How to Convert M4A to AIFF

AIFF is an uncompressed audio format that Apple software, digital audio workstations and many samplers open directly. Converting an M4A file to AIFF is useful when an editor or device rejects M4A. The conversion creates a new, larger file. It does not improve the sound of the original.

Before you start

Find out which codec your M4A file contains, because it decides what you can expect. M4A is a container that usually holds either AAC, which is lossy, or Apple Lossless (ALAC). Converting ALAC to AIFF keeps the audio exactly as it was. Converting AAC to AIFF keeps any compression artifacts that are already in the file, so the result sounds the same as the source, just in a bigger file. In the Music app or iTunes, Get Info on the track shows the kind of file. If FFmpeg is installed, running ffprobe on the file lists the codec, sample rate and bit depth.

• Free disk space: 16-bit, 44.1 kHz stereo AIFF needs about 10.6 MB per minute of audio, and 24-bit files need more.
• A backup or untouched copy of the original M4A files. All the methods below write a new file, but keeping the source lets you redo the conversion with different settings.
• Unprotected files. Older store purchases with copy protection, usually with the .m4p extension, cannot be converted with these tools.
• A decision about where the processing happens. The Music app, iTunes, FFmpeg, afconvert and Audacity convert files on your own computer. Online converters upload your audio to someone else's server, so read that service's file retention and privacy terms before you use one.

Step-by-step instructions

Music app on Mac or iTunes on Windows

• 1. Open the import settings. On a Mac, go to Music > Settings (Preferences on older macOS versions) > Files > Import Settings. In iTunes for Windows, go to Edit > Preferences > General > Import Settings.
• 2. Set Import Using to AIFF Encoder and click OK. Write down the previous setting first so you can restore it later.
• 3. In your library, select the tracks you want to convert. Tracks that are stored only in the cloud must be downloaded first.
• 4. Choose File > Convert > Create AIFF Version. A new AIFF copy appears next to each original in the library.
• 5. Return Import Using to its previous setting so future CD imports and conversions are not silently saved as AIFF.

FFmpeg on Windows, macOS or Linux

FFmpeg is a free command-line tool. The basic command is: ffmpeg -i input.m4a output.aiff. By default this writes 16-bit PCM. If the source is a 24-bit ALAC file, keep the full resolution with: ffmpeg -i input.m4a -c:a pcm_s24be output.aiff. Leave the sample rate unchanged unless the target software requires a specific rate. If it does, add an option such as -ar 48000. To write the source tags into the AIFF file, add -write_id3v2 1 before the output file name.

To convert every M4A file in a folder on macOS or Linux, run this from that folder: for f in *.m4a; do ffmpeg -i "$f" "${f%.m4a}.aiff"; done. The originals are left in place.

afconvert on macOS

macOS includes afconvert in Terminal, so nothing needs to be installed. Run: afconvert -f AIFF -d BEI16 input.m4a output.aiff. Use BEI24 instead of BEI16 to write 24-bit samples.

Audacity

Audacity needs its FFmpeg import library to open M4A files. Open the file, apply no effects, and use File > Export (called Export Audio in newer versions). Choose AIFF as the format and pick signed 16-bit or 24-bit PCM as the encoding, matching the source. Check that the export sample rate matches the original. Audacity decodes and re-renders the audio, so any edit or gain change you make before exporting ends up in the AIFF file.

Check the output

• Open the AIFF file in the application that needs it, not only in a media player.
• Compare the duration with the original M4A. The two should match.
• Inspect the file properties. Running ffprobe on the output should report a PCM codec such as pcm_s16be or pcm_s24be, with the intended sample rate and channel count.
• Expect a much larger file than the M4A. A size close to the M4A size suggests that something other than plain AIFF was written.
• Listen to the beginning and the end of the file, where truncation or clicks are easiest to spot.
• Check that the title, artist and artwork came through if you rely on them. Tag support in AIFF differs between applications.

Common problems and next steps

Create AIFF Version is missing from the Convert menu: the import encoder is still set to something else. Change Import Using to AIFF Encoder and try again. If the command is unavailable for certain tracks, those tracks are either cloud-only or protected.

The converted file has no tags in another app: some programs do not read the tag chunk in AIFF files. With FFmpeg, add -write_id3v2 1 to the command. Otherwise, keep the original M4A as the reference for metadata.

The AIFF sounds no better than the M4A: this is expected when the source is AAC. To get better quality, you need a lossless or higher-quality original.

The file is too large to store or share: AIFF is uncompressed by design. If the destination accepts it, Apple Lossless in M4A keeps the same audio quality at a smaller size.

The target app reports an unsupported format: check whether it expects AIFF or AIFF-C, and whether it needs a specific sample rate or bit depth. Then convert again from the original M4A with those settings, rather than converting the AIFF file a second time.