Dooyeol Yun

Video quality adaptation scheme for improving QoE in HTTP adaptive streaming

HTTP (Hypertext Transfer Protocol) adaptive streaming is easy to configure in existing Internet infrastructure. Also, it is typically granted traversal of firewalls and NAT (Network Address Translator). Because of these advantages, HTTP adaptive streaming has been the subject of much attention. However, because conventional video quality adaptation schemes based on bandwidth measurement are too aggressive to respond to short-term network bandwidth variation, frequent changes of video quality occur. Also, because conventional schemes based on bandwidth measurement do not reflect buffer occupancy, buffer underflow that freezes playback occurs. Due to these problems, conventional schemes can hardly guarantee the appropriate level of QoE (Quality of Experience) in HTTP adaptive streaming. In this paper, we propose a client-side video quality adaptation scheme for improving the QoE of HTTP adaptive streaming. To provide seamless and smooth video streaming, the proposed scheme adapts video quality by considering both network bandwidth variation and buffer occupancy of client. We evaluate the performance of the proposed scheme in the ns-3 (Network Simulator-3). Simulation results show that the proposed scheme provides a better QoE than conventional video quality adaptation schemes.

Context-aware multimedia quality adaptation for smart streaming

The proliferation of the Internet technology has contributed to an increasing demand for streaming applications. The adaptation of multimedia streaming content according to context information is essential to supporting these applications. In this paper, we design a context-aware multimedia quality adaptation framework for smart streaming. The proposed framework seamlessly provides multimedia data inputs from multimedia sensors. It also controls the quality of multimedia content according to variations in the context information such as content, device, and network. The implementation results show that our framework adaptively transmits the multimedia content to various mobile devices.

DASH-Based Multi-View Video Streaming System

With the rapid development of electronic and computing technology, multi-view video transmission has attracted significant attention from the research and industrial communities. A multi-view video service provides a user with various viewpoints according to the user’s input. Alongside the recent trend of shifting video streaming service platforms to HTTP adaptive streaming, dynamic adaptive streaming over HTTP (DASH)-based multi-view video services has been widely studied. However, DASH-based multi-view video streaming suffers from high view-switching delay. The delay between a request for view switching and the rendering of the target view adversely affects the quality of experience. This paper provides an analysis of the view-switching delay of DASH-based multi-view video streaming. Based on the analysis, a novel DASH-based multi-view video streaming system is proposed. It can minimize the view-switching delay by employing a buffer control, parallel streaming, and server push schemes. The results obtained from the implementation of this solution show that the proposed system significantly reduces the view-switching delay while guaranteeing the quality of multi-view video.

Short paper: Context-aware adaptive streaming in web of objects environments

The proliferation of various objects and explosive development of the Internet technologies such as Web of Objects (WoO) have contributed to an increasing demand for multimedia streaming applications. The adaptation of multimedia content according to context information is essential to supporting these applications in the WoO environments. In this study, we design a context-aware adaptive streaming framework. The proposed framework seamlessly manages multimedia content inputs from multimedia sensors. It also controls the quality of multimedia content based on the various context information such as content, device, and network. The implementation result shows that our framework adaptively transmits multimedia content to various mobile devices.

Dynamic segment duration control for live streaming over HTTP

Due to the prevalence of various mobile devices and the growth of wireless network technologies, HTTP adaptive streaming has become a new trend in video delivery. In HTTP adaptive streaming, the client pulls the video as a sequence of files called media segments from a server and adjusts the video quality. In order to maintain seamless playback with acceptable video quality, the client needs large receive buffers. However, the buffering delay is critical in live streaming. Therefore, it is important to provide the balance between buffering delay and seamless playback. In this paper, we propose a DSDC (Dynamic Segment Duration Control) scheme for live streaming over HTTP. The proposed DSDC scheme determines the segment duration according to the device information and network status. Through the simulation, we prove that our scheme significantly reduce the playback discontinuity while maintaining the low buffer delay.

