[Piotr Majdak <piotr@ma...>]

Hi *,

There is a bug calculating amplitude spectrum function in the menu 
View/Plot Spectrum (FFT): Analysing a simple harmonic I see some spikes 
in the amplitude spectrum, where they shouldn't be. They get bigger 
extending the resolution of the FFT or using more complicated analysis 
windows.

To reproduce this bug:
- Create a track with a single sine tone: Generate/Tone, Frequency: 1000, OK
- Select some seconds of the track
- Go to View/Plot Spectrum
- Change settings to:
   Spectrum           | 16384
   Rectangular window | Linear Freq.

You should see this: http://iem.at/~majdak/temp/spect16384.jpg

If you change the analysis window to hanning, the situation gets even 
worse (in terms of SNR). Look at that: 
http://iem.at/~majdak/temp/spect16384hanning.jpg
Decreasing the number of bins to 2048, you still can see the distortions 
in spectrum: http://iem.at/~majdak/temp/spect2048hanning.jpg

Can anyone confirm this?

It looks like sloppy cast conversions in the windowing/FFT algorithms 
(do you _really_ use float numbers everywhere?)



Piotr Majdak

PS: OS: Win2000 SP5, Audacity 1.2.2