A scene from the Pixar film, <i>Brave</i>.

A scene from the Pixar film, Brave.

Brave is Pixar's first fairytale, first film with a female protagonist and is the animation company's first film to be developed by a woman, Brenda Chapman, who was also the film's original director.

Producer Katherine Sarafian says, ''She based the story on her relationship with her six-year-old daughter.''

It's a story set in ancient Scotland in which an independent-minded princess, Merida (voiced by Kelly Macdonald), doesn't want to be married off by her parents, King Fergus (Billy Connolly) and Queen Elinor (Emma Thompson) as tradition dictates and seeks help from a witch to deal with her mother, who has been trying to school the aspiring archer in the behaviour expected of a future queen. But the spell that gets cast isn't quite what she expected.

Nor, perhaps, was the experience of making the film quite what Chapman expected. She ''left the project'', as Sarafian puts it, over the ''creative differences'' and the film was completed by Mark Andrews and co-director Steve Purcell.

It seems to be something of a sore point for Pixar: Sarafian and Andrews are reluctant to discuss the specific differences that led to Chapman's replacement, which happened 18 months before the film was released. Pixar has sometimes been criticised as a boys' club in terms of its key personnel and major characters. Andrews defends the company's organic creative processes, which have resulted in a string of critically acclaimed and financially successful films including Finding Nemo, Up and The Incredibles.

''It's about the right team, the right people … All the filmmakers start with something they believe in, an experience they had,'' he says. And Brave was no exception, originating with Chapman.

But creative friction and conceptual change is hardly unique or new in Hollywood. Sarafian and Andrews point out this isn't the first time a director has been replaced on a Pixar production (it also happened with Ratatouille). They also say Chapman liked the finished film, although she left Pixar for a job at Lucasfilm (both companies are now under the Disney umbrella).

Andrews says, ''We're still friends.''

Of Scottish descent himself, he had been involved with the long-in-production film as a consultant since work began in 2006 and had gone on early research trips to Scotland. Regarding specific issues, Andrews says there were ''a lot of issues over likeability'' regarding the character of Elinor and that while most of the elements of the story were Chapman's - ''I didn't want to come in and rewrite it all'' - he did a lot of work to ''get it to work just right'' and to speed up production. One substantial change he made was to alter the original snow-swept setting to a greener, more pastoral one.

Sarafian says Pixar completely upgraded its software system for the film, which enabled such effects as detailed fields of grass and realistic, flowing hair to be produced on screen as never before.

''It's painterly work.''

Some of the earlier concepts for the film can be viewed on the Blu-ray release.

Brave was Sarafian's first feature film as producer but she had a lot of prior experience with the company.

Sarafian joined Pixar in 1994 as a production co-ordinator on the company's first feature film, Toy Story and worked as production manager in Pixar's short-film department and as art department manager on its second feature, A Bug's Life. She then moved into creative services and consumer products departments, eventually becoming director of marketing, giving her a fresh perspective on what appeals to children.

In 2000 she moved back into film production, working as production supervisor on the film Monsters, Inc. and production manager on The Incredibles. She then produced the Oscar-nominated short film Lifted in 2007.

One of the best things about Pixar, she says, is the atmosphere of collaboration and support - filmmakers can count on their colleagues for input and advice even if they aren't working on the same movie - and, she says, ''Everyone treats every film as if it is the first. It's unique.''

Andrews was head of story on The Incredibles and story supervisor on Ratatouille and wrote and directed the 2005 short One-Man Band. He says co-writer Purcell - whose earlier Pixar work includes contributing screenplay material and voice work to Cars - was brought on as co-director because ''he was showing great promise and this is giving him the experience to go into being a director himself''.

And when it was finally completed, Brave was well received critically and grossed more than $500 million internationally. And everyone seems proud of the finished film. If it's not quite a happily ever after fairytale ending for all concerned, it's not bad.

Brave is out now on DVD and Blu-ray.