Convert AAC to AU
Free online AAC to AU converter. No signup required.
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Max file size: 100 MB
Why Convert AAC to AU?
Understand when and why this conversion makes sense for your workflow.
Converting AAC Audio to Sun AU Audio ensures your audio files work across the widest possible range of devices, players, and streaming platforms. Audio formats differ significantly in their compression algorithms, bitrate support, and metadata handling. Whether you're archiving a music collection, preparing tracks for a podcast, or optimizing audio for a mobile app, selecting the right output format is essential for balancing playback compatibility with sound fidelity.
AAC Audio has a known limitation: lossy compression permanently removes audio information. In contrast, Sun AU Audio offers a key advantage: simple, well-documented format with a minimal header. While AAC Audio is commonly used for apple ecosystem audio including itunes and apple music, Sun AU Audio is better suited for unix and solaris system audio and sound effects.
MegaConvert processes your AAC file and delivers a properly encoded AU output, preserving audio quality within the limits of the target format — free, instant, and private.
AAC vs AU: Format Comparison
Side-by-side comparison of the source and target formats.
| Property | AAC (Source) | AU (Target) |
|---|---|---|
| Extension | .aac | .au |
| Full Name | AAC Audio | Sun AU Audio |
| Compression | Lossy | Varies |
| File Size | Small | Varies |
| Best For | Apple ecosystem audio including iTunes and Ap… | Unix and Solaris system audio and sound effects |
| Browser Support | Universal | Varies |
How to Convert AAC to AU
Follow these simple steps to convert your file in seconds.
Upload your AAC audio
Drop your .aac audio file into the upload zone or browse to select it. Both short voice clips and full-length tracks work — typical AAC Audio files (under 100 MB) upload in seconds even on a slow connection. Album art and metadata in the file are read automatically.
Start the AU encode
Press the convert button to start. The audio stream is decoded from AAC Audio into PCM, then re-encoded as Sun AU Audio at a quality preset that matches the source bitrate where possible. Sample rate, channel count, and bit depth are preserved unless the target format restricts them.
Wait for the audio to finish encoding
Encoding speed depends on the length of the audio and the codec. Short clips finish in a few seconds; full-length albums can take 30 seconds or so. We do not throttle conversions — the limit is just the encoder's natural speed on the underlying hardware.
Download your .au file
When the conversion finishes, click the download link to save the new Sun AU Audio file to your computer. The file is yours — no watermarks, no expiration on the file itself, and no MegaConvert account is required to download it.
Tips for Converting AAC to AU
Practical advice to get the best results from this conversion.
Why this conversion is worth doing
AAC Audio has a known limitation: lossy compression permanently removes audio information. Sun AU Audio addresses this with a key advantage: simple, well-documented format with a minimal header. Converting from AAC to AU is most worthwhile when this specific trade-off matters for the way you intend to use the file.
Match the format to the actual workflow
AAC Audio is most commonly used for apple ecosystem audio including itunes and apple music, while Sun AU Audio is the standard for unix and solaris system audio and sound effects. If your workflow is closer to the second pattern, converting makes sense. If you are still working in a context where AAC is the norm, converting may create unnecessary compatibility friction with collaborators or tools that expect the source format.
Watch for this limitation in the AU output
Sun AU Audio has its own limitation worth understanding before you commit: largely obsolete for general-purpose audio use. After the conversion completes, open the AU file and verify that this limitation does not affect your specific use case — for some workflows it is irrelevant; for others it can be a deal-breaker.
Understand lossy vs. lossless before converting
Converting from a lossy format like MP3 to a lossless format like FLAC or WAV does not restore lost audio data — it only changes the container. If you need true lossless quality, always start from an uncompressed or lossless source. Converting lossless to lossy, however, is a valid way to reduce file size for streaming or mobile playback.
Understanding AAC and AU Formats
Learn about the source and target file formats to understand what happens during conversion.
Source Format
AAC Audio
audio/aacAAC (Advanced Audio Coding) is a lossy audio compression standard designed as the successor to MP3, offering better sound quality at equivalent bitrates. It is the default audio format for Apple devices, YouTube, and many streaming platforms. AAC supports sample rates from 8 to 96 kHz and up to 48 channels of audio.
Advantages
- Better audio quality than MP3 at the same bitrate
- Default format for iTunes, Apple Music, YouTube, and many streaming services
- Supports multi-channel audio up to 48 channels
Limitations
- Lossy compression permanently removes audio information
- Slightly less universal hardware support compared to MP3
- Patent-encumbered format with licensing requirements for encoders
Common Uses
- Apple ecosystem audio including iTunes and Apple Music
- YouTube and streaming platform audio encoding
- Mobile audio content and digital broadcasting
Target Format
Sun AU Audio
audio/basicAU is an audio file format introduced by Sun Microsystems and commonly associated with Unix and NeXT systems. It supports various encodings including uncompressed PCM, mu-law, and A-law compression, with a simple header structure. AU was one of the earliest audio formats supported on the web and remains used in Unix-based audio programming.
Advantages
- Simple, well-documented format with a minimal header
- Native support in Unix, Solaris, and Java audio APIs
- Supports multiple encoding types including mu-law for telephony
Limitations
- Largely obsolete for general-purpose audio use
- Limited metadata support and no modern compression options
- Poor support in consumer audio software and devices
Common Uses
- Unix and Solaris system audio and sound effects
- Java application audio playback (javax.sound)
- Legacy telephony and voice processing systems
Frequently Asked Questions
Common questions about converting AAC to AU.
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