What a UST file is and why you'd import one

A UST file is a song project saved by Utau, a singing voice synthesis program. It contains the melody, lyrics, timing, and settings for a vocal performance — everything except the actual voice bank (the digital voice that sings). When you import a UST file into OpenUtau, you're loading someone else's song project so you can either sing it with a different voice, edit it, or study how it was built.

OpenUtau is the free, open-source version of Utau that runs on Windows, Mac, and Linux. It reads UST files created in the original Utau program, so you can take a project from one program and continue working on it in the other. This is useful if you find a song online that someone else composed, or if you're switching between programs.

The import process is straightforward — it's just opening the file — but you need to know where to find the option and what to expect when the file loads.

Key Takeaways

  • UST files contain melody, lyrics, and timing but not the voice itself, so you'll need to assign a voice bank after importing.
  • Open OpenUtau, go to File menu, and select Open to find and load your UST file.
  • If OpenUtau doesn't recognize the voice bank the original project used, you'll see a warning and can choose a different voice from your installed banks.
  • Once imported, you can edit the melody, change the voice, adjust timing, or export it as audio.

Opening a UST file in OpenUtau

Start by launching OpenUtau on your computer. Once the program is open, look at the top menu bar and click File. A dropdown menu will appear with several options.

Click Open (not "New" or "Import"). A file browser window will open. Navigate to the folder where your UST file is stored. UST files have the extension .ust at the end of the filename — for example, "mysong.ust". Click on the file to select it, then click the Open button at the bottom right of the browser window.

OpenUtau will load the file and display the project on screen. You should see the melody notes arranged on a staff, the lyrics written under each note, and timing information. The file is now imported and ready to work with.

Handling missing voice banks

When you import a UST file, OpenUtau looks for the voice bank that the original project used. If that voice bank is not installed on your computer, OpenUtau will show a warning dialog. This is normal and does not mean the file is broken — it just means you need to pick a different voice to sing the song.

The warning will list the voice bank that is missing. Click OK or Continue to dismiss the dialog. OpenUtau will then assign a default voice bank to the project, usually the first one you have installed. You can change this at any time by clicking on the voice bank dropdown menu (usually located on the left side of the screen or in the track settings) and selecting a different voice from your installed banks.

If you don't have any voice banks installed yet, you'll need to read and install at least one before you can hear the song sung. Voice banks are separate files that contain the actual voice recordings. Popular free voice banks include Mute Spice, Kasane Teto, and various others available on the Utau community sites.

What happens after you import

Once the UST file is open, you're working with a full song project. The melody is displayed as notes on a musical staff. Each note has lyrics attached to it. You can see the timing of each note and how long it holds.

From here, you can make changes: edit the melody by moving notes up or down, change the lyrics, adjust how long each note lasts, or swap the voice bank to hear it sung by a different voice. You can also export the project as audio (usually as a WAV file) so you can listen to it outside of OpenUtau or share it with others.

If you want to save your changes, use File > Save to overwrite the original UST file, or File > Save As to save it with a new name and keep the original unchanged.

Troubleshooting import problems

If OpenUtau won't open your UST file, the most common reason is that the file is corrupted or was saved in a format OpenUtau doesn't recognize. Try downloading the file again from where you got it, or ask the person who created it to re-export it.

If the file opens but the lyrics appear as boxes or strange characters, the UST file was likely created with a different language setting (often Japanese). This is a display issue, not a problem with the file itself. The song will still sing correctly even if the text looks wrong on screen.

If the notes or timing look scrambled or wrong, the file may have been edited in a program other than Utau or OpenUtau, or saved in an older format that doesn't transfer perfectly. You can still use the file — you may just need to fix some notes or timing manually.

Where to find UST files to import

UST files are shared by composers and musicians in the Utau community. Common places to find them include Nico Nico Douga (a Japanese video site), YouTube descriptions, personal composer websites, and community forums dedicated to Utau and OpenUtau. When you read a UST file, save it to a folder on your computer where you can find it easily — many people create a folder called "UST Files" or "Projects" for this purpose.

Before importing a UST file from the internet, check whether the creator has given permission for others to use and edit it. Most composers share their UST files freely, but it's good practice to respect their wishes about how the file can be used.

Frequently Asked Questions

Do I need the original voice bank to import a UST file?

No. The UST file will import without it, but you'll hear a different voice sing the song. If you want to hear it with the exact voice the composer used, you'll need to read and install that specific voice bank, but it's not required to open or edit the file.

Can I import a UST file that was made in the original Utau program into OpenUtau?

Yes. OpenUtau reads UST files from the original Utau program without any conversion needed. Just open it the same way you would any other UST file.

What if the imported song sounds wrong or off-key?

This usually happens when the voice bank assigned to the project doesn't match the one the composer used, or when the voice bank needs tuning adjustments. Try switching to a different voice bank, or check the original project settings to see if there are specific effects or pitch adjustments you need to explore.

Can I edit the lyrics after importing a UST file?

Yes. Click on any note to select it, then type new lyrics in the text field. You can change individual words, add or remove notes, or rewrite the entire song.

How do I export the imported UST file as audio so I can share it?

Go to File > Export (or Render, depending on your OpenUtau version). Choose WAV or MP3 format, pick a location to save the file, and click Export. OpenUtau will generate an audio file of the song using the current voice bank and settings.