CONVERT
AU → OGG
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Fast, secure AU to OGG conversion. No registration required.
Here is the short version — AU is the Sun/NeXT audio format, a historical PCM container still found in older pipelines. Hence the need for OGG. A AU to OGG conversion is typically about compatibility: some players refuse AU, many accept OGG. The audio payload makes the round trip with minimal artefacts when bitrate is left at sensible defaults. Drop a AU file into the uploader and the OGG comes back in seconds. Technical note: AU is the Sun/NeXT audio format, a historical PCM container still found in older pipelines. Compare that with OGG is the royalty-free open container typically holding Vorbis or Opus audio streams.
Sun AU Audio
Source formatAU is a simple audio format from Sun Microsystems, commonly used on Unix systems.
OGG Vorbis Audio
Target formatOGG 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.
Why convert AU to OGG
Moving from AU to OGG usually buys compatibility or a friendlier file size. For spoken-word content the difference is inaudible; for high-resolution music pick the highest bitrate the OGG codec supports to avoid compounding compression.
HOW TO CONVERT
AU → OGG
Provide the audio file
Drag the AU onto the uploader. Files up to 25 MB run on the free tier without registration; paid plans go up to 2 GB.
ffmpeg handles the conversion
Our ffmpeg-based pipeline reads sample rate and channel layout, then writes a matching OGG with ID3 tags intact.
Save the output
Click to download the OGG. Batch uploads are bundled into a ZIP for single-click retrieval.
Common Use Cases
Share across platforms
Send OGG files to anyone without worrying about whether they have the right software for AU.
Embed in documents
Drop OGG output into Word, Google Docs, PowerPoint, Notion or a website without conversion warnings.
Optimize size
OGG often produces smaller files than AU for web, email and storage.
Archive & future-proof
Store in a widely-supported format that will still open on future operating systems without legacy plugins.
AU vs OGG — Strengths and limitations
What each format does best, and where it falls short.
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.
Limitations
- Aging — obsolete outside legacy and compatibility scenarios.
- No metadata beyond a single annotation string.
- No native multi-channel surround support.
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
- 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.
AU vs OGG — Technical specifications
Side-by-side comparison of the technical details.
AU
- MIME types
- audio/basic, audio/au, audio/x-au
- Extensions
- .au, .snd
- Header
- 24 bytes (magic, offset, size, encoding, rate, channels, info)
- Codecs
- PCM 8/16/24/32-bit, µ-law, A-law, IEEE float
- Byte order
- Big-endian
OGG
- MIME types
- audio/ogg, application/ogg
- Extensions
- .ogg (audio), .oga, .ogv (video), .ogx (app), .opus
- Codecs
- Vorbis, Opus, Speex, FLAC, Theora (video), Dirac
- Standard
- RFC 3533 (container), RFC 5334 (MIME)
- Streaming
- Native (page-based structure)
| 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) |
AU vs OGG — Typical file sizes
Approximate file sizes for common scenarios.
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
Quality & Compatibility
Sample rate, channel layout and bit depth are preserved by default: a 44.1 kHz stereo AU becomes a 44.1 kHz stereo OGG. Metadata — title, artist, album, cover art — travels where both formats support it. Protected DRM content cannot be converted legally and is rejected.
Tips for Best Results
- Check the podcast host specification before choosing bitrate — some mandate CBR 64 kbps, others accept VBR up to 192 kbps.
- Preserve ID3 tags by editing them before conversion; Mp3tag and MusicBrainz Picard handle round-tripping cleanly.
- If the AU is 24-bit studio audio, the OGG at 16-bit is sufficient for listening; higher is wasted on consumer playback gear.
Frequently Asked Questions
Lossy-to-lossy conversions (most combinations) re-compress the audio, which technically introduces some loss. At a 192 kbps or higher target it is inaudible on normal equipment. Lossy-to-lossless conversions freeze the existing quality but cannot improve it; lossless-to-lossy transcodes are only as good as the target bitrate you choose.
For voice content (podcasts, audiobooks, lectures) 128 kbps is indistinguishable from higher bitrates. For music, 192-256 kbps covers most listening; 320 kbps is the ceiling for OGG and the right choice for audio you plan to edit further. Above that, prefer a lossless target instead.
Yes. Title, artist, album, year and cover art travel from the AU container to the OGG container automatically where both formats support them. If a tag field has no OGG equivalent, it is dropped silently. Use any tag editor (Mp3tag, MusicBrainz Picard) to fine-tune afterwards.
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Your files are encrypted during transfer, processed in isolated containers, and automatically deleted within 60 minutes. We never read, share, or store your data.