An award-winning film that tells the story of China's "left-behind children" is expected to bring attention to the social dilemma.

Promise, a 16-minute film by two Los Angeles-based film producers, tells the moving story of a Chinese boy who has to choose between his best friend - a pig - and his gift for his parents - a decent dinner.

The film won the Crystal Bear Award for the best short film at the Berlin International Film Festival last month.

"I took inspiration from my own hometown in Shandong province, where we visited many families and schools and learned about the stories first hand," said Xie Tian, director of the film.

"Though the story takes place in a rural Chinese village, it tells a universal story reflecting the relations between children and parents. It can naturally resonate with international audiences," said Xie, an independent film producer.

He said it took him half a year to write the story, and the team spent more than 10 days in Taohuadao village in Yunnan province to shoot the film. It took them another three months of post production.

The film, made a cost of $5,000 raised by the team, cast local villagers as actors, including the boy, his parents and a mailman.

"We hadn't expected the film to win any award or have any influence," said Xie. "But after the Berlin International Film Festival, we hope more attention, including international attention, can be put on these 'left-behind children' in China."

The so-called "left-behind children" live in China's rural areas without day-to-day care from their parents, who have sought work in the coastal cities as migrant workers.

The 2016 migrant population survey by the National Health and Family Planning Commission found 61 million children left behind in the countryside - more than a third of those were younger than 17. Most of them see their parents no more than once a year.

The children have made headlines that shocked the entire nation. In 2015, four left-behind children from the same family committed suicide together by taking a pesticide in Guizhou province. In 2012, five boys died of carbon monoxide poisoning after starting a fire trying to stay warm inside a dumpster.

"Promise also is a tragedy," said Xia Liang, the film's editor. "The boy's parents promise to come back for the New Year, and the boy has to sell his 'best friend' to prepare a decent dinner for his parents, only to find the promise is not fulfilled."

To enhance the emotions, Xia said he decided a gloomy tone with higher contrast for the entire film.

Xia said they spent a week deciding how the film should end.

In the last sequence - the climax of the film - the boy receives a letter from his mom realizing that his parents will not come back to him. The film ends suddenly with a close-up of the boy's face when he raises his head from the letter and turns back to the dinner.

"It ends with anger and disappointment in the boy's face. It's the last blow and also the climax of emotions," said Xia.

liazhu@chinadailyusa.com