He will adapt a controversial book of the same name - an insider account of violence organised by hardcore Bluebirds fans.
The book's authors - and former hooligans - Tony Rivers and David Jones will reportedly reap a five-figure sum from a deal with Trainspotting star Robert Carlyle's production company 4Way Pictures.
 Hooliganism is being glorified by the media yet again and we're not pleased - there is no organised trouble at Cardiff  |
Vince Alm, Cardiff City Supporters Club chair |
But City fans have already leapt on the proposal, fearing it will further hurt their club's reputation for hooliganism and glamorise violence.
Welsh and Carlyle researched the production while at the club's Ninian Park ground in September for a game.
The book adaptation could be perfect material for the writer, whose work tends to chronicle urban male society's dark, violent and druggy underbelly.
"Soul Crew" was the name adopted by travelling Cardiff City supporters in the 1980s and continues to refer to the club's troublesome minority element.
Recently, eight fans were jailed for their part in violence which erupted outside Ninian Park after a crucial play-off defeat in May.
There were also ugly scenes on the pitch following the Bluebirds' FA Cup win over Leeds.
Club chief Sam Hammam has promised to "change the biggest nutters" in the thug element.
'Misrepresenting fans'
Published in March, the Soul Crew book lifted the lid on the small section of hardcore perpetrators whose actions continue to dog the club. It has sold 20,000 copies.
The authors say the film adaptation will offer a true-life portrayal of football violence - just as Trainspotting did for the lives of deprived urban heroin-users.
But Cardiff City Supporters Club is furious at the expected representation of Bluebirds' violence.
City are looking good for Division One promotion and perhaps an even more glittering future with Premiership status.
"Hooliganism is being glorified by the media yet again and we're not pleased," club chair Vince Alm told BBC News Online.
"There is no organised trouble at Cardiff - nothing goes on. The film will misrepresent fans - we're not raving lunatics.
"The book wasn't a brilliant read. If this film comes out, it will sour relations with police forces and we will have to start all over again."
"Thuggery"
He said a tough accord agreed between the club and South Wales Police - as well as further contact with UK police - would be ruined by the continued portrayal of Cardiff fans as violent thugs.
The film would up the ante, encouraging rival hooligan groups around the UK to claim the Soul Crew's scalp at violent meetings, he said.
The film project has been criticised by Cardiff North MP Julie Morgan who said she feared the film "might make legends out of what is basically thuggery".
"My fear is that it would glamorise the Soul Crew and give the story publicity that we do not really want.
"It could cause further problems for Cardiff City and for the image of Cardiff.
But the book's author's have defended their decision to cooperate with the film producers.
Tony Rivers said: "I don't think a film that comes out now or in a couple of years is going to affect Cardiff City or Cardiff."