Adaptive 360-Degree Video Streaming using Layered Video Coding
1. Introduction
While predicting the user viewport so as to request the segments that provide this viewport at higher quality, there could be a mismatch between the user’s viewport and the predicted one, which would lead to lower quality.
To minimize the occurrence of such mismatches, the video is not buffered for durations longer than the duration for which the viewport can be predicted accurately, thus increasing the probability of video freeze in the event of network bandwidth fluctuation.
In this paper, the writer argues to use Scalable Video Codec(SVC) and layered encoding for 360-degree video to improve QoE by reducing the probability of video freezes and the latency of response to the user head movements.
2. Proposed method
The client first fills the buffer with the base layer. Then, it starts predicting the viewport for the segment with earliest playback deadline based on the previous viewports. The tiles covered by the predicted viewport are identified, and the enhancement layers for those tiles are requested.
For this method, the client can always fill the buffer so that video freeze can be decreased, and the storage requirement for 360 videos and the cost of updating the quality of already downloaded segments can be reduced. The base layer can be cached at intermediate devices to reduce the load on the server.
3. Conclusion
By reducing the probability of video freezes and the latency of response to the user head movements, the method proposed in this paper provides a higher QoE.