Media playback is unsupported on your device Media caption Get to know the artists on the Sound of 2017 longlist

The rude health of British hip-hop is reflected in the BBC's Sound of 2017 line-up, with urban artists making up half of this year's longlist.

Building on the success of grime acts Stormzy, Kano and Skepta - who won this year's Mercury Prize - newcomers like Ray Blk and Nadia Rose are being tipped for success in the BBC's annual list.

Soul singer Rag N Bone Man and rock provocateurs Cabbage also make the cut.

The list was compiled using tips from a panel of 170 DJs, critics and writers.

It aims to highlight 15 of the most promising rising musical acts for the coming year. Previous winners include Adele, 50 Cent, Ellie Goulding and Sam Smith.

Image copyright Handout Image caption Catford-based singer and rapper Ray BLK has been dubbed 'the Lauryn Hill of the UK'

Many of this year's nominees have garnered attention by working outside the traditional music industry.

Classically trained rapper Dave racked up more than two million YouTube plays for his self-released single Wanna Know, which was championed, and later remixed, by hip-hop star Drake.

"I had labels playing deal or no deal like I'm Noel Edmonds," the 18-year-old rapped on the single People Know. But he stuck to his guns and released his current EP, Six Paths, on his own label.

Soul singer Jorja Smith is similarly self-sustaining, filming videos at her aunt's house and creating her own artwork.

The longlist also highlights a resurgence in political songwriting, thanks to artists like Declan McKenna, whose recent single Isombard lampoons right-wing US news network Fox News.

The 17-year-old from Hertfordshire previously took aim at Fifa on the song Brazil, which laments the destruction of thousands of homes in preparation for the 2016 World Cup.

Post-punk quartet Cabbage have written songs about Kim Jong Un and Donald Trump, while displaying a streak of dark humour that echoes fellow Mancunian John Cooper Clarke.

Image copyright Reuters

Previous BBC Sound Of... winners

2016 - Jack Garratt

2015 - Years and Years

2014 - Sam Smith

2013 - Haim

2012 - Michael Kiwanuka

2011 - Jessie J

2010 - Ellie Goulding (pictured)

2009 - Little Boots

2008 - Adele

2007 - Mika

2006 - Corinne Bailey Rae

2005 - The Bravery

2004 - Keane

2003 - 50 Cent

International artists on the list include hotly-tipped rapper Anderson .Paak, who shot to fame after featuring on Dr Dre's Compton soundtrack last year; and Maggie Rogers, who left Pharrell Williams speechless earlier this year.

The star producer was asked to critique one of her songs during a masterclass at NYU's Clive Davis Institute. But as the song progressed, the stunned look on his face gave way to quiet awe.

"Wow," he said. "I have zero notes."

A video of their encounter went viral; with the song, Alaska, streamed more than 21 million times. Rogers has since signed a deal with Polydor Records.

Image copyright I Am Other / YouTube Image caption Pharrell Williams was taken aback by Maggie Rogers' blend of folk and dance music

Gravel-voiced singer Rag N Bone Man hails from Brighton and sounds like a modern-day Joe Cocker. He may already be familiar to viewers of Later... With Jools Holland after performing a stunning acoustic version of his single Human in September.

The song is already a major hit outside the UK and is currently spending its ninth week at the top of the German singles chart.

Other acts on the longlist include grime artist AJ Tracey, pop singer Raye and straight-talking MC Stefflon Don.

There are also spots for electro-pop enigma The Japanese House, Reading-based rock band The Amazons and singer-songwriter Tom Grennan, who recently appeared on the Chase & Status single When It All Goes Wrong.

Last year's winner, Jack Garratt, praised the "very diverse" shortlist, and encouraged fans to embrace new talent.

"There's more music out there than just your favourite act," he said. "It all deserves respect and it all deserves love.

"Even though there are 15 names on the longlist, there are hundreds more that definitely could have been. I think 2017 is going to be a very interesting year."

Image caption Sound of 2016 winner Jack Garratt has a top three hit with his debut album Phase

The Sound of... list launched in 2003 and has a track record in championing new and innovative acts, many of whom have gone on to achieve global success.

According to the rules, the acts should not already be well known to the UK general public - which excludes X Factor contestants and band members pursuing a solo career.

They must not have had a top 20 single or album before 30 October 2016 - although guest vocalists remain eligible.

The 15-act longlist will be whittled down to five in the new year, with the winner announced on 6 January.

Radio 1 DJ Mistajam said the Sound of 2017 showed that the next 12 months would be "filled with amazing music from homegrown talent".

He said: "From the driving rock of The Amazons to Dave's 18-year-old inner city street tales. The list shows the breadth and quality of what we can all expect next year."

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