A video data is accompanied or multiplexed with one or more flags indicating a relation between fields or frames of video data for transmission or recording. An interlace flag determines whether the video data is interlaced or not. A still image flag determines whether the video data carries a motion image, a field still image, or a frame still image. A frame change flag determines whether or not a given frame of the still image is identical to its previous frame. At least one of the three different flags is multiplexed with its relevant video data.