The phrase "official soundtrack" refers to the collection of songs or music that has been specifically chosen and released for a particular movie, TV show, or video game. It is the official musical accompaniment to that media. Full definition
The hills are alive with the sound of Zelda Nintendo of Japan has announced an extensive official soundtrack for... (heypoorplayer.com)
Still, the term rearranged is imo very clear and it also has been used by nintendo for official soundtrack releases from the Zelda series. (gonintendo.com)
As promised by Nintendo Australia, those that purchase The Legend of Zelda: Ocarina of Time 3D can redeem a free Legend of Zelda Official Soundtrack CD to usher in the 25th Anniversary of Zelda and friends. (esperino.com)