MPEG4 to AU Converter
Processing entirely on your device — large files may take a moment.
MPEG4 is a common shorthand extension for MPEG-4 Part 2 streams — handled through the same MPEG program-stream path. Converting AU to WAV preserves the samples in a format every modern tool reads.
iLoveConverter processes everything locally on your computer, which makes it private and fast: no upload wait, no server storage, no limits. Add as many files as you like — batch conversion is built in.
How MPEG4 compares to AU
| MPEG4 | AU | |
|---|---|---|
| Compression | MPEG-1 / MPEG-2 | µ-law or PCM |
| Quality | Standard definition | Mono voice-grade (µ-law) |
| Compatibility | Universal decode | Legacy Unix tools |
| Best for | Legacy disc and capture video | Old system sounds and recordings |
How to convert MPEG4 to AU
- 1
Select your files
Select your MPEG4 video.
- 2
Convert instantly
The engine demuxes the container and encodes the audio track into your chosen format.
- 3
Download results
Download the AU audio — the video track is simply dropped.
About the MPEG4 format
MPG (MPEG program stream) usually means MPEG-1 or MPEG-2 video — the codecs of VCD, SVCD and DVD, and of countless home video captures in the 1990s and 2000s. MPEG-1 tops out around VHS-grade 352×288; MPEG-2 delivers proper standard definition and still runs inside broadcast and DVD infrastructure.
Playback compatibility is its superpower: MPEG-1/2 decode paths exist in every player and hardware made this century. Quality-to-bitrate efficiency, however, is a generation behind H.264 — converting old MPG files to MP4 typically halves their size.
+Strengths
- ✓Decodes on essentially every player and device
- ✓Simple, battle-tested standard
!Limitations
- −Inefficient codecs by modern standards
- −MPEG-1 is VHS-grade at best
About the AU format
AU is Sun Microsystems' audio format from the Unix workstation age: a small header followed by µ-law (or PCM) samples. Java's applet era shipped it everywhere, and old Unix sound tooling still emits it.
Modern players increasingly skip it. Converting AU to WAV preserves the samples bit-for-bit while moving the file into universal territory — the standard rescue path for system sounds and old recordings.
+Strengths
- ✓Simple, lossless sample storage
- ✓Native to old Unix/Java tooling
!Limitations
- −µ-law flavor sounds dated and mono
- −Dropped by modern players
Why convert MPEG4 to AU?
Think of it as moving your file to the container that fits the job. Inefficient codecs by modern standards AU works differently: Simple, lossless sample storage If any of that sounds like your task, run the conversion — it takes seconds and nothing leaves your device.
Frequently asked questions
Is this MPEG4 to AU converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
Is there a file size limit for MPEG4 to AU?
The only limit is your device's memory, since nothing is uploaded. Files up to a few hundred megabytes work fine on a modern desktop browser; very large files simply take a little longer.
Will the audio track be kept?
Yes. The audio is carried over and re-encoded to the standard audio codec of AU, staying in sync with the video. If your MPEG4 file has multiple audio tracks, the first one is used.
Why is video conversion slower than image conversion?
Every frame has to be decoded and re-encoded. This site runs that work on your own CPU via WebAssembly — nothing is uploaded, but a multi-minute video reasonably takes a few minutes. Images, by comparison, are single-frame jobs.