That depends. Are you looking at preserving the music without loss of information? Then you need to use a lossless format like flac. Formats like aac, mp3, opus can throw away information you’re less likely to hear to achieve better compression ratios. Flac can’t, so it needs more storage space to preserve the exact waveform.

You can use a lossy format if you want. On most consumer level equipment, you probably won’t notice a difference. However, if you start to notice artifacting in songs, you’ll need to go back to the originals to re-rip and encode.

There’s talk on the Linux kernel mailing list. The same person made recent contributions there.

Andrew (and anyone else), please do not take this code right now.

Until the backdooring of upstream xz[1] is fully understood, we should not accept any code from Jia Tan, Lasse Collin, or any other folks associated with tukaani.org. It appears the domain, or at least credentials associated with Jia Tan, have been used to create an obfuscated ssh server backdoor via the xz upstream releases since at least 5.6.0. Without extensive analysis, we should not take any associated code. It may be worth doing some retrospective analysis of past contributions as well…