Another aspect is non-copyright mp3s, ones freely available to download and share from various websites. Many of my mp3's are these, Also many are my own recordings from the radio, from my vinyl collection, and even from old cassettes! Mp3 is not so much a pirating medium, but a superb archiving/ storage format that is incredibly convenient. Many of the mp3s on my machine are tracks that i composed myself.
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Sussex, UK. Rio car 30Gb and Neo35