It’s no coincidence that “Halcyon Digest,” the fourth album from Atlanta indie-rock act Deerhunter, was partly produced by Ben Allen, who also had a hand in Animal Collective’s 2009 album, “Merriweather Post Pavilion.” On its past two efforts, Deerhunter has followed Animal Collective’s lead in transitioning from a rootless indie obscurity into a hook-filled songwriting force. Following 2008’s enjoyable “Microcastle,” “Halcyon Digest” is both Deerhunter’s most straightforward and best collection of songs: The melodies here are fully formed but don’t sacrifice the band’s hazy tones. The song “Revival” shimmies over guitar fuzz and frontman Bradford Cox’s elastic vocals, while the “whoa-oh” chorus and extended instrumental breakdown of “Desire Lines” leave the listener wanting more despite its nearly seven-minute running time. Having defined its gauzy sound on previous albums, “Halcyon Digest” Deerhunter finds the group expanding it with knockout results.