• Journal of Broadcast Engineering
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• v.20 no.2
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• pp.283-299
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• 2015

In this paper, we propose new broadcasting services that combine MMT (MPEG Media Transport) standard with MPEG-DASH (Dynamic Adaptive Streaming over HTTP) standard. MMT is a next-generation multimedia transport standard that is IP-friendly and provides functionalities appropriate for hybrid broadcasting that uses broadcast physical channels and the Internet simultaneously. MPEG-DASH enables media streaming services that can be dynamically adaptive both to the network traffic conditions of wired and/or wireless Internet and the receiving entity environment. We explain the scenarios of the proposed broadcasting services and demonstrate that various hybrid broadcasting services can be easily realized through the combined usage of MMT and MPEG-DASH. By making the test bitstreams containing contents for the new services and developing the receiver back-end software that performs the function of the receiving entity for the new services on personal computers, we verified that the proposed scenarios can be realized.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.2
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• pp.95-101
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• 2014

Scalable video coding (SVC) encodes multimedia data into a base layer and enhancement layers to cope with variable network conditions in an adaptive manner. In SVC, enhancement layers can be decoded only when the base layer is successively received. However, existing works on SVC transmissions in IEEE 802.11 WLANs do not fully investigate this characteristic and thus their performance can be degraded. In this paper, we propose a SVC-aware retransmission (SAR) scheme in IEEE 802.11 WLANs. The SAR scheme applies different retransmission policies for base and enhancement layers by obtaining the optimal number of frames to be retransmitted. As a result, the SAR scheme can reduce unnecessary retransmissions and minimize the transmission latency. Simulation results demonstrate that the SAR scheme can reduce unnecessary data transmission by 12.6% and the transmission latency by 6.6~19.1% compared to conventional retransmission schemes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.11B
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• pp.1151-1168
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• 2009

Improving packet loss does not necessarily coincide with the improvement in user perceivable QoS because each frame carries different degree of importance. We propose Significance-aware packet scheduling (SAPS) to maximize user perceivable QoS. SAPS carries out two fundamental issues of packet scheduling: "What to transmit" and "When to transmit?" To adapt to the available bandwidth, it is necessarily to transmit the subset of the data packets if the entire set of packets can not be transmitted. "Packet Significance" quantifies the importance of the frame by elaborately incorporating frames' dependency. Greedy approach is used in selecting packets and transmission schedule is determined based on the Packet Significance. The proposed scheme is tested using publicly available MPEG-4 video clips. Decoding engine is embedded in the simulation software and user perceivable QoS is exposeed in termstermiSNR. Throughout the simulation based experiment, the performance of the proposed scheme is compared two other schemes: Size-based packet scheduling and Bit-rate based best effort packet scheduling. SAPS successfully incorporates the semantics of a packet and improves user perceivable QoS significantly. It successfully provides unequal protection to more important packets.

• Journal of Korea Multimedia Society
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• v.19 no.7
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• pp.1166-1178
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• 2016

In Internet of Things (IoT) environments, billions of interconnected devices and multimedia sensors generate a huge amount of multimedia traffic. Since the environment are in general deployed as a server-centric architecture wireless sensor networks could be bottlenecks between IoT gateways and IoT devices. The bottleneck causes high power consumption of the device and triggers very heavy network overload by transmission of sensing data. The deterioration could decrease the quality of multimedia streaming service due to delay, loss, and waste of device power. Thus, in this paper, we propose a context-based adaptive multimedia streaming scheme to support enhanced QoS and low power consumption in IoT environments. The goal of the scheme is to increase quality score per voltage of the streaming service, given an adaptation algorithm with context that are classified network and hardware such as throughput, RTT, and CPU usage. From the both context, the quality score per voltage is used in the comparison of a only network context-based adaptive multimedia streaming scheme, a fixed multimedia streaming and our scheme. As a result, we achieves a high improvement that means the quality score per voltage is increased up to about 4, especially in case of resolution change.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.620-622
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• 2013

Real-time Video communication technology using a Web browser today is on the rise. Video communication system The existing A method of providing an Video communication via a program for a specific server on the service provider, respectively. By using the server of the company that provides an Video communication solutions, were limited by using its own network that you can use to build a separate server for performing Video communication another, using specific software and user groups it was a mechanism for using the Video communication environment. In addition, must be installed separately and ActiveX, plug-in and, use of the service has become possible. Therefore, in this paper, utilizing the real-time Video communication Web-based technology without installing the plug-in, real-time through a Web browser or Active-X of another using a script HTML5 and the Web on the Internet Using HTTP in an environment in the Internet is possible, I've implemented a system capable of Video communication.

