I am developing a chord recognition program using neural networks.I need to normalize the spectrogram or my pitch class profile to provide inputs for the neural network. The pitch class profile classifies the frequency into 12 class semitones (From note A to G).
The problem here is it produces really high values and low values: they can be on the order of ten, one million, or even a trillion. Meanwhile, the input values for the neural network should be between 1 and -1.
What is a normalization formula that I can use to transform the values to be between 1 and -1?