ref: 3bf80b9872d63282409dfc876e3dc29140c134ef
dir: /python/demos/demo_spectrogram.py/
#! /usr/bin/env python
import sys
from aubio import pvoc, source
from numpy import array, arange, zeros, shape, log10, vstack
from pylab import imshow, show, cm, axis, ylabel, xlabel, xticks, yticks
def get_spectrogram(filename, samplerate = 0):
win_s = 512 # fft window size
hop_s = win_s / 2 # hop size
fft_s = win_s / 2 + 1 # spectrum bins
a = source(filename, samplerate, hop_s) # source file
if samplerate == 0: samplerate = a.samplerate
pv = pvoc(win_s, hop_s) # phase vocoder
specgram = zeros([0, fft_s], dtype='float32') # numpy array to store spectrogram
# analysis
while True:
samples, read = a() # read file
specgram = vstack((specgram,pv(samples).norm)) # store new norm vector
if read < a.hop_size: break
# plotting
imshow(log10(specgram.T + .001), origin = 'bottom', aspect = 'auto', cmap=cm.gray_r)
axis([0, len(specgram), 0, len(specgram[0])])
# show axes in Hz and seconds
time_step = hop_s / float(samplerate)
total_time = len(specgram) * time_step
print "total time: %0.2fs" % total_time,
print ", samplerate: %.2fkHz" % (samplerate / 1000.)
n_xticks = 10
n_yticks = 10
def get_rounded_ticks( top_pos, step, n_ticks ):
top_label = top_pos * step
# get the first label
ticks_first_label = top_pos * step / n_ticks
# round to the closest .1
ticks_first_label = round ( ticks_first_label * 10. ) / 10.
# compute all labels from the first rounded one
ticks_labels = [ ticks_first_label * n for n in range(n_ticks) ] + [ top_label ]
# get the corresponding positions
ticks_positions = [ ticks_labels[n] / step for n in range(n_ticks) ] + [ top_pos ]
# convert to string
ticks_labels = [ "%.1f" % x for x in ticks_labels ]
# return position, label tuple to use with x/yticks
return ticks_positions, ticks_labels
# apply to the axis
xticks( *get_rounded_ticks ( len(specgram), time_step, n_xticks ) )
yticks( *get_rounded_ticks ( len(specgram[0]), (samplerate / 2. / 1000.) / len(specgram[0]), n_yticks ) )
ylabel('Frequency (kHz)')
xlabel('Time (s)')
if __name__ == '__main__':
if len(sys.argv) < 2:
print "Usage: %s <filename>" % sys.argv[0]
else:
for soundfile in sys.argv[1:]:
get_spectrogram(soundfile)
# display graph
show()