Ke, who has worked in Beijing and Shanghai, says before filming, he had not listened to Su's music much but was taken by Su's interactions with the folk artists through music.

"The shooting opened a new vision for me to review myself and my life. Young people leave their hometowns to seek a better life in bigger cities. It's sad to see old arts dying," Ke says. "I hope the audience will think about their hometowns (when they watch the film)."

The documentary is part of the Yellow River Runs Forth project, which Su launched in 2016 with the aim of showcasing the sounds and visual material he has gathered over the past two decades in Northwest China. He also created paintings during his visits, which he uses as multimedia material during his concerts.

Su says he wants the audience to watch the documentary and learn more about the people and art traditions of the region. Making money from it is not his goal, he adds.

Contact the writer at chennan@chinadaily.com.cn