AAC to AIFF Converter

Convert AAC to AIFF Online

This decodes lossy AAC audio into AIFF, the uncompressed big-endian PCM format Apple built in 1988 and still the natural uncompressed container on macOS. One honesty note first: AAC is lossy, so the AIFF will not sound better than the AAC. It is a faithful, much larger PCM copy of the same decoded audio, and the detail the AAC encoder threw away does not come back. The reason to do this is workflow — a stable uncompressed file to edit, sample, or feed to gear that will not read raw AAC.

How to Convert AAC to AIFF

1. Upload Your AAC File: Drag and drop your .aac files onto the page or click "+ Add Files" to browse. Queue several and they all convert with the same settings.
2. Leave Audio Sample Rate and Audio Channel on ORIGINAL: Both dropdowns start on ORIGINAL, which decodes the AAC exactly as it was encoded. Change them only when a target device demands MONO or a specific rate — resampling and downmixing are the only two steps here that can actually alter the audio.
3. Trim if You Only Need a Section: Trim starts on Unchanged and converts the whole file. Set a time range when you want just a phrase, a loop, or a single sample out of a longer recording — worth doing before the file balloons to uncompressed size.
4. Convert and Download: Click Convert and download your AIFF. Files upload over an encrypted connection, are processed on our servers, and are deleted automatically after a few hours. No sign-up, no watermark.

AAC vs AIFF — What Actually Changes

AIFF Format at a Glance

When AIFF Is the Right Target — and When It Isn't

• Right: a hardware sampler, drum machine, or older audio device that reads AIFF or WAV but has no AAC decoder at all.
• Right: a working file you will cut, fade, time-stretch, and re-save many times, where you want zero further generation loss between edits.
• Right: feeding a mastering or CD-authoring chain that expects uncompressed PCM as its input.
• Wrong: trying to make a low-bitrate AAC sound better. Nothing downstream of a lossy encode can restore what the encoder discarded.
• Wrong: archiving a large library, where the tenfold size increase buys nothing over keeping the original AAC or moving to FLAC, which is lossless and compressed.

Frequently Asked Questions

Will converting AAC to AIFF improve the audio quality?

No, and it is worth being blunt about it. AAC is a lossy codec: the encoder analysed the signal and permanently discarded the parts it judged least audible in order to shrink the file. Decoding to uncompressed AIFF reconstructs the waveform as far as the decoder can, but the discarded information is not stored anywhere, so no format conversion can bring it back. The AIFF sounds like the AAC and takes roughly ten times the space.

Then why convert AAC to AIFF at all?

For workflow, not fidelity. Hardware samplers, drum machines, and older studio gear frequently read AIFF and WAV but have no AAC decoder. Decoding once to PCM also gives you a stable working file: you can cut, fade, and process it repeatedly without a fresh lossy re-encode on every save, which is exactly the compounding-loss problem that editing a lossy file directly creates.

Why is my AIFF file about ten times bigger than the AAC?

Because AIFF stores every sample uncompressed while AAC compresses aggressively, and PCM size is fixed arithmetic rather than content-dependent. Uncompressed 44.1 kHz 16-bit stereo runs at 1,411.2 kbit/s, roughly 10 MB per minute, so a four-minute track lands near 40 MB regardless of how small the source was. A 128 kbit/s AAC of the same track is about 1 MB per minute. The extra bytes are padding out the PCM, not added detail.

Should I output AIFF or WAV?

They are close cousins and the audio is identical: both are uncompressed linear PCM, both at the same rate and depth produce the same file size. AIFF is big-endian and descends from Electronic Arts' IFF; WAV is little-endian and descends from Microsoft's RIFF. AIFF is the more natural fit on macOS and in Apple's own apps, while WAV is the safer cross-platform default. If WAV suits you better, use AAC to WAV instead.

What bit depth and byte order will the AIFF have?

16-bit linear PCM in big-endian order, which is classic AIFF and what every AIFF-capable editor and sampler expects. That matches the audio-CD standard and is ample for a source that was already a lossy stream — a deeper output would only add zeros, not resolution. Leaving Audio Sample Rate on ORIGINAL keeps the source rate, commonly 44.1 kHz or 48 kHz for music AAC.

My Mac shows AIFF files that are little-endian — is that a different format?

That is AIFF-C using the sowt codec: a pseudo-compressed variant that stores plain PCM in little-endian order without actually compressing anything. Apple adopted it as the standard on macOS while still labelling the files simply "AIFF", which is why byte order sometimes appears to contradict the format's own definition. Both variants carry identical audio; classic big-endian AIFF is the more broadly compatible of the two, especially with older samplers.

Does the AIFF keep the title, artist, and album art from my AAC?

Not reliably. AIFF can hold metadata in Name, Author, Comment, Annotation, and Copyright chunks, and ID3v2 or XMP data can be carried in Application chunks, but the mapping from MPEG-4 metadata atoms into those chunks is not standardised and many players ignore AIFF tags entirely. Treat the AIFF as an audio working file and keep the tagged AAC if the library metadata matters.

Can I go back to AAC afterwards without extra damage?

Re-encoding to AAC is a lossy step, so it adds its own generation of loss on top of the original encode — the AIFF is a clean PCM source, but it is a PCM source built from already-lossy audio. If you only need the small file again and never edited the audio, the original AAC is the better copy to keep. When you have genuinely edited the PCM, AIFF to AAC re-encodes the result.

What if I want lossless but not a 10 MB-per-minute file?

Use FLAC. It stores the decoded PCM losslessly while compressing it, typically to a fraction of the uncompressed size, so it is the better choice for archiving a decoded library. Run AAC to FLAC instead — with the same caveat that a lossless container around a lossy source preserves exactly what the AAC held, no more.

How are my files handled during conversion?

Files upload over an encrypted connection, are processed on our servers, and are deleted automatically after a few hours — no sign-up, no watermark, never shared or made public. Because AIFF output is many times the size of the AAC input, the download is usually the slowest part of the round trip.