N-Way Video Communication over Enterprise Networks Based on Adaptive Bit Stream Extraction in Scalable Video Coding

Abstract

In this paper, we explore real time N-way video communication over enterprise networks based on scalable video coding, SVC (Scalable extension of H.264/AVC). We present a bit stream extraction strategy based on GOP size prediction and perceptual importance of temporal and quality enhancements, and validate the strategy through initial subjective testing. We also compare it with extraction based on average bit rate of each constituent layer of the bitstream. Our extraction is adaptive with respect to variations in available bandwidth and is proxy driven, in that the decision process and the adaptation are preformed at proxy servers located at the edges of the backbone network. The main goals are to 1)maximize the user perceived quality even during deteriorating channel conditions, 2) maximize the reaction speed to changes in available bandwidth and 3) minimize the extraction delay. We report objective and subjective results for the N=2 case, with HD video clips encoded at 600 -900 kbps. With a channel utilization of 92.7%, our extraction algorithm based on GOP size prediction shows an average increase in PSNR of about 2.2 dB over the extraction based on average bit rate. Initial subjective tests also prove that our layer extraction strategy is perceptually more efficient than other extraction schemes.

RD optimized bitstream extraction for H.264/SVC based video streaming

“…Since SVC uses hierarchical prediction structures, the distortion reduction obtained on decoding a layer is also dependent on the number of layers decoded for the parent frame. So for each frame in a GOP, we decode and compute the distortion at the lowest and highest levels of quality of itself and its Lowest Highest M [3] Highest Lowest M [4] Highest Highest parents. This is shown in Table 1.…”

“…The base layer provides a minimum acceptable level of video quality and each additional enhancement layer provides incremental quality improvements. SVC's layer structure allows the extraction and decoding of partial bitstreams at reduced resolutions, which enables SVC to be used in a number of multimedia applications such as video streaming [2], video conferencing [3], IPTV services, etc. This paper proposes a rate-distortion optimized SVC bitstream extraction algorithm that maximizes video quality.…”