Efficient Coding of 360-Degree Pseudo-Cylindrical Panoramic Video for Virtual Reality Applications

Pseudo-cylindrical panoramas represent the data distribution of spherical coordinates closely in two-dimensional domain due to the equidistant sampling of 360-degree scene. Therefore, unlike the cylindrical projections, they do not suffer from the over stretching in the polar areas. However, due to the non-rectangular format in effective picture area and sharp edges at its borders, the compression performance is inefficient. In this paper, we propose two methods which improve the compression performance of both intra-frame and inter-frame coding of pseudo-cylindrical panoramic content and meanwhile reduce the coding artifacts. In the intra-frame coding method, border edges are smoothed by modifying the content of the image in the non-effective picture area, which are cropped at the receiver side. In the inter-frame coding method, gaining the benefit of 360-degree property of the content, non-effective picture area of reference frames at border is filled with the content of the effective picture area from the opposite border to enhance the performance of motion compensation.