The steps normally taken by a ``phase vocoder'' to measure instantaneous amplitude and frequency for each bin of the current STFT frame are as follows (extending the four steps of the previous section):
5. Convert each FFT bin
from rectangular to
polar form to get the magnitude and phase in each FFT bin, and
differentiate the unwrapped phase to obtain instantaneous frequency:
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(1) |
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(2) |
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(3) |