Image copyright Getty Images Image caption L-R: Daniel Roher, Robbie Robertson, and exec producers Brian Grazer and Ron Howard

The Toronto International Film Festival is officially under way, with documentary film Once Were Brothers kicking off proceedings.

The Canadian movie follows the career of Robbie Robertson and the creation of the roots-rock group The Band.

At 26 years old, its director Daniel Roher is one of the youngest ever to have been selected to open TIFF.

Robertson told reporters on Thursday he had a "gut feeling" Roher was the right person to direct, despite his age.

"In so many creative endeavours, you think 'this is taking a shot, taking a risk', but something tells you, 'go forward'... It's quite mysterious in a way, what trust you can have," he said.

Image caption Toronto mayor John Tory presented Robertson with the prestigious Key to the City

"And I said to him, by the way, how old are you? And he said 24 [Roher's age when production began], and I was 24 when I made Music From Big Pink with the band, and it just rang a bell, and I thought, let's give it a shot."

Robertson served as both lead guitarist and primary songwriter of The Band, who had a string of hits across the 1960s and 70s. He was born in Toronto, making it a fitting film to open the festival.

At Thursday's news conference, Mayor John Tory presented Robertson with a Key to the City, a prestigious award that honours outstanding civic contributions of its Torontonian recipients.

How prestigious is opening Toronto?

There's no doubt that it's an honour to open TIFF, but the opening film is generally of less significance than the winner of the People's Choice Award, which comes at the end of the festival.

While the audience prize winner is a better indicator of success later in the awards season (Green Book went on to win the Oscar for best picture after its triumph at TIFF last year), the opening film can often be a little more obscure.

"In one way, Once Were Brothers is an odd choice to serve as the opening-night film at the 2019 Toronto International Film Festival," wrote Steve Pond in The Wrap. in one of the movie's first reviews.

"At a festival chock-full of major awards contenders with big movie stars, it's a documentary about a musician whose music is mostly heard on the occasional oldies station or Americana Spotify channel, by a director with only one previous feature on his resume."

Image copyright TIFF Image caption Once Were Brothers follows the career of The Band

So is Once Were Brothers any good? Well, if you're a fan of The Band and have followed the career of Robbie Robertson, the answer is absolutely yes.

But, unless you're particularly keen on beards and black-and-white photos, there's arguably less on offer here for the casual viewer.

"Beyond TIFF, where the opening-night audience members of a certain age will eagerly soak up all those late '60s/early '70s vibes, the market would seem to be less assured," suggested Michael Rechtshaffen in The Hollywood Reporter.

It was announced at the press conference, however, that the film had already secured an international release thanks to distributor Magnolia Pictures.

'Self-mythologising'

Successful music documentaries in recent years include Searching For Sugar Man, the story of how US musician Sixto Rodriguez became extremely famous in South Africa without him knowing, and 20 Feet From Stardom, which told the stories of backing singers in the music industry.

But unlike those films, which had more mainstream appeal, Once Were Brothers ideally requires a background knowledge of The Band's work to be fully appreciated.

The first reviews of the film have been broadly positive - but many critics have highlighted the self-indulgent nature of the film and a lack of journalistic rigour - a result of the chosen contributors.

Writing in IndieWire, Kate Erbland said: "Without a more well-rounded selection of voices (everyone onscreen agrees Robertson is a genius, a visionary, the undisputed leader of the group even decades on) or a more critical-minded director to give the film perspective, Robertson is free to obscure the bigger questions and deeper meanings, opting for self-mythologising over self-reflection."

Part of this is due to Robertson being one of two surviving members of the five-piece. The other, Garth Hudson, features far less in the documentary than Robertson.

"Director Daniel Roher's job here is to faithfully represent his subject and gather the voices who confirm his recollections - and to put some amazing vintage black-and-white photographs on screen," said Variety's Chris Willman.

Speaking at the press conference, director Roher praised the executive producers on the film, including veteran directors Martin Scorcese and Ron Howard, for their support in making it.

"What was unique about this project is that it was a very archive heavy documentary," said director Roher. "I have this legendary team surrounding me, and I really only felt empowered.

"Editorially I had a pretty clear sense of what I wanted this film to look like. [Robertson's] memoir reads like a piece of cinema and I wanted to tap into that."

Speaking about opening the festival, he added: "TIFF is the biggest event in Canadian cinema... I never dreamed this was possible. A Canadian documentary has never opened TIFF before."

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