MPEG to AU Converter
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Supports: MPG, MPEG
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Need help?MPEG to AU Converter
An MPEG file (.mpeg / .mpg) is a program stream that usually carries MPEG-1 or MPEG-2 video alongside an MP2 (MPEG Layer II) audio track. AU is the Sun/NeXT audio format (.au, also written .snd) — a deliberately simple, big-endian container that early Unix workstations and Java audio code relied on. This converter discards the video, decodes the MPEG audio track, and writes it out as an AU file. It is an audio-extract: what you get is the soundtrack, not the picture.
Because the AU output is uncompressed linear PCM, expect the file to grow. Decoding lossy MP2 to PCM does not restore detail that compression already threw away — it just stores the same audio without compression. If you simply want a portable audio file, MP3 or M4A is the better target; reach for AU when a legacy Unix tool, a SPARC/NeXT-era workflow, or older Java audio code specifically expects it.
MPEG Audio Format at a Glance
| Property | Value |
|---|---|
| Standard | MPEG-1 (ISO/IEC 11172, published 1993); MPEG-2 (ISO/IEC 13818) |
| Container | Program stream (.mpeg / .mpg) |
| Typical audio codec | MP2 (MPEG-1/2 Audio Layer II); sometimes MP3 (Layer III) |
| Compression | Lossy |
| Typical use | Video CD, DVB broadcast, legacy video files |
| Native browser support | Not reliably playable as a raw .mpeg stream in browsers |
| Best for | Distributing or archiving the original combined video + audio |
AU Format at a Glance
| Property | Value |
|---|---|
| Origin | Introduced by Sun Microsystems; common on NeXT systems and early web pages |
| Extensions | .au, .snd |
| Header | 24-byte header (magic .snd / 0x2e736e64), big-endian |
| Default/original encoding | 8-bit µ-law at 8000 Hz, mono |
| Other encodings | 16-bit linear PCM, A-law, ADPCM variants |
| Compression | Typically uncompressed (PCM) or lightly companded (µ-law/A-law) |
| Best for | Legacy Unix/SPARC tools, Java audio pipelines, simple programmatic parsing |
How to Convert MPEG to AU
- Upload Your MPEG File: Drag and drop your
.mpegor.mpgfile onto the page, or click "Add Files" to browse. You can queue several files to convert with the same settings. - Set Audio Sample Rate: Leave it on "Original" to keep the source rate, or pick a value such as 8000 Hz to match the classic AU/Java profile. Lower rates make smaller files; higher rates do not add quality the source MP2 never had.
- Set Audio Channel: Choose "Original", "Mono", or "Stereo". Mono at 8000 Hz reproduces the historical Sun/Java AU profile and keeps the file small for voice.
- Convert and Download: Click "Convert" and download the AU file. Files are uploaded over an encrypted connection, processed on our servers, and deleted automatically after a few hours. No sign-up, no watermark.
For an everyday-portable result instead of legacy AU, see MPEG to MP3. To turn an existing AU file back into something modern, use AU to MP3.
Frequently Asked Questions
What codec does the AU output use?
The AU file is written as linear PCM (uncompressed), which is the standard payload for .au/.snd. The audio is decoded from the MPEG's MP2 track and re-stored as PCM samples in AU's big-endian layout. If you instead need the historical telephony profile, choose 8000 Hz mono, which corresponds to the µ-law-at-8kHz form Java's audio system is guaranteed to play.
Why is my AU file larger than the MPEG?
Because you are going from lossy to uncompressed. The MPEG's MP2 audio is compressed; AU PCM is not. Decompressing it stores every sample uninterpolated, so the byte count rises even though the audio content is identical to what the MP2 already contained. In our testing, a 3-minute stereo MP2 track around 4 MB expands to roughly 30 MB as 16-bit PCM AU at 44.1 kHz. Lower the sample rate or switch to mono to shrink it.
Does converting to AU improve audio quality?
No. AU being uncompressed does not recover detail that MP2 compression discarded. Quality is capped by the source MPEG audio. Converting to AU only changes how the audio is stored, not how good it sounds. If quality matters more than format, keep the audio in a modern compressed format like MP3 or AAC.
What can open an AU file?
VLC, Audacity, and many cross-platform players read AU, as do most Unix audio tools and Java's javax.sound system. On Windows and macOS you may need a player like VLC since AU is not a default-associated format anymore. For broad compatibility on phones and consumer apps, convert the audio to MP3 instead.
Is the AU format still maintained or widely used?
AU is a legacy format. It was common on Sun/NeXT systems and early web pages and remains in use mainly in older Unix pipelines, Java audio code, and simple scientific/audio-processing scripts that value its minimal header. It is not a format you would choose for new everyday audio distribution.
Does AU support stereo and higher sample rates?
Yes. Although the original profile was 8-bit µ-law mono at 8000 Hz, the AU format supports 16-bit linear PCM, stereo, and higher sample rates. Use the Audio Channel and Audio Sample Rate controls to set these. Note that very old AU readers may only handle the 8 kHz mono µ-law profile, so match your target tool's expectations.
Are my files kept private?
Yes. Your MPEG upload travels over an encrypted connection, is processed on our servers, and is deleted automatically after a few hours. There is no sign-up, no watermark, and files are never shared or made public.