FLAC, ALAC, WAV - Does The Container Actually Matter?
· by Kjell
Every few months someone asks me which lossless format they should rip their CDs into. FLAC, ALAC, or WAV. For the audio, it does not matter. All three decode to bit-identical samples. A FLAC of a track sounds exactly like the ALAC of that track, which sounds exactly like the WAV. The container wraps the same numbers. What differs is everything around the samples.
FLAC is the open format. Free Lossless Audio Codec, created in 2001, maintained by Xiph. It compresses audio losslessly to roughly half the size of raw PCM at a speed modern CPUs do not notice. Its tagging system, Vorbis Comments, is flexible, supports arbitrary fields, and has a mature ecosystem of tools. Nearly every serious audio app on every platform reads FLAC. The historical exception was Apple, which only added native FLAC support in 2021.
ALAC is Apple's answer. Apple Lossless Audio Codec, originally proprietary, opened up in 2011. Compression sits in the same ballpark as FLAC, slightly less efficient in practice but close. Its tags live inside the MP4 container, which is less flexible than Vorbis Comments but more than enough for album, artist, track, and composer. If you are on a Mac, ALAC's real advantage is native compatibility across the Apple ecosystem. Music.app, AirPlay devices, HomePods, iPhone sync - all of it understands ALAC without a second thought.
WAV is the outlier. It is uncompressed, so files are roughly twice the size of FLAC or ALAC. Its metadata support is famously poor. The official WAV spec has an INFO chunk that almost no software respects consistently, and various tools write ID3 tags into WAV in non-standard ways. If you rip a large library to WAV, you will fight your tags for years. Its only real case is as a working format during audio editing, where compression overhead actually matters.
For a local library on macOS, either FLAC or ALAC is fine. I lean FLAC because I want the tagging flexibility and the cross-platform reach. If you live entirely inside the Apple ecosystem, ALAC makes peace with that world more easily. WAV, for a library, is a mistake you only have to make once.