Oscar’s musical pieces are falling in place, as all the kudocast performers have been confirmed for the four nominated songs, while details were unveiled for the annual pre-Oscar concert that salutes musical-score contenders.

The Academy of Motion Picture Arts & Sciences on Thursday announced Karen O will perform “The Moon Song” at the March 2 event, joining previously announced Pharrell Williams, with “Happy” from “Despicable Me 2”; Idina Menzel, “Let It Go” from “Frozen”; and U2, “Ordinary Love” from “Mandela: Long Walk to Freedom.” “Moon Song” features music by Karen O and lyrics by her and Spike Jonze, written for the film “Her.”

The Academy also detailed the Feb. 27 “Oscar Concert” celebrating this year’s nominated scores and songs on Feb. 27, at 8 p.m. at UCLA’s Royce Hall. The program features an 80-piece orchestra performing suites from each of the nominated original scores, conducted by their composers.

They include: William Butler and Owen Pallett, “Her”; Alexandre Desplat, “Philomena”; Thomas Newman, “Saving Mr. Banks”; Steven Price, “Gravity”; and John Williams, “The Book Thief.” Each composer also will participate in a brief onstage conversation with critic Elvis Mitchell about their scores.

The concert also will feature “Let It Go” performed by songwriters Kristen Anderson-Lopez and Robert Lopez, and “Happy,” performed by Jill Scott. Other performers and guests will be announced on oscars.org. Tickets are $100 and $75 and can be purchased online via Ticketmaster.

Oscars, hosted by Ellen DeGeneres, will be held March 2 at the Dolby Theatre, produced by Craig Zadan and Neil Meron.