Show HN: Nevertwenty a novel approach to chord synthesis (nevertwenty.com)

I play piano and I built this for myself recently.

Type a song, hit play, and the chords come at you on the beat. It's Rock Band for real instruments: the chord you need is the one under the playhead. I've almost got the entire music database here. I dare you to find a public track that isn't in here. Catalog is 6.8M songs / 103k artists.

Librosa beat detection. ONNX graph combined with my custom tuned BTC. Bass notes processed independently.

Median over 4536 cold runs: 2.15s to decode, 122x realtime. Download is the slow part at 8.4s median. Moving the audio is the bottleneck.

MP3 search is a fancy matching algorithm; if the song is on the internet it'll find it. It was hard to make this pipeline run fast! Should probably stream the audio instead. But I have to change the entire pipeline arch to allow it. Will continue trying.

The GTA6 of RockBand play along v1

"I can sight-read along to songs I've never heard now. That isn't a thing I could do a year ago, and I didn't get there by practicing." said the computer