util/echorec.py

   1 #!/usr/bin/env python3
   2 """A wrapper module for echorec."""
   3
   4 import subprocess as sp
   5 import numpy as np
   6
   7
   8 def echorec_buffer(play_buffer, count=1, args=None, exe=None):
   9     """Invokes echorec. It passes play_buffer to stdin of rechorec and has to
  10     be a byte sequence. The output from stdout is captured and returned.
  11     Additional options are to be passed by means of subprocess.run(). The path
  12     to the echorec executeable can be passed via exe."""
  13
  14     exe = exe or 'echorec'
  15     args = args or []
  16     args += ['--count=%d' % count]
  17
  18     ret = sp.run([exe] + args, stdout=sp.PIPE, stderr=sp.PIPE, input=play_buffer)
  19     return ret.stdout
  20
  21
  22 def echorec_lambda(play_signal, starttime, endtime, rate, *pargs, **kwargs):
  23     """Invokes echorec by means of echorec_buffer(). The play buffer is formed
  24     by the function play_signal that is evaluated on the interval [startime,
  25     endtime) with the given sample rate. It is assumed that play_signal
  26     produces values in the interval [-1, 1]."""
  27
  28     amp = (1 << 15) - 1
  29     tsamples = np.arange(starttime, endtime, 1.0/rate)
  30
  31     channel = [amp * play_signal(t) for t in tsamples]
  32     play_buffer = np.array([channel, channel], dtype=np.int16).T.flatten()
  33
  34     args = ['--rate=%d' % rate]
  35
  36     return echorec_buffer(play_buffer.tobytes(), args=args, *pargs, **kwargs)