CONVERT
AU → AIFF
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Fast, secure AU to AIFF conversion. No registration required.
Here is the short version — AU is the Sun/NeXT audio format, a historical PCM container still found in older pipelines. Hence the need for AIFF. Turn your AU audio into a widely-supported AIFF file. The conversion happens server-side through FFmpeg — the same engine behind every major audio editor — so the output plays cleanly on phones, car stereos, DJ software and streaming tools. Technical note: AU is the Sun/NeXT audio format, a historical PCM container still found in older pipelines. Compare that with AIFF is Apple's uncompressed Audio Interchange File Format, the macOS equivalent of WAV.
Sun AU Audio
Source formatAU is a simple audio format from Sun Microsystems, commonly used on Unix systems.
AIFF Audio
Target formatAIFF is Apple's uncompressed audio format, equivalent to WAV in the macOS ecosystem. It stores CD-quality PCM audio and is widely used in professional audio production on Apple hardware.
Why convert AU to AIFF
The motivation for a AU → AIFF conversion is almost always practical: a playback device, hosting platform or editing suite that insists on AIFF. The audio quality trade-off is controllable via bitrate; the compatibility win is immediate and unambiguous.
HOW TO CONVERT
AU → AIFF
Give us the AU
Select a AU (or several for batch). We read the header to pick decoder settings automatically.
Re-encode to AIFF
The audio is decoded, optionally resampled, and re-encoded as AIFF at transparent default bitrate.
Retrieve your AIFF
Grab the download as soon as it is ready. Typical jobs finish in seconds for short clips.
Common Use Cases
Cross-platform music libraries
Moving libraries between iTunes, foobar2000 and Plex is smoother when tracks are standardised on AIFF.
Streaming uploads
SoundCloud, Bandcamp and YouTube Music accept AIFF directly; AU triggers a transcoding step and a delay.
Legacy hardware playback
Older car head units, portable players and boomboxes often decode AIFF exclusively — a lasting compatibility guarantee.
Ringtones and notifications
iOS, Android and Windows all accept AIFF as a system sound or custom ringtone with no further conversion.
AU vs AIFF — Strengths and limitations
What each format does best, and where it falls short.
AU Strengths
- Trivially simple format — 24-byte header, then samples.
- µ-law 8-bit variant fits hours of speech in kilobytes.
- Stable since 1988; every major audio library reads it.
- Streaming-friendly: size field is optional.
Limitations
- Aging — obsolete outside legacy and compatibility scenarios.
- No metadata beyond a single annotation string.
- No native multi-channel surround support.
AIFF Strengths
- Lossless and uncompressed — bit-exact audio reproduction.
- Native to macOS and all Apple Pro Audio apps.
- Simple structure — trivially parsed by audio libraries.
- Supports up to 32-bit float, 192 kHz, and multi-channel audio.
- Rich metadata via named chunks (annotations, markers, MIDI).
Limitations
- Enormous file sizes — 10 MB per minute at CD quality.
- No built-in compression — use FLAC for lossless with smaller files.
- Big-endian byte order confuses tools written on little-endian hardware.
AU vs AIFF — Technical specifications
Side-by-side comparison of the technical details.
AU
- MIME types
- audio/basic, audio/au, audio/x-au
- Extensions
- .au, .snd
- Header
- 24 bytes (magic, offset, size, encoding, rate, channels, info)
- Codecs
- PCM 8/16/24/32-bit, µ-law, A-law, IEEE float
- Byte order
- Big-endian
AIFF
- MIME types
- audio/aiff, audio/x-aiff
- Extensions
- .aif, .aiff, .aifc
- Byte order
- Big-endian
- Max bit depth
- 32 bits (PCM or float)
- Max sample rate
- 192 kHz (practical); unlimited (spec)
| Specification | AU | AIFF |
|---|---|---|
| MIME types | audio/basic, audio/au, audio/x-au | audio/aiff, audio/x-aiff |
| Extensions | .au, .snd | .aif, .aiff, .aifc |
| Header | 24 bytes (magic, offset, size, encoding, rate, channels, info) | — |
| Codecs | PCM 8/16/24/32-bit, µ-law, A-law, IEEE float | — |
| Byte order | Big-endian | Big-endian |
| Max bit depth | — | 32 bits (PCM or float) |
| Max sample rate | — | 192 kHz (practical); unlimited (spec) |
AU vs AIFF — Typical file sizes
Approximate file sizes for common scenarios.
AU
- 10-second clip (8-bit µ-law, 8 kHz) 80 KB
- 10-second clip (16-bit PCM, 44.1 kHz stereo) ~1.7 MB
AIFF
- 3-min song (CD quality) 30 MB
- 3-min song (24-bit / 96 kHz) 100 MB
- Full album (CD, 10 tracks) 450 MB
Quality & Compatibility
The AIFF output is as good as the AU source allows. If the AU was encoded at 96 kbps, the AIFF cannot reconstruct detail the encoder already dropped; picking a very high AIFF bitrate just produces a larger file. Match AIFF bitrate to the AU quality for the best balance.
Tips for Best Results
- Sample-rate mismatches between AU and target device (48 kHz phone output from a 44.1 kHz track) are handled automatically; no manual resampling needed.
- For audiobook delivery, match the platform spec exactly — ACX requires 192 kbps CBR 44.1 kHz stereo, for example.
- Batch-convert an album in one job so every track shares identical encoder settings and loudness normalisation.
Frequently Asked Questions
Lossy-to-lossy conversions (most combinations) re-compress the audio, which technically introduces some loss. At a 192 kbps or higher target it is inaudible on normal equipment. Lossy-to-lossless conversions freeze the existing quality but cannot improve it; lossless-to-lossy transcodes are only as good as the target bitrate you choose.
For voice content (podcasts, audiobooks, lectures) 128 kbps is indistinguishable from higher bitrates. For music, 192-256 kbps covers most listening; 320 kbps is the ceiling for AIFF and the right choice for audio you plan to edit further. Above that, prefer a lossless target instead.
Yes. Title, artist, album, year and cover art travel from the AU container to the AIFF container automatically where both formats support them. If a tag field has no AIFF equivalent, it is dropped silently. Use any tag editor (Mp3tag, MusicBrainz Picard) to fine-tune afterwards.
Related comparisons
See these formats side by side to understand which fits your use case best.
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