Playback device, playback method, and recording medium

A decoding system that decodes a video stream, which is encoded video information, comprising:

• a decoder that acquires the video steam and generates decoded video information by decoding the video stream, the video stream including, in a case where a dynamic range of luminance of the video stream is a second dynamic range that is wider than a first dynamic range, information which indicates a type of the second dynamic range of the video stream;
• a maximum luminance information acquirer that acquires, in a case where the dynamic range of luminance of the video stream is the second dynamic range, maximum luminance information indicating the maximum luminance of the video stream from the video stream;
• and
• an outputter that outputs the decoded video information along with the maximum luminance information,
• wherein, in a case where the information indicates a first type in which the dynamic range of luminance of the video stream is expressed by the maximum luminance of all pictures in the video stream as the maximum luminance information, the outputter outputs the decoded video information, along with the maximum luminance information indicating the maximum luminance of all pictures in the video stream, and
• wherein, in a case where the information indicates a second type in which the dynamic range of luminance of the video stream is expressed by maximum luminance of all pictures in the video stream and maximum luminance for each of groups made up of one or a plurality of pictures included in the video stream as the maximum luminance information, the outputter outputs the decoded video information, along with the maximum luminance information indicating the maximum luminance of all pictures in the video stream and the maximum luminance for each of the groups.