BAS-360°: Exploring Spatial and Temporal Adaptability in 360-degree Videos over HTTP/2
BAS-360°: Exploring Spatial and Temporal Adaptability in 360-degree Videos over HTTP/2
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DOI：
10.1109/infocom.2018.8486390
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发表时间：
2018-04
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通讯作者：
Mengbai Xiao;Chao Zhou;Viswanathan Swaminathan;Yao Liu;Songqing Chen
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作者：
Mengbai Xiao;Chao Zhou;Viswanathan Swaminathan;Yao Liu;Songqing Chen
如今，随着虚拟现实（VR）技术的兴起，360度视频流已经成为一种流行的互联网服务。然而，流媒体360度视频受到带宽需求的限制。现有的带宽高效解决方案主要侧重于利用360度视频固有的空间适应性，仅在观看者感兴趣的区域（ROI）内以更高的质量提供视频内容（空间切割块）。在HTTP流媒体中广泛应用的时间适应性，并没有很好地利用它来根据带宽变化选择合适的视频片段质量。当这两个适应性维度同时考虑时，位元率的选择变得更加复杂和具有挑战性。在特定时间播放具有空间协调的贴图的重要性应该被量化，这样我们就可以决定如何分配带宽以提高观看者的体验质量。此外，观众的头部方向预测是高度可变的，这使得确定重要的瓷砖高度动态。此外，网络波动在互联网上是很常见的。为了克服这些挑战，我们提出了360度视频（BAS-360°）的双自适应流媒体。在BAS-360°中，在不同贴图的比特率选择中探索了空间和时间的适应性。目标是通过将带宽分配给更重要的块（更有可能被监视的块）来最小化带宽浪费。为了解决视觉区域预测的高可变性和不可预测的网络波动，我们采用了http /2提供的两个特性：流终止和流优先级，来有效地组织图像的传递。评估结果表明，当网络波动或视口预测出现错误时，BAS-360°优于朴素的基于tile的360度视频流策略。
Today, 360-degree video streaming has become a popular Internet service with the rise of affordable virtual reality (VR) technologies. However, streaming 360-degree videos suffers from the prohibitive bandwidth demand. Existing bandwidth-efficient solutions mainly focus on exploiting the inherent spatial adaptability of 360-degree videos, delivering only video content (spatially-cut tiles) in the viewer's region of interest (ROI) with higher quality. Temporal adaptability, which has been widely leveraged in HTTP streaming, has not been well exploited to select proper quality for video segments according to the bandwidth variations. When these two dimensions of adaptability are jointly considered, bitrate selection for the tiles become more complicated and challenging. The importance of a tile with a spatial coordination played at a specific time should be quantified so that we can determine how to allocate bandwidth for improving the viewer's quality of experience. Furthermore, viewer's head orientation prediction is highly variable, which makes the determination of important tiles highly dynamic. In addition, network fluctuations are very common on the Internet. To overcome these challenges, we propose Bi-Adaptive Streaming for 360-degree videos (BAS-360°). In BAS-360°, both spatial and temporal adaptabilities are explored in the bitrate selection for different tiles. The objective is to minimize the bandwidth waste by allocating bandwidth to more important tiles (the tiles that are more likely to be watched). To tackle the high variability of visual region prediction and the unpredictable network fluctuations, we employ two features provided by HTT P /2: stream termination and stream priority, to efficiently organize tile delivery. Evaluation results show that BAS-360° outperforms naive tile-based 360-degree video streaming strategies when network fluctuations or errors in viewport predictions occur.