AU vs OGG — Differences, File Size & When to Use Each

AU vs OGG

A detailed comparison of Sun AU Audio and OGG Vorbis Audio — file size, quality, compatibility, and which format to choose for your workflow.

Convert AU → OGG Convert OGG → AU

Sun AU Audio

Audio Files

AU is a simple audio format from Sun Microsystems, commonly used on Unix systems.

About AU files

OGG

OGG Vorbis Audio

Audio Files

OGG Vorbis is an open-source, royalty-free lossy audio format. It generally offers better quality than MP3 at equivalent bitrates and is commonly used in gaming, open-source software, and web audio.

About OGG files

Strengths Comparison

AU Strengths

Trivially simple format — 24-byte header, then samples.
µ-law 8-bit variant fits hours of speech in kilobytes.
Stable since 1988; every major audio library reads it.
Streaming-friendly: size field is optional.

OGG Strengths

Completely royalty-free — no patent worries for encoders or decoders.
Container is streaming-friendly — useful for internet radio.
Native support in HTML5 <audio>, every major Linux distro, and most audio tools.
Can multiplex any number of tracks (audio, video, text) in one file.
Mature tooling via libvorbis, libopus, and FFmpeg.

Limitations

AU Limitations

Aging — obsolete outside legacy and compatibility scenarios.
No metadata beyond a single annotation string.
No native multi-channel surround support.
Limited to 8 codecs, none modern.

OGG Limitations

Apple and Microsoft avoided Ogg historically — iOS and Safari only added Opus support recently.
Hardware decoder support is rare — encoding for battery-constrained devices (phones) still favors AAC.
Confusing naming: ".ogg" could be Vorbis, Opus, Speex, or FLAC.
Metadata conventions (Vorbis comments) are simpler than MP4's tagging.

Technical Specifications

Specification	AU	OGG
MIME types	audio/basic, audio/au, audio/x-au	audio/ogg, application/ogg
Extensions	.au, .snd	.ogg (audio), .oga, .ogv (video), .ogx (app), .opus
Header	24 bytes (magic, offset, size, encoding, rate, channels, info)	—
Codecs	PCM 8/16/24/32-bit, µ-law, A-law, IEEE float	Vorbis, Opus, Speex, FLAC, Theora (video), Dirac
Byte order	Big-endian	—
Standard	—	RFC 3533 (container), RFC 5334 (MIME)
Streaming	—	Native (page-based structure)

Typical File Sizes

AU

10-second clip (8-bit µ-law, 8 kHz) 80 KB
10-second clip (16-bit PCM, 44.1 kHz stereo) ~1.7 MB

OGG

3-min music (Vorbis q5 / ~160 kbps) 3.5 MB
1-hour podcast (Vorbis q3) 45 MB
Game sound effects (Vorbis q2) 5-30 KB each

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Frequently Asked Questions

AU (Sun AU Audio) is an audio file format used to store sound recordings — music, voice, podcasts, sound effects. The format defines how the audio samples are compressed (or stored raw), what bitrates are supported, and how metadata such as title, artist, album, and cover art is embedded. It is part of the audio files family.

AU (Sun AU Audio) is an audio formatoo de arquivo used to store sound recordings — music, voice, podcasts, sound effects. The formato defines how the audio samples are comprimido (or stored raw), what bitrates are suportado, e how metadata como title, artist, album, e cover art is embedded. It is part of the audio arquivos family.

VLC, foobar2000, and the default media players on Windows and macOS handle AU natively. On mobile, iOS Music and Android media apps vary in their support — popular formats work everywhere; niche ones may need a dedicated app. If playback fails on a device, converting to MP3 or AAC usually solves it.

VLC, foobar2000, e the default media players no Windows e macOS handle AU natively. On mobile, iOS Music e Android media apps vary in their support — popular formatoos funcionar everywhere; niche ones may need a dedicated app. If playback fails em um device, convertendo to MP3 ou AAC Geralmente solves it.

Upload the AU to KaijuConverter and pick MP3, WAV, FLAC, AAC, OGG, or any other target. Our FFmpeg pipeline decodes the audio and re-encodes to the target format at sensible default bitrates (VBR ~190 kbps for music, 96 kbps for speech). Metadata and cover art travel with the audio where both formats support them.

AU can be lossy or lossless depending on the specific variant. Lossy variants (smaller files) discard some audio detail during compression in ways tuned to be inaudible; lossless variants preserve every sample exactly but produce larger files. For distribution, lossy at high bitrate is standard; for archival, lossless wins.