• Journal of KIISE:Computing Practices and Letters
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• v.11 no.1
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• pp.50-61
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• 2005

To provide adaptively video streaming services on network environment, video transcoding is introduced. The one of transcoding methods is the frame-rate conversion. it needs a re-estimation about a motion vector of the frame to refer a skipping frame. This re-estimation makes higher the computational complexity in video transcoding. To reduce the computational complexity of a motion vector refinement, this paper proposes a region & activity based motion vector composition scheme that refine the moving vector of a skipping frame. This scheme composes each motion vector from the weight based on the activity information of a macroblock and the site of the overlapped area. The experiment result shows that RABVC has a higher PSNR than the value of existing weight-based motion vector selection schemes though the computational complexity of our scheme is similar to that of other schemes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.7A
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• pp.711-723
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• 2002

A finer granular scalable (FGS) version of ISO/IEC MPEG-4 video streaming is investigated in this work with the prioritized stream delivery over loss-rate differentiated networks. Our proposed system is focused on the seamless integration of rate adaptation, prioritized packetization, and simplified differentiation for the MPEG-4 FGS video streaming. The proposed system consists of three key components: 1) rate adaptation with scalable source encoding, 2) content-aware prioritized packetization, and 3) loss-based differential forwarding. More specifically, a constant-quality rate adaptation is first achieved by optimally truncating the over-coded FGS stream based on the embedding rate-distortion (R-D) information (obtained from a piecewise linear R-D model). The rate-controlled video stream is then packetized and prioritized according to the loss impact of each packet. Prioritized packets are transmitted over the underlying network, where packets are subject to differentiated dropping and forwarding. By focusing on the end-to-end quality, we establish an effective working conditions for the proposed video streaming and the superior performance is verified by simulated MPEG-4 FGS video streaming.

• Journal of Broadcast Engineering
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• v.24 no.5
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• pp.743-754
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• 2019

System for three degrees of freedom plus (3DoF+) and 6DoF requires multi-view high resolution 360 video transmission to provide user viewport adaptive 360 video streaming. In this paper, we implement 3DoF+ 360 video compression system which removes the redundancy between multi-view videos and merges the residual into one video to provide high quality 360 video corresponding to an user's head movement efficiently. Implementations about 3D warping based redundancy removal method between 3DoF+ 360 videos and residual extraction and merger are explained in this paper. With the proposed system, 20.14% of BD-rate reduction in maximum is shown compared to traditional high-efficiency video coding (HEVC) based system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1C
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• pp.21-35
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• 2002

Nowadays, in accordance with increasing expectations of multimedia stream service on the internet, a lot of distributed applications are being required and developed. But the models of the existing systems have the problems that cannot support the extensibility and the reusability, when the QoS relating functions are being developed as an integrated modules which are suited on the centralized controlled specific-purpose application services. To cope with these problems, it is suggested in this paper to a distributed QoS management system on CORBA, an object-oriented middleware compliance. This systems we suggested can provides not only for efficient control of resources, various service QoS, and QoS control functions as the existing functions, but also QoS control real-time negotiation and dynamic adaptation in addition. This system consists of QoS Control Management Module(QoS CMM) in client side and QoS Management Module(QoS MM) in server side, respectively. These distributed modules are interfacing with each other via CORBA on different systems for distributed QoS management while serving distributed streaming applications. In phase of design of our system, we use UML(Unified Modeling Language) for designing each component in modules, their method calls and various detailed functions for controlling QoS of stream services. For implementation of our system, we used OrbixWeb 3.1c following CORBA specification on Solaris 2.5/2.7, Java language, Java Media Framework API 2.0 beta2, Mini-SQL 1.0.16 and the multimedia equipments, such as SunVideoPlus/Sun Video capture board and Sun Camera. Finally, we showed a numerical data controlled by real-time negotiation and adaptation procedures based on QoS map information to GUIs on client and server dynamically, while our distributed QoS management system is executing a given streaming service.

• The KIPS Transactions:PartA
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• v.16A no.5
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• pp.357-368
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• 2009

Mobile IP storage has been proposed to overcome storage limitation in the flash memory and hard disks. It provides almost capacity-free space for mobile devices over wireless IP networks. However, battery lifetime of the mobile devices is reduced rapidly because of power consumption with continuous use of a WLAN device when multimedia contents are being streamed through the mobile IP storage. This paper proposes an energy-efficient WLAN device power control technique for streaming multimedia contents with the mobile IP storage. The proposed technique consists of a prefetch buffer input/output module, a WLAN device power control module, and a reconfigurable prefetch buffer module. Besides, it adaptively determines the size of the prefetch buffer according to a quality of the multimedia contents, and it dynamically controls the power mode of the WLAN device on the basis of power on-off operations while streaming the multimedia contents. We evaluate the performance of the proposed technique on a PXA270-based mobile device that employs the embedded linux 2.6.11, Intel iSCSI reference codes, and a WLAN device. Extensive experiments reveal that the proposed technique can save the energy consumption of the WLAN device up to 8.5 times with QVGA multimedia contents, as compared with no power control.