For Johnny Depp, there are films and there are Tim Burton films. The Hollywood actor has teamed up with director Burton for the sixth time in Sweeney Todd: The Demon Barber of Fleet Street, a blood-spattered adaptation of Stephen Sondheim's musical that has impressed the critics.

The New York Times' A.O. Scott called it something close to a masterpiece, and Depp, as a pale-faced 19th century serial killer out for revenge, has been singled out for a performance that earned him a Golden Globe nomination and early Oscar buzz.

There are films that you do that you have enjoyed and the process is fantastic and the directors are great, Depp told Reuters in a recent interview to promote the movie.

And then there are the phone calls that you get from Tim, added the 44-year-old, sitting alongside Burton and wearing his trademark rimmed hat and glasses.

That is a magical moment for me when the phone rings from Tim, because you know you are about to embark on something very very interesting, he said, sipping red wine in a suite in London's upmarket Claridge's hotel.

The star of the hit Pirates of the Caribbean series, who has a reputation as an offbeat actor with box office clout, believes Sweeney Todd was as big a challenge as any during a career spanning more than 20 years.

It's an obtuse situation to be in when, at the ripe old age of 43, you find yourself suddenly trying to sing songs all the way through for the first time in your life, Depp said.

It's to say the least absurd and it was an odd feeling. So initially just hearing myself doing it, I was embarrassed...

He overcame his qualms, and, despite being no Sammy Davis, Jr. and no Frank Sinatra in Burton's words, convinced the movie's backers that he could pull it off.

NOT FOR THE KIDS

Burton, 49, had already directed Depp in Edward Scissorhands, Ed Wood, Sleepy Hollow, Charlie and the Chocolate Factory and animation movie Corpse Bride.

I've worked with him six times. I feel like I've worked with six different people, Burton said.

There are a lot of people that really do a very good job maintaining their persona ... they are good at being themselves in a movie. I like character actors that like to become different people, that's what energizes me.

Depp stars alongside Burton's partner Helena Bonham Carter as Mrs. Lovett, who fills her popular meat pies with the remains of Todd's victims. The movie also features Alan Rickman as Judge Turpin and Sacha Baron Cohen in a cameo role.

Released in the United States on December 21, the film has earned $40 million, according to www.boxofficemojo.com. It premieres in London on Thursday and hits theatres around the world through January and February.

Burton's Sweeney Todd is gory and bloody, earning it an R rating that prevents under-17s from seeing it without an adult and adds to the challenge of marketing the movie.

Burton said he refused to water down his film to be politically correct, and said the vivid color of the blood against a black and white background made it look obviously fake.

It's bright red, and the last time I cut myself I didn't see that color.

The New York Times