A data generation device comprises: a generating circuit configured to generate video data according to an Advanced Video Coding (AVC) standard and a second opto-electrical transfer function (OETF), an intensity of light within a second range being input into the second OETF; and a storage to store: video usability information (VUI) including a first value indicating a first OETF; and supplemental enhancement information (SEI) including a second value indicating the second OETF, wherein the first OETF supports a first range of an input intensity of light and the second range is wider than the first range, and the first value is to be referred to by a decoding device that does not support the second OETF, the second OETF is a combination of a square root function and a logarithmic function, the SEI is provided in a multiplexing layer other than a video coding layer, and the second OETF has compatibility with the first OETF.