AAC to FLAC on iPhone

Safari on iOS 15.4 and newer runs the converter completely, on the phone itself. There is no App Store download — and no converter app quietly uploading your recordings to its own servers. AAC files convert to FLAC here the same way — nothing to install.

If the file is in Voice Memos or Photos, tap the share icon and choose 'Save to Files' first — that makes it visible to Safari's file picker. The converted file lands in Files (Downloads by default), from where you can share it into Messages, Mail, or any app. Your AAC comes out as FLAC, ready to use straight away.

The AAC files people convert on an iPhone almost always originate from HLS streaming segments, broadcast pipelines, Android recording apps, and hardware recorders, and a bare .aac stream lacks the container index that tells software its duration, so players won't list it and editors import it wrong — which is precisely why they're stuck on the phone until you convert them to FLAC.

Budget for roughly 5 MB per minute — about 4× what the AAC took. You're trading disk for a format that tools actually accept. What AAC threw away is unrecoverable. FLAC preserves what's left perfectly, which is the most any format can do for it.

AAC to FLAC is a common iPhone snag specifically because a bare .aac stream lacks the container index that tells software its duration, so players won't list it and editors import it wrong, and FLAC is what your other apps and devices expect. Apple gives you no built-in way to convert audio at all, so the App Store is full of converter apps — many upload your recording to their own servers, show ads against it, and want a subscription. Doing it in Safari means the AAC file is processed on the phone itself and stays there, which matters when it is a voice memo, an interview, or a recording of your own family.

Your AAC file never leaves the handset. For iPhone that is the whole argument: HLS streaming segments are usually personal, and the App Store alternative frequently ships them to a company's servers as the price of a free conversion. Processing the AAC-to-FLAC conversion on-device means there is no server to trust in the first place.

The AAC on your drive almost certainly started life in HLS streaming segments, and a bare .aac stream lacks the container index that tells software its duration, so players won't list it and editors import it wrong. FLAC is the destination when you need uncompressed, edit-ready audio that every DAW and editor accepts. Yes, it gets larger — around 4× — since you're unpacking the audio rather than compressing it. Keep the AAC for storage and use the FLAC as the working copy. One honest note on this exact pair: AAC is already lossy, so moving to FLAC cannot restore detail the AAC encoder discarded — it hands you an uncompressed container, not better audio, and the value is a loss-free chain from here on.