A client side buffer management algorithm to improve QoE

In networks, streaming of multimedia content is a challenging issue. Video streaming services make up a large proportion of Internet traffic throughout the world. Adaptive streaming allows for dynamical adaptation of the bitrate with varying network conditions, to guarantee the best user experience. Recently, to guarantee a promised quality of experience (QoE), multiple rate adaptive algorithms have been proposed. In this paper, a rate adaptive algorithm is proposed that improves video quality by observing the available throughput and managing the playback buffer. The existing schemes download the segments quickly to avoid playback interruption which may fill the buffer with low quality segments and degrade the user experience. The proposed scheme manages the playback buffer and keeps the buffer filled with high quality segments. Furthermore, the proposed algorithm randomizes the segment request time to mitigate the client’s biased view of network conditions in the presence of competing TCP traffic. The experimental results show that the proposed algorithm significantly improves the video streaming quality.

Efficient Bandwidth Estimation for HTTP adaptive streaming

As the multimedia devices are becoming more diverse and the HTTP adaptive streaming techniques grow in popularity, the transmission of adequate video quality becomes increasingly important. HTTP adaptive streaming requires accurate information about available bandwidth of client for quality adaptation. Accurate estimation of available bandwidth is difficult, as a suitable approach must address three challenges. First, it must be accurate enough to make decisions about the admission of high-throughput high-quality streams. Second, it must be fast enough to determine the video quality. Last, it should be non-intrusive to streaming traffic. In this paper we propose a new bandwidth estimation scheme, called an Efficient Bandwidth Estimation (EBE), for HTTP adaptive streaming. To provide information which is needed to determine the representation level of HTTP adaptive streaming, the EBE scheme uses the difference between the bitrate of representation levels. We show that our approach is accurate, fast, and non-intrusive compared with other schemes.

HTTP adaptive streaming scheme for improving the quality of experience in multi-server environments

Abstract Many studies have been conducted on multi-server HTTP Adaptive Streaming (HAS). The existing schemes can highly utilize the available bandwidth by aggregating the multipath bandwidth and improve the video quality by switching servers when network congestion occurs. However, these existing schemes have problems that adversely affect the Quality of Experience (QoE) in a multi-server environment. To cope with these problems, we analyze the existing HAS schemes in multi-server environments. Through simulation-based performance analysis, we prove that these existing schemes lead to playback stalling and frequent quality changes. Based on the analysis, we propose a new HAS scheme for multi-server environments. The proposed scheme improves the QoE by alleviating the problems of the existing schemes. Through the simulation results, we prove that the proposed scheme alleviates the shortcomings of the existing schemes and improves QoE metrics compared with the existing multi-server schemes.

HTTP adaptive streaming scheme for multi-server environments

HTTP Adaptive Streaming (HAS) has become increasingly more popular. However, the research about HTTP adaptive streaming for multi-server environments is limited. Compared with traditional single-server environments, HAS for multi-server environments is able to offer expanded bandwidth, link diversity, and reliability. However, it is a challenging issue to support the seamless playback in multi-server environments due to their diversity of bandwidths. To solve this problem, we propose a partial segment based HAS scheme for multi-server environments. The proposed scheme provides seamless video streaming by adaptively controlling the size of the partial segment. The simulation results show that the proposed scheme adaptively transmits the multimedia content in multi-server environments.

Web-based multi-view video replay service system using multi-PTZ cameras

We present a novel multi-view video replay service system using multi-PTZ cameras. Proposed system firstly captures multi-view videos for an object of interest with converged multi-cameras and then synthesizes intermediate views by grid mesh-based warping at a certain time instant. Next, captured multi-camera videos and synthesized intermediate view videos are combined to generate a multi-view replay video at a certain time instant. A generated multi-view replay video is transmitted to the web-based multi-view video player and it can be showed to the viewers selectively with multi-camera videos. Test experiments verified the successful operation of the proposed system.