• Journal of Broadcast Engineering
• /
• v.15 no.4
• /
• pp.513-526
• /
• 2010

In this paper, we propose a de-blocking filter for improvement of coding efficiency and computational complexity reduction on a high definition video coding. Recently, the H.264/AVC standard-based research for high definition video coding method is under way because the amount of used of high definition videos is on the increase. The H.264/AVC de-blocking filter is designed for low bitrate video coding and it improves not only the subjective quality but also coding efficiency by minimizing the blocking artifact. However, the H.264/AVC de-blocking filter that strong filtering is performed is not suitable in a high definition video coding which occurs relatively low blocking artifact. Also, the conventional de-blocking filter has high computational complexity in decoder side. The computational complexity of the proposed method is reduced about maximum 8.8% than conventional method. Furthermore, the coding efficiency of the proposed method is about maximum 7.3% better than H.264/AVC de-blocking filter.

• Journal of Broadcast Engineering
• /
• v.20 no.4
• /
• pp.619-631
• /
• 2015

In this paper, we propose a new online content editing system to edit the broadcasting and personal contents. The proposed editing system consists of the content management server and the content editor, in which the content management server is used for storing the contents, while the content editor is used for editing the contents via the user interface. Unlike the existing content editing methods which edit the downloaded contents, the proposed editing system edits the contents stored in the content management server while the content editor plays them by using the streaming technology. However, it is not effective to edit the whole segments of contents while playing them by using the streaming technology. To resolve the problem, the proposed editing system performs the scene detection of the contents, and the detected scene information is used for playing and editing of contents. After completing the content editing, the edited information is uploaded to the content management server as a metadata format. In the proposed editing system, both scene and edited information are represented only as the metadata format, and the physical content segmentation according to the scene and edited information is not performed. The implementation results show that the proposed editing system provides similar performances with the existing content editing methods which use the content download and editing methods.

• Journal of Broadcast Engineering
• /
• v.13 no.1
• /
• pp.6-16
• /
• 2008

An instable wireless channel condition causes more packet losses and retransmissions due to interference, fading, station mobility, and so on. Therefore video streaming service over a wireless networks is a challenging task because of the changes in the wireless channel conditions and time-constraints characteristics of the video streaming services. To provide efficient video streaming over a wireless networks, QoS-enhanced MAC protocol, IEEE 802.11e, is standardized recently. Tn this paper, we propose a new network-adaptive H.264 video streaming mechanism in the IEEE 802.11e wireless networks. To improve the quality of video streaming services, video stream has to adapt to the changes in the wireless channel conditions. The wireless channel conditions are estimated by the packet loss probability and informed to the application layer by the cross-layering. According to the wireless channel information, the video streaming application filters out the low-priority data. This adaptation mechanism efficiently uses system resources because it drops the low-priority data in advance. Therefore, our cross-layer design can provide improved video streaming services to the end-user. Through the implementation and performance evaluation, we prove that the proposed mechanism improves the QoS of the video streaming by providing the smoothed playback.

• The KIPS Transactions:PartC
• /
• v.13C no.4 s.107
• /
• pp.471-480
• /
• 2006

Recently, multimedia communication services, such as video conferencing and voice over IP, have been rapidly spread. H.323 is an international standard that specifies the components, protocols and procedures that provide multimedia communication services of real-time audio, video, and data communications over packet networks, including IP based networks. H.323 is applied to many commercial services because it supports various network environments and has a good performance. But communication services based on H.323 may have some problem because of current network trouble or mis-implementation of H.323. The understanding of this problem is a critical issue because it improves the quality of service and is easy to service maintenance. In this paper, we implement the analysis system for H.323 protocol wihch includes H.245, H.225.0, RTP, RTCP, and so on. Tills system is able to capture, parse, and present the H.323 protocol in real-time. Through the operation test and performance evaluation, we prove that our system is a useful to analyze and understand the problems for communication services based on H.323.

• Journal of KIISE:Information Networking
• /
• v.37 no.5
• /
• pp.363-373
• /
• 2010

The existing QoS mechanisms for video streaming are short of the consideration for various user environments and the characteristic of streaming applying programs. In order to overwhelm this problem, studies on the video streaming protocols exploiting scalable video coding (SVC), which provide spatial, temporal, and qualitative scalability in video coding, are progressing actively. However, these protocols also have the problem to deepen network congestion situation, and to lower fairness between other traffics, as they are not equipped with congestion control mechanisms. SVC based streaming protocols also have the problem to overlook the property of videos encoded in SVC, as the protocols transmit the streaming simply by extracting the bitstream which has the maximum bit rate within available bandwidth of a network. To solve these problems, this study suggests TCP-friendly network adaptive SVC streaming(T-NASS) protocol which considers both network status and SVC bitstream property. T-NASS protocol extracts the optimal SVC bitstream by calculating TCP-friendly transmission rate, and by perceiving the network status on the basis of packet loss rate and explicit congestion notification(ECN). Through the performance estimation using an ns-2 network simulator, this study identified T-NASS protocol extracts the optimal bitstream as it uses TCP-friendly transmission property and perceives the network status, and also identified the video image quality transmitted through T-NASS protocol is improved.

