A method for storage of video data, the method comprising: receiving, by a file generation device, a bitstream that includes a sequence of bits that forms a representation of encoded pictures of the video data, the pictures of the video data including a current picture, the current picture being partitioned into a plurality of tiles, each respective tile of the plurality of tiles being a respective rectangular region; generating, by the file generation device, a Network Abstraction Layer Unit Map Entry box in a file, the NAL Unit Map Entry box associating NAL units of the bitstream with a tile set, the tile set including two or more tiles of the plurality of tiles into which the current picture is partitioned, a region of the current picture covered by the tiles in the tile set is not rectangular in shape; and generating, by the file generation device, a tile set group entry in the file, the tile set group entry including a group identifier syntax element that identifies the tile set, characterized in that the tile set group entry including a horizontal offset syntax element, a vertical offset syntax element, a width syntax element, and a height syntax element, the horizontal offset syntax element specifying a horizontal offset of a top-left pixel of a minimum rectangular region that completely covers the non-rectangular shape defined by the tiles in the tile set, the vertical offset syntax element specifying a vertical offset of the top-left pixel of the minimum rectangular region that completely covers the non-rectangular shape defined by the tiles in the tile set, the width syntax element specifying a width of the minimum rectangular region that completely covers the non-rectangular shape defined by the tiles in the tile set, and the height syntax element specifying a height of the minimum rectangular region that completely covers the non-rectangular shape defined by the tiles in the tile set. receiving, by a file generation device, a bitstream that includes a sequence of bits that forms a representation of encoded pictures of the video data, the pictures of the video data including a current picture, the current picture being partitioned into a plurality of tiles, each respective tile of the plurality of tiles being a respective rectangular region; generating, by the file generation device, a Network Abstraction Layer Unit Map Entry box in a file, the NAL Unit Map Entry box associating NAL units of the bitstream with a tile set, the tile set including two or more tiles of the plurality of tiles into which the current picture is partitioned, a region of the current picture covered by the tiles in the tile set is not rectangular in shape; and generating, by the file generation device, a tile set group entry in the file, the tile set group entry including a group identifier syntax element that identifies the tile set, characterized in that the tile set group entry including a horizontal offset syntax element, a vertical offset syntax element, a width syntax element, and a height syntax element, the horizontal offset syntax element specifying a horizontal offset of a top-left pixel of a minimum rectangular region that completely covers the non-rectangular shape defined by the tiles in the tile set, the vertical offset syntax element specifying a vertical offset of the top-left pixel of the minimum rectangular region that completely covers the non-rectangular shape defined by the tiles in the tile set, the width syntax element specifying a width of the minimum rectangular region that completely covers the non-rectangular shape defined by the tiles in the tile set, and the height syntax element specifying a height of the minimum rectangular region that completely covers the non-rectangular shape defined by the tiles in the tile set.