midmid/beat_tracker.py

"""Beat and downbeat tracking via beat_this (CPJKU)."""

from dataclasses import dataclass

import numpy as np


@dataclass
class BeatData:
    beats: np.ndarray
    downbeats: np.ndarray
    beat_numbers: np.ndarray


def track_beats(audio_path: str, device: str = "cuda") -> BeatData:
    """Run beat and downbeat tracking on an audio file."""
    from beat_this.inference import File2Beats
    processor = File2Beats(checkpoint_path="final0", device=device)
    beats, downbeats = processor(audio_path)

    beat_numbers = _assign_beat_numbers(beats, downbeats)

    return BeatData(
        beats=np.asarray(beats),
        downbeats=np.asarray(downbeats),
        beat_numbers=beat_numbers,
    )


def _assign_beat_numbers(beats: np.ndarray, downbeats: np.ndarray) -> np.ndarray:
    beats = np.asarray(beats)
    downbeats_set = set(np.round(downbeats, 6))
    numbers = np.zeros(len(beats), dtype=int)
    beat_num = 1

    for i, t in enumerate(beats):
        if round(float(t), 6) in downbeats_set:
            beat_num = 1
        numbers[i] = beat_num
        beat_num += 1

    return numbers