Voice actor admits doubt about video game tie-in after phenomenon of Frozen but says result is incredible.

Josh Gad, after voicing Olaf the always cheery snowman in Frozen, knows a bit about the keys to making a successful animated family film.

He also gets reminded of the success every day when he is mobbed by children while picking up his daughters Ava and Isabella from school.

"It's crazy," Gad laughed.

"It's like Beatlemania in the 2- to 5-year-old market." So he had reservations when a script for a new feature-length 3D animated film based on the popular video game Angry Birds landed on his desk.

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After the US$1.3 billion ($1.9 billion) global box office success of Disney's Frozen, and billions more dollars in merchandise sales, Gad receives a lot of script offers for animated films.

"When I heard the words 'The Angry Birds Movie' I was sceptical," Gad recalled.

"I said, 'Why does this have to be a thing?' But I got pitched this incredible 20-minute reel where it became almost immediately apparent to me that the movie was much more than a game that people may or may not have played.

"The comparison I think works best is The Lego Movie - we all went into it thinking it was going to be one thing and it was another."

Gad voices Chuck, a hyperactive, impatient bird who is polar opposite to the benevolent Olaf the snowman.

The voice cast also includes Jason Sudeikis as the temper tantrum-throwing Red, Danny McBride as the volatile Bomb, Maya Rudolph as reformed angry bird Matilda who runs an anger management class and Peter Dinklage as the legendary Mighty Eagle.

Unlike the Angry Bird games, which have been downloaded more than three billion times, the birds have legs.

And just like the game, the birds live on an island, get angry and use catapults to take on rival green pigs who steal their eggs.

The audience also discovers why the birds are so angry.

Gad, because his voice is associated globally with Olaf, had to change it for Chuck.

It helped that Chuck is such a frenetic bird and Olaf was chilled out in more than one way.

"I pitched Chuck particularly high because he is this little bird with this tiny, loud, fast voice," Gad said.

"But, I did play around with it.

"First I tried to do Chuck with a Brooklyn accent, but then it became a thing on a thing.

"To me it was Chuck's speed that guided my choice." Gad also fuelled up on sugar and caffeine for his multiple-hour sessions in the sound booth, which was not a problem for the chubby comedian.

"Do I look like I have ever passed up an excuse for sugar?" he asked.

Who: Josh Gad, the voice of Olaf in Frozen, now the voice of Chuck in The Angry Birds Movie
When and where: Opens at cinemas today

Also: See a review of the film by 6-year-old Barry Heath on watchme.co.nz
- AAP