I. Introduction
Virtual reality (VR) applications have become popular in recent years, hence also increasing the importance of encoding and streaming video content for VR devices as efficiently as possible. In order to provide a full immersive experience, using 360-degree omnidirectional video content with high resolution and high frame rate is inevitable. Panoramic images cover the whole 360-degree scene horizontally and up to 180-degree vertically around the capturing position and can be represented by a sphere that has been mapped onto a two dimensional image plane using a cylindrical projection.