• Title/Summary/Keyword: 가변비트율

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Trends of Speech-Based Audio Convergence Codec Technology (음성기반 오디오 융합코덱 기술동향)

  • Kim, D.Y.;Sung, J.M.;Lee, M.S.;Bae, H.J.;Lee, B.S.
    • Electronics and Telecommunications Trends
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    • v.24 no.5
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    • pp.10-19
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    • 2009
  • 본 논문에서는 통신과 방송서비스가 하나의 기기 또는 단말장치 안에서 결합되고 단말 내부에서는 디바이스의 통합에 따라 코덱의 개수를 최소화하기 위한 음성기반 오디오 융합코덱의 기술동향에 대해 기술한다. 하지만 기술적으로 완전히 태생이 다른 음성과 오디오 코덱을 진정한 의미에서 융합할 수 있는 기술적 모델과 기법은 아직 개발되지 않고 있다. 본 고에서는 이러한 시도의 일환으로 ITU-T SGl6을 중심으로 진행되고 있는 음성기반 코덱을 점진적 대역폭 확장 기술을 사용하여 광대역 음성, 슈퍼와이드 밴드 및 향후 오디오 대역까지 커버할 수 있는 임베디드 가변비트율 코덱기술을 중심으로 기술동향의 분석을 시도한다.

Enhanced East Mode Decision toy Variable Block Motion Compensation (가변 블록 움직임 보상을 위한 개선된 고속 모드 결정법)

  • 이제윤;최웅일;전병우
    • Proceedings of the IEEK Conference
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    • 2003.07e
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    • pp.2068-2071
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    • 2003
  • 최근 표준화가 완성된 H.264 는 가변 블록 움직임 보상, 복수 참조 영상, 그리고 1/4 화소 움직임 벡터 정확도를 지원하고 있다. 그러나 이러한 새로운 부호화기술은 부호화 효율 향상의 주된 요인이면서, 동시에 높은 복잡도의 요인이기도 하다 따라서 H.264 비디오 표준의 실제 응용 확대를 위해서는 이러한 기술의 속도향상이 필수적이다. [1]에서 제안한 고속 모드 결정법은 조기에 모드 결정을 할 수 있기 때문에, 움직임 벡터 탐색과 비트율-왜곡치 (Rate-Distortion cost) 계산 과정을 효율적으로 생략할 수 있는 방법이다. 하지만 [1]에서 제안된 측정치 r은 주변 블록의 정보를 이용하지 않기 때문에 모드 결정 에러를 좀 더 효과적으로 줄이지 못했다. 본 논문에서는 주변 블록의 정보를 이용하여 [1]의 방법을 개선시킨 것으로 실험 결과 큰 부호화 손실 없이 계산 량 감소에 있어 매우 높은 효율을 제공함을 확인하였다.

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Analysis of transmission effect of communication security frame synchronization information in variable message format (가변메시지 형식체계에서 COMSEC 프레임 동기정보의 전송영향 분석)

  • Hong Jin-Keun;Park Sun-Chun;Kim Ki-Hong;Kim Seng-Jo;Yoon Jang-Hong
    • Proceedings of the KAIS Fall Conference
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    • 2005.05a
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    • pp.214-216
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    • 2005
  • 본 논문에서는 가변형식메시지체계에서 COMSEC 프레임동기 정보의 전송영향을 분석하였다. 실험결과 비트오류율 $10^{-1}\~10^{-5}$ 환경에서 COMSEC 프레임 동기 정보의 강인한 특성을 고찰하였으며 암호통신을 위해 사용되는 프레임 동기정보가 동기검출 및 오검출 측면에서 영향정도를 분석하였다.

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A Study on Measurement of Objective Image Quality by Scanning Type for MPEG-2-based Terrestrial 2HD Service and Application on Experimental Broadcasting (MPEG-2 기반 지상파 2HD 서비스를 위한 주사 방식별 객관적 화질 측정 및 시험방송 적용 연구)

  • Park, Sung-hwan;Chang, Hae-rang;Lee, Jong-su;Kwon, Soon-chul;Lee, Seung-hyun
    • Journal of Digital Contents Society
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    • v.16 no.2
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    • pp.275-282
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    • 2015
  • Since starting of terrestrial digital broadcasting in 2001, there has been discussion on introduction of multiple broadcasting services, one of advantages of digital broadcasting. In the mean time, task force on terrestrial multiple channel experimental broadcasting was formed with government organizations, broadcasting companies and household appliance companies in Oct. 2013, and terrestrial multiple channel experimental broadcasting was started between Jan. to April, 2014. Based on this experimental result, EBS started 2HD MMS experimental broadcasting first in Korea on Feb. 11, 2015. This study was carried out in consideration of operation of 2 HD channels in existing 6MHz bandwidth based on MPEG-2 codec with development of compression technology. A study on image quality optimization was carried out and applied to 2HD MMS experimental broadcasting through application experiment of variable bit rate and change according to 1080i and 720p scanning type.

