model card

README.md

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+---
+license: mit
+tags:
+  - beat-tracking
+  - downbeat-tracking
+  - core-ai
+  - aimodel
+  - apple-silicon
+  - macos
+library_name: swift-music-transcriber
+---
+
+# Beat This! for Core AI (`.aimodel`)
+
+Apple Core AI conversion of **Beat This!**, the beat and downbeat tracker by Francesco Foscarin,
+Jan Schlüter and Gerhard Widmer (CPJKU) — *Beat This! Accurate Beat Tracking Without DBN
+Postprocessing*, ISMIR 2024 — checkpoint `final0` from
+[github.com/CPJKU/beat_this](https://github.com/CPJKU/beat_this) (MIT, 20M parameters).
+
+`scribe-beat-this-float32.aimodel` (79 MB) takes a log-mel spectrogram `[1, T, 128]` at 50 fps
+(22.05 kHz audio) and returns framewise beat and downbeat logits. The front end, the 1500-frame
+chunking with 6-frame borders, the minimal peak picker and the tempo/metre fit live in
+[swift-music-transcriber](https://github.com/arraypress/swift-music-transcriber), which uses this
+as the beat tracker for its MIDI grids — the same tracker MuScriptor's own pipeline uses.
+
+## Faithfulness
+
+One method (`Attention.forward`) was re-authored for the Core AI compiler, which rejected the
+original einops reshape on a dynamic sequence length; RoPE became a constant matrix. The export
+script asserts the re-authored module matches the original before exporting (max |diff| below
+1e-3 on random input, 0 in practice). End to end, beats land within one frame of upstream on the
+reference clips; resampling (julius versus soxr) is the only step not shared with upstream.
+
+## Use
+
+```sh
+hf download arraypress/scribe-beat-this --local-dir models
+scribe model install models/scribe-beat-this-float32.aimodel   # picked up automatically as the tracker
+```
+
+Reproduce with `uv run Tools/export_beat_this.py` in the library repo. macOS 27, Apple silicon.
+
+## Licence
+
+MIT, as upstream. Please cite the ISMIR 2024 paper if you use it.