mel_coefs method
Maps the power spectrum over the mel filters
to obtains a condensed spectrogram on the mel scale.
Implementation
static List<double> mel_coefs(List<double> power_spec, List<List<double>> filters){
var n_filt = filters.length;
var result = List<double>(n_filt);
for (var i = 0; i < n_filt; i++){
num sum = 0;
for (var j = 0; j < power_spec.length; j++){
sum += power_spec[j] * filters[i][j];
}
result[i] = sum;
}
return result.map((v) => safe_log(v)).toList();
}