China's Lou Ye and Iran's Bahman Ghobadi are both at the festival with movies made undercover after they were barred by the authorities from working in the film industry.
Both directors tackle subjects that make officials at home uneasy - gay relationships in Lou's "Spring Fever," and Tehran's underground music scene in Ghobadi's "No One Knows About Persian Cats."
Ghobadi has come to the south of France without the film's co-writer - his partner, U.S.-Iranian journalist Roxana Saberi.
She was in Vienna Friday after flying from Iran, where she spent four months in jail after being accused of spying for the United States. Saberi denies the charge, and Ghobadi said it was ridiculous for the Iranian government to suggest she was a spy.
"Some people told me, maybe the government has taken her because of your film - but that's impossible," Ghobadi said in an interview Friday. "This wasn't about me. It was a game."
Lou, 44, was banned from filmmaking in China for five years after he brought his last film "Summer Palace" - about the 1989 Tiananmen Square protests - to Cannes in 2006 without permission. He shot "Spring Fever," a moody and sexually explicit drama that tracks the romantic entanglements of five characters over the course of a torrid spring season, with a small camera and without authorization in the city of Nanjing.
"I was worried I might be stopped from working - worried I might get a call from the Chinese Film Bureau," he said Friday.
"At the same time, I'm very happy because it's a free process, of scriptwriting, shooting, working with the actors."
Ghobadi also said working outside the law gave him a freedom that was worth the risk.
He began "Persian Cats" after the government denied him permission to start shooting a film he had been working on for two years. The film was shot covertly in just 17 days, largely outdoors on the streets of Tehran.
"It was a relief for me, making the film," Ghobadi said. "Every negative energy came out of me when I finished this film.
"After finishing the film, I was cured - then that thing happened, Roxana was arrested and sent to jail."
Ghobadi, 40, won a prize at Cannes in 2000 for his first feature, "A Time for Drunken Horses," and subsequent films also have been well received around the world but have been virtually unscreened at home.
"Persian Cats" follows indie musicians Negar and Ashkan as they try to make a record, put on a concert and try to get visas and passports that will let them leave Iran.
Along the way we meet Tehran musicians, from rappers to rockers, forced to rehearse in secret and in some cases jailed for running afoul of Iran's cultural guardians, who have declared many forms of Western music in violation of the country's strict Islamic laws.
Ghobadi said the four months of Saberi's incarceration had been "like hell," and his own future is uncertain.
The film's two lead actors have left Iran and may not return, and Ghobadi said he was worried those performers who are still in the country would face persecution.
He is not sure whether he will go back to Iran. Saberi said she and her parents plan to return to the U.S. in the coming days.
Ghobadi said the last few months had been disorienting.
"I lost my life. I don't know where I belong at the moment, or who I belong to," he said.
"There are a lot of possibilities ahead of me. Maybe I will write a book, or make music. Maybe I will go to a remote village and live with Roxana."
Lou called on the Chinese government to relax film censorship, and said he hoped he would be allowed to continue making movies.
"I hope I will be the last director in China to be banned in this way," he said at a news conference Thursday.
"I hope nothing will happen when I get back to China. I'm just a director making a film."
By Jill Lawless