3GP to AU Converter
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Supports: 3GP, 3G2
Advanced Options - Our defaults are optimized for the best results. We recommend you keeping the defaults unless you have a specific need.
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Need help?3GP to AU Converter
3GP is the 3GPP mobile-phone container that wraps video alongside an audio track (usually AMR or AAC). AU (.au, also .snd) is Sun Microsystems' legacy Unix audio format. This converter discards the video, pulls the audio track out of your 3GP, and re-encodes it as an AU file — useful when an old Unix toolchain, a Java applet, or a telephony pipeline specifically expects .au input.
3GP Format at a Glance
| Property | Value |
|---|---|
| Full name | 3GPP multimedia container |
| Standardized by | 3rd Generation Partnership Project (3GPP) |
| Container basis | ISO base media format (MPEG-4 / .mp4 derived) |
| Typical video codec | H.263, H.264/AVC, MPEG-4 Part 2 |
| Typical audio codec | AMR-NB, AMR-WB, AAC-LC |
| Common source | 3G/feature-phone camera recordings |
| What this tool keeps | The audio track only — video is dropped |
AU Format at a Glance
| Property | Value |
|---|---|
| Full name | Sun/NeXT audio (.au / .snd) |
| Origin | Sun Microsystems; common on NeXT and early web pages |
| Magic number | 0x2e736e64 — the ASCII bytes ".snd" |
| Header | 24-byte fixed header (data offset, size, encoding, sample rate, channels) |
| Original default encoding | 8-bit μ-law at 8000 Hz |
| Other encodings | Linear PCM (8–32 bit), A-law, G.72x ADPCM, IEEE float |
| Best for | Legacy Unix audio, telephony, Java AudioClip defaults |
How to Convert 3GP to AU
- Upload Your 3GP File: Drag and drop your .3gp or .3g2 file onto the page, or click "Add Files" to browse. Multiple files queue with the same settings.
- Set Audio Channel and Sample Rate: Leave both at "Original" to mirror the source, or open "Show All Options" to force mono and a fixed rate such as 8000 Hz for a small, telephony-style μ-law AU.
- Trim (Optional): Set a start time and duration if you only need a clip rather than the full track.
- Convert and Download: Click "Convert" and save the .au file. No sign-up, no watermark — files are uploaded over an encrypted connection, processed on our servers, and deleted automatically after a few hours.
Frequently Asked Questions
Does the AU file keep any video from the 3GP?
No. AU is an audio-only format, so the converter extracts just the audio track and the video is discarded entirely. If you want to keep the picture, convert to a video target like MP4 or MOV instead.
Is the audio re-encoded, and will I lose quality?
Yes, it is re-encoded. A 3GP's audio is usually already lossy (AMR or AAC), so this is a lossy-source-to-AU pass and cannot recover detail the original recording never had. The default 8-bit μ-law output shrinks the file at the cost of some fidelity; selecting 16-bit PCM (PCM_S16BE) in the advanced options preserves what is there but will not improve it.
Should I use AU at all, or is MP3 a better choice?
For everyday portable audio, MP3 is far more practical — it is smaller, plays everywhere, and is what most people actually want. Pick AU only when a tool, applet, or legacy Unix workflow specifically requires .au. If MP3 is what you need, use 3GP to MP3 instead.
What is μ-law and why is the AU so small at 8 kHz?
μ-law (mu-law) is logarithmic companding from telephony that stores each sample in 8 bits at an 8000 Hz rate — about 8 KB per second, roughly half the size of 16-bit PCM. It is fine for speech but noticeably degrades music. In our testing, forcing mono 8000 Hz on a short voice clip produced a compact μ-law-style AU, while leaving the defaults at "Original" produced a larger, fuller-rate file.
What software opens an AU file?
AU is widely supported by open-source audio tools, including SoX, Audacity, FFmpeg, and most Unix/Linux command-line players. Java's AudioClip historically used AU as a default, which is why it still appears in older applet and game-asset workflows.
Can I get uncompressed PCM in the AU instead of μ-law?
Yes. The converter writes 8-bit μ-law by default, but you can select 16-bit PCM (PCM_S16BE) in the advanced options — uncompressed and twice the bytes per sample, avoiding companding loss. If you mainly want uncompressed audio for editing and do not specifically need the .au container, 3GP to WAV is a more broadly compatible option.
Are my files kept private?
Yes. Files are uploaded over an encrypted connection, processed on our servers, and deleted automatically after a few hours. There is no sign-up, no watermark, and files are never shared or made public.
What is the difference between a .au and a .snd file?
None in practice — they are the same Sun/NeXT audio format under two names. The format's magic number is literally the ASCII bytes .snd, and NeXT systems used the .snd extension while Sun and the early web settled on .au. A player that opens one opens the other, and you can rename between them without touching the audio. This converter writes the format either way.
Is AU the same as WAV or AIFF?
No, though all three can hold uncompressed PCM. AU uses a compact 24-byte header and stores its samples big-endian, the Unix/Sun convention; WAV is Microsoft's little-endian RIFF format; and AIFF is Apple's big-endian IFF format. The audio inside can be equivalent, but the headers and byte order differ, so pick AU only when a Unix toolchain or Java AudioClip specifically wants it — otherwise 3GP to WAV is more broadly compatible.