To Live is Better Than to Die shows how an Aids epidemic in Henan affected one family: Ma Shenyi, his wife, Lei Mei, and their three children. Only the eldest daughter escaped infection. About 65 per cent of the 800 mainly impoverished people in their village of Wenlou were infected with HIV during the 1990s, when they tried to make money by selling their blood.

The full version of the film runs for almost 90 minutes. It opens with the hysterical moans of Lei, in the late stages of Aids. It then goes back and traces her painful decline, from a woman who can recall romantic tales of her youth and her former beauty into a bag of bones towards the end of her life, lying listlessly on a cart, waiting to die, without even the energy to brush flies from her face.

The seasons of the Chinese Lunar calendar are used to trace the family's story. Lei dies on Frost Descent, the day that marks the end of a life cycle for grass and plants. She is buried under an unmarked dirt pile near heaps used to cover other bodies.

Ma, who takes loving care of his dying wife, shows his heroism when he teaches his one-year-old son to speak and walk, even though he knows the child's chances of survival are virtually nil. He knows full well that, barring miracles, his eldest daughter will witness three more deaths after their mother passes away.

'As a documentary film director, the theme of life and death always fascinates me,' says Chen, a boyish 35-year-old. 'That's why, when I first saw Ma and his family, I immediately wanted to film them.'

Chen met Ma, his wife and their youngest child in May 2001 when a Wuhan University doctor brought them and two other HIV-infected villagers to the Hubei capital, where Chen works.

'I was struck by the deep, dark eyes of the kid, and saddened by the fact that he was born with HIV,' says Chen, himself the father of a small child. 'I talked to his father about the idea of filming the family. To my surprise, he said 'yes' immediately.'

But filming was risky. To avoid being found by Henan authorities, who were trying desperately to hide the epidemic from the media, Chen had to dress as a peasant and walk some eight kilometres through a cornfield to the village every time he went there. The project could have ended at any time if he was spotted - under local rules, a villager could earn a 50 yuan reward for reporting the whereabouts of any journalist.

Instead, many of the villagers rallied around. Chen got help from several other affected families. They arranged for him to live with one of the handful of uninfected families and helped him to get his camera, hidden in a fertiliser bag, to Ma's yard, where most of the film was shot.

The project gave Chen a few awkward moments, such as when Ma offered him a cucumber, washed in murky water from a bucket. 'I hesitated whether I should take it,' he says. 'I knew if I didn't, they wouldn't trust me any more.' The director says he was so worried about contamination that, when he summoned enough courage to bite the cucumber, he bit his mouth, which started to bleed. 'I was frozen at that moment and thought, 'God, this is my end'.'

Chen overcame his fears and was soon dining regularly with Ma's family. And he says the villagers started to call him 'brother Chen' instead of 'director Chen'.

But there were times when even Chen's heart was over-ruled. Every time he went back to his home in Wuhan, his wife would order him to take off all his clothes in the hallway and shower immediately. The clothes would then be exposed in the sunshine on the balcony before he was allowed to put them on again.

Although the film is yet to be shown in China, its success has followed a gradual change in the Chinese government's attitude towards the Aids epidemic. One million people are already HIV infected, and there are fears this will rise to as many as 20 million by 2010.

On World Aids Day (December 1) in 2002, the Chinese government said Aids was a social, rather than political, issue. Since then, an Aids committee has been set up by the State Council, under Vice-Premier Wu Yi, who visited Aids patients in Wenlou village last December.

Also in the wake of Chen's film, a foundation has been set up, in Denmark, to help Ma's family, particularly the second-oldest daughter, who is now seven and is showing Aids symptoms. She can't even walk the 10 minutes from her home to school.

Chen, after much agonising, says he has decided not to make a follow-up. 'I can't persuade myself,' he says. 'I think I've got too much from this movie, which makes me feel guilty.'