After being suffocated by so many well-made but unoriginal independent films at Sundance, “Baghead” is like a blast of fresh air. It has warmth and innovation, and the mischievous good sense to subtly make fun of the type of film that it is.

And what type of film is it? It’s essentially part of the “mumblecore” sub-movement, featuring hand-held cameras, semi-improvised dialogue, and directionless hipster characters in their twenties. It’s the work of brothers Jay and Mark Duplass, whose “Puffy Chair” beguiled film festival audiences a few years ago and is well worth seeking out on DVD if you haven’t seen it.

The Duplasses stay behind the camera this time but give us four of their kindred spirits as characters. Matt (Ross Partridge) and Catherine (Elise Muller) are long-time on-and-off romantic partners; Chad (Steve Zissis) and Michelle (Greta Gerwig) have been dating a few months, though Michelle thinks of Chad as more of a brother or pal. In fact, she has a thing for Matt.

All four are struggling Los Angeles actors. When we first meet them, they’re at a small film festival enduring “We Are Naked,” a pretentious art flick made by a friend of theirs. Inspired by his relative success with such a crappy product, the four retreat to a cabin at Big Bear Lake to spend the weekend writing their own screenplay that they can produce and star in themselves.

Matt is the de facto commander of the group, with leading-man looks and some measure of ambition. Catherine is slightly aloof and less fun than the rest, while Michelle is bubbly and flighty and Chad is the chubby comic relief. In other words, the dynamics of group strongly resemble what you’d find in a typical low-budget indie comedy.

Michelle has a weird dream the first night at the cabin in which she is stalked by a man wearing a bag over his head. Matt thinks this is a terrific premise for their film and sets out to write it as a thriller. Meanwhile, Michelle tries to put the moves on Matt without Catherine or Chad finding out. But a question lingers: Did Michelle merely dream about Baghead, or is there really a man with a bag on his head prowling the woods?

And so one of the unexpected charms about “Baghead” is that it has elements of a cabin-in-the-woods horror flick, along with its more ordinary delights. The low-key comedy that passes among the four friends is witty and natural, obviously the product of familiarity — not just that the characters know each other, but that the actors do, too (or at least are good at faking it).

“Baghead” has those surface-level amusements that you can appreciate even if you haven’t seen any other mumblecore films. But if you’ve seen more than your share of these little do-it-yourself flicks about mumbly whiners, then “Baghead” has additional layers of comedy – starting with the spot-on re-creation of a film festival’s post-screening Q-and-A at the beginning of the movie, and ending with a pleasantly outrageous solution to the group’s creative woes. If you’re hungry enough to break into the film business, you’ll do just about anything, right? Even make a movie about a guy called Baghead.

B (1 hr., 24 min.; R, a lot of harsh profanity, brief sexuality, some nudity.)