New Bell, a famous prison in Douala, Cameroon, is a city within a city.

The facility has its own “taxis” (inmates who walk through congested yards to hand-deliver messages), its own law enforcement (burly prisoners who help uptight guards keep an eye on the facility), and market (a series of stalls where convicts sell and buy delicacies such as fried yucca and beignet pastries).

Basically, the occupants of New Bell have adapted the lax prison laws to work for them. The clearest example of this spirit is Jail Time Records, a music studio and record label that turns the most talented prisoners into mini stars.

Empereur, the feared gang leader in and out of prison, has racked up 24,000 views on YouTube with a music video filmed entirely in prison.

Inmate songs have gained fans as far away as South Africa, the United States and Argentina, while earlier this year Jail Time Records hosted a large concert for inmates in the New Bell yard.

“It’s this instrument of resistance… where we can really share friendship, love and our voices can be heard,” Steve Happi, the former inmate who co-founded Jail Time Records, tells the BBC’s Talking Movies programme.

“We no longer think about the four walls: we find freedom.”

The Jail Time Records studio is rudimentary: a small, sweaty recording booth attached to a room inhabited by a lone computer.

But it is also a place of great catharsis and creativity, according to a recent acclaimed documentary that bears the studio’s name.

Directed by Happi and Italian artist Dione Roach, his co-founder of Jail Time Records, it was filmed in New Bell over six years.

Last month it won three awards, including best documentary feature, at the Tribeca film festival in New York.

In the film, a prisoner named Stone pounds the studio microphone: “Heart of stone, it’s war. My senses shatter like broken glass.

“I am closed and tight like a cell door. Without solid ground I slip like a fish.”