Three days later, on July 25, 2017, Gurrumul died in Royal Darwin Hospital. Aged only 46, he'd succumbed to organ failure relating to the hepatitis B he'd contracted in childhood. His condition had worsened in recent years, to the extent that Skinnyfish had retired the singer from touring in late 2015. "It was like he was becoming a shadow of his former self," Hohnen recalls. "He was extremely ill." Williams, who had known the singer for years before beginning work on the documentary, seems a little haunted, as if Gurrumul knew his time had come. "It was a strange way to sign off a conversation," he says. "It was really only in retrospect, when we looked back, that we said, 'Maybe that was goodbye.' " The cover of Gurrumul’s eponymous studio album (2008). Credit:Courtesy of ABC Gurrumul is the highest-selling Indigenous musician in Australian history. His eponymous 2008 solo debut album was certified three times platinum in Australia, and made the top 20 in Belgium, Germany and Switzerland upon its European release. His second album, Rrakala (2011), made some small inroads into the American market, a notoriously difficult proposition. His third release, The Gospel Album (2015), cemented what those close to him had known for years – that this unassuming Indigenous Australian, who was born blind and taught himself to play a guitar held upside down, wasn't an angelic-voiced flash in the pan.

Yesterday, a posthumous album was added to his canon. Djarimirri (Child of the Rainbow) has been more than six years in the making and involves the singer, in Hohnen's words, delving "deeper into the cultural elements of his music". Preceding the release of Williams' documentary by two weeks (the film opens on April 25), Djarimirri stands as the singer's final gift to the world, one last reminder that his rise to fame was more than deserved. Gurrumul’s second studio album, Rrakala (2011). Credit:Courtesy of ABC While this rise might have seemed meteoric, Gurrumul paid his dues in a slow build that began with culture-bridging group Yothu Yindi in the late 1980s. He played a number of instruments and contributed backing vocals to four of the band's six albums, most notably its breakthrough 1991 release, Tribal Voice. With Manuel Dhurrkay he also fronted Saltwater Band, the group putting out three records in a decade from 1999. By the time Skinnyfish came to release the eponymous Gurrumul in 2008, a year before Saltwater's final album, the man and his music were match fit. "Gurrumul toured the world before he was Gurrumul," notes hip-hop artist Adam Briggs, with whom Gurrumul collaborated in 2014 on the song The Hunt. To Briggs's mind, Gurrumul's popularity was testament to his hard work, his musicality and his talent. "People forget he was in Yothu Yindi and Saltwater. So by the time he was Gurrumul, he was ready." Legendary American music producer Quincy Jones praised the singer for "one of the most unusual and emotional and musical voices that I've ever heard". It wasn't just Jones – Sting, Elton John and Australian musicians Peter Garrett and Paul Kelly all count themselves among the singer's admirers. In garnering fans like these, Gurrumul sold out venues the world over, won awards and confounded critics with his wide-ranging success.

"He was special in so many ways, in Western and Yolngu worlds," his niece, Miriam Yirrininba Dhurrkay, tells me. "He was writing these songs and the words just came into his mind and heart. Even though he couldn't see the nature, he was born to feel the nature." To see without seeing? "Yeah. He had a special place to see, which was his heart." The Gospel Album (2015). Credit:Courtesy of ABC It was his heart, having battled on through the liver and kidney damage caused by his hepatitis B, that eventually gave out. He was placed on kidney dialysis in mid-2016, but Gurrumul, who'd been admitted to the intensive care unit at Royal Darwin Hospital seven times in the year leading up to his death, had started to refuse treatment. "Dialysis was not something that he enjoyed," Hohnen says. "I believe he chose to not go on dialysis, to not stay on it. And you don't really have any options – it's dialysis or nothing." Djarimirri is essentially, an album that sets ancient Yolngu chants against an orchestral background to make them more palatable to the Western ear. Gurrumul was no stranger to orchestral work, having released a live album in 2013 with the Sydney Symphony. Where Djarimirri is different, though, is in its minimalism; Hohnen cites the likes of Michael Nyman, Steve Reich, Arvo Pärt and Philip Glass as influences.

These Yolngu songs, some thought to be more than 4000 years old, were traditionally backed by the yidaki wind instrument in repetitive rhythms, giving the lyrics a foundation on which to build. The trick with Djarimirri was in replicating this on Western instruments while leaving them recognisable to Yolngu people. "Michael had this concept of combining the more traditional songs and chanting and yidaki patterns, with this kind of contemporary minimalist orchestral tradition," explains Erkki Veltheim, the Melbourne-based composer and violinist who arranged the album. "At first I was trying to figure out how these different traditions could work together, but the more I thought about it, the more it made sense. The very nature of these traditional songs and the yidaki patterns do have a lot of repetition in them, but also a lot of variation within that repetition, which combines really well with the small orchestra." Gurrumul and Michael Hohnen were a close unit, working together beyond the stage as well as on it. Veltheim started by listening to the recordings of songs Gurrumul had already made back on Elcho. From there, the task was to transcribe the yidaki patterns into Western notation.

