Hello, I am putting together an album of opera arias and I am currently negotiating with three different karaoke companies to license some of their karaoke backing tracks for these arias. Because all of the operas I am considering are in the public domain (had to exclude Turandot, sadly) I don't believe I need to obtain a mechanical license. Is this correct? Thus, I am only negotiating with the companies for a master use license. I have no experience with licensing music, so I'm not sure what a master use license contract should stipulate. So far, two are charging a flat fee per song, and one charges a flat fee per 15 seconds of recorded music in each song. Two are saying the license is good indefinitely (this means forever, right?) and one gave me a very cryptic response: "license is valid for three years renewable, plus two years of sell off"...I have no idea what this means. I haven't seen any formal contracts from any of them yet, so I just want to know what to expect and what some of the pitfalls are. In particular, should the contract specify that I am protected if the company has lied about being the true owner of the tracks? Thanks in advance!