Convert AU to AMR
Free online AU to AMR converter. No signup required.
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Max file size: 100 MB
When to convert AU to AMR
Use this conversion when your destination needs AMR and you have a AU source. Keep the original so you can compare the result or try another supported format.
Audio is decoded and re-encoded using format-specific defaults. Sample format and some metadata may change. Embedded cover art is omitted. A lossless destination cannot recover detail lost in the source.
AU vs AMR: Format Comparison
Side-by-side comparison of the source and target formats.
| Property | AU (Source) | AMR (Target) |
|---|---|---|
| Extension | .au | .amr |
| Full Name | Sun AU Audio | AMR Audio |
| Compression | Varies | Varies |
| File Size | Varies | Small |
| Best For | Unix and Solaris system audio and sound effects | Mobile phone voice recording and voice memos |
| Browser Support | Varies | Varies |
How to Convert AU to AMR
Follow these simple steps to convert your file in seconds.
Choose a AU file
Select or drop one file up to 100 MB. Its extension must match this converter. Availability is checked before transfer.
Convert to AMR
Audio is decoded and re-encoded using format-specific defaults. Sample format and some metadata may change. Embedded cover art is omitted. A lossless destination cannot recover detail lost in the source.
Download and check the result
Use Download after conversion completes. Open the result and check its content, quality and formatting before sharing it. Download links expire one hour after upload finishes. Uploaded and converted files are removed automatically by regular cleanup. Files may become unavailable sooner when the service restarts.
Tips for Converting AU to AMR
Practical advice to get the best results from this conversion.
Why this conversion is worth doing
Sun AU Audio has a known limitation: largely obsolete for general-purpose audio use. AMR Audio addresses this with a key advantage: extremely small file sizes optimized for voice content. Converting from AU to AMR 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
Sun AU Audio is most commonly used for unix and solaris system audio and sound effects, while AMR Audio is the standard for mobile phone voice recording and voice memos. If your workflow is closer to the second pattern, converting makes sense. If you are still working in a context where AU is the norm, converting may create unnecessary compatibility friction with collaborators or tools that expect the source format.
Watch for this limitation in the AMR output
AMR Audio has its own limitation worth understanding before you commit: very poor quality for music or non-speech audio. After the conversion completes, open the AMR 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 AU and AMR Formats
Learn about the source and target file formats to understand what happens during conversion.
Source 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
Target Format
AMR Audio
audio/amrAMR (Adaptive Multi-Rate) is a compressed audio format optimized specifically for speech encoding, widely used in mobile telecommunications. It employs adaptive bitrate encoding that adjusts between 4.75 and 12.2 kbps based on network conditions, prioritizing speech intelligibility over music quality. AMR is the standard speech codec for GSM and UMTS mobile networks worldwide.
Advantages
- Extremely small file sizes optimized for voice content
- Adaptive bitrate adjusts to network conditions in real-time
- Standard codec in GSM/3G mobile networks worldwide
Limitations
- Very poor quality for music or non-speech audio
- Limited to narrowband (8 kHz) or wideband (16 kHz) sampling
- Not suitable for high-fidelity audio or media production
Common Uses
- Mobile phone voice recording and voice memos
- Cellular voice call encoding in GSM/3G networks
- MMS voice message attachments
Frequently Asked Questions
Common questions about converting AU to AMR.
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