Actress Luisa Ranieri attends the photocall during the 71st Venice Film Festival on Tuesday in Venice, Italy. Photo: CFP

The Venice film festival kicked off Wednesday with the arrival of stars by water taxi for an art house dominated line-up rich with tales of war, poetry and the mafia.

Taking the stage first at the world's oldest film festival was Mexican director Alejandro Gonzalez Inarritu's Birdman or the Unexpected Virtue of Ignorance, starring Michael Keaton of Beetlejuice and Batman fame.

In the first of 20 flicks vying for the coveted Golden Lion award, Keaton plays a washed-up actor once famous for playing a superhero, who is now struggling to put on a broadway play in a bid to regain his former glory.

Crowd-pleaser Inarritu, best known for his films 21 Grams and Babel, pampers fans by bringing on board other superhero veterans for the movie, including Emma Stone from The Amazing Spiderman and Edward Norton, star of the 2008 The Incredible Hulk.

Other hotly-awaited world premieres include Good Kill by New Zealand's Andrew Niccol, starring Ethan Hawke as a drone operator in Afghanistan, and David Gordon Green's Manglehorn with Al Pacino as an ex-con turned locksmith with a broken heart.

French film composer Alexandre Desplat - whose dozens of works include the scores for The King's Speech and Harry Potter and the Deathly Hallows - will head up the main jury at the festival, which runs until September 6.

Desplat was among the cinema luminaries quaffing prosecco at the festival's opening party on a roof terrace near Saint Mark's Square in the floating city Tuesday, kicking off a fortnight of glamorous beach galas and red-carpet ceremonies.

Festival director Alberto Barbera brushed off criticisms that this year's edition was light on Hollywood stars, saying the aim of the organizers had been to create space for high-quality, innovative flicks which risk falling through the cracks.

"I have nothing against glamour, but it cannot be the only component in a festival," he said.