• Journal of KIISE:Information Networking
• /
• v.36 no.5
• /
• pp.425-436
• /
• 2009

In recent years, the user demands have increased for multimedia service of high quality over the broadband convergence network. These rising demands for high quality multimedia service led the popularization of various user terminals and large scale display equipments, which needs a variety type of QoS (Quality of Service). In order to support demands for QoS, numerous research projects are in progress both from the perspective of network as well as end system; For example, at the network perspective, QoS guaranteeing by improving of internet performance such as Active Queue Management, while at the end system perspective, SVC (Scalable Video Coding) encoding scheme to guarantee media quality. However, existing AQM algorithms have problems which do not guarantee QoS, because they did not consider the essential characteristics of video encoding schemes. In this paper, it is proposed to solve this problem by deploying the TS- AQM (Temporal Scalability Active Queue Management) which employs the differentiated packet dropping for dependency of the temporal level among the frames, based on SVC encoding characteristics by exploiting the TID (Temporal ID) field of the SVC NAL unit header. The proposed TS-AQM guarantees multimedia service quality through video decoding reliability for SVC streaming service, by differentiated packet dropping when congestion exists.

• Journal of KIISE:Information Networking
• /
• v.35 no.2
• /
• pp.99-111
• /
• 2008

In recent years, the needs for WLANs(Wireless Local Area Networks) technology which can access to Internet anywhere have been dramatically increased particularly in SOHO(Small Office Home Office) and Hot Spot. However, unlike wired networks, there are some unique characteristics of wireless networks. These characteristics include the burst packet losses due to unreliable wireless channel. Note that burst packet losses, which occur when the distance between the wireless station and the AP(Access Point) increase or when obstacles move temporarily between the station and AP, are very frequent in 802.11 networks. Conversely, due to burst packet losses, the performance of 802.11 networks are not always as sufficient as the current application require, particularly when they use TCP at the transport layer. The high packet loss rate over wireless links can trigger unnecessary execution of TCP congestion control algorithm, resulting in performance degradation. In order to overcome the limitations of WLANs environment, MAC-layer LDA(Loss Differentiation Algorithm)has been proposed. MAC-layer LDA prevents TCP's timeout by increasing CRD(Consecutive Retry Duration) higher than burst packet loss duration. However, in the wireless channel with high packet loss rate, MAC-layer LDA does not work well because of two reason: (a) If the CRD is lower than burst packet loss duration due to the limited increase of retry limit, end-to-end performance is degraded. (b) energy of mobile device and bandwidth utilization in the wireless link are wasted unnecessarily by Reducing the drainage speed of the network buffer due to the increase of CRD. In this paper, we propose a new retransmission module based on Cross-layer approach, called BLD(Burst Loss Detection) module, to solve the limitation of previous link layer retransmission schemes. BLD module's algorithm is retransmission mechanism at IEEE 802.11 networks and performs retransmission based on the interaction between retransmission mechanisms of the MAC layer and TCP. From the simulation by using ns-2(Network Simulator), we could see more improved TCP throughput and energy efficiency with the proposed scheme than previous mechanisms.

• (The) Research of the performance art and culture
• /
• no.36
• /
• pp.75-102
• /
• 2018

Manjungpan Chunhyangga is established by Manjung Kim Sohee. She selectively chose and arranged the songs by Jung Jungryeol, Song Mangap, Jung Eungmin, Kim Yeonsoo, Park Dongsil, and Jung Kwangsil. Kim Sohee once stated that while a major section of Chunhyangga is based on the songs by Jung Jungryeol, Song Mangap, Jung Eungmin, and Kim Yeonsoo, the whole part of Okjungga is derived from Park Dongsil. However, there is not much material that will provide enough information with regard to what musical characteristics Park Dongsilje Chunhyangga possessed. Under the circumstances, the voice of Park Dongsilje, left by Kim Sohee, triggers curiosity on Park Dongsilje Chunhyangga. It can also be construed that there must be a good reason for choosing Park Dongsilje for Okjungga, unlike other parts. Therefore, this paper attempted to find out what the unique features of Par Dongsilje are and what the reasons behind Kim Sohee's musical choice were through comparison and analysis of Kim Sohee's musical features in Okjungga. The following are the results. Firstly, Okjungga is a created verse by its nature and it does not possess specific features to a school. Therefore, the reason for choosing Park Dongsilje could have been based on musical reason rather than verse. Secondly, the lyrics of Park Dongsilje Okjungga is closer to that of Song Mangap rather than that of Jung Jungryeolje. It can be argued that it falls between the two of them. Thirdly, the tone and melody of Park Dongsilje Okjungga falls in the middle section of Dongpyenje and Supyenje. Fourthly, the analysis of Jinyangjo rhythm out of the whole Manjungpan Chunhyangga shows that there are slight differences among Song Mangapje, Jung Jungryeolje, and Jung Eungminje. Park Dongsilje is very unique in the sense that it does not use utbutim in gyemyeonjo part in Manjungpan Chunhyangga. Park Dongsilje Okjungga is a song to which the tone, melody, and sigimsae of Supyeonje is added to lyric butimsae of Dongpyeonje. It can be seemed as simple and less sophisticated because, with its simple lyric butimsae, it shows a less complicated tone utilization rather than Jung Jungryeol. With lighter decoration of music, feelings can be conveyed more directly. That is probably why Kim Sohee commented on Park Dongsilje Chunhyangga that it is the most mournful song for Chunhyang and it is the song that moves anyone who listens to the song. Consequently, Kim Sohee accepted Park Dongsilje Okjungga and she created different feelings to Manjungpan Chunhyangga which has repeatedly displayed the color of Jung Jungryeol. Combining the lyric addition of Dongpyeon style and the melody of Supyeon style can crated a different language.