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 writes that same 8-bit µ-law encoding by default (at the source's sample rate unless you resample); A-law and 16-bit big-endian linear PCM (PCM_S16BE) can be selected in the advanced options. 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. Re-encoding to AU does not recover any detail the lossy encoding already threw away — and µ-law's telephony-grade companding can shave a little more off. Select 16-bit PCM if you need a full-fidelity copy of the decoded track.
• Even 8-bit µ-law stores one full byte per sample per channel, so the .au is typically larger than the compressed 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 re-encoding it into AU only makes a bigger file that sounds no better than the original; the default 8-bit µ-law output is telephony-grade companding, which can even trim a little fidelity. The quality ceiling is set by the MP2 or AC-3 inside the MPG, and no AU encoding can 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 default 8-bit µ-law (or A-law / 16-bit PCM if you select those), 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?

Yes. The historic .au people remember from Sun workstations was 8-bit µ-law at 8000 Hz, and this converter writes 8-bit G.711 µ-law by default — though at the source's sample rate unless you also set Audio Sample Rate to 8000 Hz for the full classic profile. If you would rather keep full-bandwidth audio instead of telephone-grade companding, select 16-bit big-endian linear PCM (PCM_S16BE) in the advanced options; A-law is also available.

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

Because even AU's default 8-bit µ-law stores one full byte per sample per channel — at 44.1 kHz stereo that is about 5.3 MB per minute, several times more than a typical 192 kbit/s MP2 track (~1.4 MB per minute) occupies inside the MPG. Selecting 16-bit PCM doubles the output again. The extra bytes are raw sample 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. Size-wise, expect roughly 5.3 MB per minute for the default 8-bit µ-law output at 44.1 kHz stereo (sample rate × channels × 1 byte/sec), and about double that if you select 16-bit PCM — 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 the output, since the byte rate is fixed by sample rate × channels.