Research on Panoramic Video Download Strategy Based on PI Controller

360-degree video is an essential component of virtual reality technology. With increasing demand for viewing, the development of 360-degree video has accelerated rapidly. However, due to the large data size of 360-degree videos, efficient transmission and high-definition playback have become urgent issues to address. This paper proposes a new download strategy scheme based on a PI controller, suitable for a dual-layer DASH (Dynamic Adaptive Streaming over HTTP) transmission system. A comparison is made with traditional bitrate-based dual-layer DASH transmission systems. Experimental results demonstrate that the PI controller-based download strategy outperforms existing bitrate-based algorithms in terms of average bitrate at the Enhancement Layer (EL) and Viewport-Rendered Ratio (VRR), achieving values of 7.28 Mbps and 6.45, and 5.03 Mbps and 5.49 respectively. Conversely, the PI control algorithm shows significant advantages in Freezing Rate (FR) and EL Block Arrival Rate, with values of 6% and 88%, and 5% and 90% respectively. The PI controller achieves improvements in both playback freezing ratio and EL block arrival rate to a certain extent.