Convert WAV to M4A

AAC or Apple Lossless?

Both end in .m4a, and both play in iTunes, Apple Music and on iPhones, which is why the extension alone doesn't tell you which is inside. Octoolo's file list does: each row names the codec, AAC or ALAC. If you're unsure which to make, ask whether the M4A has to replace the WAV. If it does, choose Apple Lossless; if it's a copy for listening or sending, AAC. Apple Lossless files are a little bigger than FLAC would be, but unlike FLAC they go straight into iTunes and Apple Music.

Where these M4As go

• Recordings to share. A recording from Octoolo's voice recorder is a mono WAV; as AAC at Small it drops to 64 kbps, 0.5 MB per minute, and plays on any phone.
• Music for an iPhone or iTunes library, where AAC at 256 kbps saves space and Apple Lossless keeps CD quality or better.
• Mixes and demos for Apple users, who can open an M4A anywhere they'd open an MP3.

A three-minute song as a 256 kbps M4A is under 6 MB, against about 32 MB as a CD-quality WAV, small enough to send in most chat apps. For people on other systems, MP3 is still the safer choice; WAV to MP3 works the same way in the same window. A podcast host or upload form may take M4A as well, so check its list of formats before converting a season of episodes. M4As meant for an iPhone go in through iTunes with File, Add Folder to Library, and then sync like any other song.

Settings worth knowing

AAC can't go above 48 kHz, so hi-res WAVs (88.2 kHz and up) become 48 kHz AAC files, while Apple Lossless keeps whatever sample rate the WAV has. Mono WAVs stay mono, and AAC gives them half the stereo rate (128, 96 or 64 kbps), which is plenty for one channel. The Sample rate choice under More settings works for both codecs, if a device or app asks for 44.1 or 48 kHz specifically.

For Apple Lossless, bit depth follows the WAV, so a 24-bit recording comes out 24-bit and a 16-bit one 16-bit. Under More settings you can choose 16-bit to save space on a phone, at the cost of an exact copy. Any tags the WAV carries come across into the M4A; WAVs rarely have a cover picture, but you can add one in iTunes afterward.

Should you keep the WAVs?

If you chose AAC, yes: it is lossy, and the WAV remains your full-quality master. If you chose Apple Lossless, the M4A holds exactly the same sound, so you could archive the M4As instead and convert back to WAV whenever an editor needs it, with nothing lost; see M4A to WAV.

Either way, Octoolo leaves the WAVs where they are. Each M4A is a new file under the same name, numbered “(2)” if the name is already in use, so nothing is ever written over, and you can decide about the originals once you've checked the results. If a WAV is your only copy of a recording, keep it at least until you've played a few of the M4As through. For voice notes you'll only ever listen to, AAC at Small is enough, and the WAVs can go once you're sure the M4As play.