A non-transitory computer-readable medium of a device that stores computer-executable instructions is provided. When the instructions are executed by the device, the instructions cause the device to: determine a line index of a block unit determined from an image frame in the bitstream for selecting one of reference lines; compare the line index with a first predefined value to determine whether a mode flag is included in the bitstream; determine a mode index in the bitstream for directly selecting a prediction mode from a most probable mode (MPM) list when the mode flag is not included in the bitstream; compare the mode flag to a second predefined value when the mode flag is included in the bitstream to determine whether the prediction mode is selected from the MPM list based on the mode index; and reconstruct the block unit based on the selected reference line and the prediction mode.