Which audio formats play on iPhone, and what to do with the ones that don't

Refrain plays MP3, M4A, AAC, WAV, FLAC and AIFF, and reads the title, artist, album and cover art out of each file's own tags where they exist. That covers essentially everything that comes out of a music service, a CD rip, a DAW bounce or an AI generator. It does not play OGG, OPUS, WMA, APE or DSD, and the answer for those is to convert on a computer.

The short version

Which one should you actually keep?

Depends on what the file is for, and the honest answer for most people is MP3 or M4A.

Keep lossless if it is your master. A song you made, a recording you took, a digitisation of a record you own — keep the WAV or FLAC somewhere safe, because it is the only copy that can be converted to anything else later without compounding losses. That copy does not have to be the one on your phone.

Put lossy on the phone. A 256 kbps MP3 or AAC of a four-minute song is 5–8 MB. The WAV is 40. On a 128 GB phone that is the difference between three hundred albums and forty, and in a pair of earbuds on a train the difference between them is not the one you will notice.

Keep FLAC on the phone if you care and have the space. It is lossless and about 60% the size of WAV, which makes it the sensible lossless-on-a-phone choice. Refrain plays it directly.

There is no reason to put WAV on a phone. It is uncompressed, it carries tags badly, and it is twice the size of FLAC for identical audio. If your Suno Pro exports are WAV, keep the WAVs on your computer and convert copies for the phone.

Tags: why some files show up with nothing

Refrain reads the metadata inside the file. Different formats carry it differently, and some barely carry it at all.

• MP3 uses ID3 tags, which is a well-trodden path. Title, artist, album, cover art, and sometimes lyrics.
• M4A/AAC/ALAC use MPEG-4 atoms. Usually well populated if it came from Apple.
• FLAC uses Vorbis comments and generally arrives well tagged, especially from Bandcamp.
• WAV has almost no tagging convention worth relying on. A WAV usually shows up as its filename and nothing else. This is not Refrain failing to read it; there is nothing there.
• AIFF can carry ID3 chunks but often doesn't.

If a batch imports with no artist and no artwork, the format is usually the reason. You can fix how it displays in a couple of minutes — though remember that changes what your library shows rather than what the file contains.

What Refrain won't play, and what to do

OGG Vorbis and OPUS. Common in open-source tooling, game audio and some podcast pipelines. Convert to MP3 or FLAC.

WMA. Windows Media, largely historical. Convert.

APE (Monkey's Audio) and DSD. Audiophile formats with narrow support. If you have a DSD library, you want a dedicated hi-res player, and you should be honest with yourself about whether Refrain is aimed at you — it isn't.

MIDI. Not audio, so nothing to play. Render it out of your DAW first.

M4B. Audiobook format. Refrain has no per-file resume position, so a long file restarts from zero every time. Do not use it for audiobooks.

DRM-protected files. Anything with copy protection — old iTunes Store purchases from before 2009, files from a subscription service — will not play, and there is no way around that from inside a music player.

Converting

Do it on a computer, once, properly.

• XLD (Mac) and foobar2000 (Windows) are the long-standing free options.
• ffmpeg if you are comfortable in a terminal: one command converts a whole folder.
• Convert from your lossless master, not from an MP3. Converting a lossy file to another lossy format stacks the damage.

Refrain does not convert anything, and that is deliberate rather than an omission. Building a converter into a phone music player means either a large native dependency or shipping files somewhere, and the second one is not compatible with an app that makes no network requests.

Does the format affect sound quality here?

Less than you would think, and less than the other choices you make.

A well-encoded 256 kbps MP3 is transparent to most listeners on most equipment. What changes what you hear, in rough order of size: the headphones, the room, the mastering of the track, the equalizer setting, and only then the codec.

Refrain has a ten-band equalizer running 32 Hz to 16 kHz with a preamp and the usual presets, which will make a far larger difference to a given song than moving that song from MP3 to FLAC.

What this doesn't do

• No conversion, no transcoding, no format repair.
• No hi-res exotica. No DSD, no MQA, no bit-perfect output claims.
• No repair of broken or partial files — a truncated download will not play, and the fix is to download it again.

Related

• Can iPhone play FLAC files?
• Vinyl digitisations: big WAV files on a small phone
• Four ways to get music into Refrain
• All guides · Refrain