How to add silence in front of a wav file
I did a small script which allows you to prepend your signal with a silence in order to obtain the target duration in seconds. It uses the scipy function for reading of the wav file.
#!/usr/bin/env python
from __future__ import print_function, division
import scipy.io.wavfile as wavf
import numpy as np
from sys import argv
def pad_audio(data, fs, T):
# Calculate target number of samples
N_tar = int(fs * T)
# Calculate number of zero samples to append
shape = data.shape
# Create the target shape
N_pad = N_tar - shape[0]
print("Padding with %s seconds of silence" % str(N_pad/fs) )
shape = (N_pad,) + shape[1:]
# Stack only if there is something to append
if shape[0] > 0:
if len(shape) > 1:
return np.vstack((np.zeros(shape),
data))
else:
return np.hstack((np.zeros(shape),
data))
else:
return data
if __name__ == "__main__":
if len(argv) != 4:
print("Wrong arguments.")
print("Use: %s in.wav out.wav target_time_s" % argv[0])
else:
in_wav = argv[1]
out_wav = argv[2]
T = float(argv[3])
# Read the wav file
fs, in_data = wavf.read(in_wav)
# Prepend with zeros
out_data = pad_audio(in_data, fs, T)
# Save the output file
wavf.write(out_wav, fs, out_data)