Mark Borgerding

Yes, it is to prevent overflow.

The fixed point FFT and IFFT both scale downwards to make overflow impossible.

btw .. you can't just "zero some coefficients in the FFT transform" without bad side...

Yes. It certainly is possible. A search for "fft 2d convolution" brings up several...

I don't have the time right now to dig into your code. My first suspicion is the...

I cannot think of any real limitations of KISSFFT in this regard, except perhaps...

BGZeroMeanEstimIn: fixed estimInit

Edit: This was a bug in vorbis-tools (oggdec). See my "On closer examination" post...