Audio Format Comparison

AU vs WAV — Sun Audio vs Microsoft RIFF Audio

AU is Sun Microsystems' classic audio format from 1992 — the standard format on early Unix workstations and Java applets. WAV is Microsoft's RIFF-based audio format from 1991 — the de facto standard on Windows and the universal exchange format for audio editing. Both are uncompressed PCM containers with very different ecosystems.

AUvsWAV

Quick Verdict

Use AU when…

Keep AU files only for legacy Unix and Java workflows that specifically require them. AU is essentially deprecated outside these niches.

Use WAV when…

Use WAV for everything modern. WAV's universal support across DAWs, editors, broadcast equipment, and operating systems makes it the practical choice for any new uncompressed audio.

AU vs WAV: Feature Comparison

Feature	AU	WAV
Origin	Sun Microsystems (1992)	Microsoft/IBM (1991)
Container structure	Simple header + PCM data	RIFF chunks
Codec support	PCM, μ-law, A-law	PCM, ADPCM, MP3 (rare)
Endianness	Big-endian (typical)	Little-endian (typical)
Java native support	Yes (java.applet legacy)	Via JavaSound
Modern relevance	Legacy	Universal

When AU wins

✓Origin: Sun Microsystems (1992)
✓Container structure: Simple header + PCM data
✓Codec support: PCM, μ-law, A-law

When WAV wins

✓Origin: Microsoft/IBM (1991)
✓Container structure: RIFF chunks
✓Codec support: PCM, ADPCM, MP3 (rare)

Frequently asked questions

Where do I encounter AU files in 2026?

Older Unix systems, archived Java applets (now broken), legacy academic recording systems, and a handful of voice-mail systems still use μ-law encoded AU files. They're rare in modern workflows.

Is AU lossless like WAV?

AU supports both lossless PCM (like WAV) and lossy μ-law/A-law compression at lower quality. To match WAV's typical lossless 16-bit PCM use, you'd specify PCM in your AU encoder. μ-law AU is roughly equivalent to telephone-quality audio (8-bit, 8 kHz).