Bootcamp Audio Day

import numpy as np

from scikits.audiolab import Sndfile

from scikits.audiolab import Format

#################################################

######## CREATING A SOUND FILE INSTANCE #########

#################################################

# create Sndfile instance with our example audio file

f = Sndfile('viola.wav', 'r')

#################################################

######## EXTRACTING AUDIO FILE META-DATA ########

#################################################

# extract and print sample rate

fs = f.samplerate

print "sample rate: ",fs

# extract and print the number of channels

nc = f.channels

print "number of channels: ",nc

# extract the number of samples

nsamples = f.nframes

#################################################

######## READ AUDIO SAMPLES FROM THE FILE #######

#################################################

# we can read audio samples using the read_frame method

data = f.read_frames(nsamples)

#################################################

########## APPLY A DELAY TO THE SAMPLES #########

#################################################

# delay in samples

delay = fs/2

# volume of delayed sound

alpha = 0.75

# create an empty array for the output

out = np.zeros(data.size)

# for every sample in the array

for i in range(data.size):

    # if we are safe to apply the delay without negative indexing

    if (i >= delay):

        out[i] = data[i] + data[i-delay]*alpha

    else:

        out[i] = data[i] # hacky

#################################################

########## WRITING TO A NEW AUDIO FILE ##########

#################################################

# create a name for the new file

new_filename = 'delayed_audio.wav'

# Create a Sndfile instance for writing wav files @ 44100 Hz

format = Format('wav')

f = Sndfile(new_filename, 'w', format, 1, 44100)

# Write out the samples to an audio file

f.write_frames(out)

# close the audio file

f.close()

#################################################

#################################################

#################################################

import numpy as np

from scikits.audiolab import Sndfile

from scikits.audiolab import Format

#################################################

############ CREATE SOME RANDOM NOISE ###########

#################################################

# set our sampling frequency

fs = 44100

# create a numpy array that can hold 3 seconds of sound

noise = np.empty(3*fs)

# set each element to a random value (noise)

for i in range(noise.size):

    # generate random value and turn it down!

    noise[i] = np.random.random()*0.2

#################################################

########## WRITING NOISE TO AUDIO FILE ##########

#################################################

# create a name for the new file

new_filename = 'noise.wav'

# Create a Sndfile instance for writing wav files @ 44100 Hz

format = Format('wav')

f = Sndfile(new_filename, 'w', format, 1, fs)

# Write out the samples to the file

f.write_frames(noise)

# close the audio file

f.close()

import numpy as np

from scikits.audiolab import Sndfile

from scikits.audiolab import Format

#################################################

############## CREATE A SINE TONE ###############

#################################################

# set our sampling frequency

fs = 44100

# create a numpy array that can hold 3 seconds of sound

tone = np.zeros((3*fs,2))

# set frequency to 440Hz

freq = 440

# set volume to 0.3

amp = 0.3

# set values of each channel

for i in range(tone.shape[0]):

    # calculate phase value

    phaseVal = np.float(i)/np.float(fs)

    # generate tone and set volume for left and right

    tone[i][0] = np.sin(2*np.pi*freq*phaseVal)*amp

    tone[i][1] = np.sin(2*np.pi*freq*phaseVal)*amp

#################################################

########## WRITING TONES TO AUDIO FILE ##########

#################################################

# create a name for the new file

new_filename = 'tone.wav'

# Create a Sndfile instance for writing wav files @ 44100 Hz

format = Format('wav')

f = Sndfile(new_filename, 'w', format, 2, fs)

# Write out the samples to the file

f.write_frames(tone)

# close the audio file

f.close()