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); 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 and the second OETF support a standard dynamic range (SDR) and a high dynamic range (HDR), respectively, the first value is to be referred to by a decoding device that does not support HDR, 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.