Design of Interactive Operations using Prefetching in VoD System (VoD 시스템에서 선반입 기법을 이용한 대화식 동작의 설계)

  • Kim, Soon-Cheol
    • Journal of Korea Society of Industrial Information Systems
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    • v.15 no.2
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    • pp.31-39
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    • 2010
  • VoD(Video-on-Demand) servers have to provide timely processing guarantees for continuous media and reduce the storage and bandwidth requirements for continuous media. The compression techniques make the bit rates of compressed video data significantly variable from frame to frame. A VoD system should be able to provide the client with interactive operations such as fast forward and fast rewind in addition to normal playback of movie. However, interactive operations require additional resources such as storage space, disk bandwidth, memory and network bandwidth. In a stored video application such as VoD system, it is possible that a priori disk access patterns can be used to reserve the system resources in advance. In addition, clients of VoD server spend most of their time in playback mode and the period of time spent in interactive mode is relatively small. In this paper, I present the new buffer management scheme that provides efficient support for interactive operations in a VoD server using variable bit rate continuous media. Simulation results show that our strategy achieves 34% increase of the number of accepted clients over the LRU strategy.

Automated Design of Viterbi Decoder using Specification Parameters (사양변수를 이용한 비터비 복호기의 자동설계)

  • Kong, Myoung-Seok;Bae, Sung-Il;Kim, Jae-Seok
    • Journal of the Korean Institute of Telematics and Electronics C
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    • v.36C no.1
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    • pp.1-11
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    • 1999
  • In this paper, we proposed a design method of parameterized viterbi decoder, which automatically synthsizes the diverse viterbi deciders used in the digital mobile communication systems. It is designed to synthesize a viterbi decoder specified by user-provided parameters. Those parameters are constraint length, code rate generator polynomials of teh convolutional encoder, data rate and bits/frame of the data transmission, and soft decision bits of viterbi decoder. For the design of the parameterized viterbi decoder, we designed a user interface module C-language, and a viterbi decoder module in a hierarchical atructure using VHDL language and its generic statement. For the verification of the parameterized viterbi decoder, we compared our synthesized viterbi decoder with the conventional viterbi decoder which is designed for the IS-95 CDMA system. The proposed design method of the viterbi decoder will be a new method to obtain a required viterbi decoder in a very short time only by supplying the design parameters.

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A Video Bitrate Adaptation Algorithm for DASH-Based Multimedia Streaming Services to Enhance User QoE (DASH 기반 멀티미디어 스트리밍 서비스에서 사용자 체감품질 향상을 위한 비트율 적응 기법)

  • Suh, Dongeun;Jang, Insun;Pack, Sangheon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.39B no.6
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    • pp.341-349
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    • 2014
  • Dynamic adaptive streaming over HTTP (DASH) is the most recent and promising technology to support high quality streaming services. In dynamic adaptive streaming over HTTP (DASH), a client consecutively estimates the available network bandwidth and decides the transmission rate for the forthcoming video chunks to be downloaded. In this paper, we propose a novel rate adaptation algorithm called quality of experience QoE-enhanced adaptation algorithm over DASH (QAAD), which preserves the minimum buffer length to avoid interruption and minimizes the video quality changes during the playback. We implemented a DASH test bed and conducted extensive experiments. Experimental results demonstrate that under fluctuating network conditions, QAAD provides seamless streaming with stabilized video quality while the previous buffer-aware algorithm (i.e., QDASH[9]) frequently changes the video quality and undergoes the interruption.

A Performance Measurement of Multi-channel Audio codec for HDTV Satellite Broadcasting (고선명 TV 위성 방송을 위한 멀티 채널 오디오의 성능 평가)

  • 김성한;장대영;홍진우
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.1 no.1
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    • pp.71-76
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    • 1997
  • In this paper, we describe simulation results of subjective assessments with bit rate variation of multi-channel audio codec system for the services of HDTV satellite broadcasting services. Based on this experiment results, we also describe the specification and subjective performance results for 4-channel audio codec. For multi-channel, bit rates are 384,320,256,128kbps and the results show that 320kbps bit rate is needed to compare with the original and the reproduced signal. Based on this, for 384kbps for 4-channel audio codec, three items that achieve a diffgrade worse than -0.5 are due to the noise of analog output module. This system is satisfied for the audio codec of the HDTV system.

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Video Quality Minimizing Method Using Feedback Information (피드백을 이용한 영상 품질 변화 최소화 방법)

  • Park, Sang-Hyun
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2007.10a
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    • pp.332-335
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    • 2007
  • A real-time frame-layer rate control algorithm with a transmission buffer is proposed for minimizing video quality variation. The proposed rate control method uses a non-iterative optimization method for low computational complexity, and performs bit allocation at the frame level to minimize variation in distortion between frames. In order to reflect the buffer status, we use well-known PID control method. Computational complexity of PID control is very low, so the proposed algorithm is suitable for real-time low-complexity video encoder. Experimental results indicate that the proposed control method provides better PSNR performance than the existing rate control method.

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A Differential Index Assignment Scheme for Tree-Structured Vector Quantization (나무구조 벡터양자화 기반의 차분 인덱스 할당기법)

  • 한종기;정인철
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.2C
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    • pp.100-109
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    • 2003
  • A differential index assignment scheme is proposed for the image encoding system in which a variable-length tree-structured vector quantizer is adopted. Each source vector is quantized into a terminal node of VLTSVQ and each terminal node is represented as a unique binary vector. The proposed index assignment scheme utilizes the correlation between interblocks of the image to increase the compression ratio with the image quality maintained. Simulation results show that the proposed scheme achieves a much higher compression ratio than the conventional one does and that the amount of the bit rate reduction of the proposed scheme becomes large as the correlation of the image becomes large. The proposed encoding scheme can be effectively used to encode R images whose pixel values we, in general, highly correlated with those of the neighbor pixels.