Jacob Obrecht’s Missa Graecorum is a bit of a mystery; no one is quite sure where it got its name or the cantus firmus melody on which it’s based. This is, in fact, the world premiere recording of that work; the disc also includes the first-ever recording of his motet O beata Basili. Other material is more familiar, notably the Salve regina setting that opens the program. As always, the Brabant Ensemble sets the standard for choral blend and intonation.