Casey Affleck to chart Phoenix's music career

Casey Affleck is to direct a documentary tracking the musical career of fellow actor and brother-in-law Joaquin Phoenix.

Phoenix announced his plans to retire from Hollywood in October at the age of 34, and is now pursuing a new path as a singer, reportedly teaming up with Sean 'Diddy' Combs to record.

And Affleck is getting behind the camera to track every step of Phoenix's transition from movie star to musician in a forthcoming feature film.

The 'Gone Baby Gone' star will start shooting on Friday, when Phoenix is scheduled to make his first public performance at a Las Vegas club.