In [1]:
%matplotlib inline
import numpy, scipy, matplotlib.pyplot as plt, IPython.display as ipd
import librosa, librosa.display
import stanford_mir; stanford_mir.init()
from ipywidgets import interact
Beat Tracking¶
librosa.beat.beat_track¶
Load an audio file:
In [2]:
x, sr = librosa.load('audio/58bpm.wav')
ipd.Audio(x, rate=sr)
Out[2]:
Your browser does not support the audio element.
Use librosa.beat.beat_track to estimate the beat locations and the global tempo:
In [3]:
tempo, beat_times = librosa.beat.beat_track(x, sr=sr, start_bpm=60, units='time')
print(tempo)
print(beat_times)
58.72691761363637
[1.06811791 2.11301587 3.11147392 4.17959184 5.20126984 6.2461678
7.2678458 ]
Plot the beat locations over the waveform:
In [4]:
plt.figure(figsize=(14, 5))
librosa.display.waveplot(x, alpha=0.6)
plt.vlines(beat_times, -1, 1, color='r')
plt.ylim(-1, 1)
Out[4]:
(-1, 1)
Plot a histogram of the intervals between adjacent beats:
In [5]:
beat_times_diff = numpy.diff(beat_times)
plt.figure(figsize=(14, 5))
plt.hist(beat_times_diff, bins=50, range=(0,4))
plt.xlabel('Beat Length (seconds)')
plt.ylabel('Count')
Out[5]:
Text(0,0.5,'Count')
Visually, it's difficult to tell how correct the estimated beats are. Let's listen to a click track:
In [6]:
clicks = librosa.clicks(beat_times, sr=sr, length=len(x))
ipd.Audio(x + clicks, rate=sr)
Out[6]:
Your browser does not support the audio element.
Use the IPython interactive widgets to observe how the output changes as we vary the parameters of the beat tracker.
In [7]:
def f(start_bpm, tightness_exp):
return librosa.beat.beat_track(x, sr=sr, start_bpm=start_bpm, tightness=10**tightness_exp, units='time')
interact(f, start_bpm=60, tightness_exp=2)
Out[7]:
<function __main__.f>
Questions¶
Try other audio files:
In [8]:
ls audio
125_bounce.wav jangle_pop.mp3
58bpm.wav latin_groove.mp3
README.md oboe_c6.wav
brahms_hungarian_dance_5.mp3 prelude_cmaj.wav
busta_rhymes_hits_for_days.mp3 simple_loop.wav
c_strum.wav simple_piano.wav
clarinet_c6.wav sir_duke_piano_fast.mp3
classic_rock_beat.wav sir_duke_piano_slow.mp3
conga_groove.wav sir_duke_trumpet_fast.mp3
drum_samples/ sir_duke_trumpet_slow.mp3
funk_groove.mp3 tone_440.wav