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What is AU?

Sun AU is the native audio format for Sun Microsystems workstations, using simple mu-law encoding or uncompressed PCM.

What is ALAC?

Apple Lossless Audio Codec (ALAC) provides lossless compression for Apple Music and iTunes libraries without compromising audio quality.

When Should You Use AU vs ALAC?

Use AU When...

Reach for AU when your priority is legacy unix audio, sun workstation sound — its uncompromising quality ensures every detail is preserved.

Use ALAC When...

Reach for ALAC when your priority is apple ecosystem lossless audio, itunes library — its uncompromising quality ensures every detail is preserved.

AU vs ALAC: Key Differences

  • •The core technical difference: AU relies on lossless compression whereas ALAC uses lossless compression.
  • •Both formats share lossless compression, so quality behavior is similar across the two — file size differences come from algorithm efficiency rather than compression philosophy.
  • •How transparency is handled: ALAC supports transparency, so alpha information is preserved during conversion.
  • •Storage footprint: Small to medium, similar to WAV for AU vs 40-60% of original WAV size for ALAC.
  • •AU is optimized for legacy unix audio, sun workstation sound while ALAC is designed for apple ecosystem lossless audio, itunes library — choose based on your specific workflow needs

Advantages of AU

  • ✓At its core, AU relies on lossless encoding — a design choice that makes it perfect for Legacy Unix audio, Sun workstation sound.
  • ✓You won't run into compatibility issues with AU — it's a universal standard across platforms.
  • ✓File size management with AU: larger files guaranteed to match the original exactly.
  • ✓Every major application in the Legacy Unix audio, Sun workstation sound space supports AU natively.

Advantages of ALAC

  • ✓ALAC applies lossless compression specifically calibrated for Apple ecosystem lossless audio, iTunes library.
  • ✓ALAC enjoys broad native support across operating systems, browsers, and creative tools alike.
  • ✓ALAC guarantees every bit of the original data survives — no approximations, no shortcuts.
  • ✓You will find ALAC support built into virtually every tool that handles Apple ecosystem lossless audio, iTunes library — no plugins or converters needed.

Common Use Cases for AU to ALAC Conversion

  • Radio commercials
  • Guided meditation recordings
  • Audiovisual installation
  • Music education
  • Conference call recordings
  • Field recording preservation

Industry Applications

Audiobook PublishingMusic StreamingLive SoundForensic AudioMedical TranscriptionRadio Broadcasting

Best Practices for AU to ALAC Conversion

  • →For AU to ALAC: match the sample rate and bit depth to your delivery platform — 44.1 kHz / 16-bit is the standard for music
  • →Apply loudness normalization (LUFS) before conversion to ensure consistent volume across your audio library
  • →ALAC prioritizes quality — ensure your storage can accommodate the resulting file sizes
  • →Check that metadata tags (artist, album, track number) survive the conversion
  • →Convert a short segment first to verify quality at your chosen bitrate
  • →Keep a lossless master copy in case you need to re-encode for a different platform

Related Article

Video Compression Guide: Reduce File Size Without Losing Quality

Learn more about AU and ALAC formats in our detailed guide.

Troubleshooting AU to ALAC Conversion

  • !ALAC audio quality degraded vs AU → use a higher bitrate (at least 256 kbps for music)
  • !ALAC file won't play on your device → check format compatibility with your player or platform
  • !Metadata (artist, album, title) lost after AU to ALAC conversion → some formats like ALAC may not support ID3 tags
  • !Volume changed after converting AU to ALAC → normalize audio levels before conversion for consistent playback

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About AU and ALAC

AU

AU (AU audio) - Sun AU, legacy Unix audio format for Sun workstations. Best for legacy unix audio, sun workstation sound.

ALAC

ALAC (ALAC audio) - Apple Lossless Audio Codec, lossless audio for iTunes/Apple Music. Ideal for apple ecosystem lossless audio, itunes library.

Format Comparison

CompressionLossless → Lossless
TransparencySupported
Use CaseConvert from legacy unix audio, sun workstation sound to apple ecosystem lossless audio, itunes library
File Size~40-60% of original WAV size after conversion

FAQs

Is converting AU to ALAC free?

Yes, GoConvertFile offers free conversion of AU to ALAC for files up to 100MB. No registration required.

How long does it take to convert AU to ALAC?

Most AU to ALAC conversions complete within seconds for standard-sized files. Larger files may take longer depending on the conversion complexity.

What is ALAC best used for?

ALAC is ideal for apple ecosystem lossless audio, itunes library. Apple Lossless Audio Codec, lossless audio for iTunes/Apple Music

What file size should I expect after converting AU to ALAC?

File size after AU to ALAC conversion depends on the content complexity and quality settings. Both formats use similar compression approaches so sizes are comparable.

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