Ice-T dug deep into his rolodex to bring out all-stars while filming his new documentary, "Something From Nothing: The Art of Rap." The film, which opened in theaters Friday, includes appearances from legends like KRS-One and Melle Mel, to current powerhouses like Dr. Dre and his protégé Eminem.

During his recent visit to "RapFix Live," Ice-T discussed the process of putting the film together, explaining that Dr. Dre and Eminem both made important contributions to the finished product. Ice caught up with Dr. Dre at his California home for an important chat about hip-hop's past and present, during which he broke down the difference between writing regular rhymes and being able to craft a song, while detailing his memories of recording with Tupac.

"[Dre] said there's a difference between a rapper and a songwriter," Ice-T explained of his conversation with the legendary West Coast producer. "Dre says, 'You've gotta write me a song. I don't need bars — I know you've got skills, but we need songs, so give me the hook first.' He says a lot of rappers get lost, but that's what Eminem does. They write these incredible songs, and that's basically what Dre likes to take to the marketplace."

In the documentary, Ice-T also links up with Eminem in the studio, where the Detroit native explains that being a white rapper forced him to work harder to prove himself. During the conversation, Eminem broke down his method of writing rhymes, but it's hard to say that the explanation really clarified things. Of the Shady Records CEO's explanation of his complicated rhyme scheme, Ice said, "It was like you were listening to a scientist."

Learn how more of hip-hop's greatest MCs craft their rhymes in Ice-T's informative documentary, "Something From Nothing: The Art of Rap," in theaters now.