Sony Music Group is sending out warnings to what sources say are around 700 AI developers and music streaming services, warning them not to use its content to train AI. These so-called “opt-out” letters, which have been obtained by Variety, state that developers will need explicit permission to use that content and warns that some may already be in violation. “Due to the nature of your operations and published information about your AI systems, we have reason to believe that you and/or your...