Animal magic: Oddsac by Animal Collective

The group talk about their visual album Oddsac, which had its premiere at the Sundance festival.

The visually stunning film Oddsac was premiered at this year's Sundance festival.

Received wisdom has it that music careers these days are a flash in the pan, fitting the familiar cycle of rapturously received debut album, disappointing second, and slow fade into obscurity. Which makes Animal Collective seem all the more peculiar. Active since 2000, a procession of eight albums has seen these four childhood friends from Baltimore, Maryland, evolve organically - from skittish experimentalists with faces hidden by masks, channelling freakish folk songs through a bramble of loop and delay pedals, to a marginally more familiar indie-rock band who as much by accident as design, have ended up somewhere just south of the mainstream.

It was 2009's Merriweather Post Pavilion that finally saw a wider public pay attention. A record in which their sound was bolstered by scintillating electronics and added bass, augmented by the producer Ben Allen (formerly the in-house engineer for P Diddy's Bad Boy Records), Merriweather had a rapturous reception. Voted the album of 2009 in several end-of-year polls, the British music magazine Uncut called it "one of the landmark American albums of the century so far". These unlikely stars even cracked the Top 20 of the US Billboard 200. All this, though, while retaining something of their homespun quality. Take the song My Girls, with its tumbling, Beach Boys-style vocal from the group's Noah Lennox, which found him declaring "I don't mean to seem like I care about material things" and wishing for a simple life in Lisbon with his wife and child: "I just want four walls and adobe slats/For my girls."

The success of Merriweather Post Pavilion may have pulled Animal Collective closer to popular success, but their new so-called "visual album" proves their more outré impulses are deep-held. Four years in the making, Oddsac came to life when the DVD company Plexi Films approached Animal Collective with the idea of making a tour documentary and, as the band's Dave Portner puts it, they suggested something "more ambitious".

Instead, the band mooted a collaborative project with the experimental director Danny Perez, a long-time friend and unofficial fifth Collective member, who works with the band on promotional videos and helps them transform idea fragments into visuals and short films. "We would always fire ideas at Danny," says Portner. "Like, can we do a music video with a turtle and a rabbit racing on little girls' bikes? Or an ice sculpture, slowly melting? Danny would take those ideas and make all these drawings, and then translate them from paper to the screen."

The 54-minute Oddsac, though, feels like a leap into a different universe. Visually astounding and creatively restless, it is both a glorious feast for the eyes and thoroughly bewildering to anyone grasping at the few threads of narrative. A girl peels at old wallpaper, triggering a sudden flood of gloopy black oil. A Nosferatu-style vampire paddles sadly along a still lake. A family on a camping trip deep in the wilderness gorge themselves on sticky marshmallows.

"There is a structure, but there was intentionally never a narrative," explains Perez. "We had all these separate disparate moments. At the beginning, the guys in the band said: 'We don't know how it's going to come together - it's up to you to figure it out.' But I really like the idea of the structure coming out of the editing - it kind of lends itself to this weird, organic tension." Portner says the title of the project was inspired by the band's love of sweets such as Gummi Bears and Haribo - an aesthetic that's echoed in the film's pick'n'mix approach to editing, and its love of gooey textures. Things ooze, drip, seep, splatter; and the music is similarly malleable - not just a soundtrack, but woven in and out of the moving images, so the two seem inseparable. "As a visual motif, ooze sort of lends itself to a feeling," says Perez. "It's neither solid nor liquid - it's amorphous, and that's a lot like the movie itself."

Oddsac has been quite the labour of love for the band, and particularly Perez. Work started on the project in 2006, with all involved batting ideas back and forth, and Perez setting out to try to capture them, filming in rural New York and around the band's home of Baltimore. Early rushes informed the first music, which in turn fed back into new visual ideas. Editing was done in short bursts, with scenes slowly taking shape, and sound and vision gradually pieced together with painstaking care.

The film contains fragments of some familiar movie tropes - the psychedelic abstraction popular in 1960s movies, or the gloopy B-movie schlock of vintage horror, where budgets were tight and imagination filled the space. Taken as a whole, though, it's trickier to pin down, mutating unpredictably but clearly guided throughout by an internal logic. Portner cites numerous inspirations, from Asian horror cinema to the 1960s art films of Kenneth Anger to The Legend Of Boggy Creek, an ersatz documentary about the hunting of a Bigfoot character in rural Arkansas. In particular, though, he mentions YouTube - and the viewing habits it engenders - as an influence on the film's skippy, high-energy style. "Going on YouTube and happening on one great minute-long clip from a horror film - if you saw the whole thing, maybe the film's not that great, but out of context it can look amazing."

The band themselves star, albeit fleetingly. Through darkness, we glimpse a masked Portner, playing autoharp amid a band of fire jugglers. At one point Lennox, in a blonde wig, assembles a drum kit in the middle of a humid rock field. Elsewhere, Perez invited in extras, improvising scenes and letting chance and coincidence lead the way. "There were all these weird repetitions at work," he explains. "For example, there's a scene where I shot some girls having a food fight, and it was done very quickly, not really rehearsed. Then, a year or two later, I shot some footage of these little kids and they were doing exactly the same thing as one of the girls - rolling around on the ground, kicking one leg up - really similar. I used that. It was completely unintended but it becomes a weird moment of symmetry in a chaotic experience." New fans who came to Animal Collective through the sunny, domestic songs of Merriweather Post Pavilion might be left bewildered by Oddsac's darker, wilder tone. Sonically, certainly, there is much here that recalls the untamed spirit of the band's earlier work.

"A lot of people have been saying that," admits Portner. "It's a different thing to think about, making a record like this - we didn't have to think about making people dance. But it was circumstance that made our older records sound the way they did - we had quite chaotic lives back then. This time, it was about making sounds to match the visuals. It was cool to do things a little darker. There's space for ambient bits, drones - you can throw it all in there."

For Perez, who worked on Oddsac for four years, right up until its premiere at Sundance in January, it has been an epic undertaking. "Before the premiere, we all watched it all the way through twice, and we were crossing our fingers - we didn't know how, or even if, it would all fit together." Luckily, he's happy. "This was a dream scenario in terms of working with my favourite band. I felt like if this was the only movie I ever got to make, it had to be something I was 100 per cent excited about."

Oddsac is due for release on August 9.