def specgram(x, NFFT=256, shift=128, Fs=1.0, drange=60,
ax=None, cmap=mplt.cm.gray_r, **kwargs):
from numpy import hanning
from libtfr import stft, fgrid, tgrid, dynamic_range
w = hanning(NFFT)
S = stft(x, w, shift)
F,ind = fgrid(Fs,NFFT,(0,Fs/2))
T = tgrid(x.size, Fs, shift)
S = nx.log10(dynamic_range(S, drange))
if ax is None: ax = mplt.gca()
ax.imshow(S, extent = (T[0],T[-1],F[0]-0.01,F[-1]), cmap=cmap, **kwargs)
return S
def specgram(x, NFFT=256, shift=128, Fs=1.0, drange=60,
ax=None, cmap=mplt.cm.gray_r, **kwargs):
from numpy import hanning
from libtfr import stft, fgrid, tgrid, dynamic_range
w = hanning(NFFT)
S = stft(x, w, shift)
F,ind = fgrid(Fs,NFFT,(0,Fs/2))
T = tgrid(x.size, Fs, shift)
S = nx.log10(dynamic_range(S, drange))
if ax is None: ax = mplt.gca()
ax.imshow(S, extent = (T[0],T[-1],F[0]-0.01,F[-1]), cmap=cmap, **kwargs)
return S
def load_signal(self, locator, dtype='d'):
"""
Loads the signal and computes the spectrogram.
dtype: the data type to store the output in. Use
single-precision floats if needed to reduce storage
requirements.
"""
from ewave import wavfile
from libtfr import fgrid, dynamic_range
from chirp.common.signal import spectrogram
from chirp.common.geom import elementlist, masker
from numpy import linspace, log10
fp = wavfile(locator)
signal = fp.read()
Fs = fp.sampling_rate
speccr = spectrogram(**self.options)
# adjust window size to get correct number of frequency bands
df = 1. * (self.options['freq_range'][1] - self.options['freq_range'][0]) / self.options['nfreq']
nfft = int(Fs / df)
spec, extent = speccr.linspect(signal, Fs / 1000, nfft=nfft)
F, ind = fgrid(Fs, nfft, self.options['freq_range']) # in Hz
spec = spec[ind, :]
T = linspace(extent[0], extent[1], spec.shape[1]) # in ms
# first convert the spectrogram to its final scale
if self.options['powscale'].startswith('log'):
# TODO calculate dynamic range of the signal for non 16 bit PCM?
spec = log10(dynamic_range(spec, 96))
# recenter spectrogram
if self.options['subtract_mean']:
spec -= spec.mean()
if self.options['mask'] != 'none':
eblfile = os.path.splitext(locator)[0] + elementlist.default_extension
if os.path.exists(eblfile):
mask = elementlist.read(eblfile)
spec = masker(boxmask=self.options['mask'] == 'box').cut(spec, mask, T, F / 1000.)
return spec.astype(dtype)
def dbspect(self, signal, Fs, dBrange=96, *args, **kwargs):
from numpy import log10
from libtfr import dynamic_range
S, extent = self.linspect(signal, Fs, *args, **kwargs)
return log10(dynamic_range(S, dBrange)), extent
