A video processing method includes receiving a bitstream, and decoding, by a video decoder, the bitstream to generate a decoded frame. The decoded frame is a projection-based frame that has a 360-degree image/video content represented by triangular projection faces packed in an octahedron projection layout. An omnidirectional image/video content of a viewing sphere is mapped onto the triangular projection faces via an octahedron projection of the viewing sphere. An equator of the viewing sphere is not mapped along any side of each of the triangular projection faces.