Document Type

Other

Publication Date

10-2001

Abstract

Traditionally, the Internet had been dominated by text-based applications such as file transfer, electronic mail and recently the Web. With the rapid improvement in computer and network technologies, high-bandwidth, interactive streaming multimedia applications are now possible on the Internet. However, the Internet does not provide the necessary Quality of Service (QoS) guarantees needed to support high-quality, real-time multimedia transmission, causing Internet multimedia applications to suffer from delay, jitter and loss. Among these, loss, typically caused by network congestion, degrades the perceptual quality of multimedia streams the most.

We propose two new techniques to repair video damaged by network data loss: redundancy and interleaving. The redundancy approach transmits a small, low-quality frame after each full-quality primary frame. In the even the primary frame is lost, we display the low-quality frame, rather than display the previous frame or retransmit the primary frame. Redundancy works well in case of single loss, but becomes less effective when multiple consecutive losses occurs in the video stream. To address this problem, we propose a video interleaving approach that ameliorates the effects of loss by spreading out bursty packet losses. The sender first re-sequences data before transmission to help distribute packet loss, and returns the data to their original order at the receiver. We apply both approaches to MPEG and evaluate the benefits to perceptual quality with user studies. Our results show that with approximately 10%-15% bandwidth overhead, both interleaving and redundancy significantly improve the perceptual quality of Internet video, while interleaving performs better in the case of consecutive loss, at the expense of increased latency.

DOI

WPI-CS-TR-01-05

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