FILM musicals, once hugely popular, are no longer so.

That was recently the case with Clint Eastwood’s stagey The Jersey Boys and Stephen Sondheim’s Into the Woods — featuring Meryl Streep in excessively irritating “Gimme the Oscar!” mode — which got few bums warming seats.

Happily Anna Kendrick — Cinderella in Sondheim’s cinematic whimsy — is wonderful as Cathy Hiatt in this funny and emotionally perceptive film of Tony award-winner lyricist-composer Jason Robert Brown’s off-Broadway success.

Richard LaGravenese’s witty screenplay and deft direction creates a charming tale of the five-year romance and disintegration of the marriage of struggling actress Kendrick and rising Jewish novelist Jamie Wellerstein (Jeremy Jordan).

Their journey of love, hope and disillusion is almost entirely sung through and, unexpectedly, this approach works wonderfully without any of opera’s frequent lack of credibility.

Kendrick scores with a sweet, frequently funny and moving performance, Jordan is excellent and LaGravenese showcases them and their story with wit and an apt use of New York locations. Delightful.