A measurement study of YouTube 360° live video streaming

360° live video streaming is becoming increasingly popular. While providing viewers with enriched experience, 360° live video streaming is challenging to achieve since it requires a significantly higher bandwidth and a powerful computation infrastructure. A deeper understanding of this emerging system would benefit both viewers and system designers. Although prior works have extensively studied regular video streaming and 360° video on demand streaming, we for the first time investigate the performance of 360° live video streaming. We conduct a systematic measurement of YouTube's 360° live video streaming using various metrics in multiple practical settings. Our key findings suggest that viewers are advised not to live stream 4K 360° video, even when dynamic adaptive streaming over HTTP (DASH) is enabled. Instead, 1080p 360° live video can be played smoothly. However, the extremely large one-way video delay makes it only feasible for delay-tolerant broadcasting applications rather than real-time interactive applications. More importantly, we have concluded from our results that the primary design weakness of current systems lies in inefficient server processing, non-optimal rate adaptation, and conservative buffer management. Our research insight will help to build a clear understanding of today's 360° live video streaming and lay a foundation for future research on this emerging yet relatively unexplored area.