A playback method performed by a playback device that plays content, the playback method comprising: obtaining a type of a display device connected to the playback device; selecting each of a version of HDMI (High-Definition Multimedia Interface) and a version of HDCP (High-bandwidth Digital Content Protection), according to the obtained type of the display device; obtaining a video signal of content recorded on a recording medium; decoding the obtained video signal; and encrypting the decoded video signal using the HDCP of the selected version, and outputting the encrypted video signal to the display device using the HDMI of the selected version; the method characterized in that the type of the display device is: a first type of display device when its resolution is a first resolution and it supports a first luminance range; a second type of display device when its resolution is a second resolution and it supports the first luminance range; a third type of display device when its resolution is the first resolution and it supports a second luminance range; and a fourth type of display device when its resolution is the second resolution and it supports the second luminance range, wherein the second resolution is the 4K resolution that has a larger number of pixels than the first resolution being the 2K resolution, and wherein the second luminance range is the High Dynamic Range, HDR, that includes the first luminance range being the Standard Dynamic Range, SDR, ranging from 0 nit to 100 nit such that the second luminance range has a higher peak luminance than the first luminance range. obtaining a type of a display device connected to the playback device; selecting each of a version of HDMI (High-Definition Multimedia Interface) and a version of HDCP (High-bandwidth Digital Content Protection), according to the obtained type of the display device; obtaining a video signal of content recorded on a recording medium; decoding the obtained video signal; and encrypting the decoded video signal using the HDCP of the selected version, and outputting the encrypted video signal to the display device using the HDMI of the selected version; the method characterized in that the type of the display device is: a first type of display device when its resolution is a first resolution and it supports a first luminance range; a second type of display device when its resolution is a second resolution and it supports the first luminance range; a third type of display device when its resolution is the first resolution and it supports a second luminance range; and a fourth type of display device when its resolution is the second resolution and it supports the second luminance range, wherein the second resolution is the 4K resolution that has a larger number of pixels than the first resolution being the 2K resolution, and wherein the second luminance range is the High Dynamic Range, HDR, that includes the first luminance range being the Standard Dynamic Range, SDR, ranging from 0 nit to 100 nit such that the second luminance range has a higher peak luminance than the first luminance range. a first type of display device when its resolution is a first resolution and it supports a first luminance range; a second type of display device when its resolution is a second resolution and it supports the first luminance range; a third type of display device when its resolution is the first resolution and it supports a second luminance range; and a fourth type of display device when its resolution is the second resolution and it supports the second luminance range, wherein the second resolution is the 4K resolution that has a larger number of pixels than the first resolution being the 2K resolution, and wherein the second luminance range is the High Dynamic Range, HDR, that includes the first luminance range being the Standard Dynamic Range, SDR, ranging from 0 nit to 100 nit such that the second luminance range has a higher peak luminance than the first luminance range.