The plot of 2012’s “Pitch Perfect” was pretty simple.

Act One: A cappella is stupid.

Act Two: A rag-tag team of zany misfits forms to perform a cappella.

Act Three: A cappella is awesome!

If you enjoy a cappella, this formula works great. But if you don’t, the cinematic bait-and-switch feels a bit disingenuous.

“Pitch Perfect 2” isn’t as sneaky as its predecessor, but in spite of some funny moments, the franchise is still struggling to find harmony between self-parody and sincerity.

The good news for fans of the first film is that “Pitch Perfect 2” has more of what we got in the first installment: lots of singing, choreography and snarky humor. A few flashes of genuine wit are almost enough to cover for the lack of plot, but not enough to distract audiences from a bloated run time and a mean-spirited sense of humor.

In the time since the first film, The Barden Bellas have become three-time national a cappella champions. But a catastrophic performance puts the group’s future in jeopardy, and its only hope is to win an international competition against the German a cappella juggernaut, Das Sound Machine.

If you guessed that the German group is stiff, arrogant and dressed in all black, you’re correct. And unfortunately, that is far from the only two-dimensional stereotype that gets mined in “Pitch Perfect 2.”

At times you wonder if screenwriter Kay Cannon was trying to set a record for offending the most minority groups in a single PG-13 film. In some cases, Cannon seems to be exaggerating bigotry in order to subvert it, a la “All In the Family.” But even in those cases, “Pitch Perfect 2” is trying way too hard.

But back to the plot. As if the showdown with DSM isn’t enough to deal with, de facto leader Beca (Anna Kendrick) has picked up an internship with a local music studio that threatens her loyalty to the group. (This subplot leads to one of the film's funnier moments, as Beca helps Snoop Dogg record an album of Christmas favorites under the tutelage of “Key & Peele’s” Keegan-Michael Key.)

In other news, the team has added a new girl (Hailee Steinfeld) in spite of a supposed recruiting freeze, and Fat Amy (Rebel Wilson) has found herself in a budding relationship with Bumper (Adam DeVine), the Jack Black impersonator from the first movie.

It’s a bit much to cover, especially when the film shoehorns in extended sequences like a five-team a cappella improv showdown (think of the walk-off in “Zoolander,” only about seven times longer and without David Bowie) and a team-building retreat in the woods.

The former gives us the non sequitur highlight of Clay Matthews leading several of his Green Bay Packer teammates in a cover of “Bootylicious,” but at 115 minutes, “Pitch Perfect 2” could afford to be a little less self-indulgent. There’s just not enough conflict to justify the ride.

Again, none of this is a real problem if you’re a fan. The vocal performances are well produced, and there are lots of new a cappella puns. But there’s nothing here that hasn’t already been done, and the tone of the finale gives you the feeling even the filmmakers recognize that there’s nowhere else to go.

This last point is underscored by one of “Pitch Perfect 2’s” most effective themes: the need for originality. At some point, re-inventing familiar material just gets old, no matter how deep the pop catalog goes. When that happens, you’ve got to mine new ground to survive.

Even Bob Dylan eventually hired a full band.

“Pitch Perfect 2” is rated PG-13 for profanity, some sexual content, and considerable vulgar and offensive dialogue.