Just-in-Time Transcoding of 360° Video Streams

Felix Hechler, Michael Rudolph, Amr Rizk

Abstract: Adaptive streaming of 360° tiled video requires encoding tiles to multiple qualities to support client decisions in the light of fluctuating bandwidth and dynamic view-ports. Some static approaches allocate fixed encoding resources independently of the scene complexity introducing a significant resource overhead while other static approaches add a substantial time delay relative to the source. As tiles of 360 ° video have a skewed popularity with a statistical concentration of the user requests static approaches are resource inefficient. Specifically, in live streaming the tile popularity and encoding time statistics are not present beforehand.We present JITENC, a 360° streaming backend for network edge deployment that employs just-in-time encoding in response to incoming tile requests. JITENC leverages encoding time prediction to optimize the scheduling of tile encoding tasks, hence, it can also be used for live streaming given a real-time transcoding time deadline. Our prototype demonstrates that JITENC can achieve a perceived quality that is comparable to oversized static systems that encode all tiles in every quality while significantly reducing the computing resource utilization and power consumption.