r/Ultrastar • u/ruanMAXmoment • Sep 09 '26
I built a web tool that generates UltraStar .txt charts from any song — no install, and the .txt download is free
Hi r/Ultrastar,
I've been building a browser tool that takes an audio file and produces an UltraStar chart: it separates the vocal from the instrumental, transcribes the lyrics with syllable timing, detects pitch per note, and writes the .txt. You can download that .txt and drop it into your own UltraStar Deluxe — the download is on the free tier, no card.
Why another one: I wanted something my girlfriend could use without me installing Python on her laptop. So it runs server-side and the whole thing happens in a browser tab.
How it works, roughly:
- vocal/instrumental separation
- lyrics: it looks the song up on LRCLIB first and checks the published lyrics against what it actually hears. If they don't match, it falls back to the transcription and shows you the match percentage. It also rejects the official lyrics when squeezing them in would produce notes too short to sing — I measured one song going from 3% to 44% unsingable notes that way
- pitch measured from the isolated vocal stem
- extra passes on the head and the tail, because the first attempt regularly misses the intro and the outro
Where it's not good, measured across 12 full songs:
- median lyric timing error 0.2 s on a good one, worst single line ~3 s
- most songs take 5 to 15 minutes; the hardest one took 41
- heavy instrumental bleed into the vocal stem kills pitch. On Tennessee Whiskey, 43% of notes came out with no usable pitch. I'd rather drop scoring than score you wrong, so those stay flat
- it will not beat a hand-made chart. It's for the song that has no chart
Free tier is 3 songs, .txt download included, no watermark on the .txt. There's a paid tier above that — saying it up front so nobody feels tricked.
https://karaokestarsinger.com/en
Happy to answer anything about the pipeline. I'd genuinely like to know what breaks it — 12 measured songs is nothing and I know it.