Organizers of Denver's annual April 20 marijuana festival on Wednesday announced that rapper B.o.B and singer Wyclef Jean will headline the event as they try to draw a big post-legalization crowd and shake the memory of last year's event, which was marred by a still-unsolved shooting, CBS News reported.

Reflecting the changes in Colorado since voters legalized the recreational use of the drug in 2012, organizers are trying to make the event less of an ad hoc political rally and more of an organized festival, according to CBS.

Organizers have hired a professional event management firm and are fencing the perimeter of the park in front of the state capitol where the event occurs, relying on private security to screen entrants and are announcing acts ahead of time rather than handing over the mic to musicians who happen by, CBS reported.

They're also still smarting from a tussle with City Hall over whether they can officially condone smoking pot at the event because public consumption of marijuana remains illegal in Colorado, and are trying to make the once countercultural event part of the state's mainstream, according to CBS.

"People should feel a sense of belonging," organizer Miguel Lopez said, CBS reported.

The event's uneasy position in Colorado was underscored last year, when three people were wounded in what police described as a shooting between rival gangs while rapper Lil' Flip performed for tens of thousands of spectators, according to CBS.

Organizers have said the shooting is out of character for the peaceful event and have vowed to maintain safety this year, CBS reported. They also blame police for being too preoccupied with trying to stop people from smoking pot publicly to intervene.

Public pot smoking remains an issue and organizers sought a more formal permit from City Hall this year that requires them to purchase insurance and provide port-a-potties but also said they wanted to formally encourage people to smoke up, according to CBS.

After the city warned it could not issue a permit for such an event, the festival backed down and now must formally discourage public smoking, CBS reported.

Lopez compared the public pot smoking ban to "cancer-causing tobacco that's used in the park, or hard alcohol that's consumed in other festivals," according to CBS.

The festival will run over two days, April 19 and April 20 with performances from Wyclef Jean, previously of The Fugees, headlining the first day, CBS reported.

Atlanta-based B.o.B will headline the second, the traditional marijuana holiday of 4/20, which also happens to be Easter Sunday, according to CBS. Lopez said there will still be a political edge to the festival, noting that marijuana remains illegal under federal law and racial disparities in incarceration linger from the drug war.