A video decoding method includes decoding a part of a bitstream to generate a decoded frame, and parsing at least one syntax element from the bitstream. The decoded frame is a projection-based frame that has projection faces packed in a cube-based projection layout. At least a portion of a 360-degree content of a sphere is mapped to the projection faces via cube-based projection. The at least one syntax element is indicative of packing of the projection faces in the cube-based projection layout.