Apple seem to have always disliked free and open codecs. Instead of embracing FLAC, they made ALAC 00 same principle but uses MPEG compatible containers. Initia

Apple seem to have always disliked free and open codecs. Instead of embracing FLAC, they made ALAC 00 same principle but uses MPEG compatible containers. Initially it was a proprietary (closed source) format, but they made it open source after a few years (presumably for support from the community). They never supported Ogg Vorbis, and they don't support it's successor Opus now (except in Safari where is required as part of the WebRTC spec.) Fortunately, being lossless it's safe and easy to convert between FLAC and ALAC (or vice versa). FFmpeg can do it, and also supports Apples "CAF" (Core Audio Format) as an intermediate format if required (e.g piping between different encoders) - that's handy for keeping metadata intact between formats.