• Journal of KIISE:Information Networking
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• v.34 no.4
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• pp.276-286
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• 2007

Existing streaming mechanisms have no consideration for the characteristics of streaming applications because they only consider network stability. In this paper, in order to overcome limitations of the previous work on video streaming, we propose a new video streaming mechanism called "HAViS(Hybrid Approach for Video Streaming)". The proposed mechanism includes more sophisticated features that consider both network and user requirements. Therefore, the HAViS mechanism improves the network stability by adjusting the sending rate of video stream based on the network state and it also provides the smooth playback by preventing the buffer underflow or overflow. Moreover, it is designed to take into consideration the streaming video content. Through the simulation, we prove that the HAViS mechanism efficiently uses the buffer resources and provides improved network stability and smooth playback.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.7
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• pp.1335-1341
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• 2017

In this paper, a new architecture of multiple conference servers which use extended control channel framework in SIP(session initiation protocol) session has been presented. For this purpose, in this study, a new extended control channel framework architecture which can distribute total conference system loads to multiple servers effectively has been presented. In the implementation, extended control channels have been connected by using SIP sessions that was established between each conference servers, and extended control channel messages which can be transferred through control channels have been designed in this study. These extended control channel messages can distribute system load effectively between multiple conference servers, and conference information data format that can represent extended control channel framework has also been designed. Furthermore, exchange procedures of extended control channel messages have also been presented. The performance of the proposed system has been analysed by simulation. The analysis results show that average SIP messages delay time and average media stream delay time have improved.

• The Transactions of the Korea Information Processing Society
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• v.3 no.1
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• pp.9-32
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• 1996

In this paper, we describe a multimedia data processing model that supports wide variety of applications based on multimedia production model. This model supports network-transparent access to stored multimedia data, real-time mult media input devices, and multimedia processing. The model addresses real-time dato a switching and delivery, as well as acquisition, processing, and output. Most translation, compression, and synchronization services are integrated. This model consists of three layers: (1) stream, (2) multimedia presentation, (3) hyperpresentaion. This paper describes the data abstractions associated with each layer. These data abstractions provide a framework for defining the services provided by each layer, and describe the object-oriented mechanisms that provide those services. A sample scenario is presentated to illustrate the use of this model. A server-client architecture and implementation issues, and future directions are also discussed. sed.

• Journal of Broadcast Engineering
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• v.12 no.2
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• pp.120-127
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• 2007

In this paper, we describe a new 1/4 rate robust modulation techniques for Enhanced-x VSB system which is fully backward compatible with ATSC 8-VSB standard. 1/4 rate mode Enhanced-xVSB system provides broadcasters with a wide choice of trade-offs of data rate vs amount of robustness of enhanced data for pedestrian/mobile services. Lab test results of proposed Enhanced-x VSB 1/4 rate mode robust stream are a significantly improved multipath as well as AWGN reception performance for Enhanced-x VSB receiver. We suggest an Enhanced-x VSB terrestrial broadcasting system for ATSC HDTV and pedestrian/portable TV simultaneous broadcasting service providing.

• Journal of Broadcast Engineering
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• v.6 no.2
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• pp.121-130
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• 2001

We propose an efficient DCT-domain video transcoding algorithm for flexible for bit-rate video communications. Video transcoding provides communication fiexibility by adaptively changing the bit-rate of compressed bit stream. During the transcoding process, adrift error is unavoidable because of the difference between reference images in the series of encoding and decoding. For solving the drift error problem, cascade pixel-domain transcoder (CPDT) has been proposed. CPDT, however, requires highly complex hardware and heavy computational overhead. In this paper we propose a DCT-domain transcoding technique, which enables efficient transcoding without any drift error. The proposed cascade DCT-domain transcoder (CDDT) is realized by new motion compensation and down-sampling methods in the DCT-domain.

