When the James Brown biopic 'Get On Up' arrives in theaters on Aug. 1, it'll do so with the involvement of Brown's family -- and bearing the production stamp of Mick Jagger, who discussed his work on the film, and his relationship with Brown, during a recent interview with Billboard.

"He was always so very nice to me, polite to me, respectful," recalled the Rolling Stones frontman. "Even when I was very young, he didn't treat me like I was a whippersnapper. He always was encouraging to me. I watched him a lot, and I think he inspired me and I learned a lot from him. Not like doing imitations but just learning his general attitudes and the way he worked. I'll always admire him for what he did."

Of course, even those closest to Brown were occasionally subjected to his mercurial temper, and Jagger was no exception -- although they were never exactly at odds. Jagger was the one tasked with mollifying Brown after the latter discovered he hadn't received top billing over the Stones during the 1964 T.A.M.I. Show festival. Brown's legendary 18-minute performance, the show's unquestionable highlight, is dramatized in 'Get On Up,' and Jagger insisted that while the filmmakers had to take "a lot of poetic license" with the facts, the essential vibe remains.

"The true part of it is James was very miffed about not being the top of the bill," he explained. "In real life, they asked me to go and chill him out because I’d already met him and already talked to him. They thought I’d be a good person because they didn't want to do the dirty work. So, they asked me to try and go chill him out, which I did to a certain extent. But, of course, he wanted to show the real thing that we show in the film -- he wanted to go out there and kill, you know. And that probably made for a better performance than normal. He talked about that a lot afterwards and it meant a lot to him. And I think it was probably the first time that his entire show had been put down on film like that. That’s important for you as an artist."

Next up on the biopic front is an Elvis Presley movie, of which Jagger says, "We've got a new script and it’s moving forward. But no actor yet." And as for a dramatization of the Rolling Stones story? He closed the interview with a smirk, coyly responding, "Who knows? Who knows, my dear?"