Ejemplo n.º 1
0
def ssc(signal,samplerate=16000,winlen=0.025,winstep=0.01,
          nfilt=26,nfft=512,lowfreq=0,highfreq=None,preemph=0.97):
    """Compute Spectral Subband Centroid features from an audio signal.
    :param signal: the audio signal from which to compute features. Should be an N*1 array
    :param samplerate: the samplerate of the signal we are working with.
    :param winlen: the length of the analysis window in seconds. Default is 0.025s (25 milliseconds)    
    :param winstep: the step between successive windows in seconds. Default is 0.01s (10 milliseconds)    
    :param nfilt: the number of filters in the filterbank, default 26.
    :param nfft: the FFT size. Default is 512.
    :param lowfreq: lowest band edge of mel filters. In Hz, default is 0.
    :param highfreq: highest band edge of mel filters. In Hz, default is samplerate/2
    :param preemph: apply preemphasis filter with preemph as coefficient. 0 is no filter. Default is 0.97. 
    :returns: A numpy array of size (NUMFRAMES by nfilt) containing features. Each row holds 1 feature vector. 
    """          
    highfreq= highfreq or samplerate/2
    signal = __sigproc.preemphasis(signal,preemph)
    frames = __sigproc.framesig(signal, winlen*samplerate, winstep*samplerate)
    pspec = __sigproc.powspec(frames,nfft)
    pspec = numpy.where(pspec == 0,numpy.finfo(float).eps,pspec) # if things are all zeros we get problems
    
    fb = get_filterbanks(nfilt,nfft,samplerate,lowfreq,highfreq)
    feat = numpy.dot(pspec,fb.T) # compute the filterbank energies
    R = numpy.tile(numpy.linspace(1,samplerate/2,numpy.size(pspec,1)),(numpy.size(pspec,0),1))
    
    return numpy.dot(pspec*R,fb.T) / feat
Ejemplo n.º 2
0
def fbank(signal,samplerate=16000,winlen=0.025,winstep=0.01,
          nfilt=26,nfft=512,lowfreq=0,highfreq=None,preemph=0.97):
    """Compute Mel-filterbank energy features from an audio signal.
    :param signal: the audio signal from which to compute features. Should be an N*1 array
    :param samplerate: the samplerate of the signal we are working with.
    :param winlen: the length of the analysis window in seconds. Default is 0.025s (25 milliseconds)    
    :param winstep: the step between successive windows in seconds. Default is 0.01s (10 milliseconds)    
    :param nfilt: the number of filters in the filterbank, default 26.
    :param nfft: the FFT size. Default is 512.
    :param lowfreq: lowest band edge of mel filters. In Hz, default is 0.
    :param highfreq: highest band edge of mel filters. In Hz, default is samplerate/2
    :param preemph: apply preemphasis filter with preemph as coefficient. 0 is no filter. Default is 0.97. 
    :returns: 2 values. The first is a numpy array of size (NUMFRAMES by nfilt) containing features. Each row holds 1 feature vector. The
        second return value is the energy in each frame (total energy, unwindowed)
    """          
    highfreq= highfreq or samplerate/2
    signal = __sigproc.preemphasis(signal,preemph)
    frames = __sigproc.framesig(signal, winlen*samplerate, winstep*samplerate)
    pspec = __sigproc.powspec(frames,nfft)
    energy = numpy.sum(pspec,1) # this stores the total energy in each frame
    energy = numpy.where(energy == 0,numpy.finfo(float).eps,energy) # if energy is zero, we get problems with log
        
    fb = get_filterbanks(nfilt,nfft,samplerate,lowfreq,highfreq)
    feat = numpy.dot(pspec,fb.T) # compute the filterbank energies
    feat = numpy.where(feat == 0,numpy.finfo(float).eps,feat) # if feat is zero, we get problems with log
    
    return feat,energy