I am trying my hands at Audio Processing in python with this Beat Detection algorithm. I have implemented the first (non-optimized version) from the aforementioned article. While it prints some results, I have no way to detect whether it works with some accuracy or not as I do not know how to play sound with it.
Currently, I am using Popen
to asynchronously start my media player with the song before going into the computation loop, but I am not sure if this strategy works and is giving synchronous results.
#!/usr/bin/python
import scipy.io.wavfile, numpy, sys, subprocess
# Some abstractions for computation
def sumsquared(arr):
sum = 0
for i in arr:
sum = sum + (i[0] * i[0]) + (i[1] * i[1])
return sum
if sys.argv.__len__() < 2:
print 'USAGE: wavdsp <wavfile>'
sys.exit(1)
numpy.set_printoptions(threshold='nan')
rate, data = scipy.io.wavfile.read(sys.argv[1])
# Beat detection algorithm begin
# the algorithm has been implemented as per GameDev Article
# Initialisation
data_len = data.__len__()
idx = 0
hist_last = 44032
instant_energy = 0
local_energy = 0
le_multi = 0.023219955 # Local energy multiplier ~ 1024/44100
# Play the song
p = subprocess.Popen(['audacious', sys.argv[1]])
while idx < data_len - 48000:
dat = data[idx:idx+1024]
history = data[idx:hist_last]
instant_energy = sumsquared(dat)
local_energy = le_multi * sumsquared(history)
print instant_energy, local_energy
if instant_energy > (local_energy * 1.3):
print 'Beat'
idx = idx + 1024
hist_last = hist_last + 1024 # Right shift history buffer
p.terminate()
What modification/additions can I make to the script in order to get audio output and the algorithm (console) output in a time synchronised manner? i.e When console outputs result for a particular frame, that frame must be playing on the speakers.
Working beat detection code (NumPy / PyAudio)
If you are using NumPy this code might help. It assumes the signal (read with PyAudio) is 16-bit wide Int. If that is not the case change or remove the signal.astype() and adjust the normalization-divider (max int16 here).
The PyAudio examples for wav read or mic record will give you the needed signal data. Create a NumPy array efficiently with
frombuffer()