def to_envelopes(path,num_bands,freq_lims,window_length=None,time_step=None):
sr, proc = preproc(path,alpha=0.97)
proc = proc/sqrt(mean(proc**2))*0.03;
bandLo = [ freq_lims[0]*exp(log(freq_lims[1]/freq_lims[0])/num_bands)**x for x in range(num_bands)]
bandHi = [ freq_lims[0]*exp(log(freq_lims[1]/freq_lims[0])/num_bands)**(x+1) for x in range(num_bands)]
if window_length is not None and time_step is not None:
use_windows = True
nperseg = int(window_length*sr)
noverlap = int(time_step*sr)
window = hanning(nperseg+2)[1:nperseg+1]
step = nperseg - noverlap
indices = arange(0, proc.shape[-1]-nperseg+1, step)
num_frames = len(indices)
envelopes = zeros((num_bands,num_frames))
else:
use_windows=False
sr_env = 120
t = len(proc)/sr
numsamp = ceil(t * sr_env)
envelopes = []
for i in range(num_bands):
b, a = butter(2,(bandLo[i]/(sr/2),bandHi[i]/(sr/2)), btype = 'bandpass')
env = filtfilt(b,a,proc)
env = abs(hilbert(env))
if use_windows:
window_sums = []
for k,ind in enumerate(indices):
seg = env[ind:ind+nperseg] * window
window_sums.append(sum(seg))
envelopes[i,:] = window_sums
else:
env = resample(env,numsamp)
envelopes.append(env)
return array(envelopes).T
def to_mfcc(filename, freq_lims,num_coeffs,win_len,time_step,num_filters = 26, use_power = False):
#HTK style, interpreted from RastaMat
sr, proc = preproc(filename,alpha=0.97)
minHz = freq_lims[0]
maxHz = freq_lims[1]
L = 22
n = arange(num_filters)
lift = 1+ (L/2)*sin(pi*n/L)
lift = diag(lift)
nperseg = int(win_len*sr)
noverlap = int(time_step*sr)
window = hanning(nperseg+2)[1:nperseg+1]
filterbank = filter_bank(nperseg,num_filters,minHz,maxHz,sr)
step = nperseg - noverlap
indices = arange(0, proc.shape[-1]-nperseg+1, step)
num_frames = len(indices)
mfccs = zeros((num_frames,num_coeffs))
for k,ind in enumerate(indices):
seg = proc[ind:ind+nperseg] * window
complexSpectrum = fft(seg)
powerSpectrum = abs(complexSpectrum[:int(nperseg/2)]) ** 2
filteredSpectrum = dot(sqrt(powerSpectrum), filterbank)**2
dctSpectrum = dct_spectrum(filteredSpectrum)
dctSpectrum = dot(dctSpectrum , lift)
if not use_power:
dctSpectrum = dctSpectrum[1:]
mfccs[k,:] = dctSpectrum[:num_coeffs]
return mfccs
def to_gammatone_envelopes(path,num_bands,freq_lims,window_length=None,time_step=None):
sr, proc = preproc(path)
cfs = make_erb_cfs(freq_lims,num_bands)
filterOrder = 4 # filter order
gL = 2**nextpow2(0.128*sr) # gammatone filter length at least 128 ms
b = 1.019*24.7*(4.37*cfs/1000+1) # rate of decay or bandwidth
tpt=(2*pi)/sr
gain=((1.019*b*tpt)**filterOrder)/6 # based on integral of impulse
tmp_t = arange(gL)/sr
if window_length is not None and time_step is not None:
use_windows = True
nperseg = int(window_length*sr)
noverlap = int(time_step*sr)
window = hanning(nperseg+2)[1:nperseg+1]
step = nperseg - noverlap
indices = arange(0, proc.shape[-1]-nperseg+1, step)
num_frames = len(indices)
envelopes = zeros((num_frames,num_bands))
else:
use_windows=False
sr_env = 120
t = len(proc)/sr
numsamp = t * sr_env * 2
envelopes = []
# calculate impulse response
for i in range(num_bands):
gt = gain[i]*sr**3*tmp_t**(filterOrder-1)*exp(-2*pi*b[i]*tmp_t)*cos(2*pi*cfs[i]*tmp_t)
bm = fftfilt(gt,proc)
env = abs(hilbert(bm))
if use_windows:
for k,ind in enumerate(indices):
seg = env[ind:ind+nperseg] * window
envelopes[k,i] = sum(seg)
else:
env = resample(env,numsamp)
envelopes.append(env)
return array(envelopes).T
def to_melbank(filename, freq_lims,win_len,time_step,num_filters = 26):
sr, proc = preproc(filename,alpha=0.97)
minHz = freq_lims[0]
maxHz = freq_lims[1]
nperseg = int(win_len*sr)
noverlap = int(time_step*sr)
window = hanning(nperseg+2)[1:nperseg+1]
filterbank = filter_bank(nperseg,num_filters,minHz,maxHz,sr)
step = nperseg - noverlap
indices = arange(0, proc.shape[-1]-nperseg+1, step)
num_frames = len(indices)
melbank = zeros((num_frames,num_filters))
for k,ind in enumerate(indices):
seg = proc[ind:ind+nperseg] * window
complexSpectrum = fft(seg)
powerSpectrum = abs(complexSpectrum[:int(nperseg/2)]) ** 2
melbank[k,:] = dot(sqrt(powerSpectrum), filterbank)**2
return melbank
