At a bustling Indian market, a child labourer carrying bags of flowers was captivated by cameramen riding huge cranes during film shoots. Two decades later the boy has become his country's latest cinematic sensation.

P.S. Vinothraj's low-budget debut movie "Koozhangal" -- internationally known by its translated title "Pebbles" -- has been selected as India's entry to the international feature film category at next year's Oscars.

The 32-year-old drew from his family's battle with poverty and his sister's experience of marital abuse to tell the story of an alcoholic father and his young son walking through a barren, unforgiving landscape in his home state of Tamil Nadu.

"My real-life experience gave me toughness and has helped in this film. That kind of life has become the film," Vinothraj told AFP.

The result is an observational drama Indian critics have described as a "masterpiece" and a "sensational debut... that is evocative, visceral and powerful".

It won the Tiger Award at the International Film Festival Rotterdam, with the jury saying the "seemingly simple and humble" effort was a "lesson in pure cinema".

Vinothraj joins an emerging movement of Tamil directors -- many from disadvantaged backgrounds like his own -- addressing societal inequities through the voices and lives of everyday people.

Had it not been picked up by the festival circuit his original plan was to show "Pebbles" in the villages where it was shot -- with fewer than 40 actors and crew.

It is the culmination of the young filmmaker's long journey to the big screen.

He started selling flowers in Madurai at the age of nine to support his family after his father died.

"So much has happened in my life and those things have made me ready for this," he said through a translator.

"I don't speak English nor do I have an education. Life's journey has taught me everything. Those are the metaphors in the film -- that is life's journey."

Vinothraj worked throughout his childhood and teenage years, moving to different towns and cities.

At one point, he was a labourer at a textile company in Tiruppur, where he "witnessed many people's lives being ruined in front of my eyes" over personal and financial woes.

"Some got married very young and went through multiple struggles. All of that stayed with me, wanting to express those struggles."

'Simple, honest stories'

Believing that education could help him fulfil his dream of becoming a director, the aspiring auteur tried to go back to school, but was told he was too old.

He eventually moved to the state capital Chennai and broadened his cinematic knowledge by watching movies while working at a DVD store, before getting work as an assistant on short films and in theatre.

As he sought ideas for his first feature film, Vinothraj's sister walked through the door of the family home, crying, her two-year-old child in her arms.

She had been forced out of her marital home by her husband, and made the 13-kilometre (eight-mile) journey back on foot.

"I had pain and I wondered why real life is such a struggle. And I realised, I am in cinema -- that's my tool. I can talk about my pain through cinema."

The father-and-son journey in "Pebbles" is told through the eyes of the child, while Tamil Nadu's harsh rural environment and the toll it takes on his characters is a central theme of the film.

The title comes from a synonym Tamils use for hills -- and the stones country-dwellers put in their mouths to ward off thirst on long journeys.

"To know that this film has won the Tiger Award and is being sent as India's entry to the Oscars, I feel very proud," Vinothraj said.

"Watching this film with an audience that has been so supportive, it feels like a big celebration for me."

His next project is also inspired by a family situation, and he wants to keep making "simple, honest stories about life".