Wang Xiaoshuai's latest film charts the lives of two parents who struggle to overcome the sorrow of losing their only child through decades of change in China.

When director Wang Xiaoshuai was shooting his latest film So Long, My Son in the Inner Mongolia autonomous region, there was a moment during one scene when he couldn't hold back his tears as he sat behind the monitor.

The scene depicted an elderly couple who were sweeping their son's tomb many years after an accident caused the death of their only child.

The actors - with Wang Jingchun starring as the father and Yong Mei playing the mother - not only touched their director with their acting, but also won over the jury at the 69th Berlin International Film Festival earlier this year.

As an original story written by Wang Xiaoshuai and scriptwriter A Mei, the film scooped two Silver Bear awards for best actor and best actress, respectively, setting a record for a Chinese-language film by taking home the two main prizes at the festival.

In the past, only a handful of Chinese actors have won the Berlin festival's top awards. Two best actress awards went to Maggie Cheung for Center Stage in 1992 and Josephine Siao for Summer Snow in 1995; while Liao Fan won a best actor award for his role in Black Coal, Thin Ice in 2014.

"The awards went far beyond our expectations and are quite unprecedented," says auteur Wang Xiaoshuai, whose last Berlin-awarded directorial feature is In Love We Trust, which won him a Silver Bear for best script in 2008.

"They are such excellent actors that they seemingly didn't perform, but really inhabited the story of the film and endured the characters' sufferings in their battle against fate," adds the director.