Convert FLAC to ALAC

Why FLAC has to become ALAC for Apple

Apple's music software doesn't import FLAC. iTunes for Windows, Apple Music and the iPhone's Music app all pass it over, while they handle Apple Lossless (ALAC) natively. Both formats are lossless and hold identical sound; they differ only in the file around it. ALAC dates from 2004 and has been open source since 2011.

So there is no quality decision to make: an ALAC made from a FLAC is the same music, sample for sample, and converting it back to FLAC later gives you the identical sound again. You can keep both copies, or keep only the ALACs if every device you listen on is an Apple one. Nothing about this conversion is a compromise, which is rare in audio. Windows 10 and 11 play both formats themselves, so on the PC nothing changes; the conversion is purely for Apple's apps and devices.

What comes across

• Tags: title, artist, album and the rest go into the M4A's tags, so iTunes files the songs under the right album and artist, with track and disc numbers keeping multi-disc sets in order.
• Cover art: the picture embedded in each FLAC is copied in, so albums show their covers in iTunes and on the iPhone.
• Bit depth and sample rate: a 16-bit, 44.1 kHz FLAC becomes a 16-bit, 44.1 kHz ALAC; 24-bit, 96 kHz stays 24-bit, 96 kHz.
• Channels: stereo stays stereo, and multichannel files keep their channels.

ALAC files come out about the same size as the FLACs, often slightly larger, since FLAC tends to pack a little tighter. Covers kept only as a separate cover.jpg in the album folder aren't embedded; add those in iTunes if an album shows up blank.

Hi-res files and phone space

A 24-bit, 96 kHz album can approach a gigabyte even as ALAC, because uncompressed it runs to about 35 MB a minute. For listening on a phone you may prefer CD quality: under More settings, set Bit depth to 16-bit and Sample rate to 44.1 kHz. The result is a lossless CD-quality copy, but no longer an exact copy of the hi-res file, so keep the FLACs as your masters. A CD-quality album as ALAC takes roughly 250 to 300 MB, so a 128 GB phone holds a few hundred of them. If space is tighter still, pick M4A with AAC instead: a 256 kbps copy takes about a third of the room, though it is no longer lossless.

Converting only some albums? Drop just those folders. Each folder you drop can hold up to 500 tracks, and four are converted at a time while the rest wait their turn; the summary at the end counts them and adds up the sizes.

Getting them into iTunes or Apple Music

By default, Octoolo writes each ALAC into the album folder of the FLAC it came from. In iTunes, File, Add Folder to Library brings a whole folder in at once; iTunes sorts the songs by their tags, so the folder layout doesn't matter much. To gather everything in one place first, pick A folder I choose… as the place to save instead.

From there, sync the iPhone the way you normally do. If you also want small copies for a car or an old player, make MP3s from the same FLACs: FLAC to MP3. Making them from the FLACs rather than the ALACs gives the same result, since both hold identical sound. For a library of tens of thousands of tracks, work in several rounds; each round's summary says how many files were converted and whether any did not work.