82 lines
2.3 KiB
Python
82 lines
2.3 KiB
Python
# -*- coding: utf-8 -*-
|
|
"""!
|
|
Author: J.A. de Jong - ASCEE
|
|
|
|
Description:
|
|
Reverberation time estimation tool using least squares
|
|
"""
|
|
from .lasp_common import getTime
|
|
import numpy as np
|
|
|
|
|
|
class ReverbTime:
|
|
"""
|
|
Tool to estimate the reverberation time
|
|
"""
|
|
def __init__(self, fs, level):
|
|
"""
|
|
Initialize Reverberation time computer.
|
|
|
|
Args:
|
|
fs: Sampling frequency [Hz]
|
|
level: (Optionally weighted) level values as a function of time, in
|
|
dB.
|
|
|
|
"""
|
|
assert level.ndim == 1, 'Invalid number of dimensions in level'
|
|
self._level = level
|
|
# Number of time samples
|
|
self._N = self._level.shape[0]
|
|
self._t = getTime(fs, self._N, 0)
|
|
|
|
def compute(self, tstart, tstop):
|
|
"""
|
|
Compute the reverberation time using a least-squares solver
|
|
|
|
Args:
|
|
tstart: Start time of reverberation interval
|
|
stop: Stop time of reverberation interval
|
|
|
|
Returns:
|
|
dictionary with result values, contains:
|
|
- istart: start index of reberberation interval
|
|
- istop: stop index of reverb. interval
|
|
- T60: Reverberation time
|
|
- const: Constant value
|
|
- derivative: rate of change of the level in dB/s.
|
|
"""
|
|
|
|
# Find start and stop indices. Coerce if they are outside
|
|
# of the valid domain
|
|
istart = np.where(self._t >= tstart)[0][0]
|
|
istop = np.where(self._t >= tstop)[0]
|
|
|
|
if istop.shape[0] == 0:
|
|
istop = self._level.shape[0]
|
|
else:
|
|
istop = istop[0]
|
|
|
|
points = self._level[istart:istop]
|
|
x = self._t[istart:istop][:, np.newaxis]
|
|
|
|
# Solve the least-squares problem, by creating a matrix of
|
|
A = np.hstack([x, np.ones((x.shape))])
|
|
|
|
# derivative is dB/s of increase/decrease
|
|
sol, residuals, rank, s = np.linalg.lstsq(A, points)
|
|
|
|
# Derivative of the decay in dB/s
|
|
derivative = sol[0]
|
|
|
|
# Start level in dB
|
|
const = sol[1]
|
|
|
|
# Time to reach a decay of 60 dB (reverb. time)
|
|
T60 = -60./derivative
|
|
|
|
return {'istart': istart,
|
|
'istop': istop,
|
|
'const': const,
|
|
'derivative': derivative,
|
|
'T60': T60}
|