Command-line tool in Python that synchronizes a funk beat into a song (must be .wav format)

sync.py

from math import floor
from pathlib import Path
import sys
import os
import numpy as np
import librosa
import librosa.beat
import soundfile as sf

def synchronize(file_path_1, file_path_2, output_path="mashup.wav", second_iteration=False):
    """
    Synchronizes the audio in `file_path_2` to the tempo of `file_path_1` and also does phase alignment. Saves the result to `output_path`.
    """
    file_path_1 = Path(file_path_1)
    file_path_2 = Path(file_path_2)
    print(f"Synchronizing {file_path_2} into {file_path_1}")

    # Load the audio file
    audio_1, sr_1 = librosa.load(file_path_1)
    audio_2, sr_2 = librosa.load(file_path_2)

    # Estimate the tempo (BPM) of the audio file
    onset_env_1 = librosa.onset.onset_strength(y=audio_1, sr=sr_1)
    bpm_1 = librosa.beat.tempo(onset_envelope=onset_env_1, sr=sr_1)[0]
    print(f"{file_path_1} has {bpm_1} BPM")
    onset_env_2 = librosa.onset.onset_strength(y=audio_2, sr=sr_2)
    bpm_2 = librosa.beat.tempo(onset_envelope=onset_env_2, sr=sr_2)[0]
    print(f"{file_path_2} has {bpm_2} BPM")

    stretch_factor = bpm_1/bpm_2
    stretched_audio_2 = librosa.effects.time_stretch(audio_2, rate=stretch_factor)
    onset_env_2 = librosa.onset.onset_strength(y=stretched_audio_2, sr=sr_2)

    beat_index_1 = np.argmax(onset_env_1)
    beat_index_2 = np.argmax(onset_env_2)
    time_shift_samples = beat_index_1 - beat_index_2

    aligned_audio_2 = np.roll(stretched_audio_2, -time_shift_samples)

    if len(audio_1) > len(aligned_audio_2):
        mashup = 0.5 * audio_1[:len(aligned_audio_2)] + 0.5 * aligned_audio_2
    else:
        mashup = 0.5 * audio_1 + 0.5 * aligned_audio_2[:len(audio_1)]
    if not second_iteration:
        sf.write("temp.wav", aligned_audio_2, sr_2)
        synchronize(file_path_1, "temp.wav", output_path, second_iteration=True)
    else:
        os.remove("temp.wav")
        print(f"Saving mashup to {output_path}")
        sf.write(output_path, mashup, sr_1)
    


if len(sys.argv) != 4:
    print(f"Usage: python {sys.argv[0]} TARGET_FILE BEAT_FILE OUTPUT_FILE")
    exit(1)

song = sys.argv[1]
beat = sys.argv[2]
output = sys.argv[3]

synchronize(song, beat, output)