 Then computing an amplification factor, for the decoder to use to re-expand each sub-band to the proper frequency range.Layer II can also optionally use intensity stereo coding, a form of joint stereo.This means that the frequencies above 6 kHz of both channels are combined/down-mixed into one single (mono) channel, but the "side channel" information on the relative intensity (volume, amplitude) of each channel is preserved and encoded into the bitstream separately.