3GPP to AU Converter
Initializing... drag & drop files here
Supports: 3GPP
Advanced Options - Our defaults are optimized for the best results. We recommend you keeping the defaults unless you have a specific need.
Reset to defaults
Need help?3GPP to AU Converter
This tool extracts the audio track from a 3GPP mobile-video file and writes it to AU, the Sun Microsystems audio format. The video is discarded — only the sound is kept. AU is a legacy container most useful on old Unix, Solaris, and Java systems; for everyday playback, 3GPP to MP3 or 3GPP to WAV are far more compatible targets.
3GPP Format at a Glance
| Property | Value |
|---|---|
| Standard | 3GPP file format, based on ISO Base Media File Format (ISO/IEC 14496-12 / MPEG-4 Part 12) |
| Extensions | .3gpp and .3gp (interchangeable — same container) |
| MIME type | video/3gpp, audio/3gpp |
| Video codecs | H.263, MPEG-4 Part 2, or H.264 (AVC) |
| Audio codecs | AMR-NB, AMR-WB, AAC-LC, HE-AAC (all lossy) |
| Designed for | Low-bandwidth 3G mobile capture and streaming |
| Note | The audio inside a 3GPP file is already lossy; converting it cannot add back lost detail |
AU Format at a Glance
| Property | Value |
|---|---|
| Developer | Sun Microsystems (released 1992) |
| Extensions | .au, .snd |
| Structure | 24-byte big-endian header + audio payload |
| Original encoding | Headerless 8-bit μ-law (G.711) at 8000 Hz |
| Supported encodings | μ-law, A-law, linear PCM, and ADPCM variants |
| Byte order | Big-endian (network byte order) |
| Historically used by | NeXT, Sun Solaris, Java applets (AU was Java's default sound format), telephony |
| Best for | Legacy Unix/Java pipelines and scientific audio tooling, not general playback |
How to Convert 3GPP to AU
- Upload Your 3GPP File: Drag and drop your
.3gppor.3gpfile onto the page, or click "+ Add Files" to browse. You can queue several clips and convert them with one set of settings. - Set the Audio Sample Rate: Leave it on "Original" to keep the source rate, or drop it to 8000 Hz to match AU's classic telephone-grade μ-law profile and shrink the file.
- Choose the Audio Channel (Optional): Keep "Original", or pick Mono to halve the size when the recording is speech. You can also use Trim to export only part of the clip.
- Convert and Download: Click "Convert" and download your
.aufile. No sign-up, no watermark.
Frequently Asked Questions
Does the AU file keep the video from my 3GPP clip?
No. AU is an audio-only format, so this conversion extracts just the sound track from the 3GPP file and discards the video entirely. If you need to keep the picture, convert to a video format instead — AU output is sound only.
Will converting 3GPP audio to AU improve the quality?
No. The audio inside a 3GPP file is almost always AMR or AAC, both of which are lossy codecs. Once detail has been discarded at recording time it cannot be restored, so the AU file is at best a faithful copy of the existing audio — never an upgrade. Picking a high sample rate only preserves what is already there.
Is AU a lossy or lossless format?
It depends on the encoding the AU file carries. Linear PCM AU files are uncompressed and lossless but large; μ-law and A-law AU files pack roughly 16 bits of range into 8 bits per sample, which is technically lossy and telephone-grade. The original 1992 AU profile — 8-bit μ-law at 8000 Hz — is the low-fidelity end of that range.
Why would anyone still use the AU format?
AU survives mainly in legacy and technical niches. Java applets historically defaulted to AU for sound, and its compact, easy-to-parse big-endian header keeps it in some scientific-computing and audio-processing pipelines. For phones, browsers, and modern media players, MP3 or WAV are far more widely supported.
What is the difference between .3gpp and .3gp?
There is none — .3gpp and .3gp are two extensions for the exact same 3GPP container, both built on the ISO Base Media File Format. This converter accepts either spelling and treats them identically.
Should I convert to AU, MP3, or WAV?
For almost everyone, AU is the wrong choice. Use 3GPP to MP3 if you want a small, universally playable file, or 3GPP to WAV for a standard uncompressed copy that editing software accepts. Pick AU only when a specific old Unix, Solaris, or Java system requires it.
Is the conversion private and is there a file size limit?
Files are uploaded over an encrypted connection, processed on our servers, and deleted automatically after a few hours — no sign-up, no watermark, never shared or made public. There is no hard file-count limit; the practical constraint on a large clip is the upload size and time, not the conversion itself.