AV1 to AU Converter

Convert AV1 to AU: Read This First

This page converts an .av1 file to .au, the legacy Sun/NeXT audio format. There is a catch worth knowing before you upload: a bare .av1 file is a raw AV1 video bitstream — a sequence of Open Bitstream Units (OBUs) that holds picture only, no sound. AV1 is a video codec from the Alliance for Open Media, and its specification defines no audio at all; the soundtrack that accompanies an AV1 video lives in a container (MP4, WebM, or MKV), never in the raw stream. So extracting audio from a true .av1 file usually produces a silent or empty AU, because there is nothing inside to extract. If you actually want the soundtrack, you almost certainly need to convert the container file instead — keep reading for exactly how.

How to Convert AV1 to AU

1. Upload Your AV1 File: Drag and drop your .av1 file onto the page, or click "+ Add Files" to browse. You can queue several files and convert them in one batch with the same settings.
2. Set the Audio Channel: Open Advanced Options and leave Audio Channel on "Original" to keep the source layout, or force Mono/Stereo if a target device needs it.
3. Set the Audio Sample Rate or Trim (Optional): Leave Audio Sample Rate on "Original" for a 1:1 transfer, or pick a specific rate such as 44100 Hz. Set Trim (default "Unchanged") to export only a start-and-duration window.
4. Convert and Download: Click "Convert" and download your AU file. No sign-up, no watermark.

Walk-through: Why a Raw AV1 File Has No Sound to Extract

AV1 is purely a video coding format. The raw bitstream — the kind of file that carries an .av1 (or .obu) extension — packetizes everything into Open Bitstream Units, and the AV1 specification defines those units for coded video only. Audio is never part of the AV1 stream; when you watch an AV1 video with sound, that audio is a separate track (commonly Opus or AAC) multiplexed alongside the video inside a container such as MP4, WebM, or Matroska (MKV).

That distinction is the whole story here:

• If you genuinely have a raw .av1 bitstream, there is no audio track inside it, so converting it to AU gives you an empty or silent file. That is not a fault in the tool — there is simply no sound in the source to write into the AU.
• If your "AV1 file" is really an .mp4 / .webm / .mkv whose video happens to use the AV1 codec, the soundtrack you want is in that container. Convert the container directly with MP4 to AU or WebM to AU and you will get the audio. People often call those files "AV1 files" loosely because the video codec is AV1, but the extension on disk decides which tool to use.

When AU is written here, the audio is stored as uncompressed PCM, 16-bit, big-endian. That is a natural fit for the format: the AU header stores all fields, including sample data, in big-endian order, and 16-bit linear PCM is one of its standard encodings. AU is a simple format introduced by Sun Microsystems, common on NeXT systems and early web pages, using the .au/.snd extensions and the audio/basic MIME type.

AV1 (source) vs AU (output here) at a Glance

Common Errors and How to Fix Them

• "My AU is silent or empty" — Expected for a true raw .av1 bitstream: it contains no audio to extract. Convert the container that holds your AV1 video instead — MP4 to AU, WebM to AU, or MKV to AU.
• "I wanted to keep the video" — This is an audio target. To keep the picture, convert AV1 to a video format such as AV1 to MP4.
• "The AU won't play on my phone" — AU is an old desktop format with thin native support outside Unix and macOS tooling. VLC and Audacity open it on every platform; for broader compatibility, AV1 to WAV or AV1 to MP3 is the safer target.
• "The AU file is large" — AU here is uncompressed PCM, so size scales with sample rate, bit depth, and channels — there is no quality slider to shrink it. If you need a small file, pick the lossy AV1 to MP3 instead.
• "The file won't upload or convert" — A raw .av1 stream that is truncated or non-conformant may fail to decode. Confirm the file plays in a current build of VLC first.

When This Doesn't Work

This tool can only write audio that actually exists in the source. A genuine raw .av1 bitstream is video-only, so there is no soundtrack for it to produce — the realistic path to an AU file with sound is to start from the container that carries both the AV1 video and its audio track and use MP4 to AU or WebM to AU. If you only want to keep the video, reach for AV1 to MP4 instead, and if you need a small, broadly playable audio file rather than legacy AU, AV1 to MP3 is the better target.

Frequently Asked Questions

Why is my AV1-to-AU output silent or empty?

Because a raw .av1 file is a video-only bitstream. AV1 is a video codec, and its raw Open Bitstream Unit stream carries no audio track at all — sound always rides in a container (MP4, WebM, MKV) alongside the AV1 video. With nothing to extract, the AU comes out empty or silent. To get the soundtrack, convert the container file with MP4 to AU or WebM to AU.

My video uses AV1 but it's an MP4 — which tool do I use?

Use the tool that matches the file's actual extension. If the file on disk ends in .mp4, the audio is inside that MP4 container even though the video codec is AV1, so MP4 to AU is the right choice. Use this AV1-to-AU page only for true raw .av1 (or .obu) bitstreams — and those have no audio to extract.

Does converting AV1 to AU keep the video?

No. AU is an audio-only format, so this is an audio-extraction tool with no picture in the output. Because a raw .av1 stream is video-only to begin with, you would also be extracting from a file that has no sound. If you want to keep the video, convert to a video format such as AV1 to MP4.

What encoding does the AU file use, and is it compressed?

It is uncompressed. The AU here is written as 16-bit linear PCM in big-endian byte order, which matches the AU format's native big-endian layout — the format stores all fields, including sample data, most-significant-byte first. AU can technically also carry μ-law and other encodings, but this converter writes the uncompressed PCM form, so files are larger than a lossy MP3 of the same audio.

Should I pick AU, WAV, or MP3 for audio from an AV1 video?

Once you are converting the right file — the container, not a raw .av1 — AU is the niche pick: choose it only when an old Unix or NeXT-era tool specifically requires .au/.snd. For editing on modern systems, the uncompressed AV1 to WAV is far more widely supported; for a small, broadly playable file, AV1 to MP3 is the better target. AU is rarely the default choice today.

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 — no sign-up, no watermark, never shared or made public. In our testing, a true raw .av1 stream produced an empty AU file exactly as the format dictates, while a container that actually held an audio track decoded its sound to PCM cleanly.