beat_tracker.py

'''
CREATED:2013-02-11 18:37:30 by Brian McFee <brm2132@columbia.edu>

Track beat events in an audio file

Usage:   ./beat_tracker.py [-h] input_file.mp3    output_beats.csv
'''
from __future__ import print_function

import argparse
import sys
import librosa

def run_beat_tracker(audio_filename):
    # Run the beat tracker
    beats = beat_track(audio_filename)

    # print(audio_filename)
    return beats


def beat_track(input_file):
    '''Beat tracking function

    :parameters:
      - input_file : str
          Path to input audio file (wav, mp3, m4a, flac, etc.)

      - output_file : str
          Path to save beat event timestamps as a CSV file
    '''

    print('Loading ', input_file)
    y, sr = librosa.load(input_file, sr=22050)

    # Use a default hop size of 512 samples @ 22KHz ~= 23ms
    hop_length = 512

    # This is the window length used by default in stft
    print('Tracking beats')
    tempo, beats = librosa.beat.beat_track(y=y, sr=sr, hop_length=hop_length)

    print('Estimated tempo: {:0.2f} beats per minute'.format(tempo))

    # save output
    # 'beats' will contain the frame numbers of beat events.
    beat_times = librosa.frames_to_time(beats, sr=sr, hop_length=hop_length)

    return beat_times


def process_arguments(args):
    '''Argparse function to get the program parameters'''

    parser = argparse.ArgumentParser(description='Beat tracking example')

    parser.add_argument('input_file',
                        action='store',
                        help='path to the input file (wav, mp3, etc)')

    parser.add_argument('output_file',
                        action='store',
                        help='path to the output file (csv of beat times)')

    return vars(parser.parse_args(args))