My Wedding and Other Secrets is the second time Auckland director Roseanne Liang has put her married life on screen.

This time though it's in a cross-cultural romantic comedy that has local box office hit written all over it.

Roseanne Liang is not one to find herself lost for words. She's a lively and fiercely determined over-achiever who turned the camera on her family and boyfriend for Banana in a Nutshell, one of the most-talked-about local docos of 2005.

But, on this Sunday night, as she faces the first audience to see her debut feature film My Wedding and Other Secrets, she chokes up.

"It's lots of things; scary, weird, and a little bit fraught as well," she says, of seeing the film through to fruition and finally showing it to people.

My Wedding and Other Secrets is the second time she has told her true love story of how a Chinese girl (Liang) falls for a white boy (her husband Stephen Harris) and dares not tell her conservative Hong Kong immigrant parents.

John Barnett, the producer, and the man who makes the funding decisions at South Pacific Pictures, takes the microphone and recalls the night, five-and-a-half years ago, that he saw Banana in a Nutshell and approached Liang about turning it into a romantic comedy for mainstream release.

Liang admits now that she hadn't quite thought the implications of such a project through before throwing herself at the opportunity. At the time, her documentary was in its first days of release and praise was flooding in from the Chinese and wider community.

She faced unexpected criticism from small pockets who believed she had produced a brash expose of her parents. And then there were the taunts from racial separatists. But that did not deter her from wanting to tell her story again.

After four years of script development, Liang found herself in the difficult position of selecting an actress to play herself.

One of the first steps was to rename her characters. Roseanne became Emily, and Stephen became James, giving the actors and writers the freedom to build on the characters and their story.

Liang says she was very particular about who she wanted to play Emily: a New Zealand Chinese actress with a New Zealand accent. She says she knew from her previous projects, that Wellington-raised actress Michelle Ang - best known for her roles on Outrageous Fortune, Neighbours and The Tribe - was perfect.

While Ang is typically cast in confident, sexy roles, Liang says she had noticed a nerdy persuasion which reminded her of herself.

"There's the way she will say something, and then correct herself, and giggle in an embarrassed way. It's something I find myself doing, it's about a lack of confidence or a self-deprecating nervousness or a twitch. So I did feel a sort of kindred spirit with her," she says.

Like her character, Ang is a bit of an over-achiever, having completed a double degree in chemistry and accounting with commercial law by correspondence while acting full-time on Neighbours. And she is a first generation New Zealand born-Chinese girl.

Unlike her character, Ang's parents have never disapproved of her dating outside her race. These days she has a boyfriend "so white he can't tan", she jokes.

Go Girls' actor Matt Whelan was an obvious choice for the role of James, firstly because he looked a lot like Harris - tall, dark, with a thick, deep-set brow - and secondly because he performed his audition in Mandarin.

As for Emily's parents, Liang set herself a high bar by insisting on actors who could speak Cantonese with a Hong Kong accent, but also speak fluent English with a Hong Kong accent.

She was lucky enough to pin down renowned Hong-Kong-based actors Kenneth Tsang and Cheng Pei Pei, who are tipped to earn the film a devoted audience among the local Chinese community.

Ang says she worked painstakingly on getting Liang's mannerisms down pat in order to tell her story with conviction.

"I was always watching her, whether she knew it or not. How she sat, how she stood, how she walked, the way she talked when she was excited," she says.

She made sure she nailed Liang's distinctively crooked smile first, and then found that sporting thick, dated glasses really helped her delve into the character.

Ang was asked to put her own very thick lenses in the gawky frames, because one of Liang's pet peeves was watching films in which there was no optical distortion through the glasses.

"I'm extremely blind and those glasses are really thick, so as a result it makes my eyes smaller. It was slightly harder to find Emily without the glasses," Ang says.

Meanwhile Whelan says James' outfits - including grey, slightly-too-short track pants and faded, slightly too-short T-shirts helped him capture the essence of a character who was nerdy and proud of it.

"You get an instant impression of someone who is comfortable in his own skin," he says.

He adds that he felt very much at home in the role, as the set of his character Brad's flat on Go Girls doubled as his character James' flat in the film - just with the addition of some dated wallpaper - and he admits to having supplied some of the T-Shirts, and a pair of hilarious chinos from his own wardrobe.

Ang says the experience was poignant because she found she was learning about herself, and getting a stronger grasp of her own cultural identity.

Like Liang's father, Ang's rarely says the words "I love you", but shows that he does by providing - sending his children to the best schools and ensuring there is food on the table.

"And the way that Emily's mum leaves food out for her when she comes home late at night - I relate to that so much. My mum and dad have always made sure that I was looking after myself and was eating.

"And when they came to the premiere, they gave me a bag of fruit, which is just so lovely, and typical. I had just arrived in, I'm in living in a hotel, I don't have access to fresh fruit. That's the best thing they could have given me.

"It's just their very practical way of saying I love you, I care about you, I need to make sure that you are caring for yourself," she says.

In a way, she says the film cemented what she had always tried to make sense of, as a young person split between two very different worlds.

"I guess it's really understanding the love that Chinese parents have for their kids. Not that I was ever an ungrateful kid, but going through this process shows it is that they were always there."

"I guess playing this showed me, okay, I'm not alone, there are a lot of people who are of Asian descent, living in New Zealand, who feel the same way."

Liang says that has always been the motivation behind the project, and that even though her parents are not comfortable with the documentary - her dad has still not seen it - they seem to accept it.

"Mum is okay with it, but she doesn't feel the need to really praise it. Which is kind of a Chinese thing, or maybe it's just my parents.

"They don't need to exalt the virtues of anything we do. They find that emoting is kind of embarrassing. They don't feel the need to say, this is great, I'm really happy with it, you've done a great job. All they need to say is, 'yep'. That should signify everything."

In many ways, Liang says Banana in a Nutshell was always about her coming to terms with her parents. The fact her parents have accepted her invitation to the premiere of My Wedding and Other Secrets and dressed up for the event speaks louder than praise, she says.

She watches as her mum thanks Pei Pei for portraying her with such heart, and her father takes photos of the family in their opening night frocks. This his way of showing his pride, she says.

But it is her husband's reaction, which she describes as "profound", that renders her speechless.

"I guess the love and heart in the room was really palpable to me. I worry that this is the happiest I am going to be, that I have peaked too early," she says.

Showing her documentary was an enormous feat, but she says the premiere of My Wedding and Other Secrets feels "grand". Her parents came. And they stayed.

"It meant the world to me," she says.

What: My Wedding and Other Secrets
Director: Roseanne Liang
Starring: Michelle Ang, Matt Whelan, Kenneth Tsang, Cheng Pei Pei
Where and when: Nationwide release MArch 17th