• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.8
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• pp.3121-3135
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• 2015

Owing to the increase in consumption of multimedia content and the improvement of device capacity, user demand for high-quality content has increased. However, it is difficult to transport such large amounts of content over the existing broadcasting network with limited bandwidth. To provide high-definition broadcasting, some studies suggest methods of transporting multimedia over heterogeneous networks after encoding content hierarchically. MPEG Media Transport (MMT), standardized by Moving Picture Experts Group (MPEG), is a solution that enables large-volume media transport over heterogeneous networks such as digital broadcasting networks and packet-switched networks. In the case of delivering a scalable encoded video over different networks, synchronization of each stream is an important issue. MMT defines a synchronization scheme, but does not contain sufficient functions to implement it. In this paper, we propose a synchronization scheme for media streams that are encoded hierarchically, divided into layers, and transported over heterogeneous networks. We implement our scheme using MMT and HTTP, and experimented using three encapsulated video streams with different durations. As a result, we show that the proposed scheme can reduce the waiting time to display high-quality video, relative to Dynamic Adaptive Streaming over HTTP-Scalable Video Coding (DASH-SVC) by requesting segments of enhanced layers after calculating the transmission time. Additionally, we find out that the selection of durations have a relation to the characteristics of the video.

• Journal of Broadcast Engineering
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• v.10 no.3
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• pp.313-320
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• 2005

The increasing popularity of multimedia streaming services introduces new challenges in content distribution. Especially, it is important to provide the QoS guarantees as they are increasingly expected to support the multimedia applications. Multimedia streams typically experience the high start-up delay due to the large protocol overhead, the delay, and the loss properties of the wireless networks. The service providers can improve the performance of multimedia streaming by caching the initial segment (prefix) of the popular streams at proxies near the requesting clients. The proxy can initiate transmission to the client while requesting the remainder of the stream from the server. In this paper, we propose the traffic based caching algorithm (TSLRU) to improve the performance of caching proxy. TSLRU classifies the traffic into three types, and improve the performance of caching proxy by reflecting the several elements such as traffic types, recency, frequency, object size when performing the replacement decision. In simulation, TSLRU performs better than the existing schemes in terms of byte hit rate, hit rate, startup latency, and throughput.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.527-530
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• 2014

DASH is a well-known streaming technology, which was proposed in 2010 by MPEG and standardized in 2011. Major multimedia contents service providers, including Apple, Microsoft, and Adobe are all using this technology to support their media streaming services. Whenever a new service is requested to the server, the DASH technology helps servicing the multimedia streaming to client by recognizing the capacity of network and by adapting the quality of the multimedia contents. In DASH, the quality of multimedia contents will be automatically lowered to meet the fluctuating network status, when undesirable breaks interrupt the network. In this paper, we classified and analysed the advantages and disadvantages of DASH researches in three aspects: bit-rate measurement method, bandwidth aggregation method; rate adaptation metrics, algorithms and logics; user's experiences and QoE.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.11a
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• pp.12-17
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• 2001

본 논문에서는 낮은 대역폭의 무선 네트워크상에서 MPEG 스트리밍을 위한 방법으로, DCT 계수의 제거에 기반한 QoS 필터링 방법과 매크로 블록상의 움직임 벡터와 인트라 블록의 비율을 고려한 영상분식을 통하여 분석된 내용에 가장 알맞는 필터의 선택과 필터의 적용 수준을 네트워크의 상태에 따라 결정하여 대역폭을 만족시킬 수 있는 비트레이트의 조절로서 원활한 스트리밍을 가능하게 하며 영상분석을 통하여 영상의 품질을 높여 고품질의 영상 멀티미디어 서비스와 최소한의 부하를 줄 수 있는 설계로서 서버운용시 과효율을 놀일 수 있도록 한다.

• Proceedings of the Korea Multimedia Society Conference
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• 2002.05c
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• pp.416-421
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• 2002

본 논문에서는 인터넷 상에서 UDP 소켓 인터페이스를 이용하여 실시간 스트리밍 전송을 시뮬레이션 하였고 또한 수신자로부터 피드백 된 정보를 이용하여 송신자가 전송률을 제어하는 것을 시뮬레이션 하였다. 수신자로부터 제어정보를 피드백 받아 송신자가 전송률을 제어하는 경우와 송신자가 전혀 전송률제어를 하지 않는 경우의 패킷 손실 값을 비교했다. 결과로서, 피드백 되는 정보를 이용하여 제어를 하는 경우가 지속적인 패킷손실을 방지함을 보여 준다.

