How to calculate FFT using NAudio in realtime (ASIO out)

Question

I am programming clone of guitar (violin) Hero as a final project for this school year.

The idea is to take input from my electric violin, analyse it via FFT, do so

Answer 1

The problem was as I thought in conversion between data about samples from Asio (4 bytes in a row in buf array) to float for fft. BitConvertor should do the trick but it somehow makes fft output NaN in my case. So I tried this conversion instead.

for (int i = 0; i < e.SamplesPerBuffer * 4; i=i+4)
{
    float sample = Convert.ToSingle(buf[i] + buf[i+1] + buf[i+2] + buf[i+3]);
    sampleAggregator.Add(sample);
}

And it works very well. Even with 192 000 sample rate.