DRM Software for Music Site - Digital Rights Management Software

I am launching a music site and interested in implementing DRM (digital rights management) for the media files. Users will be able to stream music and then buy it if they wanted to. I want the content owner (musician who wrote the music/video) to have the option to select whether they want DRM applied to their media. I will want to host the DRM licenses on my server and perform authentication. I currently use [login to view URL] as my content delivery network of my media and [login to view URL] for my processing. I want a DRM solution that will integrate everything together. DRM will only be applied music by the major record companies (sony bmg, universal, emi, warner). Independent artists will not be required to use DRM. My server is Unix / MySQL. Programming language of site is php.