Pimps, prostitutes and thugs often have big parts in Hollywood movies set in black America, but if Jeff Clanagan succeeds, audiences may soon see a greater number of smart, independent films about mainstream African-American life. Clanagan formed Codeblack Entertainment this year to distribute films like “Preaching to the Choir,” a drama that played at festivals in 2005 and debuts in 150 commercial theaters on Friday. Independent films with mainstream portrayals of urban life most often play at festivals. If lucky, they might be shown in art houses or on a small screen at a megaplex. But for the most part, even independent film backers and distributors have shunned middle-road movies about black America. Bob Tourtellotte reports.