Convert AU to subtitles

Sonix transcribes your AU file and creates timestamped subtitles in SRT, VTT, and other formats.

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SRT & VTT
5-min turnaround
All platforms
AU conversion guide

Create subtitles from AU in 6 steps

  1. 1
    Create account~30 sec

    Sign up for a free Sonix trial with 30 free minutes.

  2. 2
    Upload file~1 min

    Upload your AU file from your computer or cloud storage.

    44+ formats supported
  3. 3
    Select language~10 sec

    Select the language spoken in your file.

    54+ languages
  4. 4
    Auto-transcribe~5 min

    Sonix AI transcribes your AU with word-level timestamps.

  5. 5
    Split subtitles~2 min

    Customize line length, duration, and subtitle breaks.

  6. 6
    Export~10 sec

    Download your subtitles as SRT or VTT files.

    30+ export formats
The AU file format

Understanding AU files

What is a AU file?

Audacity project audio chunks

Audacity, an open source audio editor, breaks long tracks into small pieces so it can edit them more efficiently. Thus, when you save an Audacity Project File (.AUP), Audacity will automatically create a _data folder that has the same name as the AUP file and breaks the longer audio file into smaller chunks that have the .AU extension. Thus, when Audacity opens up the AUP Project File, it loads the individual AU files in the correct sequence automatically. The user should not move or rename and AU files in the _data folder.

Common uses for AU files

  • Audacity audio editing
  • Audio project files
  • Audacity project folders

Who works with AU files?

Podcast editors and home-studio producers usually run into AU files when recovering audio from legacy Audacity projects, since older versions of the editor stored each track as small AU chunks. Unix system administrators and Java developers may also recognize the format from its origins as the standard sound file on Sun and NeXT workstations.

AU vs WAV: which should you use?

AU and WAV are both simple header-plus-data audio formats: WAV, created by Microsoft and IBM, became the de facto standard for uncompressed audio, while AU originated on Sun and NeXT systems and survives mainly in legacy Unix software and older Audacity project folders. Both can hold uncompressed PCM, but WAV has far broader support in modern editors, players, and web tools. Choose WAV when exporting or sharing audio; AU is typically something a legacy project or system hands to you rather than a format you pick.

Convert WAV to text
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Get your AU subtitles in minutes
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Industry-leading AI for AU files
53+
Languages
Subtitles in any language
30+
Export formats
SRT, VTT, FCPXML, and more
AU conversion FAQ

AU subtitles: frequently asked questions

Can you create subtitles from AU files?

Yes! Sonix transcribes your AU file with word-level timestamps and creates professional subtitles in SRT, VTT, and other formats.

What subtitle formats are supported?

Export subtitles as SRT (most universal), VTT (web video), FCPXML (Final Cut Pro), and many more formats.

Can I customize subtitle timing?

Yes! Adjust max characters per line, lines per caption, max duration, and manually fine-tune any timing.

How do I add subtitles to my video?

Upload the SRT/VTT file to YouTube, Vimeo, or import into your video editor. You can also burn subtitles directly into the video.

Can I translate subtitles?

Yes! Sonix can translate your subtitles into 55+ languages, making your content accessible globally.

Are the subtitles accurate?

Sonix achieves up to 99% accuracy. Use our editor to make any corrections before exporting.

Why is my Audacity project folder full of small AU files?

Older versions of Audacity split a project's audio into small AU block files inside a _data folder so long tracks could be edited efficiently, and the .aup project file reassembles them in order. Avoid moving or renaming these chunks; open the project and export the audio instead.

How do I play a standalone AU file?

Standalone AU files use the Sun audio format and open in players such as VLC and editors such as Audacity. Converting to WAV or MP3 gives the broadest compatibility with modern software and devices.

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