Free tool
Audio Format Checker — will it play on your iPhone?
Drop a file and find out what it actually is, and what will play it. Reads the container and codec out of the header rather than trusting the extension, then says where the file stands with Apple's Music app, with iOS and macOS themselves, and with Trove.
Why a file refuses to play
Nearly every “this won't play on my iPhone” problem is one of three things, and they need different fixes.
- The format is fine, the Music app is the obstacle. This is the FLAC case. iOS decodes it; the Music app refuses to import it. A player app solves this in a minute and converting to ALAC also works, losslessly.
- Apple genuinely does not support the format. DSD, APE, WavPack, Musepack, TTA. Nothing Apple ships will open these, so it is a player app or a conversion — and conversion out of DSD is not lossless.
- The file is not what it says it is. A
.flacthat is really an MP3, or a truncated download. The checker above catches both, because it reads the header rather than the name.
What the three columns mean
Apple Music app is whether the file can be imported into your library and synced. This is the narrowest of the three and the one that surprises people.
iOS / macOS itself is whether the operating system can decode it at all — whether tapping it in the Files app produces sound. Wider than the Music app, and the distinction between these two columns is the single most misunderstood thing about audio on Apple devices.
Trove is our player. Fifteen-plus formats: MP3, AAC, ALAC, WAV, AIFF, CAF and FLAC natively, then APE, OGG, Opus, WMA, DSD (DSF and DFF), WavPack, TTA and Musepack through extended decoding. All of that is in the free app.
If your library is bigger than your phone
The formats that fail most often — DSD especially — are also the largest, which is usually the real problem underneath the format problem. A DSD64 album runs 1.5–2 GB. At that size the answer is not to sync smarter but to leave the library on a NAS and reach it over WebDAV or SMB; how to set that up is written out step by step.
Questions
Why won't my FLAC file play on my iPhone?
It almost certainly can. iOS has decoded FLAC since iOS 11 — what it will not do is import FLAC into Apple's Music app, because that sync pipeline only accepts ALAC. So the file is fine and the OS is fine; you need a player app that gives you a library rather than a folder, or you convert to ALAC, which is lossless and therefore costs you nothing but time.
Does this upload my music anywhere?
No. The checker reads the file's header in your browser and there is no server behind this page to upload to. It keeps working with the network switched off once the page has loaded.
How is this different from just looking at the file extension?
The extension is a claim, not a fact. This reads the container and codec out of the file itself, so a file named .flac that is really an MP3 — common in downloads that were re-encoded somewhere along the way — shows up as what it is. The extension is only used as a fallback when the header cannot be read.
What does 'partial' mean in the Trove column?
Trove decodes MP3, AAC, ALAC, WAV, AIFF, CAF and FLAC natively. APE, OGG, Opus, WMA, DSD, WavPack, TTA and Musepack play through its built-in extended decoding — the same result for you, a different path inside the app.
It says my file is lossless but the bitrate looks low.
Bitrate is only meaningful for lossy formats, so the checker hides it for lossless ones. If you want to know whether a lossless file was made from a lossy source — an upconverted MP3 wrapped in FLAC — a header cannot tell you that. You need a spectrogram: a genuine lossless file carries content up to the Nyquist limit, while an upconverted one shows a hard shelf where the lossy encoder cut everything off.
A player that opens all of them
Trove plays every format in the table above on iPhone, iPad, Mac and Apple Watch — gapless, with your tags, artwork and lyrics. Free to download.