Heterogeneous Spatial Quality for Omnidirectional Video

Heterogeneous spatial quality in 360-degree videos is characterized by regions of high and low quality appearing in the same video chunk. Encoding quality-varying omnidirectional videos enables bandwidth waste optimization without compromising the quality inside the client's viewport. Heterogeneous spatial quality has been implemented using either the concept of tiling or Facebook's offset projection. In this paper, we study the preparation of heterogeneous 360-degree videos with three main contributions. We propose two novel approaches that prepare heterogeneous quality versions of a 360-degree video based on two video decomposition techniques: the Gaussian pyramid and the Laplace pyramid. We also introduce a spherical filter for omnidirectional videos which allows to further reduce the video bit-rate by exploring the spherical properties of the 360-degree videos. We compare the performance of the proposed three methods to tiling and the offset projection in representative scenarios of heterogeneous spatial quality in 360-degree videos and highlight the key trade-off between bit-rate and video quality to consider when implementing these approaches.