number of shape description methods have been reported in the literature. For shape description, both global information and local contour variations play important roles. In this paper a new included-angular ternary pattern (IATP) based shape descriptor is proposed for shape image retrieval. For each point on the shape contour, IATP is derived from its neighbor points, and IATP has good properties for shape description. IATP is intrinsically invariant to rotation, translation and scaling. To enhance the description capability, multiscale IATP histogram is presented to describe both local and global information of shape. Then multiscale IATP histogram is combined with included-angular histogram for efficient shape retrieval. In the matching stage, cosine distance is used to measure shape features' similarity. Image retrieval experiments are conducted on the standard MPEG-7 shape database and Swedish leaf database. And the shape image retrieval performance of the proposed method is compared with other shape descriptors using the standard evaluation method. The experimental results of shape retrieval indicate that the proposed method reaches higher precision at the same recall value compared with other description method.

• Journal of the Korea Society of Computer and Information
• /
• v.24 no.1
• /
• pp.93-100
• /
• 2019

One of critical issues in dealing with 360-degree realistic contents is the performance degradation in searching and recognition process since they support up to 4K UHD quality and have all image angles including the front, back, left, right, top, and bottom parts of a screen. To solve this problem, in this paper, we propose an efficient search and comparison method for 360-degree realistic contents. The proposed method first corrects the distortion at the less distorted regions such as front, left and right parts of the image excluding severely distorted regions such as upper and lower parts, and then it extracts feature points at the corrected region and selects the representative images through sequence classification. When the query image is inputted, the search results are provided through feature points comparison. The experimental results of the proposed method shows that it can solve the problem of performance deterioration when 360-degree realistic contents are recognized comparing with traditional 2D contents.

• Journal of the Korea Society of Computer and Information
• /
• v.24 no.1
• /
• pp.85-92
• /
• 2019

In this paper, we propose a efficient feature point extraction method that can solve the problem of performance degradation by introducing a preprocessing process when extracting feature points by utilizing the characteristics of 360-degree realistic media. 360-degree realistic media is composed of images produced by two or more cameras and this image combining process is accomplished by extracting feature points at the edges of each image and combining them into one image if they cover the same area. In this production process, however, the stitching process where images are combined into one piece can lead to the distortion of non-seamlessness. Since the realistic media of 4K-class image has higher resolution than that of a general image, the feature point extraction and matching process takes much more time than general media cases.

• 한국정보컨버전스학회:학술대회논문집
• /
• 2008.06a
• /
• pp.53-56
• /
• 2008

This paper reports on the ACQA(Animated agent for Conversational Question Answering) project conducted at LIMSI. The aim is to design an expressive animated conversational agent(ACA) for conducting research along two main lines: 1/ perceptual experiments(eg perception of expressivity and 3D movements in both audio and visual channels): 2/ design of human-computer interfaces requiring head models at different resolutions and the integration of the talking head in virtual scenes. The target application of this expressive ACA is a real-time question and answer speech based system developed at LIMSI(RITEL). The architecture of the system is based on distributed modules exchanging messages through a network protocol. The main components of the system are: RITEL a question and answer system searching raw text, which is able to produce a text(the answer) and attitudinal information; this attitudinal information is then processed for delivering expressive tags; the text is converted into phoneme, viseme, and prosodic descriptions. Audio speech is generated by the LIMSI selection-concatenation text-to-speech engine. Visual speech is using MPEG4 keypoint-based animation, and is rendered in real-time by Virtual Choreographer (VirChor), a GPU-based 3D engine. Finally, visual and audio speech is played in a 3D audio and visual scene. The project also puts a lot of effort for realistic visual and audio 3D rendering. A new model of phoneme-dependant human radiation patterns is included in the speech synthesis system, so that the ACA can move in the virtual scene with realistic 3D visual and audio rendering.

• Journal of KIISE:Computer Systems and Theory
• /
• v.33 no.4
• /
• pp.242-255
• /
• 2006

In the recent years, Popularization of mobile devices such as Smart Phones, PDAs and MP3 Players causes rapid increasing necessity of Power management technology because it is most essential factor of mobile devices. On the other hand, despite low price, hard disk has large capacity and high speed. Even it can be made small enough today, too. So it appropriates mobile devices. but it consumes too much power to embed In mobile devices. Due to these motivations, in this paper we had suggested methods of minimizing Power consumption while playing multimedia data in the disk media for real-time and we evaluated what we had suggested. Strict limitation of power consumption of mobile devices has a big impact on designing both hardware and software. One difference between real-time multimedia streaming data and legacy text based data is requirement about continuity of data supply. This fact is why disk drive must persist in active state for the entire playback duration, from power management point of view; it nay be a great burden. A legacy power management function of mobile disk drive affects quality of multimedia playback negatively because of excessive I/O requests when the disk is in standby state. Therefore, in this paper, we analyze power consumption profile of disk drive in detail, and we develop the algorithm which can play multimedia data effectively using less power. This algorithm calculates number of data block to be read and time duration of active/standby state. From this, the algorithm suggested in this paper does optimal scheduling that is ensuring continual playback of data blocks stored in mobile disk drive. And we implement our algorithms in publicly available MPEG player software. This MPEG player software saves up to 60% of power consumption as compared with full-time active stated disk drive, and 38% of power consumption by comparison with disk drive controlled by native power management method.