MPG to AU Converter

MPG to AU Converter

This tool extracts the audio track from an MPG (MPEG-1/MPEG-2) video and writes it into an .au file — the Sun Microsystems audio format from the Unix-workstation and early-Web era, also seen with the .snd extension. The video is discarded; only the soundtrack is kept. AU is a niche target today, so be clear on why you'd want it: a legacy Unix tool, an old Java program, or a retro-computing or academic pipeline that specifically reads the Sun audio format. If you just want the audio to play or share normally, MPG to MP3 or MPG to WAV (the standard uncompressed-PCM choice) is almost always the better pick — AU gives you no quality or size advantage over those.

MPG Format at a Glance

AU Format at a Glance

What This Converter Writes Into the AU

The .au most people picture is 8-bit µ-law at 8 kHz — the lossy companded format SunOS exposed through /dev/audio. This converter does not down-convert to that by default; it writes 16-bit big-endian linear PCM into the AU container, which is the muxer's default and a lossless encoding. What you get out therefore depends on what was inside the MPG:

• An MPG soundtrack is almost always MPEG-1 Audio Layer II (MP2), sometimes AC-3 on MPEG-2/DVD-style streams. Both are lossy. Wrapping that audio in PCM does not recover any detail the lossy encoding already threw away — you simply get a larger, uncompressed file that sounds the same as the source track.
• Because AU's linear PCM is uncompressed, the .au is typically larger than the audio occupied inside the MPG. You are paying bytes for the container, not gaining fidelity.

How to Convert MPG to AU

1. Upload Your MPG File: Drag and drop your .mpg or .mpeg onto the page, or click "+ Add Files". Several files can be queued and converted with the same settings.
2. Set Audio Sample Rate and Audio Channel: Leave Audio Sample Rate and Audio Channel on "Original" to copy the MPG track's native rate and layout untouched, or change them to resample or downmix to mono if a legacy target needs it.
3. Trim (Optional): Use the Trim control to export just a section of the audio, or leave it "Unchanged" to extract the whole track.
4. Convert and Download: Click "Convert" and download your AU file. No sign-up, no watermark.

Files are uploaded over an encrypted connection, processed on our servers, and deleted automatically a few hours after conversion — never shared or made public.

Frequently Asked Questions

Will extracting MPG audio to AU improve the sound quality?

No. Converting cannot add detail that was never in the source. An MPG soundtrack is lossy to begin with — usually MPEG-1 Audio Layer II (MP2), sometimes AC-3 — so writing it into AU's linear PCM only makes a bigger file that sounds identical to the original. The quality ceiling is set by the MP2 or AC-3 inside the MPG, and an uncompressed container cannot raise it.

What audio codec does an MPG actually contain?

MPG is a container, not a codec. MPEG-1 program streams almost always carry MPEG-1 Audio Layer II (MP2), the audio standard used by Video CD and digital broadcast. MPEG-2 streams may instead carry MP2 or AC-3 (Dolby Digital). This tool decodes whichever stream is present and re-encodes it as AU's 16-bit PCM, so you don't need to know the source codec in advance.

Does the AU output use 8-bit µ-law like classic Unix .au files?

No. The historic .au people remember from Sun workstations was 8-bit µ-law at 8000 Hz — lossy and telephone-grade. This converter writes 16-bit big-endian linear PCM by default, the AU container's lossless default, preserving full-bandwidth audio rather than companding it down to µ-law. If a specific legacy tool requires exactly 8-bit µ-law, this output will not match that encoding, and you would need a tool that lets you force the µ-law codec.

Why is my .au file larger than the MPG's audio?

Because AU's linear PCM is uncompressed. The audio inside an MPG is stored with a compressed codec like MP2 or AC-3, which is far smaller than raw PCM. When that track is written out as 16-bit PCM, every sample is stored in full, so the .au commonly grows several times larger than the compressed audio occupied in the MPG. The extra bytes are uncompressed data, not added quality.

Why would anyone convert to AU instead of MP3 or WAV?

Only for compatibility with something that specifically expects .au. Early Java was the classic case: its original sound API supported one format — Sun .au — so applet and desktop audio of that era shipped as AU. Other realistic cases are a legacy Unix or NeXT-lineage program that reads the Sun format natively, or an academic or retro-computing pipeline that documents .au as its interchange format. For listening, sharing, or editing, MPG to MP3 or MPG to WAV is the better choice.

What if my MPG has no audio track?

Then there is nothing to extract, and the result is an empty or zero-length .au. Some MPG files are video-only, and a few carry more than one audio stream; the extractor takes the first audio stream it finds. If your output is silent, re-check that the source clip actually contains the audio you expect.

How are my files handled, and how long do you keep them?

Files are uploaded over an encrypted connection, processed on our servers, and deleted automatically a few hours after conversion — never shared, never made public, with no sign-up and no watermark. In our testing, a one-minute MPG with stereo 16-bit/44.1 kHz audio produced an .au of roughly 10 MB, since CD-quality stereo PCM runs about 10 MB per minute regardless of how compact the audio was inside the original MPG.

Can I resample the AU or convert it to mono for an older tool?

Yes. The Audio Sample Rate and Audio Channel controls default to "Original," copying the MPG track's native rate and layout into the .au. If a legacy reader expects something specific — classic Sun .au pipelines often assume 8000 Hz mono — set those dropdowns before converting. Downmixing to mono also roughly halves the size of an otherwise uncompressed PCM file.