Adds a simple spectrogram to your wavesurfer.js instances.
wavesurfer - required - a WaveSurfer instance.container - required - the element in which to place the spectrogram, or a CSS selector to find it.fftSamples - number of FFT samples (512 by default). Number of spectral lines and default height of the spectrogram will be a half of this parameter.height - height of the spectrogram view in CSS pixels (fftSamples/2 by default).frequencyMin - Min frequency to scale spectrogram(0 by default).frequencyMax - Max frequency to scale spectrogram(12000 by default). Set this to samplerate/2 to draw whole range of spectrogram.splitChannels - Render with separate spectrograms for the channels of the audiofrequenciesDataUrl - URL to load spectral data from.labels - Whether or not to display frequency labels.colorMap - Specifies the colormap to be used when rendering the spectrogram.