Did your authority as director put a strain on your relationship with your wife and co-star Charlotte Gainsbourg?

Of course, on the set you have power over her, and then when you go home you don't have the power any more! But the main thing is you don't want to betray her. You don't want to make a bad movie or have her act badly in the film, so it puts you under pressure. On the other hand there are a lot of great things too, because when it goes right and it's funny and nice, then it's really great to do something with your wife that you both enjoy.

But the story does cast light on the schizophrenic quality that actors have, doesn't it?

It's very strange to live with an actress, or to be an actor. You might be making a film or your partner is making a film and she's like a stranger to you and you to her. She has another family for those few weeks. She's in another thing, in this bubble and when she comes home you just want to say "wake up".

The film offers meditations on the theme of celebrity and stardom. Have you ever asked anyone for an autograph?

When I was a kid, sure. And a few years ago I was in a restaurant and Robert De Niro was there. I really wanted to ask him for an autograph. Of course I knew how ridiculous that would be – apart from anything else what would I do with it once I had it? I didn't dare ask him, but I can understand the desire of someone to get your autograph.

"Ma Femme est une Actrice" opens in UK cinemas on Friday 27th September 2002.