The Cambodian Space Project had barely launched in December of 2009 when German filmmaker Marc Eberle started shooting his documentary about the band.

Julien Poulson, an Australian musician, had met and struck up a musical, as well as personal, relationship with karaoke singer Kak Channthy, better known as Srey Thy, just a few weeks before in a Phnom Penh bar. Their plan was to start playing covers of Cambodian golden age rock ’n’ roll classics.

Eberle immediately saw the potential to make a film not only exploring Cambodian music and history but also the dynamics of relationships between Western men and Cambodian women.

“They couldn’t actually talk to each other,” Eberle recalled last week in an interview at Phnom Penh’s Equinox bar. “Thy didn’t speak a word of English. Julien didn’t bother to learn a word of Khmer.

“And it was really like: ‘Wow, how is this going to happen? I’m going to film this. This is fantastic.’ I knew there was a great story there. It was just a great subject.”

For the next four years, Eberle shadowed the pair as they grew in popularity, started writing original songs and even released Cambodia’s first vinyl single since the Khmer Rouge.

He filmed their gigs in Phnom Penh and around Cambodia, their overseas tours, Thy’s visits back to her village in Prey Veng, and hours of interviews with her and Poulson in their home, bars, airports, minibuses and tuk-tuks. At one point, Eberle literally became a member of the group, playing bass as a way of paying his way on an Australian tour.

“It’s been an incredible trip,” he said. “Five years in the making, following basically Srey Thy’s story of how she developed from this very shy traditional village karaoke singer girl into a feisty front-woman of the Space Project. The challenges and obstacles she had to overcome, and the band had to overcome, and the relationship she had with Julien.”

The resulting documentary, Rocking Cambodia: Rise of a Pop Diva, is a rich, dynamic, multi-layered story incorporating vibrant animations drawing on sci-fi and Angkorian imagery. Intercut with new-found archival footage – including scenes of uniformed soldiers doing the twist as Prince Norodom Sihanouk watches on – it provides an engaging primer on Cambodia's recent history and the music scene of the 1960s and 1970s.

It also touches on different aspects of Cambodian society including the impact of the Khmer Rouge, the role of women and the culture of alcoholism.

However, above all, the film is the story of charismatic, vulnerable and funny Srey Thy. From the beginning of her journey, Eberle and his camera were her confidante.

In early scenes, she talks about being a social outcast, selling songs and sex (“I was so tired of myself”); how she felt scared sleeping with Poulson, her first time with a foreigner (“My body was shaking, I felt like a virgin again”); how all the Khmer people laughed when they saw white people playing Khmer rock (“I laughed too”) and how her life had changed since she had joined the band (“I was so happy, I couldn’t sing”).

At times, the film is emotionally raw. During her first visit to Australia, her mother, who has tuberculosis, is admitted to hospital. Thy weeps as they talk over Skype. “I don’t want to be here,” she says.

When Thy and Poulson are married at his home in Tasmania, Thy, marvelling at her beautiful white wedding dress, says she’s happy even though her family isn’t there. “It would have been great to have Khmer food on my wedding day,” she adds while eating white bread and ham.

As the film progresses, the tension grows between Poulson, who thrives on life on the road gigging constantly, and Thy, who wants some stability and money to show for her work (“I’m fed up with music. I’ve spent the last two years touring nearly 20 countries, but I haven’t made any money”) before the denouement at the Space Project’s most important and prestigious gig yet in Berlin.

Eberle spent six months in Australia editing the film and has already secured distribution with the BBC – which screened it as part of the prestigious Storyville series of documentaries in March – and Australia’s ABC, among others. He said the Cambodian premiere would probably be during the Cambodian International Film Festival in December.

However, Poulson – who was also originally planning to make a film focusing on Srey Thy – doesn’t like it, describing it as a “wasted opportunity”.

“You can walk out of a music film with a skip in your step, having really enjoyed experiencing something,” he said over the phone from Kampot, where he is setting up the Kampot Arts and Music Association, “This one’s a little too … I don’t know if it’s a cultural thing, a Germanic thing ... It’s like reportage: [in a German accent] ‘You will not laugh in this film’. Although there are of course lots of funny moments. It jumps all over the place. There’s really not a lot of interesting footage of [the concerts]. I just think it could be better.”

Eberle said he could understand why Poulson was unhappy, as it was “difficult to see yourself through someone else’s eyes” but he dismissed criticisms that the film was a “missed opportunity”.

“I’m interested in telling good stories with depth, not commercials for Julien,” he said in an email.

Thy, speaking over the phone from Australia, said she liked the film. Even though it revealed some of her dark truths and showed her behaving badly at times, she said it showed the reality of her life.

“Plus I get to see my parents,” she said. “Now that they both passed away, I’m so happy to still have them on film. I feel shock sometimes when I watch it, because it seems so real I have a feeling that they are still alive.”

Above all, she was “happy that I can show the world about my life and how hard I worked to get to the point that I am today”.

Additional reporting by Vann Sreynoch.

Srey Thy will be performing with Australian hip hop group Astronomy Class at The Mansion on April 18. See the What’s On section for more details.