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An Effective Rate Control Algorithm for Region-based H.263 Video Codec under Time-varying Channels
Hwangjun Song 한국정보과학회 1999 Journal of Electrical Engineering and Information Vol.4 No.6
A region-based video coding scheme based on H.263+ standard is proposed and an effective rate control algorithm under time-varying low-bit-rate channel bandwidth is presented. The region-based coding scheme is a hybrid method that consists of the traditional block DCT coding and the object-based coding. Basically, we employ H.263+ as the platform, and develop a fast macroblock-based segmentation method to implement the region-based video codec. The proposed rate control algorithm consists of three levels: encoding frame rate control, frame-layer rate control and macroblock-layer rate control. The goal is to enhance the visual quality of decoded frames without obvious motion unsmoothness under time-varying channels. Finally, the experimental results are presented to show the efficiency of proposed region-based video coding and rate control algorithm.
Region-based H.263 Video Codec with Effective Rate Control Algorithm for Low VBR Video
Song, Hwangjun The Korea Institute of Information and Commucation 1999 韓國通信學會論文誌 Vol.24 No.9
A region-based video codec based on the H.263+ standard is examined and its associated novel rate control scheme is proposed in this work. The region-based coding scheme is a hybrid method that consists of the traditional block DCT coding and the object-based coding. Basically, we adopt H.263+ as the platform, and develop a fast macroblock-based segmentation method to implement the region-based video codec. The proposed rate control solution includes rate control in three levels: encoding frame selection, frame-layer rate control and macroblock-layer rate control. The goal is to enhance the visual quality of decoded frames at low bit rates. The efficiency of proposed rate control scheme applied to the region-based video codes is demonstrated via several typical test sequences.
메타데이터에 기초한 효율적인 Video-on-Demand 전송시스템에 대한 연구
宋璜準,李大鵬 弘益大學校 科學技術硏究所 2002 科學技術硏究論文集 Vol.13 No.-
This paper presents an effective video-on-demand server architecture for the robust transmission under time-varying channel environments and traffic-smoothing/ admission control/rate adaptation algorithms under Renegotiated Constant Bit Rate network. The proposed video-on-demand server system consists of video database and metadata database that includes various compression history information such as the quantization parameters versus output rate profile, encoded frame positions and encoding types, etc. The traffic-smoothing, rate adaptation and admission control algorithms are performed based on these metadata.
실시간 미디어 전송을 위한 응용계층 멀티캐스트 트리 구성 알고리즘
송황준,이동섭,Song Hwangjun,Lee Dong Sup 한국통신학회 2004 韓國通信學會論文誌 Vol.29 No.11B
최근까지 네트워크 계층에서 수행되는 IP 멀티캐스트는 많은 관심과 연구가 진행되고 있다. 하지만 유니캐스트 라우터들로 구성된 현재의 인터넷 망에서 IP 멀티캐스트의 적용은 불가능한 상태이다. 때문에 응용계층 멀티캐스트가 IP 멀티캐스트의 대안으로 제시되고 있다. IP 멀티캐스트가 네트워크 라우터들에 의존적인 반면 응용계층 멀티캐스트는 네트워크 계층과 독립적으로 수행된다. 본 논문에서는 실시간 미디어의 효과적인 전송을 위한 source에서 end-system들에 이르는 평균 지연 시간을 최소화하는 응용계층 멀티캐스트 트리 구성 알고리즘을 제안한다. 제안하는 알고리즘은 제어 변수로써 각 end-system들의 계산 수행능력과 네트워크 조건을 고려하며 트리를 구성하는 몇몇 end-system들에게만 부하가 집중되는 현상을 방지하도록 구성되었다. 제안하는 알고리즘에 의한 응용계층 멀티캐스트 트리는 clustering과 변형된 Dijkstra 알고리즘에 의해 구성된다. 즉, source와 proxy-sender들 사이의 트리와 각 cluster안에서 트리를 구성함으로써 전체 트리를 생성한다. 실험을 통하여 제안하는 알고리즘이 기존 알고리즘 보다 효과적임을 보였다. This paper presents an application layer multicast tree constructing algorithm to minimize the average time delay from the sender to end-systems for the effective real-time media delivery. Simultaneously, the proposed algorithm takes into account the computing power and the network condition of each end-system as a control variable and thus avoids the undesirable case that loads are concentrated to only several end-systems. The multicast tree is constructed by clustering technique and modified Dijkstra's algorithm in two steps, i.e. tree among proxy-senders and tree in each cluster. By the experimental results, we show that the proposed algorithm can provide an effective solution.
Dongju Lee,Hwangjun Song IEEE 2011 IEEE transactions on multimedia Vol.13 No.4
<P>In this paper, we propose a Luby transform encoding pattern-aware symbol packetization algorithm to minimize the quality degradation of video streaming service caused by packet losses over wireless network. To achieve this goal, the relationship among Luby transform encoded symbols is analyzed based on Luby transform encoding pattern, and the proposed packetization algorithm is designed to minimize packet loss effects by reducing the dependency among packets conveying Luby transform encoded symbols. Finally, experimental results are provided to show the performance of the proposed algorithm.</P>
Reliable and Energy-Efficient Hybrid Screen Mirroring Multicast System
Go, Yunmin,Song, Hwangjun IEEE Computer Society 2018 IEEE TRANSACTIONS ON MOBILE COMPUTING Vol.17 No.2
<P>This paper presents a reliable and energy-efficient hybrid screen mirroring multicast system for sharing high-quality real-time multimedia service with adjacent mobile devices over WiFi network. The proposed system employs overhearing-based multicast transmission scheme with Raptor codes and NACK-based retransmission to overcome well-known WiFi multicast problems such as low transmission rate and high packet loss rate. Furthermore, to save energy on mobile devices, the proposed system not only shapes the screen mirroring traffic, but also determines the target sink device and Raptor encoding parameters such as the number of source symbols, symbol size, and code rate while considering the energy consumption and processing delay of the Raptor encoding and decoding processes. The proposed system is fully implemented in Linux-based single board computers and examined in real WiFi network. Compared to existing systems, the proposed system can achieve good energy efficiency while providing a high-quality screen mirroring service.</P>