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Music apps and sorting music
(slrpnk.net)
F-Droid is an installable catalogue of FOSS (Free and Open Source Software) applications for the Android platform. The client makes it easy to browse, install, and keep track of updates on your device.
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I keep both on my pc (or external drive), but because .flac files are about 6 times bigger than .opus, I only copy the .opus files to my phone (not enough space for .flac).