Kung Fu Panda crew

Take one overweight panda, add hundreds of years of martial arts knowledge, an arch villain, the voices of Jack Black, Dustin Hoffman and Angelina Jolie (amongst others) and the Dreamworks animation studio and what do you get? Only the best Dreamworks animated movie since Shrek, that's what.

"I took a year of karate..."

Jack Black is discussing his credentials for his role as Po, the Kung Fu obsessed panda who's the 'star' of Dreamworks latest (and excellent) animated movie.

"It was obligatory, every kid was taking one year of karate and one year of piano in my town," he continues. "It was Bruce Lee and Liberace. And I was not a white belt. I had a coloured belt. That's all you need to know. It could have been black. It could have been yellow. It could have been somewhere inbetween..."

As it happens, Kung Fu wasn't Jack's only martial arts training.

"I was pretty good at judo," he adds, "and I was heavier than most of the other kids, which gave me an advantage. It's easier to flip people if you outweigh them." He pats his not-actually-that-big stomach. "It's not all downside. There are advantages to being a little 'extra' around the waist."

Before anyone can get a question in, Jack's co-star, Dustin Hoffman, leans into the mic. "If I may Jack..." he interrupts. "Because of this film, Jack and I have been cast in a new film, about the relationship between Bruce Lee and Liberace..."

"I play Bruce Lee," reveals Jack. "And I play the piano," adds Dustin.

Happily, the film is even better than the press conference. And the press conference – from the game of musical chairs as the cast and directors shuffle in to Dustin leading the assembled journalists in a chorus of a rude word – is hilarious. It shouldn't though detract from the obvious hard work that went into the film. Some four years of hard work in fact.

"There's nothing for free on an animated movie," explains co-director John Stevenson. "Everything in the frame, from the huge vista of Mongolian mountains to a teaspoon, everything has to be researched and designed and built and painted and very often we end up throwing it out of focus in the background and nobody notices anyway."

And all because of a panda doing Kung Fu.

"The idea of a panda doing kung fu is comical," says co-director Mark Osborne, explaining the origin of the idea. "Even my grandfather, who doesn't know much about Kung Fu, laughs when I say the title."

Hoffman, who voices Po's teacher, Master Shifu, has a different take on the film's origins. "When (Dreamworks supremo) Jeffrey Katzenberg asked me if I wanted to be in Kung Fu Panda, I thought it was the end of a distinguished career," he reveals, deadpan - although, as he cheerfully points out later, "this was the first time I did all my stunts."

Joking aside, the Kung Fu action is surpringly well drawn, from the villain, Tai Lung (voiced by Ian McShane) escaping his Hannibal Lecter-esque prison to the final showdown with Po.

"We went right to the crispy edge of Kung Fu," explains Stevenson. "We wanted to make sure it was real Kung Fu, albeit done by animals. We wanted it to have consequences, otherwise there's no emotional investment."

"We wanted to make the action as intense as possible, to make the comedy as effective as possible in contrast," continues Osborne. "Walt Disney made a pact with his audience: I'm going to scare you but it's going to be okay. That was the same pact we adopted."

It's a vision that works well. As Hoffman points out, it all ultimately comes down to the directors: "Had this film flopped each of us would be pointing," he says. Pointing. "But", he adds, gesturing to John and Mark, "they deserve the credit. It's their vision, it's their imagination, it's their taste and we're lucky."

How far though does the realism go? The cast of Madagascar claimed to have studied their relevant animals in depth in order to voice them. Did Jack go to similar lengths?

Black looks incredulous. "I don't believe they studied their animals. They later said they did. Right before the press conference.

"I was told to use my own voice. I wasn't basing my performance on a panda. I was just being me. Guilty. Sue me. I've never even seen a panda face to face..."

"That's not true, man," cuts in Dustin. "Jack demanded a panda in his hotel room."

"That's different," says Jack with a grin. "But I think I did the pandas proud." He nods, proudly. "I think they're going to be pleased with my performance..."

Kung Fu Panda opens nationwide on 4 July.