Keeping it reel

Paul Haggis's acclaimed Crash, meanwhile, features the Dirty South rapper Ludacris as an eloquent carjacker, while My Left Foot director Jim Sheridan will soon usher 50 Cent on to the big screen in Get Rich Or Die Tryin'. From Ice Cube in Are We There Yet? to Eminem in 8 Mile, the avalanche of rappers-turned-actors is so intense, Samuel L. Jackson has complained that real black actors are being squeezed out of cinema. Musicians have always dabbled in the movies. This sustained assault from one medium into another, though, is something new.

When rappers first made inroads into Hollywood, they were used with genuine purpose. John Singleton's Boyz N the Hood (1991) not only gave Ice Cube his screen debut, its setting in South Central LA's deadly streets was a cinematic equivalent to the racially radical records that Cube and other gangsta-rappers were then making. Mario Van Peebles' New Jack City, retooling blaxploitation crime movies for the new hip-hop nation the same year, wittily inverted Ice-T's pimp persona by casting him as a cop. Both films would prove templates for the next decade's burgeoning black cinema. Their careful use of rappers would be replaced, however, by a more wholesale approach.

You can see why rappers would be deemed ideal movie stars. Not only verbally facile, they also often rely on aliases as crafted as any actors. As Andre Benjamin says of Andre 3000, the extravagant super-playa of OutKast's dazzling videos: "He's a character I play." The same is true of Marshall Mathers' hysterical Mr Hyde Slim Shady, or Cube's instrument of racial vengeance, the Predator.

Rap also drips with cinematic influences. The cokehead bling and machine-gun ultra-violence of Al Pacino in Scarface (1984) has been as central to hip-hop as James Brown. Gangster and martial arts movies are adored and aspired to. The gunfire and spoken-word "skits" that punctuate gangsta albums also make them more like audio movies than any other music. The emotional authenticity of the best hip-hop, whether the inner-city depression of The Geto Boys' "Scarface" or Eminem's convulsive rage, also seems prime preparation for acting. The likes of the notoriously bullet-riddled, orphaned ex-drug dealer 50 Cent, meanwhile, come trailing potential biopics behind them, as Get Rich Or Die Tryin' proves. Compared to all this, the stage performance credentials of a rock wannabe actor like Bowie seem painfully thin.

Tupac Shakur is, though, one of only two rappers so far with a convincing screen career. Tellingly, he was a trained actor, who completed his debut as Bishop in Juice (1991) before his first album as 2Pac. It was Shakur's tragedy that Bishop's charismatic self-destruction seemed to overwhelm his real, insecure personality, driving him into a similar downward spiral in both his gang-adoring albums, and a violent life that saw him shot dead in 1996. But though it's his loss to rap that's still mourned today, cinema was his stronger suit. Playing a mailman in Singleton's romantic road movie Poetic Justice (1993), and a junkie trying to get clean with pal Tim Roth in Gridlock'd (1997), he showed ambition and vulnerability sometimes smothered in his music. Roth found him a fine acting foil, bare of the machismo gangsta-rap required of him. That world's obsession with "keeping it real" had helped kill him; cinema may have saved him.

The other substantial rap acting career, Ice Cube's, is a stark contrast. He was one of the most brilliant and controversial rappers in his prime. But as a movie star he has been cannily affable, almost imperceptibly manoeuvring himself into the heart of Hollywood. His sullen intensity in Boyz N the Hood has never really been repeated. Instead, he's appeared in endless B-movies. But, with his company, he's also co-produced sleeper comedy hits, from Friday (1996) to Barbershop 2 (2004), aimed squarely at black audiences. Patchy in quality, they've succeeded because they fill a need white-run Hollywood studios can't comprehend. This year has seen the once-feared gangsta-rapper as a harassed Dad in the family comedy Are We There Yet?, and as a modern James Bond in XXX. Getting mainstream audiences comfortable with a black man as both is as radical an achievement as any of his albums.

There are equally admirable rap performances in recent cinema. Ludacris's speech vilifying rap's negative stereotyping of black men, before he attempts a carjack, is a nervy turn in Crash, with the same wish to taunt racial taboos as hip-hop at its greatest. John Singleton, having given Cube his break, has specialised in drawing fine performances from Tyrese and Snoop. In Britain, too, Ashley Walters, previously known as Asher D in So Solid Crew, oozed sad conviction as the south-London estate teen destroyed by gun crime in Bullet Boy.

The debit side of rappers' contributions to cinema, though, is equally full. Samuel L. Jackson, who refused to co-star in 50's new movie (while appearing with Cube in XXX) explained his objections to rap dabblers in his trade: "Anybody can go out there and be themselves. But at some point you're going to be asked to be something else, and that's when it's going to be time to go to work."

The contrast between rapping and real acting was felt by Eminem on 8 Mile, even as he played a Detroit rapper based largely on himself. "A persona like Slim Shady is artificial, you hide behind it," its director Curtis Hanson says. "It takes great courage to tear yourself open, to give the sort of performance I wanted. He found it wearing." Tellingly, despite his acclaim in 8 Mile, Eminem has left wider cinematic challenges alone.

Most other rappers' screen CVs are, frankly, forgettable. Though the likes of LL Cool J, DMX and Snoop regularly fill out the casts of assorted horror, comedy and action films, their ambitions rarely seem nobler than P Diddy's recently announced intention: "I'm trying to hit the big screen, baby. I'm trying for my head to be six feet tall."

While Tupac, Benjamin and Ashley Walters all had stage training and ambitions before they were musicians, most rappers treat acting with the same seriousness as their personal fashion, porn video, and computer game lines: just one more trapping of multi-media success. For the corporations who back them, too, a rapper in a movie is a cross-marketing dream. As DefJam Island group president Lyor Cohen said on the occasion of the latest dumb doper comedy starring once-credible rapper Method Man: "DefJam has always believed that we are a lifestyle company... seeking additional ways to make money."

Many rappers say Amen to that, as they plot their futures as 21st-century all-round entertainers. Once, they were would-be Malcolm Xs. Now, they dream of being Bing Crosby.