Taehyun Kim

Publications (4)0 Total impact

• Article: Optimal quality adaptation for scalable encoded video.

  Taehyun Kim, Mostafa H. Ammar
  IEEE Journal on Selected Areas in Communications. 01/2005; 23:344-356.
• Source

  Available from: psu.edu

  Article: A comparison of heterogeneous video multicast schemes: Layered encoding or stream replication.

  Taehyun Kim, Mostafa H. Ammar
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  ABSTRACT: The heterogeneity of the Internet's transmission resources and end sys tem capability makes it difficult to agree on acceptable traffic characteristics among the multiple receivers of a multicast video stream. Three basic approaches have been proposed to deal with this problem: 1) multicasting of replicated video streams at different rates, 2) multicasting the video encoded in cumulative layers, and 3) multicasting the video encoded in non-cumulative layers. Even though there is a common belief that the layering approach is better than the replicated stream approach, there has been no studies that compare these schemes. This paper is devoted to such a systematic comparison. Our starting point is an observation (substantiated by results in the literature) that a bandwidth penalty is incurred by encoding a video stream in layers. We argue that a fair comparison of these schemes needs to take into account this penalty as well as the specifics of the encoding used in each scheme, protocol complexity, and the topological placement of the video source and the receivers relative to each other. Our results show that the believed superiority of layered multicast transmission relative to stream replication is not as clear cut as is widely believed and that there are indeed scenarios where replication is the preferred approach.
  IEEE Transactions on Multimedia. 01/2005; 7:1123-1130.
• Source

  Available from: psu.edu

  Article: Optimal Quality Adaptation for MPEG-4 Fine-Grained Scalable Video

  Taehyun Kim, Mostafa H. Ammar
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  ABSTRACT: Dynamic behavior of the Internet's transmission resources makes it difficult to provide perceptually good quality of streaming video. MPEG-4 Fine-Grained Scalable coding is proposed to deal with this problem by distributing the data in enhancement layers over a wide range of bit rates. However, encoded video also exhibits significant data rate variability to provide a consistent quality video. We are, therefore, faced with the problem of trying to accommodate the mismatch between the available bandwidth variability and the encoded video variability. In this paper, we investigate quality adaptation of the layered VBR video generated by MPEG-4 FGS. Our goal is to develop a quality adaptation scheme that maximizes perceptual video quality through minimizing quality variation while at the same time increasing the usage of available bandwidth. We develop an optimal adaptation scheme and an online heuristic based on whether the network conditions are known apriori. Experimental results show that the online heuristic as well as the optimal adaptation algorithm provide consistent video quality when used over both TFRC and TCP.
  03/2003;
• Source

  Available from: psu.edu

  Article: Receiver buffer requirement for video streaming over TCP

  Taehyun Kim, Mostafa H Ammar
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  ABSTRACT: TCP is one of the most widely used transport protocols for video streaming. However, the rate variability of TCP makes it difficult to provide good video quality. To accommodate the variability, video streaming applications require receiver-side buffering. In current practice, however, there are no systematic guidelines for the provisioning of the receiver buffer, and smooth playout is insured through over-provisioning. In this work, we are interested in memory-constrained applications where it is important to determine the right size of receiver buffer in order to insure a prescribed video quality. To that end, we characterize video streaming over TCP in a systematic and quantitative manner. We first model a video streaming system analytically and derive an expression of receiver buffer requirement based on the model. Our analysis shows that the receiver buffer requirement is determined by the network characteristics and desired video quality. Experimental results validate our model and demonstrate that the receiver buffer requirement achieves desired video quality.