"[That] was a real challenge, but also a great pleasure to come up with these arrangements," he recalls. "And the most nerve-racking thing for me was whether Gurrumul himself and his family and the other people on Elcho would actually relate to these arrangements. That was the key. The important thing was that, in every step of the process, we've made sure that we haven't done anything that doesn't communicate those songs." The 12 songs that make up Djarimirri all relate to specific totems and aspects of Yolngu culture, including Waak (Crow), Ngarrpiya (Octopus), Gapu (Freshwater), Baru (Saltwater Crocodile), Marrayarr (Flag). All of the songs ended up in major keys, a coincidence which to Hohnen's mind gives it a happy vibe. The cover of Gurrumul's posthumous album, Djarimirri (2018). Credit:Courtesy of ABC But initially, Djarimirri isn't an easy listen. It relies heavily on repetition, and Yolngu songs are traditionally quite short, so Gurrumul's vocal contributions are fleeting. Further listening casts new light on what's happening, though. There's a depth to it all, and the drone of the strings and the popping of horns add their own weight to what is, within each song, a slow-building story. The purity of the singer's voice tops it off. Djarimirri is essentially an exercise in ethnomusicology – the keeping alive of this ancient music, albeit in a more modern fashion, so that those yet to come are able to access it, no matter their cultural background. "Gurrumul had hundreds of songs in his head," says Hohnen. "He wasn't writing a lot of new, contemporary style songs but he probably knew 400 or 500 songs, traditionally."

Completed early in 2017, the album was slated for release in the middle of last year. When Gurrumul died, the record label pressed pause, in part because in Yolngu culture, when a person dies, their name, image and any music or art is retired for some time. "We held it for a year," Hohnen confirms. "It would just not have been right to put it out. Although, spending a lot of time with his family, they said to us, even at his funeral, that no one's stopped listening to his music. They all play it." A note released with the advance stream of Djarimirri addresses these questions. It says, in part, "The family have given permission that, following the final funeral ceremony (which occurred at Galiwin'ku on Elcho Island on November 24 last year), his name and image may once again be used publicly, to ensure that his legacy will continue to inspire both his people and Australians more broadly." Explains Hohnen, "In most situations when an Aboriginal person up here passes away, the name gets changed, and the music and imagery gets stopped," explains Hohnen. "But it's hard when someone's as famous as this. I think it's more that they're really proud. And I think Yolngu don't want him forgotten, that's what they said to us. There's this ownership of him." When we speak, eight months after Gurrumul's death, Hohnen is just pulling himself together after what he describes as a fairly dysfunctional time. "It's affected Mark and I very personally," he says, referring to his Skinnyfish Music co-founder, Mark Grose. "Gurrumul was such a unique and happy person, someone who, no matter how recalcitrant, always made you feel that fun and music and traditional culture were here to be lived and loved."

Gurrumul was Skinnyfish Music's most successful artist and his success enabled the label to expand and focus on other acts like Lonely Boys, Manuel Dhurrkay and Mambali. Royalties from Djarimirri will flow, in part, into the Gurrumul Yunupingu Foundation, which has a vision statement that speaks of creating "greater opportunities for remote Indigenous young people to realise their full potential and contribute to culturally vibrant and sustainable communities". It's not lost on anyone involved with the making of the record how sad it is that its main player won't be here to enjoy its launch. "We wanted to release the album while he was alive so he could live it out on the airwaves around his community and further afield," says Hohnen. "But I now feel like we did everything possible to live up to the standards that he and his family expected of us. The recording is as much a representation of all Yolngu." Djarimirri is primarily about legacy. "There are different ways people can go about activism," Hohnen continues. "There's anger, abuse, there's hurt, there are quite sinister ways, destructive ways. The journey that we took with him was almost the opposite. And, for me, his legacy was opening people's hearts to one of the greatest assets of this country." Briggs, who became friends with Gurrumul after their 2014 collaboration, agrees. "This last record is testament to him transcending genre and transcending what's expected of an Indigenous artist," he says. "This album is an orchestral piece, so it's sheet music. It could be read by a conductor or composer in Germany and they'd understand it.

"It transcends cultural barriers, because music is an international language. Anyone will be able to read this, and translate it, and play it. Even in his death, he's transcended genres and cultural barriers. Him and Michael, they've delivered this gift of music." His niece, Miriam Yirrininba Dhurrkay, says Gurrumul's life and music are still inspiring Yolngu people. "A lot of youngsters in the north-east Arnhem Land region, where G comes from, and other youngsters from all around NT, from every Aboriginal community, a lot of youngsters are doing music today. Most of the young people I know, they want to continue his legacy, they want to show the world that they can do it. If he can do it, why can't we do it, you know?" To read more from Good Weekend magazine, visit our page at The Sydney Morning Herald or The Age.