• Journal of Broadcast Engineering
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• v.17 no.4
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• pp.584-595
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• 2012

Recently, 3D stereoscopic video and HTTP adaptive streaming technologies have received a lot of attention from relevant industrial fields and markets in terms of multimedia contents and delivery services, respectively. It is expected that promising and marketable service models can be created by means of these noticeable two technologies. However, current standard specifications do not provide a method for organized connection between those two technologies. 3D stereoscopic video services are weighted in broadcasting and storage services that are only available under environments in which the network bandwidth is guaranteed or free. Also, HTTP adaptive streaming technologies only provide plain 3D service methods that are dependent on particular Codec. Therefore, this paper proposes 3D video delivery format for HTTP adaptive streaming service which enables stable and seamless display for various stereoscopic video sequences over internet networks. The proposed technology is designed on the basis of Stereoscopic Video Application Format which is a service-oriented standard specification for storing stereoscopic video sequences. Also, this delivery format is directly applicable over DASH that is the representative standard technology for HTTP adaptive streaming services. The delivery format proposed in this paper has been submitted to MPEG and it has been accepted as a working draft, thus it expected to pave the way for practical industrialization in relevant fields from now on.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.7
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• pp.1599-1609
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• 2014

TCP does not ensure the bandwidth and delay bound required for multimedia streaming services in broadband wireless network environments. In this paper, we propose a new congestion control scheme for efficient multimedia transmission, called COLO TCP (Concave Increase Slow Start Logarithmic Increase Congestion Avoidance TCP). The COLO TCP prevents the burst packet loss by applying the concave increase algorithm in slow start phase. In the congestion avoidance phase, COLO TCP uses the logarithmic increase algorithm that quickly recovers congestion window after packet loss. To highly utilize network bandwidth and reduce packet loss ratio, COLO TCP uses additive increase algorithm and adaptive decrease algorithm. Through simulation results, we prove that our COLO TCP is more robust for random loss. It is also possible for efficient multimedia transmission.

• Journal of information and communication convergence engineering
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• v.8 no.3
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• pp.245-250
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• 2010

To support various bandwidth requirements for many kinds of devices such as PC, notebook, PDA, cellular phone, a transcoding proxy is usually necessary to provide not only adapting multimedia streams to the client by transcoding, but also caching them for later use. Due to huge size of streaming media, we proposed the 3 kinds of segmentation - PT-2, uniform, bitrate-based segmentation. And to reduce the CPU cost of transcoding video, we proposed the DQS service policy. In this paper, we simulate the combined our previous two researches that are bitrate-based segmentation and DQS(Degraded Quality Service) policy. Experimental results show that the combined policy outperforms companion schemes in terms of the byte-hit ratios and delay saving ratios.

• Journal of Korea Multimedia Society
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• v.19 no.11
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• pp.1871-1877
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• 2016

In this paper, a Wireless USB (WUSB) protocol is adopted for development of ASMD (Adaptive Source Multi Device) N-screen wireless services. WUSB is the USB technology merged with WiMedia PHY and Distributed-MAC (D-MAC). However, the current WUSB protocol can't provide seamless N-screen streaming services to moving WUSB devices in home network environment. Therefore, to provide the ASMD N-screen services through WUSB based on D-MAC protocol, a channel management scheme is proposed to support seamless mobility between adjacent ASMD groups for wireless IPTV N-screen services. In simulation results, proposed ASMD channel management (ACM) scheme is compared with conventional WUSB channel management scheme in view points of throughput, average path interference and energy consumption according to various numbers of nodes and elapsed simulation times. Through simulation results, it is explained that proposed ASMD channel management (ACM) scheme should be adopted in the WUSB protocol to realize ASMD N-screen wireless services.

• Journal of KIISE:Software and Applications
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• v.33 no.10
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• pp.823-835
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• 2006

Multimedia is a very popular service in the Internet. But, we cannot provide multimedia service at a uniform content, because networks and devices are various. Thus, an adaptive service is needed for multimedia transmission. Video Transcoding is the good solution that can service multimedia adaptively. This paper proposes the streaming system that is composed of encoder, transcoder, decoder The encoder enhanced time complexity and PSNR in case of transcoding using PP(Prediction Period). The decoder is almost same as the traditional media player. Transcoder reduced time complexity through combination of prediction period in encoder and skipping period to control frame rate in transcoder. In simulation results, the performances of proposed scheme outperform the system with traditional transcoder in time complexity and PSNR.