[gstreamer-bugs] [Bug 492098] [GstFFT] Broken scaling

[GStreamer (bugzilla.gnome.org)]

If you have any questions why you received this email, please see the text at
the end of this email. Replies to this email are NOT read, please see the text
at the end of this email. You can add comments to this bug at:
  http://bugzilla.gnome.org/show_bug.cgi?id=492098

  GStreamer | gst-plugins-base | Ver: HEAD CVS




------- Comment #1 from Sebastian Dröge  2007-11-05 10:02 UTC -------
Ok, after some investigation it seems that the following might be a good
solution:
a) Document that behaviour of _fft() and _inverse_fft(), i.e. for floating
point that iFFT(FFT(x)) = x*nfft and for fixed point iFFT(FFT(X)) = x/nfft and
that one has to apply the required scaling to get iFFT(FFT(x)) = x. For fixed
point this will be rather hard though... think of overflows, etc :)

b) Fix the magnitude calculation or what I would currently prefer, drop the
magnitude and phase calculation functions. Dropping them seems to make sense as
it's a rather special use case that requires them and even the spectrum element
has it's own implementation for them as it has special needs. When dropping
them it might make sense to add an example on how to calculate the magnitude in
the docs though...

What do you think?


-- 
See http://bugzilla.gnome.org/page.cgi?id=email.html for more info about why you received
this email, why you can't respond via email, how to stop receiving
emails (or reduce the number you receive), and how to contact someone
if you are having problems with the system.

You can add comments to this bug at http://bugzilla.gnome.org/show_bug.cgi?id=492098.