Lossy audio compression
Lossy audio compression refers to a process where audio signals are first stripped down and then compressed. The compressed data can be decompressed to something which can sound fine but isn't a 1:1 copy of the original. MP3, Vorbis and Opus are typical examples of lossy compressed audio files. In contrast, there's lossless audio compression. This is preferable. Lossless audio formats like FLAC and APE can be decompressed to an exact 1:1 copy of the original.
There seems to be a lot of misconceptions in the music community regarding the differences between 320kbps mp3 and FLAC format. It is true that 320kbps is technically as good as FLAC when it comes to audible quality, but there are other reasons to get music in a lossless format. Most importantly, you can convert a FLAC to any lossy fad format of the day. MP3 was the go-to lossy format, then it was AAC, who knows what's next. Converting MP3 to AAC will degrade sound quality because it is a conversion from one lossy format to another. FLAC to AAC will, on the other hand, result in a AAC file that only lost what the conversion to AAC threw away. But there's more.
Hearing the difference now isn’t the reason to encode to FLAC. FLAC uses lossless compression, while MP3 is ‘lossy’. What this means is that for each year the MP3 sits on your hard drive, it will lose roughly 12kbps, assuming you have SATA – it’s about 15kbps on IDE, but only 7kbps on SCSI, due to rotational velocidensity. You don’t want to know how much worse it is on CD-ROM or other optical media.
I started collecting MP3s in about 2001, and if I try to play any of the tracks I downloaded back then, even the stuff I grabbed at 320kbps, they just sound like crap. The bass is terrible, the midrange…well don’t get me started. Some of those albums have degraded down to 32 or even 16kbps. FLAC rips from the same period still sound great, even if they weren’t stored correctly, in a cool, dry place. Seriously, stick to FLAC, you may not be able to hear the difference now, but in a year or two, you’ll be glad you did.