• Journal of Broadcast Engineering
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• v.8 no.3
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• pp.217-227
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• 2003

This paper describes an implementation of the slide-show functionality, which is one of the services that can be provided by the Digital Multimedia Broadcasting (DMB). While the existing analog radio broadcasting services provide audio only, DMB slide-show is the functionality that can deliver still images associated with the audio. For example, it can deliver the photographs of the singer, album cover images, or the lyrics of the song that correspond to the audio. There are two modes for the transmission of the slide-show. Firstly. the program-associated data (PAD) field within the DMB audio frame can be utilized and secondly, the slide-show data can be transmitted, after being multiplexed, with other service data as individual data stream separated from the audio. This paper describes PC-based implementations of a transmitter-side module that inserts slide-show data into the PAD area within audio bitstream and a receiver-side application module that plays the slide-show through decoding the PAD within the received audio bitstream and demonstrates their validity through experiments.

• Journal of Broadcast Engineering
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• v.8 no.3
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• pp.288-296
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• 2003

ATSC (Advanced Television System Committee) has specified 18 video formats for DTV (Digital Television), e.g., scan format, size format, and frame rate format conversion. Effective MPEG-2 video transcoders should support any conversion between the above-mentioned formats. Scan format conversion Is hard to Implement because it may often induce frame rate and size format conversion together. Especially. because of picture type conversion caused by scan format conversion, the computational burden of motion estimation (ME) in transcoding becomes serious. This paper proposes a fast ME algorithm for MPEG-2 video transcoding supporting scan format conversion. Firstly, we extract and compose a set of candidate motion vectors (MVs) from the input bit-stream to comply with the re-encoding format. Secondly, the best MV is chosen among several candidate MVs by using a weighted median selector. Simulation results show that the proposed ME algorithm provides outstanding PSNR performance close to full search ME, while reducing the transcoding complexity significantly.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.12
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• pp.983-987
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• 2009

One of the critical themes in the language acquisition is its exposure to linguistic environments. Linguistic environments, which interact with infants, include not only human beings such as its parents but also artificially crafted linguistic media as their functioning elements. An infant learns a language by exploring these extensive language environments around it. Based on such large linguistic data exposure, we propose a machine learning based method on the cognitive mechanism that simulate flexibly and appropriately infant's language learning. The infant's initial stage of language learning comes with sentence learning and creation, which can be simulated by exposing it to a language corpus. The core of the simulation is a memory-based learning model which has language hypernetwork structure. The language hypernetwork simulates developmental and progressive language learning using the structure of new data stream through making it representing of high level connection between language components possible. In this paper, we simulates an infant's gradual and developmental learning progress by training language hypernetwork gradually using 32,744 sentences extracted from video scripts of commercial animation movies for children.

• The KIPS Transactions:PartC
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• v.13C no.6 s.109
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• pp.669-676
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• 2006

In this paper, we present a new framework and stream synchronization mechanism to effectively support developing real-time multimedia streaming services by using a real-time object model named TMO (Time-triggered Message-triggered Object). The purpose of the framework is twofold. Firstly, the framework helps developers to design complex distributed real-time multimedia streaming services. Secondly, it supports timely streaming facilities. In order to achieve these goals, our framework is consist of Multimedia Streaming TMO, MMStreaming TMO Support Library and TMO Support Middleware. The time-triggered spontaneous feature of the MMStream TMO and a global-time based synchronization scheme is used as a regulator against the irregular deliveries and processing of media units caused by QoS non-guaranteed systems and communication channels. In conclusion, timely service capability of our framework is expected to contributed to overall enhancement of the real-time multimedia streaming.

• Journal of KIISE:Information Networking
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• v.37 no.3
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• pp.187-197
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• 2010

The fusion stream of recent broadcasting and communication make multimedia content served in the area of broadcasting into IPTV service which transmits it through high-speed internet, cable TV net and satellite net in realtime. However, as the digital broadcasting service is extended to various media, the security of IPTV service content provided to users by service provider is not fully supported by CAS(Conditional Access System) provided by existing broadcasting system. This paper proposes interactive certification protocol which can efficiently distinguish the receiving-qualification of user between Set-Top Box and Smart Card which are parts of configurations for IPTV system. The proposed protocol uses hash function to make Set-Top Box transmit receiving-qualification about the channel fee which user pays more properly than existing protocol. Also, the proposed protocol uses session key generated between receiver and smart card through inter certification process and encrypts EMM not the service to be used by anyone illegally.