For remixes, mashups & collaborative work, copyright is impossible. Authors/publishers don't recognize co-creations and new artists risk legal action.
Managing copyright is a challenge in the digital world, as there is not a perfect solution for emerging artists who rely on existing works and therefore can never claim the opera as original and get rewards.
There continues to be a problematic identification process of who retains authorship, and copyright, surrounding music and digital media that deploys the use of existing works.
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