BEIJING, May 21 (Xinhua) -- Jiao Xiang, 31, a true film aficionado, watches movies frame by frame.

Jiao stares at a screen for hours to spot flaws in old films so they can be restored. His waist hurts and head spins after a day's work. But that is the life of a film restorer at the China Film Archive.

Old films decay over the years, leading to blurred images and fuzzy sound. Some even crack into pieces and cannot screen again.

"Preserving the recording medium for history has been a high priority and very meaningful," Jiao said.

China launched a digital restoration project for old films in 2005 to save them and preserve their stories. Six years later, Jiao joined the archive after college graduation.

"There were few professional film restorers in China at that time. Everyone has to start from zero," he said. He was sent to Bologna, Italy to study advanced international restoration techniques in 2016.

Old films are regularly sent to Beijing from Shaanxi Province's Xi'an Film Vault, a huge climate-controlled warehouse designed for careful storage of the delicate materials.

Jiao and his colleagues clean and physically repair the films with chemical reagents, scan them using a telecine machine, and transfer the footage to the archive's central system for digital restoration.

"Through digital technology, scratches, dirt and flickering can be treated first. Then we fix color, lighting and sound changes," he said.

The most difficult project he has taken on was the silent film "The Goddess," starring Ruan Lingyu, a prominent Chinese film star of the 1930s.

"The Goddess," regarded as one of the best films of Chinese cinema's golden age, was severely damaged. It was impossible to erase the mildew stains on the film's surface with chemicals.

Jiao worked hard to scan the film frame by frame, erasing the stains with computer software. He and his colleagues spent around a year reviving the film.

Jiao can restore around 3,000 frames of film footage daily. It takes his 15-member team between two weeks and a month to restore a 90-minute feature film.

"We have to give up recreational activities that other young people enjoy. Our heads are spinning after a day's work," Jiao said. But he doesn't think his work is boring.

"I like watching movies. My job gives me more exposure to classic films," Jiao said.

The restored films will be exhibited at international film festivals or released in rural areas. But most will be stored on tape or uploaded to the archive's digital library.

In 2014, the remastered version of "The Goddess" was released with live music in Britain.

During this year's Beijing International Film Festival, the archive showed two restored classic films, "Yellow Earth" and "The Horse Thief," both masterpieces of China's film industry in the mid-1980s.

China Film Archive has restored more than 2,000 classic Chinese films over the past 10-plus years, including the country's earliest existing feature-length film, "Laborer's Love," produced in 1922.

"Valuable old films are usually damaged due to improper storage. Digital restoration can help them survive and give the public a chance to appreciate them," said Li Tao, director with the archive's business development department.

Li said that the principle they follow in film restoration is the same as for restoring other cultural items: bring it back to a version most faithful to its initial release.

Despite the success, the archive faces obstacles. Li said that there are only a few hundred film restorers in China. The intensive and tiring nature of the work keeps many young engineers away.

Film sourcing is another obstacle. "For example, we are looking for the Tibetan-language version of 'The Horse Thief' by director Tian Zhuangzhuang. But we have failed to find the original copy," he said.

"For the film industry, restoration is an indispensable part of keeping the legend alive," Li said.

Jiao said a good film restorer should love watching movies, have patience, pay attention to details, and understand the significance of the job.

"Films record the development of an era. When future generations want to watch movies of the past, I'm sure they would not want to see that these precious archives have disappeared," he said.