M4A to AU - Online Audio Converter

Convert M4A to AU online. Private, client-side - no uploadrequired. Batch conversion, quality presets, codec control.

Convert M4A to AU

[+] Drop M4A audio here or click to select M4A

Output format

AU (PCM 16-bit)

Mode[i]

Simple Advanced

Quality[i]

Sample Rate[i]

Channels[i]

About M4A to AU

Convert M4A to AU. M4A is the MPEG-4 audio container usually holding AAC or ALAC. AU is Sun's simple container, usually holding 8 kHz telephony audio. Headers are minimal; verify sample rate after conversion..

Why convert M4A to AU?

Larger files than lossy shares with AU uncompressed quality.
Keep quality where supported.
Private, no upload - runs in your browser.

M4A vs AU

Codec	AAC	PCM 16-bit
Compression	lossy	uncompressed
Sample behavior	Quality set by bitrate	Full quality kept
Typical use	M4A is the MPEG-4 audio container usually holding AAC or ALAC.	AU is Sun's simple container, usually holding 8 kHz telephony audio.

When not to convert M4A to AU

Skip AU for the smallest share: lossless output stays large, so prefer a lossy target when sending M4A files.
Keep a master copy: repeated exports stack small losses, so archive M4A before batch AU shares.

Limits

Starting point: M4A - M4A is the MPEG-4 audio container usually holding AAC or ALAC. Check whether the track is AAC or ALAC before picking settings. Headers are minimal; verify sample rate after conversion. Encode AU (PCM 16-bit) from M4A at 256k for music or 128k for speech, starting from the master.

How conversion works

Conversion runs entirely in your browser with FFmpeg WASM. Files never leave your device.

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FAQ

How do I convert M4A to AU?

Drop your M4A file onto this page, choose quality and codec settings, then click Convert. The result downloads as AU instantly. All processing runs in your browser.

What codec is used for AU?

The default codec for AU is PCM 16-bit. You can change audio parameters in Advanced mode.

How do you store my files?

We do not store any processed audio. All conversion happens entirely in your browser using FFmpeg WASM.