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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 CAF?

Core Audio Format (CAF) is Apple's audio container designed to overcome the file size and sample rate limitations of AIFF and WAV.

When Should You Use AU vs CAF?

Use AU When...

For legacy unix audio, sun workstation sound, nothing beats AU. It sets the standard for quality, trusted by professionals who cannot afford compromises.

Use CAF When...

CAF is built for apple audio production, professional editing. Think of it as the perfectionist — every pixel, every sample, preserved exactly as intended.

AU vs CAF: Key Differences

  • •The core technical difference: AU relies on lossless compression whereas CAF 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: CAF supports transparency, so alpha information is preserved during conversion.
  • •Storage footprint: Small to medium, similar to WAV for AU vs Flexible, supports very large files for CAF.
  • •Primary audience: AU is built for legacy unix audio, sun workstation sound scenarios, while CAF focuses on apple audio production, professional editing — pick the format that matches your output requirement.

Advantages of AU

  • ✓The lossless nature of AU means file sizes stay reasonable while handling Legacy Unix audio, Sun workstation sound efficiently.
  • ✓From mobile devices to enterprise servers, AU is recognized and supported everywhere.
  • ✓The trade-off for AU's perfection is larger files — but for archival work, it is worth every megabyte.
  • ✓AU is a first-class citizen in all major software ecosystems, from creative suites to development environments.

Advantages of CAF

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

Common Use Cases for AU to CAF Conversion

  • Podcast distribution
  • Voice recordings
  • Streaming services
  • Audio books
  • Sound design
  • Language learning

Industry Applications

PodcastingBroadcastingAudio EngineeringLanguage LearningAccessibilityVoice-over

Best Practices for AU to CAF Conversion

  • →Converting AU to CAF: CAF preserves full audio fidelity — ideal for archiving master recordings
  • →Normalize audio levels before conversion for consistent playback volume
  • →CAF excels in professional audio workflows
  • →Always keep a backup of your original files before converting
  • →Choose the appropriate quality settings for your specific use case

Related Article

Video Compression Guide: Reduce File Size Without Losing Quality

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

Troubleshooting AU to CAF Conversion

  • !Clicks or pops in the converted CAF → sample rate conversion can introduce artifacts; use a clean multiple of the source rate
  • !CAF file has silence at the beginning or end → trim the source AU file before converting to avoid unnecessary padding
  • !Stereo image collapsed after converting AU to CAF → verify that the converter preserves channel mapping for multichannel audio
  • !The converted CAF clips or distorts at peaks → reduce the gain or apply a limiter before conversion to prevent hard clipping

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Convert AU files to CAF online for free. High-quality conversion with no registration required.

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About AU and CAF

AU

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

CAF

CAF (CAF audio) - Core Audio Format, Apple's professional audio format. Ideal for apple audio production, professional editing.

Format Comparison

CompressionLossless → Lossless
TransparencySupported
Use CaseConvert from legacy unix audio, sun workstation sound to apple audio production, professional editing
File Size~Flexible, supports very large files after conversion

FAQs

Is converting AU to CAF free?

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

How long does it take to convert AU to CAF?

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

What is CAF best used for?

CAF is ideal for apple audio production, professional editing. Core Audio Format, Apple's professional audio format

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

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

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