I often get emails asking how to play FLAC (Free Lossless Audio Codec) files in iTunes. Users are surprised that Apple doesn’t support FLAC files, and generally rant against Apple not supporting open source formats. There’s no conspiracy or lock-in here; there’s a very logical reason why Apple, and iTunes, don’t support FLAC.
First, a quick overview of lossless audio files. These are files that use data compression to shrink the size of audio files, the same way zip compression makes an image much smaller than its original size. On average, lossless files – in FLAC or Apple Lossless format – are about half the size of the original, uncompressed music on CDs. (See this article for some examples of Apple Lossless compression results.)
Apple Lossless is Apple’s home-brewed lossless codec. Introduced in 2004, Apple Lossless – sometimes called ALAC – provides the same bit-for-bit quality as FLAC, and is supported by iTunes and iOS devices. In October, 2011, Apple let the Apple Lossless format go open source, so anyone can use it in hardware or software. (Note that Apple Lossless files look, in the Finder or Windows Explorer, exactly like AAC files, because they use an .mp4 container, and have the same file extension.)
Supporting FLAC in iTunes and on iOS devices could be a legal nightmare for Apple. Many open source software algorithms can be targets of patent trolls. While no one cares much about FLAC use in small apps and hardware devices, were a big company such as Apple – or Microsoft, who doesn’t support FLAC either – to start supporting that format, it’s very likely that someone would dredge up a patent and seek copious damages.
So, if you want to play FLAC files in iTunes, you need to convert them to Apple Lossless. Don’t convert to uncompressed AIFF or WAV, as they’ll take up about twice as much space. The free app XLD can convert to and from any lossless format with no loss of quality; use this tool to turn your FLACs into Apple Lossless files.
Note that Apple Lossless also supports high-resolution audio, up to 24-bit, 192 kHz sample rate. (See How To: Listen to High-Resolution Audio Files on a Mac.) The highest I have are 24/96 files:
I can’t see Apple ever supporting FLAC files in iTunes; it’s too risky. Apple created their own lossless format for this reason. It provides the same quality, supports high-resolution audio, and is compatible with iTunes and iOS devices.
Note: A commenter on the Guardian website, which linked to this article, suggested that this theory makes no sense, because Android – developed by Google – supports FLAC, and they’re a big target. I’m not sure that’s an issue. Android is technically – for the most part – open source, and is certainly using open source FLAC libraries. I don’t know what the legal status of that usage would be, but I’m sure it wouldn’t be as clear as a closed-source app like iTunes, or Windows Media Player, supporting FLAC.
Update, January, 2015: Microsoft has announced that Windows 10 will support FLAC on the desktop, and on mobile devices. It will be interesting to see what happens with this.