MPEG to AU Converter

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 default AU output is 8-bit µ-law (one byte per sample per channel), expect the file to grow versus the compressed MP2 track. Decoding lossy MP2 does not restore detail that compression already threw away — and µ-law's telephone-grade companding trims a little more; select 16-bit PCM (PCM_S16BE) in the advanced options if you need a full-fidelity linear copy. 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

AU Format at a Glance

How to Convert MPEG to AU

1. Upload Your MPEG File: Drag and drop your .mpeg or .mpg file onto the page, or click "Add Files" to browse. You can queue several files to convert with the same settings.
2. 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.
3. 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.
4. 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 8-bit µ-law (G.711) by default — the classic .au/.snd payload. The audio is decoded from the MPEG's MP2 track, companded to µ-law, and stored in AU's big-endian layout. Choose 8000 Hz mono as well to reproduce the historical telephony profile Java's audio system is guaranteed to play; A-law and 16-bit linear PCM (PCM_S16BE) are selectable in the advanced options if you need an uncompressed copy.

Why is my AU file larger than the MPEG?

Because you are going from lossy compression to a fixed byte-per-sample encoding. The MPEG's MP2 audio is compressed; the default µ-law AU stores one byte per sample per channel, so a 3-minute stereo track at 44.1 kHz comes to roughly 16 MB (44,100 × 2 channels × 180 s) — several times a ~4 MB MP2 track. Selecting 16-bit PCM doubles that to about 32 MB. Lower the sample rate or switch to mono to shrink it.

Does converting to AU improve audio quality?

No. Converting to AU does not recover detail that MP2 compression discarded — and the default 8-bit µ-law encoding is telephone-grade, so it can shave a little more off. 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.

AU or WAV — which uncompressed format should I pick?

Both can store uncompressed PCM (for AU here, select 16-bit PCM in the advanced options — the default is 8-bit µ-law), and as PCM the audio quality is identical; the difference is heritage and support. AU is big-endian with a minimal 24-byte header and comes from the Sun/NeXT world, while WAV is little-endian (RIFF) and is the Windows and general-purpose standard that far more editors and players open without fuss. Choose AU only when a legacy Unix, SPARC, or Java audio tool specifically expects .au/.snd; for a modern uncompressed handoff, MPEG to WAV is the safer target.

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.