# FFT blues

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### #1rouncer

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Posted 22 September 2008 - 11:55 PM

is there another algorythm apart from the fft for doing frequency work, because the fft packs phase information with the amplitude and it makes it useless to use.

but is there a way to get the average phase in each bin as well as the average amplitude separately? cause thats exactly what i want.

### #2Reedbeta

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Posted 22 September 2008 - 11:59 PM

The FFT should return an array of complex values, where the magnitude/phase of each complex number are the amplitude/phase of the associated wave.
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### #3rouncer

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Posted 23 September 2008 - 12:25 AM

amplitude/phase?!?

### #4Reedbeta

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Posted 23 September 2008 - 03:10 AM

The magnitudes of the complex numbers are the amplitudes of the waves, and the phases of the complex numbers are the phases of the waves.
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### #5rouncer

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Posted 23 September 2008 - 11:24 PM

but a number is only one number... it only has an amplitude! i dont understand - what does phase mean? the differences between the adjacent bins? that doesnt make sense to me

### #6Reedbeta

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Posted 24 September 2008 - 12:10 AM

No, the output of the FFT should be a complex number for each bin. As such it has two components, real and imaginary. If you think of this as a 2D vector, its length is the amplitude and its angle from the x-axis is the phase.
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### #7rouncer

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Posted 27 September 2008 - 05:13 AM

oh- thankyou. now i understand.

im coding a phase vocoder by the way, and its going pretty well.

im doing the filter bin approach, but now i might try the fft.

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