What importing a UST file means and why you'd do it

A UST file is a project file used by singing voice synthesis software — most commonly Utau and OpenUtau. It contains the notes, lyrics, timing, and settings for a vocal performance. When you import a UST file into OpenUtau, you're loading someone else's project (or your own from another device) so you can edit it, add new vocals, or render it with different voice banks.

OpenUtau is the modern, open-source version of Utau that runs on Windows, Mac, and Linux. If you have a UST file from the original Utau software or from another user, OpenUtau can read it directly — you don't need to convert it first. The import process is straightforward, but a few setup steps beforehand will save you from common problems like missing voice banks or broken file paths.

Key Takeaways

  • OpenUtau opens UST files the same way you open any document — through File menu or by dragging the file into the window.
  • Before importing, make sure OpenUtau knows where your voice banks are stored, or the project will load with no voice assigned.
  • If the UST file references voice banks you don't have installed, OpenUtau will warn you but still open the project — you can assign different voices afterward.
  • UST files created in the original Utau software import without conversion, though some advanced settings may not transfer perfectly.

Setting up voice banks before you import

OpenUtau needs to know where your voice banks live on your computer before it can use them. A voice bank is the folder containing the voice data and samples that OpenUtau uses to sing. If you skip this step, your UST file will open but show no voice assigned, and you'll have to manually select one.

Open OpenUtau and go to Tools in the menu bar, then select Settings. Look for the section labeled Voice Bank Locations or Voice Libraries (the exact name depends on your version). Click the button to add a folder, then navigate to wherever you keep your voice banks. Common locations are a folder called "VoiceBanks" on your Desktop, in Documents, or in your Downloads folder. Select the folder and confirm. OpenUtau will scan it and show you how many voice banks it found.

If you don't have any voice banks yet, you can download them from sites like VoiceBankResources or directly from voice bank creators. Once you've added at least one location, close Settings and you're ready to import.

Opening a UST file in OpenUtau

The simplest way is to open OpenUtau, then go to File in the menu bar and click Open. A file browser will appear. Navigate to wherever your UST file is stored and select it, then click Open. The project will load into the editor.

Alternatively, you can drag and drop the UST file directly into the OpenUtau window if it's already open. This works on Windows, Mac, and Linux. If you double-click a UST file on your computer and OpenUtau is set as the default program for that file type, it will open automatically — though you may need to set this up the first time.

The file will load with all its original notes and lyrics intact. If the UST was created in the original Utau software, OpenUtau reads it without any conversion step. You may see a message asking about voice bank compatibility if the original project used voices you don't have installed — this is normal and doesn't prevent the file from opening.

What to do if voices are missing or mismatched

When you open a UST file, OpenUtau checks whether the voice banks it references are installed on your system. If they're not, you'll see a warning dialog. This doesn't break the file — it just means OpenUtau can't find the exact voice the original creator used. You have two choices: install the missing voice bank, or assign a different voice you already have.

To assign a different voice, look at the track panel on the left side of the editor. You'll see a dropdown menu showing the current voice (or "No Voice" if none is assigned). Click the dropdown and select a voice bank from your installed collection. The notes will immediately re-render with the new voice. You can change voices as many times as you want without affecting the notes or lyrics.

If you want to use the original voice, search for it by name online and download it. Once you've placed it in one of your voice bank folders, restart OpenUtau or refresh the voice list (usually through Tools > Refresh Voice Banks or similar). Then open the UST file again and the voice should appear in the dropdown.

Checking and fixing file paths after import

Sometimes a UST file references audio files or resources using a path that doesn't exist on your computer. This happens when someone shares a project that was organized differently on their system. OpenUtau will usually warn you if it can't find a linked file, and the project will still open — but any audio or effects tied to that path won't load.

To check for broken paths, open the UST file and look at the track list. If you see any error messages or missing indicators next to audio files or effects, you'll need to re-link them. Right-click on the affected track or element and look for an option like "Set Audio File" or "Browse for File". Navigate to the correct file on your system and select it. This re-establishes the connection without changing the project itself.

If the UST file is just a vocal project with no external audio files, you won't encounter this problem. Most basic UST files only contain notes and lyrics, which travel perfectly between computers.

Saving your imported project in OpenUtau format

Once you've imported a UST file and made changes, you can save it as a UST file again (keeping it compatible with the original Utau software) or save it as an OpenUtau project file. To save as UST, go to File and select Export as UST. This creates a new UST file with your edits. To save as an OpenUtau project, select File > Save or Save As, which creates a file with the .utau extension that preserves all OpenUtau-specific settings.

If you're collaborating with someone who uses the original Utau software, export as UST so they can open your changes. If you're working only in OpenUtau, saving as a native project file is faster and preserves more detail. You can do both — save a native copy for yourself and export a UST copy to share.

Troubleshooting common import problems

If OpenUtau won't open your UST file at all, the file may be corrupted or in an unrecognized format. Try opening it with a text editor (like Notepad on Windows or TextEdit on Mac) to see if it contains readable text. A valid UST file starts with [#VERSION=] at the top. If it's gibberish or empty, the file is corrupted and can't be recovered.

If the file opens but shows no notes, the UST may have been saved incorrectly or is an empty template. Check that you're looking at the right track — sometimes projects have multiple tracks and notes are on a different one than expected. Use the arrow keys or scroll to navigate between tracks.

If OpenUtau crashes when you try to import, update to the latest version. Older versions sometimes have bugs with certain UST formats. You can download the newest version from the OpenUtau GitHub page. If it still crashes after updating, try opening the UST in the original Utau software first, re-saving it, and then importing it into OpenUtau.

Frequently Asked Questions

Can I import a UST file from the original Utau into OpenUtau?

Yes. OpenUtau reads UST files created in the original Utau software without any conversion. Open the file through File > Open or drag it into the window. Some advanced Utau settings may not transfer perfectly, but all notes and lyrics will load correctly.

What if the UST file uses voice banks I don't have?

OpenUtau will warn you but still open the project. You can assign a different voice bank from your installed collection using the voice dropdown on the left panel. If you want to use the original voice, download and install it, then refresh OpenUtau's voice list.

Do I need to convert a UST file before importing it?

No. OpenUtau opens UST files directly. There's no conversion step required. If you want to save your edits in OpenUtau's native format, you can export as UST or save as a .utau project file, but importing requires no conversion.

Why does my imported UST file have no sound?

The most common reason is that no voice bank is assigned to the track. Check the voice dropdown on the left side — if it says "No Voice", select one from the list. If voices aren't showing up, make sure you've added voice bank locations in Tools > Settings and that your voice banks are in those folders.

Can I edit a UST file after importing it?

Yes. Once imported, you can edit notes, lyrics, timing, vibrato, and all other parameters the same way you would in a new project. You can also change voice banks, add effects, and render audio. Save your changes as a new UST file or as an OpenUtau project file.